Patent Application
20050184756
The present patent document claims priority under 35 U.S.C. § 119(a)-(d) to German Application 103 52 812. 1, filed in Germany on Nov. 12, 2003, which is hereby incorporated by reference.
1. Technical Field
The present invention relates to a method and a circuit arrangement for the generation of ternary signals, in particular, the output of ternary signals from an output structure of a semiconductor module.
2. Background Information
Ternary interfaces may produce signal outputs that have three active states and are used with semiconductor modules having a small number of connections. The ternary interfaces may be analog semiconductor modules and can include line drivers for fan-out purposes.
The three active states of an output structure of a ternary interface are graphically represented in
In order to form a ternary signal output, the circuit of
Alternatively, a higher voltage that will be used as a signal output may be introduced to the semiconductor module from an outside source. By way of example, where a semiconductor module has an internal supply voltage of 1.5 V, it may be possible for a voltage of 3.3 V to be introduced from outside. In many circuit environments, a higher external supply voltage is available in addition to the lower internal supply voltage of the semiconductor modules. To conduct the external supply voltage into the semiconductor module, however, an additional connection is required. In addition, problems may arise with respect to over-voltage protection for the internal structures of the semiconductor module.
This application provides a circuit arrangement for an output structure and a method that will generate a ternary signal output for a semiconductor module. The circuit arrangement includes a switching means for connecting the signal output of the circuit output structure with a first potential that produces a first signal level. Also included in the circuit arrangement is a further or second switching means for connecting the signal output with a second potential that produces a second signal level. The signal output may be connected to an external source that provides a third potential. Between the third potential and the signal output is a resistance means that provides a resistance value. The resistance means may be a resistor. The switching means and the further switching means may decouple the first potential and the second potential from the signal output so that the signal output reaches the voltage level of the third potential. The first potential may be a ground potential. The second potential may be a power supply potential of the output structure. The third potential may be a potential that is greater than the power supply potential of the output structure.
The switching means and the further switching means may be controlled with control signals. The switching means and the further switching means may be a first transistor and a second transistor. The transistor may be a bipolar junction transistor or a metal-oxide semiconductor field effect transistor (“MOSFET”). When the transistor used is a MOSFET transistor, the first and second transistors may be arranged in a complementary mode (“CMOS”). The control signals may be binary signals that are fed directly to a gate or base on the first and second transistor. Preferably, the binary signals are fed to a conditioner or a control block that will provide a single control signal that will control the first and second transistor.
When no control voltage is applied to the first transistor and the second transistor, the transistors may have a resistance that is greater than the resistance of the resistance means. When the transistors have a resistance that is greater than the resistance means, the signal output is essentially decoupled from the first potential and the second potential. In this state, a signal level is imposed at the signal output which corresponds substantially to the third potential.
Further advantages of the invention can be derived from the following detailed description. Other systems, methods, features and advantages of the invention will be, or will become, apparent to one with skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features and advantages be included within this description, be within the scope of the invention, and be protected by the following claims
The invention can be better understood with reference to the following drawings and description. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. Moreover, in the figures, like referenced numerals designate corresponding parts throughout the different views.
Each transistor 12, 14 has a control voltage connection. For a CMOS structure, the control connection 2 is a gate on each of the transistors 12, 14. In the embodiment of
The first transistor 12 has a connection 12a connected with a first potential V1. The potential V1 may be a ground potential. A further connection 12b of the first transistor 12 is connected to a signal output 1 of the output structure 20 and to a connection 14b of the second transistor 14. A further connection 14a of the second transistor 14 is connected to a second potential V2. The second potential V2 may be an internal supply voltage for the output structure 20, which in this embodiment is 1.5 V.
The signal output 1 of the output structure 20 is connected via a resistance means 5 in the form of a conventional resistor to a third potential V3. The resistance means 5 may have a resistance on the order of 1 kΩ to 100 kΩ. The third potential V3 is an external voltage supply in a circuit environment of the semiconductor module, which may be approximately 3.3 V. The ternary signal 3 may be tapped at the signal output 1 of the output structure 20.
The function of the output structure 20 may be explained in connection with a method for producing the ternary signal 3 in a preferred embodiment. According to one method, a first signal level may be produced at a signal output 1 by connecting the signal output 1 to a first potential. A second signal level is produced by connecting the signal output 1 to a second potential. To produce a third signal level, the signal output 1 is connected via a resistance means 5 to a third potential and the signal output 1 is decoupled from the first potential and the second potential. The third signal level is produced at the signal output 1.
The first potential can be a ground potential V1, the second potential an internal supply voltage V2 of a semiconductor module, and the third potential an external supply voltage V3, which differs from the internal supply voltage of the output structure 20. The internal supply voltage V2 may be 1.5 Volts while the external supply voltage V3 may be 3.3 Volts. Utilizing the present method and the embodiment described above, the ternary signal output 1 may be produced without an additional voltage generated internally in the corresponding output structure 20 or by supplying an external voltage to the output structure 2. It is therefore possible for the number of connections for the semiconductor module to remain at a minimum.
In the preferred embodiment, the transistors 12, 14 may be controlled and actuated with a common control signal 2. The control signal 2 is generated in a control block 4 and is dependent upon binary signals 2a, 2b which may assume one of two states. The control block 4 may be designed in such a way that the control signal 2 may assume one of two possible values or that the input to the transistors be allowed to float or remain potential-free.
In an example for producing a LO signal, a control signal 2 may be applied to a gate of the transistors 12, 14 so that the first transistor 12 adopts a low-resistance state, while the second transistor 14 adopts a high-resistance state. In this case, the signal output 1 of the output structure 20 is connected along a path with low resistance to the first potential V1. The first potential V1 may have a potential that equals ground or earth potential and is provided at the signal output 1 as first signal level LO.
The voltage of the first signal level LO corresponds substantially to the level of the ground potential V1. A volume resistance of the first transistor 12, that is the resistance between the connection 12a and the connection 12b, is substantially less than the resistance of the resistance means 5. The volume resistance of the second transistor 14, that is the resistance between the connection 14a and the connection 14b, is substantially higher than the resistance 5. The resistances of the transistors 12, 14 ensure that the voltage present at signal output 1 is approximately equal to the ground potential.
In an example for producing a MID signal output, the transistors 12, 14 may be controlled and actuated by applying the control signal to the control connection 2 so that the second transistor 14 adopts a low-resistance state and the first transistor 12 adopts a high-resistance state. The signal output 1 of the output structure 20 is connected through the low-resistance of the second transistor 14 to the second potential V2. The second potential V2 may be the supply voltage V2 to the output structure 20. The second potential V2 will establish the value of the second signal level MID imposed at the signal output 1. In a preferred embodiment, the supply voltage of the semiconductor module may be 1.5 V. In this state, the forward resistance of the second transistor 14 may be substantially lower than the resistance of the resistance means 5 and the forward resistance of the first transistor 12 is substantially higher than the resistance of the resistance means 5.
In an example for producing a HI signal output, the common control signal applied to the control connection 2 for the transistors 12, 14 may be switched off, removed or allowed to float and be potential-free. Both the first transistor 12 and the second transistor 14 will adopt a high-resistance state. The high-resistance of the transistors 12, 14 will decouple the signal output from the first potential and the second potential sources. Therefore, the signal output 1 connects to the third potential source V3 via the resistance means 5. The third potential V3 may be an external supply voltage that provides a third signal level HI at the signal output 1. The external supply voltage may be 3.3 V. To provide a HI voltage level that reflects the potential of the external supply, the resistance of the first transistor 12 and the resistance of the second transistor 14 should be substantially higher than the resistance of the resistance means 5. The signal output 1 and the ternary signal 3 are essentially the same point electrically, thus whatever signal is present at the signal output 1 also may be present at the ternary signal 3 in
The conditions for obtaining the results for all three signal outputs may be optimized by selecting the value of the resistance means 5 to correspond with the resistances of transistors 12, 14. The resistances for the transistors 12, 14 may be obtained through dimensioning and configuring of the transistors 12, 14. The resistance value of the resistance means may range from 1 kΩ to 100 kΩ.
In the embodiment described, a common signal was applied to the control connection 2 of the transistors 12, 14 simultaneously. The transistors 12, 14 are controlled and actuated by the common control signal from the control block 4. As an alternative, however, it is possible for the transistors 12, 14 to be actuated and controlled separately. In other words, the binary signals 2a, 2b may be applied directly to the gates of transistors 12, 14 respectively. Therefore, a conversion of the binary signals 2a, 2b is effected directly to the transistors 12, 14, thus the control block 4 may be omitted. Further, the binary signals 2a, 2b may be allowed to float simultaneously in order to provide the decoupling of the potentials V1, V2 so that the third potential V3 may be realized.
The signal output 1 is connected via a resistance means 5 to the third potential V3. The resistance means 5 may be an external resistor outside of the output structure 20. There may be several output structures 20 in a semiconductor module. The resistance means 5 may be internal to the semiconductor module but yet still remain external to each of the output structures 20. Where the semiconductor module comprises several output structures 20, the resistance means 5 may be made available to the other output structures 20 that are connected to the ternary signal 3.
The method and the corresponding circuit arrangement for the output structure 20 of a semiconductor module offer an advantage that the ternary signal 3 may be produced from an output structure 20 that occupies a small surface area of a semiconductor chip. Another advantage that may be realized is the reduction in the number of connection pins. The output structure may be operated in a manner similar to a standard binary output structure having only two active states. The third potential may be provided externally when the control voltages are allowed to float effectively decoupling the potentials V1, V2 from the signal output. In addition, there is no need to provide a second supply voltage to the output structure 20. With the higher potential of the second power supply V3 in another module, problems regarding over-voltage protection for internal structures, particularly the output structure 20 of the semiconductor module may be avoided.
It is therefore intended that the foregoing detailed description be regarded as illustrative rather than limiting, and that it be understood that it is the following claims, including all equivalents, that are intended to define the spirit and scope of this invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 103 52 812.1 | Nov 2003 | DE | national |
