The present invention relates to a logic integrated circuit in which a logic circuit is reconfigurable, and particularly relates to a technique for reduced power consumption and increased integration of a logic integrated circuit.
A programmable logic integrated circuit in which a logic circuit is reconfigurable is also referred to as a reconfigurable circuit, and can reconfigure various logic circuits by rewriting internal setting information.
The number of configurable logics (circuit scale of a reconfigurable circuit) can be adjusted by designing a logic block (configurable logic block (CLB)) including an LB and an RB of a certain scale. Then, by adjusting the number of CLBs to be arranged in such a way as to be connected to one another, a semiconductor chip including a reconfigurable circuit of a different circuit scale according to customer needs can be manufactured. The reconfigurable circuit is currently used widely in a field such as generation of a prototype, image processing, and communication.
The RB being a switching unit of a signal is mounted by using a static random access memory (SRAM) switch constituted of an SRAM and a pass transistor. In recent years, as indicated in Patent Literature 1 (PTL1) and Patent Literature 2 (PTL2), a technique capable of reducing a chip area and power consumption by replacement with a resistance change element is proposed. As illustrated in
When a resistance change element is used as a switch on the reconfigurable circuit, a voltage is always applied to all the switches on the circuit. For this reason, higher reliability is required than that in a case of a memory switch to which a current and a voltage are applied only during an operation of reading data. Thus, instead of a switch cell having a 1T1R structure in which one resistance change element and one transistor are combined as a set, a complementary (1T2R) structure using one transistor and a pair of resistance change elements as illustrated in
The switch cell in a crossbar switch is disposed near each cross point of a wire (RV[j]) in a vertical direction and a wire (RH[k]) in a horizontal direction. Further, when the resistance change element near a certain cross point is turned on/off, two wires (SV[j] and GH[k]) for controlling the selection transistor (Tr.) are also connected in order to prevent false writing (disturbance) to the resistance change element being present near a different cross point. As illustrated in
The switch cell using the resistance change element described above constitutes a crossbar switch, and is used as a switching switch (multiplexer) for signal input and signal switching of a routing block (RB). A switch cell array using such a resistance change element is proposed in Patent Literature 5 (PTL5).
[PTL1] Japanese Patent No. 4356542
[PTL2] International Patent Publication No. WO2012/043502
[PTL3] International Patent Publication No. WO2013/190742
[PTL4] International Patent Publication No. WO2014/030393
[PTL5] International Patent Publication No. WO2016/042750
[NPL1] “Architecture of Reconfigurable-Logic Cell Array with Atom Switch: Cluster Size & Routing Fabrics”, Xu Bai, et. al., Proceedings of the 2015 ACM/SIGDA International Symposium on Field-Programmable Gate Arrays, pp. 269, (2015).
When a switch cell using a resistance change element constitutes a programmable logic integrated circuit, it is desired that a leakage current can be reduced while suppressing an increase in the number of connection wires and an area increase due to the increase in the number of connection wires.
An object of the present invention is to provide a logic integrated circuit capable of reducing a leakage current while suppressing an increase in the number of connection wires and an area increase due to the increase in the number of connection wires.
To achieve the above-mentioned object, a logical operation circuit according to the present application that comprises a plurality of first switch cells each including a resistance change element and a plurality of second switch cells each including a resistance change element, the logical operation circuit comprises:
a first output port and a second output port;
a plurality of first wires disposed along a first direction and connected to the first output port;
a plurality of second wires disposed along the first direction and connected to the second output port;
a plurality of first writing control lines disposed along the first wire and the second wire;
a plurality of third wires disposed along a second direction;
a plurality of second writing control lines disposed along the third wire;
the plurality of first switch cells that are disposed at a place where the first wire and the third wire intersect each other, have one of diffusion layers being connected to the first writing control line, and another diffusion layer being connected to the second writing control line, and switch an electrical connection between the first wire and the third wire;
the plurality of second switch cells that are disposed at a place where the second wire and the third wire intersect each other, have one of diffusion layers being connected to the first writing control line, and another diffusion layer being connected to the second writing control line, and switch an electrical connection between the second wire and the third wire;
a first control transistor that is connected to the first wire, and switches an electrical connection between a first power source line supplying power to the first wire and the first wire;
a third control transistor that is connected to the first writing control line, and switches an electrical connection between a second power source line supplying power to the first writing control line and the first writing control line; and a fourth control transistor that is connected to the third wire, and switches an electrical connection between a third power source line supplying power to the third wire and the third wire.
The present invention is able to provide a programmable logic integrated circuit capable of reducing a leakage current while suppressing an increase in the number of connection wires and an area increase due to the increase in the number of connection wires.
A problem to be solved by the present invention and a comparative example will be described prior to description of a specific example embodiment.
A crossbar switch circuit 10 in
The crossbar switch circuit 10 in
The switch cells 11d to 11f share a writing control line GH[k] and a signal line RH[k] being wires in the x direction. The writing control line GH[k] and the signal line RH[k] are wires independent of each other. The signal line RH[k] is connected to one of diffusion layers of the first control transistor 12b connected to the switch cells 11d to 11f. The power source line PS[0] is connected to the other diffusion layer of the first control transistor 12b. A writing control line GSH[k] is connected to a gate electrode of the first control transistor 12b. The writing control line GSH[k] is a wire used for changing a resistance of the switch element included in the switch cells 11d to 11f.
The switch cells 11g to 11i share a writing control line GH[k+1] and a signal line RH[k+1] being wires in the x direction. The writing control line GH[k+1] and the signal line RH[k+1] are wires independent of each other. The signal line RH[k+1] is connected to one of diffusion layers of the first control transistor 12c connected to the switch cells 11g to 11i. The power source line PS[0] is connected to the other diffusion layer of the first control transistor 12c. A writing control line GSH[k+1] is connected to a gate electrode of the first control transistor 12c. The writing control line GSH[k+1] is a wire used for changing a resistance of the switch element included in the switch cells 11g to 11i.
The switch cells 11a, 11d, and 11g share a writing control line SV[j−1] and a signal line RV[j−1] being wires in a y direction. The writing control line SV[j−1] and the signal line RV[j−1] are wires independent of each other. The writing control line SV[j−1] is connected to one of diffusion layers of the second control transistor 131a connected to the switch cells 11a, 11d, and 11g. A power source line PS[1] is connected to the other diffusion layer of the second control transistor 131a. A driver control line PGV[j−1] is connected to a gate electrode of the second control transistor 131a. Furthermore, the signal line RV[j−1] is connected to one of diffusion layers of the third control transistor 132a connected to the switch cells 11a, 11d, and 11g. A power source line PS[2] is connected to the other diffusion layer of the third control transistor 132a. The driver control line PGV[j−1] is connected to a gate electrode of the third control transistor 132a.
The switch cells 11b, 11e, and 11h share a writing control line SV[j] and a signal line RV[j] being wires in the y direction. The writing control line SV[j] and the signal line RV[j] are wires independent of each other. The writing control line SV[j] is connected to one of diffusion layers of the second control transistor 131b connected to the switch cells 11b, 11e, and 11h. The power source line PS[1] is connected to the other diffusion layer of the second control transistor 131b. A driver control line PGV[j] is connected to a gate electrode of the second control transistor 131b. Furthermore, the signal line RV[j] is connected to one of diffusion layers of the third control transistor 132b connected to the switch cells 11b, 11e, and 11h. The power source line PS[2] is connected to the other diffusion layer of the third control transistor 132b. The driver control line PGV[j] is connected to a gate electrode of the third control transistor 132b.
The switch cells 11c, 11f, and 11i share a writing control line SV[j+1] and a signal line RV[j+1] being wires in the y direction. The writing control line SV[j+1] and the signal line RV[j+1] are wires independent of each other. The writing control line SV[j+1] is connected to one of diffusion layers of the second control transistor 131c connected to the switch cells 11c, 11f, and 11i. The power source line PS[1] is connected to the other diffusion layer of the second control transistor 131c. A driver control line PGV[j+1] is connected to a gate electrode of the second control transistor 131c. Furthermore, the signal line RV[j+1] is connected to one of diffusion layers of the third control transistor 132c connected to the switch cells 11c, 11f, and 11i. The power source line PS[2] is connected to the other diffusion layer of the third control transistor 132c. The driver control line PGV[j+1] is connected to a gate electrode of the third control transistor 132c.
The crossbar switch circuit 10a can function as a memory when the power source level (Vdd) and the ground level (GND) are input to two RV ports of a crossbar switch configuration. An output level of an output node of the crossbar switch circuit 10a can be controlled to the Vdd or the GND when a switch cell at the Vdd or the GND is brought into an on state.
The multiplexer 15 in
A memory for a lookup table (LUT) in an LB can also be mounted by the same process without using another memory by using a resistance change switch cell (crossbar switch) used as a switch of an RB illustrated in
The number of wires constituting the crossbar switch circuit 10a (2×K crossbar) of 2 inputs and K outputs in
On the other hand, another mounting method is also conceivable.
A crossbar switch circuit 10b1 that inputs a power source level (Vdd) as the signal line RV* of the crossbar switch circuit 10b (1×K crossbar) of 1 input and K outputs in
This mounting method (LUT architecture B) has a configuration in which an operating voltage (Vdd=1 V) is applied to only one switch cell in an off state. When an off resistance per switch cell is assumed to be 100 NM, a leakage current is 10 nA per LUT, which enables reducing a leakage current occurring in a resistance change element in an off state to ½N in the LUT architecture B as compared to that in the LUT architecture A.
On the other hand, the LUT architecture B needs 2×2N=2×K, which is twice that in the case of
Next, a logic integrated circuit and a reconfigurable circuit according to a first example embodiment will be described.
A crossbar switch circuit 30 in
The switch cells 11a and 11b share a writing control line GH[k−1] (also referred to as a first writing control line) being a wire in the x direction (also referred to as a first direction). A signal line RH1[k−1] is connected to one of diffusion layers of the control transistor 171a connected to the switch cell 11a. A signal line RH2[k−1] is connected to one of diffusion layers of the control transistor 172a connected to the switch cell 11b. A power source line PS[0] (also referred to as a first power source line) is connected to the other diffusion layer of the control transistor 171a and the control transistor 172a. A writing control line PGV[1] (also referred to as a second writing control line) is connected to a gate electrode of the control transistor 171a. A writing control line PGV[2] (also referred to as a third writing control line) is connected to a gate electrode of the control transistor 172a.
The switch cells 11d and 11e share a writing control line GH[k] being a wire in the x direction. A signal line RH1[k] is connected to one of diffusion layers of the control transistor 171b connected to the switch cell 11d. A signal line RH2[k] is connected to one of diffusion layers of the control transistor 172b connected to the switch cell 11e. The power source line PS[0] is connected to the other diffusion layer of the control transistor 171b and the control transistor 172b. The writing control line PGV[1] is connected to a gate electrode of the control transistor 171b. The writing control line PGV[2] is connected to a gate electrode of the control transistor 172b.
The switch cells 11g and 11h share a writing control line GH[k+1] being a wire in the x direction. A signal line RH1[k+1] is connected to one of diffusion layers of the control transistor 171c connected to the switch cell 11g. A signal line RH2[k+1] is connected to one of diffusion layers of the control transistor 172c connected to the switch cell 11h. The power source line PS[0] is connected to the other diffusion layer of the control transistor 171c and the control transistor 172c. The writing control line PGV[1] is connected to a gate electrode of the control transistor 171c. The writing control line PGV[2] is connected to a gate electrode of the control transistor 172c.
The switch cells 11a, 11d, and 11g share a writing control line SV[1] (also referred to as a second writing control line) and a signal line RV[1] being a wire in the y direction (also referred to as a second direction). The writing control line SV[1] is connected to one of diffusion layers of the control transistor 181a connected to the switch cells 11a, 11d, and 11g. A power source line PS[1] (also referred to as a second power source line) is connected to the other diffusion layer of the control transistor 181a. The signal line RV[1] is connected to one of diffusion layers of the control transistor 182a connected to the switch cells 11a, 11d, and 11g. A power source line PS[2] (also referred to as a third power source line) is connected to the other diffusion layer of the control transistor 182a.
The switch cells 11b, 11e, and 11h share a writing control line SV[2] and a signal line RV[2] being wires in the y direction. The writing control line SV[2] is connected to one of diffusion layers of the control transistor 181b connected to the switch cells 11b, 11e, and 11h. The power source line PS[1] is connected to the other diffusion layer of the control transistor 181b. The signal line RV[2] is connected to one of diffusion layers of the control transistor 182b connected to the switch cells 11b, 11e, and 11h. The power source line PS[2] (also referred to as a third power source line) is connected to the other diffusion layer of the control transistor 182b.
In the crossbar switch circuit 30 in
The power source line PS[0] for writing that runs in the vertical direction in
In
In the crossbar switch circuit 30 in
A lookup table 32 (LUT 32) in
The multiplexer 31a is constituted of the plurality of PMOS switches 311a, and
As illustrated in
When a switch cell connected to a source on the PMOS side in two crossbars connected to both ends of one conduction path is brought into an on state, and a Vdd is output, a switch cell in a crossbar connected to a drain on the opposite NMOS side is brought into an off state, and a high resistance state (high impedance state: Hi-Z) is output.
In this way, a Vdd level can be output in the output node OUT in which the source and the drain of the PMOS switch 311a being a final stage of the multiplexer 31a in the LUT 32 and the NMOS switch 311b being a final stage of the multiplexer 31b are connected to each other.
In contrast, when the switch cell in the crossbar switch connected to the source on the PMOS switch 311a side is brought into an off state, and the high impedance state (Hi-Z) is output, the switch cell in the crossbar switch connected to the drain on the NMOS switch 311b side on the opposite side is brought into an on state, and a GND is output. In this way, a GND level can be output in the output node OUT in which the source and the drain of the NMOS switch 311b and the PMOS switch 311a in the LUT 32 are connected to each other.
In this way, a desired logical operation can be performed as the LUT 32 when one rewrites a switch cell on a path selected for each gate input signal set to the LUT 32 with paying attention to the complementarity described above.
Next, a logic integrated circuit and a reconfigurable circuit according to a second example embodiment will be described. In the first example embodiment, the crossbar switch circuit used as the memory for the lookup table (LUT) is described as one example of the logic integrated circuit and the reconfigurable circuit. However, the present invention is not limited to the logic integrated circuit and the reconfigurable circuit in the first example embodiment having the configuration described above. For example, the multiplexers 31a and 31b constituting the LUT 32 according to the example embodiment illustrated in
In a case of the LUT 32 constituted of the multiplexers 31c and 31d illustrated in
Next, a logic integrated circuit and a reconfigurable circuit according to a third example embodiment will be described. In the first example embodiment, the crossbar switch circuit used as the memory for the lookup table (LUT) is described as one example of the logic integrated circuit and the reconfigurable circuit. The present example embodiment is an application example using the crossbar switch circuit according to the first example embodiment.
The logic integrated circuit and the reconfigurable circuit in
The multiplexer 41a selects an output from a second output port of the crossbar switch circuit 40a, and outputs the output. The multiplexer 41b selects an output from a second output port of the crossbar switch circuit 40b, and outputs the output. The LUT[0] is constituted of the crossbar switch circuit 40a and the multiplexer 41a. The LUT[1] is constituted of the crossbar switch circuit 40a and the multiplexer 41a.
Next, a logic integrated circuit and a reconfigurable circuit according to a fourth example embodiment will be described. In the first example embodiment, the crossbar switch circuit used as the memory for the lookup table (LUT) is described as one example of the logic integrated circuit and the reconfigurable circuit. The present example embodiment is an application example using the crossbar switch circuit according to the first example embodiment.
A logic integrated circuit and a reconfigurable circuit in
The present example embodiment makes use of a first output port that is not used as a crossbar memory of the LUT and is different from the second output port which constitutes a part of the LUT of the crossbar switch circuit 50a. In this way, a memory circuit for parameter setting can be constituted by connecting the output port of the crossbar switch circuit 50b being prepared separately and the first output port of the crossbar switch circuit 50a to each other via the CMOS switch 52. Such a configuration can make effective use of the unused output port (first output port) of the crossbar switch circuit 40a present at the end as in
Next, an integrated circuit including a logic integrated circuit and a reconfigurable circuit according to a fifth example embodiment will be described.
As illustrated in
While the preferable example embodiments have been described above, the present invention is not limited to the example embodiments. As in
Further, a synchronous circuit such as a DFF may be present in a logic block (LB) of a reconfigurable circuit as necessary, and the setting memory described in the fourth example embodiment described above as synchronous and asynchronous selections of a signal may be used as an input signal to a selector.
An input-output signal between LBs may be connected via a routing block (RB) mounted by a crossbar as illustrated in
An input-output signal between LBs is connected via the routing block (RB) as illustrated in
As a resistance change element used for a switch cell, a resistance change element that has a resistance state being changed by application of a voltage equal to or greater than a certain value for a predetermined period of time or longer and being held, such as a resistance random access memory (ReRAM) using a transition-metal oxide and NanoBridge (Registered Trademark of NEC Corporation) using an ion conductor, may be used. Further, from a viewpoint of high disturb tolerance, it is desirable that a resistance change element is a bipolar-type resistance change element having polarity in an application direction of a voltage, and a configuration in which a bipolar-type resistance change elements are connected in series while opposing each other and a switch (transistor) is disposed at a connecting point of the two switches.
The whole or part of the example embodiments disclosed above can be described as, but not limited to, the following supplementary notes.
A logical operation circuit that comprises a plurality of first switch cells each including a resistance change element and a plurality of second switch cells each including a resistance change element, the logical operation circuit comprising:
a first output port and a second output port;
a plurality of first wires disposed along a first direction and connected to the first output port;
a plurality of second wires disposed along the first direction and connected to the second output port;
a plurality of first writing control lines disposed along the first wire and the second wire;
a plurality of third wires disposed along a second direction;
a plurality of second writing control lines disposed along the third wire;
the plurality of first switch cells that are disposed at a place where the first wire and the third wire intersect each other, have one of diffusion layers being connected to the first writing control line, and another diffusion layer being connected to the second writing control line, and switch an electrical connection between the first wire and the third wire;
the plurality of second switch cells that are disposed at a place where the second wire and the third wire intersect each other, have one of diffusion layers being connected to the first writing control line, and another diffusion layer being connected to the second writing control line, and switch an electrical connection between the second wire and the third wire;
a first control transistor that is connected to the first wire, and switches an electrical connection between a first power source line supplying power to the first wire and the first wire;
a second control transistor that is connected to the second wire, and switches an electrical connection between the first power source line supplying power to the second wire and the second wire;
a third control transistor that is connected to the first writing control line, and switches an electrical connection between a second power source line supplying power to the first writing control line and the first writing control line; and a fourth control transistor that is connected to the third wire, and switches an electrical connection between a third power source line supplying power to the third wire and the third wire.
The logical operation circuit according to supplementary note 1, wherein a plurality of the first control transistors are provided according to a number of the plurality of first wires, and a gate of the plurality of first control transistors is connected in a shared manner.
The logical operation circuit according to supplementary note 1 or 2, wherein
a plurality of the second control transistors are provided according to a number of the plurality of second wires, and
a gate of the plurality of second control transistors is connected in a shared manner.
The logical operation circuit according to any one of supplementary notes 1 to 3, wherein,
among a plurality of second writing control lines, a gate of a third control transistor connected to a second writing control line connected to the plurality of first switch cells and a gate of a fourth control transistor connected to a third wire connected to the plurality of first switch cells are connected to a gate of the plurality of first control transistors in a shared manner.
The logical operation circuit according to any one of supplementary notes 1 to 4, wherein,
among a plurality of second writing control lines, a gate of a third control transistor connected to a second writing control line connected to the plurality of second switch cells and a gate of a fourth control transistor connected to a third wire connected to the plurality of second switch cells are connected to a gate of the plurality of second control transistors in a shared manner.
A lookup table comprising:
The lookup table according to supplementary note 6, further comprising:
a plurality of the logical operation circuits according to any one of supplementary notes 1 to 5;
a plurality of switches of a first conductive-type transistor being a plurality of switches that select an output from the first output port of one of the logical operation circuits;
a plurality of switches of a second conductive-type transistor being a plurality of switches that selects an output from the second output port of another of the logical operation circuits; and
an output node derived from a switch of an output stage of the plurality of switches of the first conductive-type transistor and a switch of an output stage of the plurality of switches of the second conductive-type transistor.
The lookup table according to supplementary note 7, further comprising:
a switch of a first conductive-type transistor inserted between a switch of an output stage of the plurality of switches of the first conductive-type transistor and the output node; and
a switch of a second conductive-type transistor inserted between a switch of an output stage of the plurality of switches of the second conductive-type transistor and the output node.
The lookup table according to any one of supplementary notes 6 to 8, wherein
the first output port or the second output port on a side that is not selected by the multiplexer that selects an output from the first output port or the second output port among the first output port and the second output port outputs data for parameter setting.
A reconfigurable circuit comprising:
a first crossbar memory including the logical operation circuit according to any one of supplementary notes 1 to 5;
a second crossbar memory including the logical operation circuit according to any one of supplementary notes 1 to 5; and
a multiplexer that selects an output from a first output port of the first crossbar memory, and outputs the output to a second output port of the second crossbar memory.
An integrated circuit that comprises a plurality of the logical operation circuits according to any one of supplementary notes 1 to 5, a plurality of the lookup tables according to any one of supplementary notes 6 to 9, or a plurality of the reconfigurable circuits according to supplementary note 10, and is configured by connecting the above to one another.
An integrated circuit comprising:
the logical operation circuit according to any one of supplementary notes 1 to 5, the lookup table according to any one of supplementary notes 6 to 9, or the reconfigurable circuit according to supplementary note 10 or 11; and
an arithmetic circuit that is not reconfigurable but enables a signal processing function, wherein
the logical operation circuit, the lookup table, or the reconfigurable circuit, and an arithmetic circuit that enables the signal processing function transmit and receive a signal to and from each other via a signal switching unit.
The logical operation circuit according to any one of supplementary notes 1 to 5, wherein
a complementary element included in the plurality of first switch cells and the plurality of second switch cells is a first resistance change element and a second resistance change element of a bipolar type, and
the first resistance change element and the second resistance change element are disposed in such a way that resistance change polarities face each other.
The logical operation circuit according to supplementary note 13, wherein
the first resistance change element and the second resistance change element are an atom transfer-type element using an ion conductive layer.
The present invention has been described above by taking the above-described example embodiments as exemplary examples. However, the present invention is not limited to the above-described example embodiment. In other words, various aspects that can be understood by those skilled in the art can be applied to the present invention within the scope of the present invention.
This application is based upon and claims the benefit of priority from Japanese patent application No. 2017-182658, filed on Sep. 22, 2017, the disclosure of which is incorporated herein in its entirety by reference.
Number | Date | Country | Kind |
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2017-182658 | Sep 2017 | JP | national |
Filing Document | Filing Date | Country | Kind |
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PCT/JP2018/034150 | 9/14/2018 | WO | 00 |