Patent Application
20090033403
The present invention relates to a level shifter, and in particular, to a level shifter in which a leakage current characteristic is improved when a first power source is controlled.
A level shifter is used in a system LSI including two or more power sources; for example, as shown in
To deal with the requirement, it has been proposed, as disclosed in, for example, U.S. Pat. No. 5,669,684, that a pull-down circuit is disposed on an output side of a level shifter to fix a p-MOS cross-coupled latch state to thereby prevent the leakage current.
The technique disclosed by the article uses, as can be seen from
However, in the technique disclosed by the U.S. patent, when the first power source turns off and a level shift input signal is indefinite, the pull-down n-MOS is connected to the high state side of a p-MOS cross-coupled latch of the level shifter and hence the gate terminal voltage of the n-MOS possibly exceeds a threshold value of the n-MOS.
In this case, since a conduction path appears between the second power source and a GND power source, there occurs a problem that short circuit current flows.
Additionally, in a case in which the first power source turns on and an input signal is inverted in a hold state, there exits a problem that the short circuit current flows until the power source level increases to a predetermined level and the level shift output is completely changed.
Moreover, the additional n-MOS has a function to enhance the function of the level converter circuit to hold the state of the p-MOS cross-coupled latch. Therefore, the level shift delay increases, particularly, when the potential difference between the first and second power sources becomes large; the level shift margin is lost and hence the level shift cannot be conducted. That is, there also occurs a problem that even the input signal changes, the desired output cannot change.
It is a first object of the present invention to provide a level shifter in which occurrence of short circuit current can be suppressed even when the first power source is controlled and the increase in delay can also be suppressed in the level shift.
In accordance with the invention of a level shifter of a first embodiment, there is provided a level shifter for converting a signal level of a first logic circuit to which a first power source is supplied into a signal level of a second logic circuit to which a second power source is supplied, characterized by including a switching circuit between a GND power source terminal (ground power source terminal) of a level shift core circuit and a GND power source (ground power source), the switching circuit being controlled by a third logic circuit which generates control signals in accordance with control of the first power source, and a pull-up and/or pull-down circuit at an output of the level shift core circuit, the pull-up and/or pull-down circuit being controlled by the third logic circuit.
In accordance with the invention of a level shifter of a second embodiment, there is provided a level shifter for converting a signal level of a first logic circuit to which a first power source is supplied into a signal level of a second logic circuit to which a second power source is supplied, characterized by including a switching circuit between a power source terminal of a level shift core circuit and the second power source, the switching circuit being controlled by a third logic circuit which generates control signals in accordance with control of the first power source, and a pull-up and/or pull-down circuit at outputs of the level shift core circuit, the pull-up and/or pull-down circuit being controlled by the third logic circuit.
In accordance with the invention of a level shifter of a third embodiment, the level shifter in the first and second embodiments is characterized in that the level shift core circuit includes a p-MOS cross-coupled latch including at least two p-MOSs and a differential n-MOS including at least two n-MOSs; each of the p-MOSs includes a source terminal connected to the second power source terminal and a gate terminal connected to a level shift output which is each drain terminal; and each of the n-MOSs includes a source terminal connected to the GND power source terminal, a drain terminal connected to the level shift output, and a gate terminal connected to a level shift input.
In accordance with the invention of a level shifter of a fourth embodiment, the level shifter in the first and second embodiments is characterized in that the level shift core circuit includes: a p-MOS cross-coupled latch including at least two p-MOSs each of which includes a source terminal connected to the second power source and a gate terminal connected to each level shift output; at least two p-MOSs switches in which a source terminal of the other p-MOS is connected to each drain terminal of the p-MOS, each gate terminal of the switches is connected to each level shift input, and each drain terminal of the switches is connected to the level shift output; and a differential n-MOS switch including at least two n-MOSs each of which includes a source terminal connected to the GND power source terminal, a drain terminal connected to the level shift output, and a gate terminal connected to a level shift input.
In accordance with the invention of a level shifter of a fifth embodiment, the level shifter in the first and second embodiments is characterized in that the pull-up and/or pull-down circuit is replaced with a pull-down circuit, the pull-down circuit including one n-MOS or at least two n-MOSs, each of the n-MOSs including a source connected to a GND power source, a gate terminal connected to an inverted signal of a control signal, and a drain terminal connected to at least one of the level shift outputs.
In accordance with the invention of a level shifter of a sixth embodiment, there is provided a level shifter for converting a signal level of a first logic circuit to which a first power source is supplied into a signal level of a second logic circuit to which a second power source is supplied, characterized by including a pull-up and/or pull-down circuit in which the second power source is supplied to level shift outputs of a level shift core circuit, a control circuit to which the second power source is supplied and which receives as inputs thereto a level shift input signal and the level shift output signal, and a switching circuit which is disposed between a power source terminal of the level shift core circuit and the second power source and which is controlled by a third logic circuit, the third logic circuit generating control signals in accordance with control of the first power source, wherein the control circuit is controlled by a control signal from the third logic circuit.
In accordance with the invention of a level shifter of a seventh embodiment, the level shifter in the sixth embodiment is characterized in that the third logic circuit controls the control circuit by control signals from the third logic circuit, and the control circuit produces control signals to control the pull-up and/or pull-down circuit and the level shift core circuit.
In accordance with the invention of a level shifter of an eighth embodiment, the level shifter in the fifth embodiment is characterized in that the control circuit further produces control signals to control the pull-up and/or pull-down circuit to thereby control the pull-up and/or pull-down circuit.
In accordance with the invention of a level shifter of a ninth embodiment, the level shifter in the first, third or sixth embodiments is characterized in that the pull-up and/or pull-down circuit includes at least two p-MOSs each of which including a source terminal connected to the second power source, a gate terminal connected to a control signal, and a drain terminal connected to each of the level shift core outputs.
In accordance with the invention of a level shifter of a tenth embodiment, the level shifter in the first, third or eighth embodiments is characterized in that the pull-up and/or pull-down circuit comprises a p-MOS including a source terminal connected to the second power source, a gate terminal connected to a control signal, and a drain terminal connected to one of the level shift outputs and an n-MOS including a source terminal connected to a GND power source, a gate terminal connected to an inverted signal of a control signal, and a drain terminal connected to other one of the level shift outputs.
In accordance with the invention of a level shifter of an eleventh embodiment, there is provided a level shifter for converting a signal level of a first logic circuit to which a first power source is supplied into a signal level of a second logic circuit to which a second power source is supplied, characterized by comprising a pull-down circuit at level shift output signals of a level shift core circuit and a control circuit to which the second power source is supplied and which receives as inputs thereto level shift input signals and the level shift output signals to produce control signals for the pull-down circuit and the level shift core circuit, wherein the control circuit and the pull-down circuit are controlled by control signals from the third logic circuit.
In accordance with the invention of a level shifter of a twelfth embodiment, the level shifter in the eleventh embodiment is characterized in that the NAND circuit is of a CMOS circuit configuration and the p-MOS transistor to which the level shift input signal is connected includes a transistor at least having a small ratio of a channel width/a channel length or a high threshold value.
In accordance with the invention of a level shifter of a thirteenth embodiment, the level shifter in the eleventh embodiment is characterized in that the NAND circuit is of a CMOS circuit configuration and the n-MOS transistor to which a control signal output of the third logic circuit is connected includes a source terminal connected to a GND power source.
In accordance with the invention of a level shifter of a fourteenth embodiment, the level shifter in the fifth embodiment is characterized in that the pull-up and/or pull-down circuit includes at least two p-MOSs each of which includes a source terminal connected to the second power source and a gate terminal connected to a control signal from the control circuit, each drain terminal of other p-MOS being connected to each of the level shift outputs; at least two n-MOSs each of which includes a source terminal connected to the GND power source, a gate terminal connected to a control signal from the control circuit, and a drain terminal connected to the level shift outputs; and additionally at least two p-MOSs each of which includes a source terminal connected to the second power source and a gate terminal connected to a control signal from the third logic circuit, a drain terminal of other p-MOS being connected to each of the level shift outputs.
In accordance with the invention of a level shifter of a fifteenth embodiment, the level shifter in the fifth embodiment is characterized in that the pull-up and/or pull-down circuit includes at least two p-MOSs each of which includes a source terminal connected to the second power source and a gate terminal connected to a control signal from the control circuit, each drain terminal of other p-MOS being connected to each of the level shift outputs; at least two n-MOSs each of which includes a source terminal connected to the GND power source, a gate terminal connected to a control signal from the control circuit, and a drain terminal connected to the level shift outputs; and additionally a p-MOS including a source terminal connected to the second power source, a gate terminal connected to a control signal from the third logic circuit, a drain terminal connected to one of the level shift outputs.
In accordance with the invention of a level shifter of a sixteenth embodiment, the level shifter in the seventh embodiment is characterized in that the pull-up and/or pull-down circuit includes at least two p-MOSs each of which includes a source terminal connected to the second power source, a gate terminal connected to a control signal from the control circuit, and a drain terminal connected to each of the level shift outputs; at least two n-MOSs each of which includes a source terminal connected to the GND power source, a gate terminal connected to a control signal from the control circuit, and a drain terminal connected to the level shift outputs; additionally a p-MOS including a source terminal connected to the second power source, a gate terminal connected to a control signal from the third logic circuit, and a drain terminal connected to one of the level shift outputs; and additionally an n-MOS including a source terminal connected to the GND power source, a gate terminal connected to a control signal from the third logic circuit or to an inverted signal of the control signal, and a drain terminal connected to other one of the level shift outputs.
In accordance with the invention of a level shifter of a seventeenth embodiment, the level shifter in the fifth embodiment is characterized in that the pull-up and/or pull-down circuit includes at least two p-MOSs each of which includes a source terminal connected to the second power source and a gate terminal connected to a control signal from the control circuit, a drain terminal of other p-MOS being connected to each of the level shift outputs; at least two n-MOSs each of which includes a source terminal connected to the GND power source, a gate terminal connected to a control signal from the control circuit, and a drain terminal connected to the level shift outputs; and additionally an n-MOS including a source terminal connected to the GND power source, a gate terminal connected to a control signal from the third logic circuit or to an inverted signal of the control signal, and a drain terminal connected to one of the level shift outputs.
In accordance with the invention of a level shifter of an eighteenth embodiment, the level shifter in the fifth embodiment is characterized in that the control circuit comprises a NAND circuit to which the second power source is supplied and which receives as inputs thereto a positively inverted signal of the level shift input signal, an inverted signal of the level shift output signal, and a control output of the third logic circuit and a NAND circuit to which the second power source is supplied and which receives as inputs thereto an inverted signal of the level shift input signal, a positively inverted signal of the level shift output signal, and a control output of the third logic circuit, wherein an output signal of the NAND circuit is produced as a control signal.
In accordance with the invention of a level shifter of a nineteenth embodiment, the level shifter in the eighteenth embodiment is characterized in that the pull-up and/or pull-down circuit further includes at least two p-MOSs each of which includes a source terminal connected to the second power source and a gate terminal connected to a control signal from the control circuit, a drain terminal of other p-MOS being connected to each of the level shift outputs; and additionally at least two p-MOSs each of which includes a source terminal connected to the second power source and a gate terminal connected to a control signal from the third logic circuit, a drain terminal of other p-MOS being connected to each of the level shift outputs.
In accordance with the invention of a level shifter of a twentieth embodiment, the level shifter in the eighteenth embodiment is characterized in that the pull-up and/or pull-down circuit further includes at least two p-MOSs each of which includes a source terminal connected to the second power source, a gate terminal connected to a control signal from the control circuit, and a drain terminal connected to each of the level shift outputs; and additionally a p-MOS including a source terminal connected to the second power source, a gate terminal connected to a control signal from the third logic circuit, and a drain terminal connected to one of the level shift outputs.
In accordance with the invention of a level shifter of a twenty-first embodiment, the level shifter in the eighteenth embodiment is characterized in that the pull-up and/or pull-down circuit includes at least two p-MOSs each of which includes a source terminal connected to the second power source, a gate terminal connected to a control signal from the control circuit, and a drain terminal connected to each of the level shift outputs; additionally a p-MOS including a source terminal connected to the second power source, a gate terminal connected to a control signal from the third logic circuit, and a drain terminal connected to one of the level shift outputs; and additionally an n-MOS including a source terminal connected to the GND power source, a gate terminal connected to a control signal from the third logic circuit or to an inverted signal of the control signal, and a drain terminal connected to other one of the level shift outputs.
In accordance with the invention of a level shifter of a twenty-second embodiment, the level shifter in the eighteenth embodiment is characterized in that the pull-up and/or pull-down circuit includes at least two p-MOSs each of which includes a source terminal connected to the second power source, a gate terminal connected to a control signal from the control circuit, and a drain terminal connected to each of the level shift outputs; and additionally an n-MOS including a source terminal connected to the GND power source, a gate terminal connected to a control signal from the third logic circuit or an inverted signal of the control signal, and a drain terminal connected to one of the level shift outputs.
In accordance with the invention of a level shifter of a twenty-third embodiment, the level shifter in the fifth embodiment is characterized in that the control circuit comprises a NAND circuit to which the second power source is supplied and which receives as inputs thereto a positively inverted signal of the level shift input signal, an inverted signal of the level shift output signal, and a control output of the third logic circuit, a NAND circuit to which the second power source is supplied and which receives as inputs thereto an inverted signal of the level shift input signal, a positively inverted signal of the level shift output, and a control output of the third logic circuit, and at least two inverters to which the second power source is supplied and which respectively receive as inputs thereto outputs from the NAND circuits, wherein each output signal from the inverters is produced as a control signal.
In accordance with the invention of a level shifter of a twenty-fourth embodiment, the level shifter in the eighteenth embodiment is characterized in that the pull-up and/or pull-down circuit includes at least two n-MOSs each of which includes a source terminal connected to the GND power source, a gate terminal connected to a control signal from the control circuit, and a drain terminal connected to the level shift outputs and additionally at least two p-MOSs each of which includes a source terminal connected to the second power source and a gate terminal connected to a control signal from the third logic circuit, a drain terminal of other p-MOS being connected to each of the level shift outputs.
In accordance with the invention of a level shifter of a twenty-fifth embodiment, the level shifter in the twenty-third embodiment is characterized in that the pull-up and/or pull-down circuit includes at least two n-MOSs each of which includes a source terminal connected to the GND power source, a gate terminal connected to a control signal from the control circuit, and a drain terminal connected to the level shift outputs and additionally a p-MOS including a source terminal connected to the second power source, a gate terminal connected to a control signal from the third logic circuit, and a drain terminal connected to one of the level shift outputs.
In accordance with the invention of a level shifter of a twenty-sixth embodiment, the level shifter in the twenty-third embodiment is characterized in that the pull-up and/or pull-down circuit includes at least two n-MOSs each of which includes a source terminal connected to the GND power source, a gate terminal connected to a control signal from the control circuit, and a drain terminal connected to the level shift outputs; additionally a p-MOS including a source terminal connected to the second power source, a gate terminal connected to a control signal from the third logic circuit, and a drain terminal connected to one of the level shift outputs; and additionally an n-MOS including a source terminal connected to the GND power source, a gate terminal connected to a control signal from the third logic circuit or an inverted signal of the control signal, and a drain terminal connected to other one of the level shift outputs.
In accordance with the invention of a level shifter of a twenty-seventh embodiment, the level shifter in the twenty-third embodiment is characterized in that the pull-up and/or pull-down circuit includes at least two n-MOSs each of which includes a source terminal connected to the GND power source, a gate terminal connected to a control signal from the control circuit, and a drain terminal connected to the level shift outputs and additionally an n-MOS including a source terminal connected to the GND power source, a gate terminal connected to a control signal from the third logic circuit or to an inverted signal of the control signal, and a drain terminal connected to other one of the level shift outputs.
In accordance with the invention of a level shifter of a twenty-eighth embodiment, the level shifter in the fourteenth to seventeenth embodiments is characterized in that the control circuit comprises a NOR circuit to which the second power source is supplied and which receives as inputs thereto an inverted signal of the level shift input signal, a positively inverted signal of the level shift output signal, and a control output of the third logic circuit or an inverted signal of the control output, a NOR circuit to which the second power source is supplied and which receives as inputs thereto a positively inverted signal of the level shift input signal, an inverted signal of the level shift output, and a control output of the third logic circuit or an inverted signal of the control output, and at least two inverters to which the second power source is supplied and which respectively receive as inputs thereto outputs from the NOR circuits, wherein output signals respectively from the at least two NOR circuits and the at least two inverters are produced as control signals.
In accordance with the invention of a level shifter of a twenty-ninth embodiment, the level shifter in the twenty-eighth embodiment is characterized in that the NOR circuits are of a CMOS circuit configuration and a p-MOS to which the level shift input signal is connected includes a transistor at least having a small ratio of a channel width/a channel length or a threshold value which is of a negative polarity and which is a large absolute value.
In accordance with the invention of a level shifter of a thirtieth embodiment, the level shifter in the twenty-eighth embodiment is characterized in that the NOR circuits are of a CMOS circuit configuration and a control signal from the third logic circuit or an inverted signal thereof is connected to a p-MOS on a power source side.
In accordance with the invention of a level shifter of a thirty-first embodiment, the level shifter in the nineteenth to twenty-second embodiments is characterized in that the control circuit comprises a NOR circuit to which the second power source is supplied and which receives as inputs thereto an inverted signal of the level shift input signal, a positively inverted signal of the level shift output signal, and a control output of the third logic circuit or an inverted signal of the control output, a NOR circuit to which the second power source is supplied and which receives as inputs thereto a positively inverted signal of the level shift input signal, an inverted signal of the level shift output, and a control output of the third logic circuit or an inverted signal of the control output, and at least two inverters to which the second power source is supplied and which receive as inputs thereto outputs from the respective NOR circuits, wherein each output signal from the inverters is produced as a control signal.
In accordance with the invention of a level shifter of a thirty-second embodiment, the level shifter in the twenty-fourth to twenty-seventh embodiments is characterized in that the control circuit comprises a first NOR circuit to which the second power source is supplied and which receives as inputs thereto an inverted signal of the level shift input signal, a positively inverted signal of the level shift output signal, and a control output of the third logic circuit or an inverted signal of the control output and a second NOR circuit to which the second power source is supplied and which receives as inputs thereto a positively inverted signal of the level shift input signal, an inverted signal of the level shift output, and a control output of the third logic circuit or an inverted signal of the control output, wherein each output signal from the first and second NOR circuits is produced as a control signal.
In accordance with the invention of a level shifter of a thirty-third embodiment, the level shifter in the sixth embodiment is characterized in that the control circuit comprises an AND-NOR circuit to which the second power source is supplied and which receives as inputs thereto a positively inverted signal of the level shift input signal, an inverted signal of the level shift output signal, and a control output of the third logic circuit or an inverted signal of the control output, a NAND circuit to which the second power source is supplied and which receives as inputs thereto an inverted signal of the level shift input signal, a positively inverted signal of the level shift output, and a control output of the third logic circuit, and at least two inverters to which the second power source is supplied and which receive as inputs thereto outputs from the respective NAND circuits, wherein output signals from the AND-NOR circuit, the NAND circuit, and the inverters are produced as control signals.
In accordance with the invention of a level shifter of a thirty-fourth embodiment, the level shifter in the sixth and eighth embodiments is characterized in that the pull-up and/or pull-down circuit includes at least two p-MOSs each of which includes a source terminal connected to the second power source and a gate terminal connected to a control signal from the control circuit, a drain terminal of other p-MOS being connected to each of the level shift outputs and at least two n-MOSs each of which includes a source terminal connected to the GND power source, a gate terminal connected to a control signal from the control circuit, and a drain terminal connected to the level shift outputs.
In accordance with the invention of a level shifter of a thirty-fifth embodiment, the level shifter in the sixth embodiment is characterized in that the control circuit comprises an AND-NOR circuit to which the second power source is supplied and which receives as inputs thereto a positively inverted signal of the level shift input signal, an inverted signal of the level shift output signal, and a control output of the third logic circuit or an inverted signal of the control output and a NAND circuit to which the second power source is supplied and which receives as inputs thereto an inverted signal of the level shift input signal, a positively inverted signal of the level shift output, and a control output of the third logic circuit, wherein respective output signals from the AND-NOR circuit and the NAND circuit are produced as control signals.
In accordance with the invention of a level shifter of a thirty-sixth embodiment, the level shifter in the thirty-fifth embodiment is characterized in that the pull-up and/or pull-down circuit includes at least two p-MOSs each of which includes a source terminal connected to the second power source and a gate terminal connected to a control signal from the control circuit, a drain terminal of other p-MOS being connected to each of the level shift outputs.
In accordance with the invention of a level shifter of the thirty-seventh embodiment, the level shifter in the sixth embodiment is characterized in that the control circuit comprises an AND-NOR circuit to which the second power source is supplied and which receives as inputs thereto a positively inverted signal of the level shift input signal, an inverted signal of the level shift output signal, and a control output of the third logic circuit or an inverted signal of the control output, a NAND circuit to which the second power source is supplied and which receives as inputs thereto an inverted signal of the level shift input signal, a positively inverted signal of the level shift output, and a control output of the third logic circuit, and at least two inverters to which the second power source is supplied and which receive as inputs thereto outputs from the respective NAND circuits, wherein each output signal from the inverters is produced as a control signal.
In accordance with the invention of a level shifter of a thirty-eighth embodiment, the level shifter in the thirty-seventh embodiment is characterized in that the pull-up and/or pull-down circuit includes at least two n-MOSs each of which includes a source terminal connected to the GND power source, a gate terminal connected to a control signal from the control circuit, and a drain terminal connected to the level shift outputs.
In accordance with the invention of a level shifter of a thirty-ninth embodiment, the level shifter in the thirty-fourth embodiment is characterized in that the control circuit comprises an OR-NAND circuit to which the second power source is supplied and which receives as inputs thereto an inverted signal of the level shift input signal, a positively inverted signal of the level shift output signal, and a control output of the third logic circuit, a NOR circuit to which the second power source is supplied and which receives as inputs thereto a positively inverted signal of the level shift input signal, an inverted signal of the level shift output, and a control output of the third logic circuit or an inverted signal of the control output, and at least two inverters to which the second power source is supplied and which receive as inputs thereto outputs from the each of the NOR circuits, wherein each output signal from the OR-NAND circuit, the NOR circuits, and the inverters is produced as a control signal.
In accordance with the invention of a level shifter of a fortieth embodiment, the level shifter in the thirty-ninth embodiment is characterized in that the OR-NAND circuit is of a CMOS circuit configuration and a p-MOS to which the level shift input signal is connected has at least one condition that the p-MOS has a small ratio of a channel width/a channel length or a threshold value which is of a negative polarity and which is a large absolute value.
In accordance with the invention of a level shifter of a forty-first embodiment, the level shifter in the thirty-ninth embodiment is characterized in that the OR-NAND circuit is of a CMOS circuit configuration and a control signal from the third logic circuit is connected to an n-MOS on a GND power source side.
In accordance with the invention of a level shifter of a forty-second embodiment, the level shifter in the thirty-sixth embodiment is characterized in that the control circuit comprises an OR-NAND circuit to which the second power source is supplied and which receives as inputs thereto an inverted signal of the level shift input signal, a positively inverted signal of the level shift output signal, and a control output of the third logic circuit, a NOR circuit to which the second power source is supplied and which receives as inputs thereto a positively inverted signal of the level shift input signal, an inverted signal of the level shift output, and a control output of the third logic circuit or an inverted signal of the control output, and at least two inverters to which the second power source is supplied and which receive as inputs thereto outputs from the respective NOR circuits, wherein each output signal from the inverters is produced as a control signal.
In accordance with the invention of a level shifter of a forty-third embodiment, the level shifter in the thirty-eighth embodiment is characterized in that the control circuit comprises an OR-NAND circuit to which the second power source is supplied and which receives as inputs thereto an inverted signal of the level shift input signal, a positively inverted signal of the level shift output signal, and a control output of the third logic circuit and a NOR circuit to which the second power source is supplied and which receives as inputs thereto a positively inverted signal of the level shift input signal, an inverted signal of the level shift output, and a control output of the third logic circuit or an inverted signal of the control output, wherein each output signal from the OR-NAND circuit and the NOR circuit is produced as a control signal.
In accordance with the invention of a level shifter of a forty-fourth embodiment, the level shifter in the thirty-sixth embodiment is characterized in that the control circuit comprises an AND-NOR circuit to which the second power source is supplied and which receives as inputs thereto a positively inverted signal of the level shift input signal, an inverted signal of the level shift output signal, and a control output of the third logic circuit or an inverted signal of the control output and an AND-NOR circuit to which the second power source is supplied and which receives as inputs thereto an inverted signal of the level shift input signal, a positively inverted signal of the level shift output, and a control output of the third logic circuit or an inverted signal of the control output, wherein each output signal from the AND-NOR circuits is produced as a control signal.
In accordance with the invention of a level shifter of a forty-fifth embodiment, the level shifter in the thirty-sixth embodiment is characterized in that the control circuit comprises an OR-NAND circuit to which the second power source is supplied and which receives as inputs thereto an inverted signal of the level shift input signal, a positively inverted signal of the level shift output signal, and a control output of the third logic circuit, an OR-NAND circuit to which the second power source is supplied and which receives as inputs thereto a positively inverted signal of the level shift input signal, an inverted signal of the level shift output, and a control output of the third logic circuit, and at least two inverters to which the second power source is supplied and which receive as inputs thereto outputs from the respective OR-NAND circuits, wherein each output signal from the inverters is produced as a control signal.
In accordance with the invention of a level shifter of a forty-sixth embodiment, the level shifter in the thirty-eighth embodiment is characterized in that the control circuit comprises an AND-NOR circuit to which the second power source is supplied and which receives as inputs thereto a positively inverted signal of the level shift input signal, an inverted signal of the level shift output signal, and a control output of the third logic circuit or an inverted signal of the control output, an AND-NOR circuit to which the second power source is supplied and which receives as inputs thereto an inverted signal of the level shift input signal, a positively inverted signal of the level shift output, and a control output of the third logic circuit or an inverted signal of the control output, and at least two inverters to which the second power source is supplied and which receive as inputs thereto outputs from the respective AND-NOR circuits, wherein each output signal from the inverters is produced as a control signal.
In accordance with the invention of a level shifter of a forty-seventh embodiment, the level shifter in the thirty-eighth embodiment is characterized in that the control circuit comprises an OR-NAND circuit to which the second power source is supplied and which receives as inputs thereto an inverted signal of the level shift input signal, a positively inverted signal of the level shift output signal, and a control output of the third logic circuit and an OR-NAND circuit to which the second power source is supplied and which receives as inputs thereto a positively inverted signal of the level shift input signal, an inverted signal of the level shift output, and a control output of the third logic circuit, wherein each output signal from the OR-NAND circuits is produced as a control signal.
In accordance with the invention of a level shifter of a forty-eighth embodiment, the level shifter in the forty-seventh embodiment is characterized in that the level shift core circuit comprises a p-MOS cross-coupled latch including at least two of the p-MOS in which each source terminal is connected to the second source and a gate terminal of other p-MOS is connected to each of the level shift outputs, at least two p-MOS switches including a source terminal connected of a drain terminal of the p-MOS, each gate terminal connected to a control signal from the control circuit, and each drain terminal connected to the level shift outputs, and a differential n-MOS switch including at least two n-MOSs each of which includes a source terminal connected to a GND power source, a drain terminal connected to the respective level shift outputs, and a gate terminal connected to a level shift input.
In accordance with the invention of a level shifter of a forty-ninth embodiment, the level shifter in claim one of the fourteenth to seventeenth, nineteenth to twenty-second, and twenty-fourth to twenty-seventh embodiments, characterized in that the control circuit comprises a first NAND circuit to which the second power source is supplied and which receives as inputs thereto a positively inverted signal of the level shift input signal, an inverted signal of the level shift output signal, and a control output of the third logic circuit, a second NAND circuit to which the second power source is supplied and which receives as inputs thereto an inverted signal of the level shift input signal, a positively inverted signal of the level shift output, and a control output of the third logic circuit, and at least two inverters to which the second power source is supplied and which receive as inputs thereto outputs from the respective NAND circuits, wherein each output signal from the first and second NAND circuits and the at least two inverters is produced as a pull-up and/or pull-down control signal and each output signal of the inverters is produced as a control signal of the level shift core circuit.
In accordance with the invention of a level shifter of claim 50 a fiftieth embodiment, the level shifter in one of the fourteenth to seventeenth, nineteenth to twenty-second and twenty-fourth to twenty-seventh embodiments, characterized in that the control circuit comprises a NOR circuit to which the second power source is supplied and which receives as inputs thereto an inverted signal of the level shift input signal, a positively inverted signal of the level shift output signal, and a control output of the third logic circuit or an inverted signal of the control output, a NOR circuit to which the second power source is supplied and which receives as inputs thereto a positively inverted signal of the level shift input signal, an inverted signal of the level shift output, and a control output of the third logic circuit or an inverted signal of the control output, and at least two inverters to which the second power source is supplied and which respectively receive as inputs thereto outputs from the respective NOR circuits, wherein each output signal from the NOR circuits and the inverters is produced as a pull-up and/or pull-down control signal and each output signal of the NOR circuits is produced as a control signal of the level shift core circuit.
In accordance with the invention of a level shifter of a fifty-first embodiment, the level shifter in claim one of the first, third and sixth to the ninth embodiments characterized in that the switching circuit comprises an n-MOS including a source terminal connected to a GND power source, a gate terminal connected to a control signal, and a drain terminal connected to a GND power source terminal of the level shift core circuit.
In accordance with the invention of a level shifter of a fifty-second embodiment, the level shifter in the thirty-fourth embodiment, characterized in that the control circuit comprises an AND-NOR circuit to which the second power source is supplied and which receives as inputs thereto a positively inverted signal of the level shift input signal, an inverted signal of the level shift output signal, and a control output of the third logic circuit or an inverted signal of the control output, a NAND circuit to which the second power source is supplied and which receives as inputs thereto an inverted signal of the level shift input signal, a positively inverted signal of the level shift output, and a control output of the third logic circuit, and at least two inverters to which the second power source is supplied and which receive as inputs thereto outputs from the respective NAND circuits, wherein each output signal from the AND-NOR circuit, the NAND circuit, and the at least two inverters is produced as a pull-up and/or pull-down control signal and each output signal of the inverters is produced as a control signal of the level shift core circuit.
In accordance with the invention of a level shifter of a fifty-third embodiment, the level shifter in the thirty-ninth embodiment, characterized in that each output signal from the OR-NAND circuit, the NOR circuit, and the inverters is produced as a pull-up and/or pull-down control signal and each output signal of the OR-NAND circuit and the NOR circuit is produced as a control signal of the level shift core circuit.
In accordance with the invention of a level shifter of a fifty-fourth embodiment, the level shifter in the eighth embodiment, characterized in that the control circuit comprises a first AND-NOR circuit to which the second power source is supplied and which receives as inputs thereto a positively inverted signal of the level shift input signal, an inverted signal of the level shift output signal, and a control output of the third logic circuit or an inverted signal of the control output, a second AND-NOR circuit to which the second power source is supplied and which receives as inputs thereto an inverted signal of the level shift input signal, a positively inverted signal of the level shift output, and a control output of the third logic circuit or an inverted signal of the control output, and at least two inverters to which the second power source is supplied and which receive as inputs thereto outputs from the first and second AND-NOR circuits, wherein each output signal from the first and second AND-NOR circuits is produced as a pull-up and/or pull-down control signal and each output signal of the inverters is produced as a control signal of the level shift core circuit, and the pull-up and/or pull-down circuit includes at least two p-MOSs each of which includes a source terminal connected to the second power source and a gate terminal connected to a control signal from the control circuit, a drain terminal of other p-MOS being connected to each of the level shift outputs.
In accordance with the invention of a level shifter of a fifty-fifth embodiment, the level shifter in the eighth embodiment, characterized in that the control circuit comprises a first OR-NAND circuit to which the second power source is supplied and which receives as inputs thereto an inverted signal of the level shift input signal, a positively inverted signal of the level shift output signal, and a control output of the third logic circuit, a second OR-NAND circuit to which the second power source is supplied and which receives as inputs thereto a positively inverted signal of the level shift input signal, an inverted signal of the level shift output, and a control output of the third logic circuit, and at least two inverters to which the second power source is supplied and which receive as inputs thereto outputs from the first and second OR-NAND circuits, wherein each output signal from the at least two inverters is produced as a pull-up and/or pull-down control signal and each output signal from the OR-NAND circuits is produced as a control signal of the level shift core circuit, and the pull-up and/or pull-down circuit includes at least two p-MOSs each of which includes a source terminal connected to the second power source and a gate terminal connected to a control signal from the control circuit, a drain terminal of other p-MOS being connected to each of the level shift outputs.
In accordance with the invention of a level shifter of a fifty-sixth embodiment, the level shifter in one of the fourth to seventh and ninth to eleventh embodiments, characterized in that the control circuit comprises an AND-NOR circuit to which the second power source is supplied and which receives as inputs thereto a positively inverted signal of the level shift input signal, an inverted signal of the level shift output signal, and a control output of the third logic circuit or an inverted signal of the control output, an AND-NOR circuit to which the second power source is supplied and which receives as inputs thereto an inverted signal of the level shift input signal, a positively inverted signal of the level shift output, and a control output of the third logic circuit or an inverted signal of the control output, and at least two inverters to which the second power source is supplied and which receive as inputs thereto outputs from the respective AND-NOR circuits, wherein each output signal from the inverters is produced as a pull-up and/or pull-down control signal, each output signal from the inverters is produced as a control signal of the level shift core circuit, and the pull-up and/or pull-down circuit includes at least two n-MOS each of which includes a source terminal connected to the GND power source, a gate terminal connected to a control signal from the control circuit, and a drain terminal connected to the level shift outputs.
In accordance with the invention of a level shifter of a fifty-seventh embodiment, the level shifter in one of the fourth to seventh and ninth to eleventh embodiments, characterized in that the control circuit comprises a first OR-NAND circuit to which the second power source is supplied and which receives as inputs thereto an inverted signal of the level shift input signal, a positively inverted signal of the level shift output signal, and a control output of the third logic circuit and a second OR-NAND circuit to which the second power source is supplied and which receives as inputs thereto a positively inverted signal of the level shift input signal, an inverted signal of the level shift output, and a control output of the third logic circuit, wherein each output signal from the first and second OR-NAND circuits is produced as a pull-up and/or pull-down control signal, each output signal from the OR-NAND circuits is produced as a control signal of the level shift core circuit, and the pull-up and/or pull-down circuit includes at least two n-MOSs each of which includes a source terminal connected to the GND power source, a gate terminal connected to a control signal from the control circuit, and a drain terminal connected to the level shift outputs.
In accordance with the invention of a level shifter of a fifty-eighth embodiment, the level shifter in one of the fourth to seventh and ninth to eleventh embodiments, characterized in that the control circuit comprises an AND-NOR circuit to which the second power source is supplied and which receives as inputs thereto a positively inverted signal of the level shift input signal, an inverted signal of the level shift output signal, and a control output of the third logic circuit or an inverted signal of the control output, an AND-NOR circuit to which the second power source is supplied and which receives as inputs thereto an inverted signal of the level shift input signal, a positively inverted signal of the level shift output, and a control output of the third logic circuit or an inverted signal of the control output, and at least two inverters to which the second power source is supplied and which receive as inputs thereto outputs from the respective AND-NOR circuits, wherein each output signal of the inverters is produced as a control signal of the level shift core circuit.
In accordance with the invention of a level shifter of claim 59 a fifty-ninth embodiment, the level shifter in one of the fourth to seventh and ninth to eleventh embodiments, characterized in that the control circuit comprises an OR-NAND circuit to which the second power source is supplied and which receives as inputs thereto an inverted signal of the level shift input signal, a positively inverted signal of the level shift output signal, and a control output of the third logic circuit and an OR-NAND circuit to which the second power source is supplied and which receives as inputs thereto a positively inverted signal of the level shift input signal, an inverted signal of the level shift output, and a control output of the third logic circuit, wherein each output signal from the OR-NAND circuits is produced as a control signal of the level shift core circuit.
In accordance with the invention of a level shifter of a sixtieth embodiment, the level shifter in one of the first, third, tenth, fifty-ninth and the sixtieth embodiments, characterized in that: the level shift core circuit comprises a p-MOS cross-coupled latch including at least two first p-MOS, a differential n-MOS including at least two n-MOSs, and at least two second p-MOS, wherein: the p-MOS cross-coupled latch includes a source terminal connected to the second power source and a gate terminal connected to a level shift output which is each drain terminal; the differential n-MOS includes each source terminal connected to the GND power source, each drain terminal connected to the level shift output, and each gate terminal connected to a level shift input; and the second p-MOS includes each drain terminal connected to the second power source, each gate terminal connected to the level shift input, and each source terminal connected to the level shift output.
In accordance with the invention of a level shifter of a sixty-first embodiment, there is provided a level shifter for converting a signal level of a first logic circuit to which a first power source is supplied into a signal level of a second logic circuit to which a second power source is supplied, characterized by including a pull-down circuit at level shift outputs of a level shift core circuit and a control circuit to which the second power source is supplied and which receives as inputs thereto level shift input signals and the level shift output signals to produce control signals for a pull-down circuit and a level shift core circuit, wherein the control circuit is also connected to control signals from the third logic circuit.
In accordance with the invention of a level shifter of a sixty-second embodiment, the level shifter in the sixty-first embodiment, characterized in that the control circuit, the control circuit comprises a first OR-NAND circuit to which the second power source is supplied and which receives as inputs thereto an inverted signal of the level shift input signal, a positively inverted signal of the level shift output signal, and a control output of the third logic circuit and a second OR-NAND circuit to which the second power source is supplied and which receives as inputs thereto a positively inverted signal of the level shift input signal, an inverted signal of the level shift output, and a control output of the third logic circuit, wherein each output signal from the first and second OR-NAND circuits is produced as a pull-up and/or pull-down control signal, each output signal from the OR-NAND circuits is produced as a control signal of the level shift core circuit, and the pull-down circuit, the pull-up and/or pull-down circuit include at least two n-MOSs each of which includes a source terminal connected to the GND power source, a gate terminal connected to a control signal from the control circuit, and a drain terminal connected to the level shift outputs.
In accordance with the invention of a level shifter of a sixty-third embodiment, the level shifter in the sixty-first embodiment, characterized in that the control circuit, the control circuit comprises a first OR-NAND circuit to which the second power source is supplied and which receives as inputs thereto an inverted signal of the level shift input signal, a positively inverted signal of the level shift output signal, and a control output of the third logic circuit and a second OR-NAND circuit to which the second power source is supplied and which receives as inputs thereto a positively inverted signal of the level shift input signal, an inverted signal of the level shift output, and a control output of the third logic circuit or an inverted signal of the control output, wherein each output signal from the first and second OR-NAND circuits is produced as a pull-up and/or pull-down control signal, each output signal from the OR-NAND circuits is produced as a control signal of the level shift core circuit, and the pull-down circuit, the pull-up and/or pull-down circuit include at least two n-MOSs each of which includes a source terminal connected to the GND power source, a gate terminal connected to a control signal from the control circuit, and a drain terminal connected to the level shift outputs.
In accordance with the invention of a level shifter of a sixty-fourth embodiment, the level shifter in one of the second, seventh to the ninth and sixty-first embodiments, characterized in that the switching circuit comprises a p-MOS including a source terminal connected to the second power source, a gate terminal connected to a control signal or an inverted signal thereof, and a drain terminal connected to a power source terminal of the level shift core circuit.
In accordance with the invention of a level shifter of a sixty-fifth embodiment, the level shifter in one of the third, fifth, sixth and sixty-first embodiments, characterized in that the control circuit comprises at least two NOR circuits to which the second power source is supplied and which receives as inputs thereto an inverted signal of the level shift input signal, a positively inverted signal of the level shift output signal, and a control output of the third logic circuit or an inverted signal of the control output and a NOR circuit to which the second power source is supplied and which receives as inputs thereto a positively inverted signal of the level shift input signal, an inverted signal of the level shift output, and a control output of the third logic circuit or an inverted signal of the control output, wherein each output signal from the NOR circuits is produced as a control signal of the level shift core circuit.
In accordance with the invention of a level shifter of a sixty-sixth embodiment, the level shifter in one of the third, eleventh, twelfth and sixty-first embodiments, characterized in that the control circuit comprises at least two NAND circuits to which the second power source is supplied and which receives as inputs thereto a positively inverted signal of the level shift input signal, an inverted signal of the level shift output signal, and a control output of the third logic circuit, a NAND circuit to which the second power source is supplied and which receives as inputs thereto an inverted signal of the level shift input signal, a positively inverted signal of the level shift output signal, and a control output of the third logic circuit, and at least two inverters to which the second power source is supplied and which receives as inputs thereto outputs from the respective NAND circuits, wherein each output signal from the inverters is produced as a control signal of the level shift core circuit.
Incidentally, reference numeral 1 is a level shift core circuit. Reference numeral 2 is a control circuit. Reference numeral 3 is a pull-up/pull-down circuit. Reference numeral 3-1 is a pull-up circuit. Reference numeral 3-2 is a pull-down circuit. Reference numeral 10 is a switching circuit. Reference numeral 11 is a first logic circuit. Reference numeral 12 is a second logic circuit. Reference numeral 13 is a third logic circuit.
Referring to the accompanying drawings, description will be given in detail of an embodiment of the present invention.
The level shifter of the present invention is characterized in that a switching circuit controlled by a control signal is disposed between a GND power source terminal of a level shift core circuit and a GND power source, and a pull-up and/or pull-down circuit controlled by a control signal is connected to a level shift output.
Each of the switching circuit and the pull-up and/or pull-down circuit conducts an operation (function) in which to control a first power source, each of the circuit exclusively turns off (on); and to turn the first power source off, each of the circuit prevents short circuit current and fixes a level shift output signal. There are hence obtained advantages of reliable suppression of the short circuit current and suppression of the delay increase in the level shift.
The level converter circuit converts a signal level of a first logic circuit 11 supplied with a first power source (VDDL) into a signal level of a second logic circuit 12 supplied with a second power source (VDDH), and the level converter includes a level shift core circuit 1.
A signal (data; INL,INLB) at the first power source level is fed from the first logic circuit 11 to the core circuit 1 to be converted into a signal at the second power source level (the level shift output is indicated by OUTH,OUTHB in
Moreover, in the first embodiment of the level converter in accordance with the present invention, a switching circuit 10 controlled by a control signal (E0) from a third logic circuit and a pull-up and/or pull-down circuit 3 connected to a level shift output and controlled by a control signal (E1) from the third logic circuit 13 are disposed between a GND power source terminal of the core circuit 1 and a GND power source. To control the first power source (VDDL), the switching circuit 10 and the pull-up and/or pull-down circuit 3 are controlled by the third logic circuit 13; to turn the first power source (VDDL) off, the switching circuit 10 is beforehand turned off and the pull-up and/or pull-down circuit 3 is turned on to prevent short circuit current and to determine a level shift output signal when the level shift input is indefinite. Additionally, to turn the first power source (VDDL) on, when the first power source and the level shift input are stabilized thereafter, the pull-up and/or pull-down circuit 3 is turned off and the switching circuit 10 is turned on to conduct the level shift. The level shift output signal (OUTH, OUTHB) thus obtained is supplied to the second logic circuit 12.
In the configuration of the switching circuit 10 shown in
As shown in
Each logic circuit of
Next, description will be given of an operation example of the first embodiment. First, operation of the level shift core circuit 1 will be described using the timing chart shown in
On the other hand, the operation of the level converter including the switching circuit 10 and the pull-up/pull-down circuit 3 is conducted according to the timing chart shown in
At transition of the first power source VDDL 12 to “off”, the control signals E0 and E1 are first changed to Low and the switching circuit 10 is set to off such that the pull-up/pull-down circuit 3 is in an on state, which prevents short circuit current of the level converter and which fixes the level shift outputs (OUTH,OUTHB) respectively to High.
As a result, even when the level shift inputs (INL,INLB) are indefinite when VDDL is set to off, the short circuit current and random output changes (random change-over between “on” and “off”) can be prevented. Next, to turn the first power source VDDL on, VDDL is first turned on to a stable state and then the control signals E0 and E1 are changed to High; the pull-up/pull-down circuit is turned off, the switching circuit is turned on; when one (OUTH) of the level shift outputs rises up according to a level shift input, the level converting operation is conducted in a way similar to that of
As above, in the operation to control the first power source VDDL, since the switching circuit 10 is changed to off and the pull-up/pull-down circuit 3 is changed to on, it is possible to prevent the short circuit current and the random change of the output associated with the indefinite level shift input.
Therefore, even in an LSI having many power sources, reduction in leakage current can be achieved by turning the power source of an unused block off while suppressing the overhead as described above.
When only the level shift output OUTH is connected to the second logic circuit 11 (e.g., only the output of OUTH or OUTHB is inputted as shown in
Furthermore, when the level shift output OUTH or OUTHB is required to be Low, the circuit may be replaced by a pull-down circuit including one n-MOS 101302 and an inverter 101303 to invert a control signal as shown in
As the level shift core circuit 1 used in the embodiment, one of the circuits of
Moreover, although the switching circuit is controlled using the control signal E0 of the third logic circuit in the embodiment, the control signal E1 may be adopted without using E0; or, inverted signals thereof (E0B, E1B) may also be used. Incidentally, in another embodiment, control signals E1 and E2 other than the control signal E0 and inverted signals thereof (E0B, E1B, E2B) may also be employed appropriately.
In addition, although the switching circuit is controlled using the control signal E0 from the third logic circuit 13 in the embodiment, the control signal E1 may be adopted in place of E0. The replacement of the control signal can also be used in embodiments described below; furthermore, in the following embodiments, E2 may be adopted in place of E0 in the control operation.
The second embodiment of a level shifter in accordance with the present invention has a basic configuration similar to that of the first embodiment as shown in
Moreover, as shown in
In the above configuration, the system executes processing similar to that of the first embodiment described above.
When only the level shift output OUTH is connected to the second logic circuit, the pull-down circuit 3-2 used in the embodiment may be replaced by a circuit including an (only one) n-MOS 103-201 and an inverter as in the pull-down circuit shown in
Description will be given of, as the third embodiment of a level shifter in accordance with the present invention, a level shifter capable of improving a level shift margin when a large potential difference exists between the first and second power sources. In the embodiment, control has been devised for the control circuit 2 to which the second power source is supplied and the pull-up/pull-down circuit 3 to which the second power source (VDDH) is supplied.
As shown in
The short circuit current of the logic gate which is a problem when the level shift input (INL, INLB) of which the state changes depending on the first power source to conduct power source control is indefinite is solved by disposing the NAND circuits 103201 and 103202 to receive the control input E2 as an input thereto.
As shown in
Operation of the embodiment will be described. When E2 shown in the control circuit 2 of
Moreover, as shown in
To turn the first power source VDDL to off, the control signals E0 and E1 are first changed to Low, the switching circuit 10 is turned off, and the pull-up/pull-down circuit 3 is set to an ON state to prevent the short circuit current of the level converter on one hand and to fix the level shift outputs (OUTH, OUTHB) respectively to High on the other.
As a result, even when conversion outputs (OUTH, OUTHB) are indefinite when VDDL is turned off, the short circuit current and the random changes in the output (random change-over between on and off) can be prevented. Next, to turn the first power source VDDL on, VDDL is first turned on to be stabilized, the control signals E0 and E1 are then changed to High, the pull-up/pull-down circuit is turned off (OFF), the switching circuit is turned on (ON); after one (OUTH) of the level shift outputs rises up according to the level shift input, the level shift is conducted in a way similar to that of
As above, to control the first power source VDDL, the switching circuit 10 is set to OFF and the pull-up/pull-down circuit 3 is set to ON, and hence the short circuit current and the random changes in the output associated with the indefinite level shift input can be prevented.
Therefore, even in an LSI having many power sources, the leakage current caused by turning off a power source of an unused block can be reduced while the overhead is suppressed as described above.
In a case in which the first power source (VDDL) is turned off, E0 is beforehand set to Low to turn the switching circuit 10 off and E1 is set to Low to fix the level shift output (either one of OUTH and OUTHB) to High, and then the first power source (VDDL) is turned off.
To turn the first power source (VDDL) on, the first power source is first turned on; after the power source is stabilized, the control signals are controlled.
When the level converter and the second logic circuit 11 are only connected (input) to OUTH, the pull-up and/or pull-down circuit 3 used in the embodiment may be replaced with the pull-up/pull-down circuit 3 shown in
Furthermore, in the pull-up and/or pull-down circuit 3 used in the embodiment, when it is required to fix OUTH to High and OUTHB to Low, the circuit 3 may be replaced with the pull-up and/or pull-down circuit 3 shown in
In the embodiment, to include only a pull-up circuit 3-1 at level shift, the control circuit 2 and the pull-up and/or pull-down circuit 3 may be respectively replaced by
To operate only the pull-down (3-2) function at level shift, the control circuit 2 and the pull-up and/or pull-down circuit 3 used in the embodiment may be respectively replaced by
Restrictions on the replacement by
Moreover, the control circuit adopted in the embodiment may be respectively replaced by
In conjunction with
Incidentally, in the description of the embodiment, the control signals E0 to E2 outputted from the third logic circuit are used in this case such that the pull-up and/or pull-down circuit uses E1, the control circuit utilizes E2, and the switching circuit 10 employs E0 for control. However, the control signals E0 to E2 inputted to the pull-up and/or pull-down circuit, the control circuit, and the switching circuit 10 may be respectively replaced by other control signals according to need. Additionally, the level shifter may also be configured by using either one of the OUTH signal and the OUTHB signal and by exchanging the layout of the level shift circuit 1 and the switching circuit in an example of change from the first embodiment 1 to the second embodiment.
The fourth embodiment of the present invention is implemented by devising the control circuit 2 such that the control signal E1 is removed from the third logic circuit 13 and the pull-up and/or pull-down circuit 3 is simplified, adopting other fundamental configurations similar to one of the embodiments described above.
The AND-NOR circuit of
The timing chart of
The control circuit 2 and the pull-up/pull-down circuit 3 used in the embodiment may be replaced by the circuits respectively shown in
The OR-NOR circuit used in
The control circuit 2 used in the embodiment may be replaced by any either one of
The fifth embodiment of the present invention has devised control in a configuration of a level shifter capable of improving the level shift margin when a large potential difference exists between the first and second power sources, the circuit including a control circuit 2 to which the second power source is supplied and a pull-up/pull-down circuit 3 to which the second power source is supplied. In this embodiment, control of a level shift core circuit 1 is particularly devised.
The level shift core circuit adopted in the level converter of
In addition,
The control circuit 2 used in the embodiment may also be replaced by, in place of the control circuit 2 shown in
In an operation example of the fifth embodiment described above, in a case in which INL is Low, INLB is High, OUTH is Low, and OUTHB is High, when the INL signal produced from the first logic circuit becomes High (INLB is Low), the control circuit 2 receives the INL signal as an input thereto and then produces a C0 signal and the like. The C0 signal thus produced is Low and then the p-MOS in the pull-up and/or pull-down circuit 3 connected to OUTH turns on to pull up OUTH; at the same time, the control circuit 2 produces C3 of High. As a result, the n-MOS connected to OUTHB in the pull-up and/or pull-down circuit 3 turns on to pull down OUTHB; the control circuit 2 produces C4 of High to turn a p-MOS switch in the pull-up and/or pull-down circuit 3 connected to OUTHB off to suppress the pull-up of OUTHB; at the same time, when OUTHB is reduced to Low by an operation of the level shift core circuit 1, the control circuit 2 produces C0 of High to turn the n-MOS in the pull-up and/or pull-down circuit 3 to finish the pull-up, and the control circuit p2 produces C3 of Low to turn the n-MOS in the pull-up and/or pull-down circuit 3 off to finish the pull-down; the control circuit 2 produces C4 of Low to turn the p-MOS switch in the pull-up and/or pull-down circuit 3 on. Resultantly, INL is High, INLB is Low, OUTH is High, and OUTHB is Low.
Next, when an external first logic circuit 4 sets INLB to High (INL is Low), this signal is fed to the controller 2 and the controller 2 produces C1 of Low to turn on the p-MOS in the pull-up and/or pull-down circuit 3 connected to OUTHB to pull up OUTHB; moreover, the controller 2 produces C2 of High to turn on the n-MOS in the pull-up and/or pull-down circuit 3 connected to OUTH to pull down OUTH; the controller 2 produces C5 of High to turn on the p-MOS in the pull-up and/or pull-down circuit 3 connected to OUTH to suppress the pull-up of OUTH; at the same time, when OUTH is reduced to Low by an operation of the level shift core circuit 1, the control circuit 2 produces C1 of High to turn the p-MOS in the pull-up and/or pull-down circuit 3 off to finish the pull-up; furthermore, the control circuit 2 produces C2 of Low to turn the n-MOS in the pull-up and/or pull-down circuit 3 off to finish the pull-down; the control circuit 2 produces C5 of Low to turn the p-MOS switch in the pull-up and/or pull-down circuit 3 on. As a result, INL is Low, INLB is High, OUTH is Low, and OUTHB is High. In this connection, description has been given of a case in which the configuration shown in
In the sixth embodiment of the present invention, the idea or the device of
As shown in
The control circuit 2 shown in
Operation of the embodiment is similar to that of the operation of the embodiments described above.
As shown in
That is, when E2 is Low, C4 and C5 are at a High level, and the p-MOS of the level shift core circuit 1 including a gate terminal connected thereto functions as a switch disposed on the power source side to turn these signals off. Through this operation, resultantly, the power source GND short circuit current path can be prevented regardless of the level shift input.
Moreover, in the embodiment described above, it is assumed that the control signal outputs (E0, E1, E2) from the third logic circuit 13 are set to Low when the first power source is turned off; however, the control circuit and the pull-up/pull-down circuit 3 can also be respectively simplified by appropriately using inverted signals. In the diagrams used to described the embodiments, p-MOS (transistor) has a circle (∘) on the gate section. Incidentally, the present invention is not restricted by the embodiments, and the embodiments can be appropriately modified within a scope of the technical idea of the present invention, and those modified embodiments are also included in the invention of this application. Additionally, E0, E1, and E2 can be collectively used as one signal when they have common timing. Moreover, in the timing charts of
As described above, in accordance with the present invention, short circuit current and the delay increase can be suppressed on the basis of a fundamental configuration of a level shifter for converting a signal level of a first logic circuit to which a first power source is supplied into a signal level of a second logic circuit to which a second power source is supplied, characterized by including a switching circuit between a GND power source terminal (ground power source terminal) of a level shift core circuit and a GND power source (ground power source), the switching circuit being controlled by a third logic circuit which generates a control signal under control of the first power source, and a pull-up and/or pull-down circuit at an output of the level shift core circuit, the pull-up and/or pull-down circuit being controlled by the third logic circuit. In this connection, as the basic configurations of the level shift core circuit 1, the switching circuit 10, the control circuit 2, and the pull-up and/or pull-down circuit 3, those described above can be adopted; however, these may be used such that two or more circuits are connected in parallel in a circuit configuration; for example, it is also possible that two or more level shift core circuits or the like are connected in parallel to be utilized as a level shift core circuit.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2002-319151 | Oct 2002 | JP | national |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 10533304 | Apr 2005 | US |
| Child | 12196422 | US |
