AREA AND POWER EFFICIENT CIRCUITS FOR HIGH-DENSITY STANDARD CELL LIBRARIES

Abstract

Example embodiments provide a four input multiplexer integrated circuit (MXT4) associated with an integrated circuit (IC) and a method for reducing area and power of an integrated circuit (IC) using a MXT4, the MXT4 including a complementary signal generator circuit configured to receive first and second selection signals and to generate first and second complementary selection signals based on respective ones of the first and the second selection signals; and a p-type metal oxide semiconductor (PMOS) and an n-type metal oxide semiconductor (NMOS) stack switch circuit configured to transmit at least one input signal to an output based on the first and the second selection signals and the first and the second complementary selection signals.

Claims

1. A four input multiplexer integrated circuit (MXT4) associated with an integrated circuit (IC), the MXT4 comprising: a complementary signal generator circuit configured to receive first and second selection signals and to generate first and second complementary selection signals based on respective ones of the first and the second selection signals; and a p-type metal oxide semiconductor (PMOS) and an n-type metal oxide semiconductor (NMOS) stack switch circuit configured to transmit at least one input signal to an output based on the first and the second selection signals and the first and the second complementary selection signals.

2. The MXT4 of claim 1, wherein the complementary signal generator circuit includes one or more inverters.

3. The MTX4 of claim 2, wherein the one or more inverters of the complementary signal generator circuit include two inverters configured to receive the respective ones of the first and the second selection signals without the first and the second input signals being passed through buffers, and to generate the first and the second complementary selection signals.

4. The MTX4 of claim 1, wherein the PMOS and NMOS stack switch circuit is configured to receive first to fourth input signals, and to transmit one of the first to the fourth input signals to the output based on the first and the second selection signals and the first and the second complementary selection signals.

5. The MTX4 of claim 4, wherein the PMOS and NMOS stack switch circuit is configured to transmit one of the first to the fourth input signals to the output without the first to the fourth input signal being passed through a transmission gate.

6. The MTX4 of claim 4, wherein the PMOS and NMOS stack switch circuit comprises: first to fourth PMOS transistors connected to a source, the first to fourth PMOS transistors configured to receive the first to the fourth input signals, respectively; and first to fourth NMOS transistors connected to a ground, the first to fourth NMOS transistors configured to receive the first to the fourth input signals, respectively, wherein the first to the fourth input signals are only provided to a circuit including the first to the fourth PMOS transistors and the first to the fourth NMOS transistors.

7. The MTX of claim 6, wherein the PMOS and NMOS stack switch circuit further comprises: fifth and sixth PMOS transistors connected to the first and the third PMOS transistors in series, respectively, the fifth and sixth PMOS transistors configured to receive the first selection signal; seventh and eighth PMOS transistors connected to the second and the fourth PMOS transistors in series, respectively, the seventh and eighth PMOS transistors configured to receive the first complementary selection signal; fifth and sixth NMOS transistors connected to the first and the third NMOS transistors in series, respectively, the fifth and sixth NMOS transistors configured to receive the first complementary selection signal; and seventh and eighth NMOS transistors connected to the second and the fourth NMOS transistors in series, respectively, the seventh and eighth NMOS transistors configured to receive the first selection signal, wherein the first selection signal and the first complementary selection signal are only provided to a circuit including the fifth to the eighth PMOS transistors and the fifth to the eighth NMOS transistors.

8. The MTX of claim 7, wherein the PMOS and NMOS stack switch circuit further comprises: a ninth PMOS transistor connected to the fifth and the seventh PMOS transistors at a first node, the ninth PMOS transistor configured to receive the second selection signal; a tenth PMOS transistor connected to the sixth and the eighth PMOS transistors at a second node, the tenth PMOS transistor configured to receive the second complementary selection signal; a ninth NMOS transistor connected to the fifth and the seventh NMOS transistors at a third node, the ninth NMOS transistor configured to receive the second complementary selection signal; and a tenth NMOS transistor connected to the sixth and the eighth NMOS transistors at a fourth node, the tenth NMOS transistor configured to receive the second selection signal, wherein the second selection signal and the second complementary selection signal are only provided to a circuit including the ninth and the tenth PMOS transistors and the ninth and the tenth NMOS transistors.

9. The MTX of claim 8, wherein the ninth and the tenth PMOS transistors and the ninth and the tenth NMOS transistors are connected to a fifth node, and the PMOS and NMOS stack switch circuit further comprises: an inverter having an input connected to the fifth node, the inverter configured to generate an output signal at the output.

10. A method for reducing area and power of an integrated circuit (IC) using a four input multiplexer Integrated circuit (MXT4), the method comprising: generating, by a complementary signal generator circuit, first and second complementary selection signals based on respective ones of first and second selection signals; and transmitting, by a PMOS and a NMOS stack switch circuit, at least one input signal to an output based on the first and the second selection signals and the first and the second complementary selection signals.

11. The method of claim 10, wherein the generating the first and the second complementary selection signals comprises: generating the first and the second complementary selection signals based on the respective ones of first and second selection signals without the first and the second selection signals passing through buffers.

12. The method of claim 10, wherein the transmitting the at least one input signal to the output comprises: receiving first to fourth input signals, the first and the second selection signals, and the first and the second complementary signals; and transmitting one of the first to the fourth input signals to the output based on the first and the second selection signals, and the first and the second complementary signals.

13. The method of claim 12, wherein the transmitting one of the first to the fourth input signals to the output comprises: transmitting one of the first to the fourth input signals to the output based on the first and the second selection signals, and the first and the second complementary signals without the first to the fourth input signal being passed through a transmission gate.

14. The method of claim 12, wherein the receiving the first to the fourth input signals, the first and the second selection signals, and the first and the second complementary signals comprises: providing the first to the fourth input signals to first to fourth PMOS transistors, respectively; and providing the first to the fourth input signals to first to fourth NMOS transistors, respectively, wherein the first to the fourth input signals are only provided to a circuit including the first to the fourth PMOS transistors and the first to the fourth NMOS transistors.

15. The method of claim 14, wherein the receiving the first to the fourth input signals, the first and the second selection signals, and the first and the second complementary signals comprises: providing the first selection signal to fifth and sixth PMOS transistors connected to the first and the third PMOS transistors, respectively; providing the first complementary selection signal to seventh and eighth PMOS transistors connected to the second and the fourth PMOS transistors, respectively; providing the first complementary selection signal to fifth and sixth NMOS transistors connected to the first and the third NMOS transistors, respectively; and providing the first selection signal to seventh and eighth NMOS transistors connected to the second and the fourth NMOS transistors, respectively, wherein the first selection signal and the first complementary selection signal are only provided to a circuit including the fifth to the eighth PMOS transistors and the fifth to the eighth NMOS transistors.

16. The method of claim 15, wherein the receiving the first to the fourth input signals, the first and the second selection signals, and the first and the second complementary signals comprises: providing the second selection signal to ninth PMOS transistor connected to a source via the first and the fifth PMOS transistors and via the second and the seventh PMOS transistors; providing the second complementary selection signal to tenth PMOS transistor connected to the source via the third and the sixth PMOS transistors and via the fourth and the eighth transistors; providing the second complementary selection signal to ninth NMOS transistor connected to a ground via the first and the fifth NMOS transistors and via the second and the seventh NMOS transistors; and providing the second selection signal to tenth NMOS transistor connected to the ground via the third and the sixth NMOS transistors and via the fourth and the eighth NMOS transistors, wherein the second selection signal and the second complementary selection signal are only provided to a circuit including the ninth and tenth PMOS transistors and the ninth and the tenth NMOS transistors.

17. The method of claim 16, wherein the ninth and the tenth PMOS transistors, and the ninth and the tenth NMOS transistors are commonly connected at an internal node, and wherein the transmitting one of the first to the fourth input signals to the output comprises: generate an output signal at the output by inverting an internal signal of the internal node.

18. A four input multiplexer integrated circuit (MXT4) associated with an integrated circuit (IC), the MXT4 comprising: a complementary signal generator circuit configured to receive first and second selection signals, and to generate first and second complementary selection signals by inverting the first and the second selection signals, respectively; and first to fourth PMOS stacks configured to receive first to fourth input signals, respectively, and to receive one of the first selection signal and the first complementary selection signal; first to fourth NMOS stacks configured to receive the first to fourth input signals, respectively, and to receive one of the first selection signal and the first complementary selection signal; a first PMOS and NMOS stack and a second PMOS and NMOS stack, the first PMOS and NMOS stack and the second PMOS and NMOS stock each configured to receive the second selection signal and the second complementary selection signal; and an inverter configured to receive an internal signal from the first stack and the second stack, and to generate an output signal at an output.

19. The MXT4 of claim 18, wherein the first PMOS stack and the second PMOS stack are connected in parallel between a source and a first node, the third PMOS stack and the fourth PMOS stack are connected in parallel between the source and a second node, the first NMOS stack and the second NMOS stack are connected in parallel between a ground and a third node, and the third NMOS stack and the fourth NMOS stack are connected in parallel between the ground and a fourth node.

20. The MXT4 of claim 19, wherein the first PMOS and NMOS stack is connected between the first node and the third node, and the second PMOS and NMOS stack is connected between the second node and the fourth node.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Example embodiments herein are illustrated in the accompanying drawings, throughout which like reference letters indicate corresponding parts in the various figures. The example embodiments herein will be better understood from the following description with reference to the drawings, in which:

[0019] FIG. 1 illustrates a conventional full adder circuit;

[0020] FIG. 2 illustrates a conventional 4-input multiplexer (MXT4) circuit;

[0021] FIG. 3 illustrates a full adder (ADDF) circuit for high density standard cell libraries according to at least one example embodiment;

[0022] FIG. 4 illustrates a circuit layout of the ADDF circuit according to at least one example embodiment;

[0023] FIG. 5 illustrates 4-input multiplexer (MXT4) circuit for high density standard cell libraries according to at least one example embodiment;

[0024] FIG. 6 illustrates a circuit layout of the MXT4 circuit according to at least one example embodiment;

[0025] FIG. 7 is a block diagram illustrating various unit of the ADDF circuit according to at least one example embodiment; and

[0026] FIG. 8 is a block diagram illustrating various unit of the MXT4 circuit according to at least one example embodiment.

DETAILED DESCRIPTION

[0027] Example embodiments herein and the various features and advantageous details thereof are explained more fully with reference to the non-limiting example embodiments that are illustrated in the accompanying drawings and detailed in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the example embodiments herein. The description herein is intended merely to facilitate an understanding of ways in which the example embodiments herein can be practiced and to further enable those of skill in the art to practice the example embodiments herein. Accordingly, this disclosure should not be construed as limiting the scope of the example embodiments herein.

[0028] The example embodiments herein provide a full adder (ADDF) circuit for improving (or, alternatively optimizing) area and power of an integrated circuit (IC). The ADDF includes a complementary signal generator circuit to receive three input signals and generate corresponding complementary output signals for the received three input signals. The three input signals include at least one of a high logic level and a low logic level. Further, the ADDF includes an internal signal generator circuit to generate an internal signal using two complementary output signals out of the generated three corresponding complementary output signals, and one of the three input signals. Further, the ADDF includes a summation (SUM) output signal generator circuit to generate an output summation (SUM) signal using one complementary output signal out of the generated three corresponding complementary output signals, the generated internal signal and a complementary internal signal of the generated internal signal. Further, the ADDF include a carryout (CO) signal generator circuit configured to generate a carry-out signal (CO) using two complementary output signal out of the generated three corresponding complementary output signals, the generated internal signal and the complementary internal signal of the generated internal signal.

[0029] The example embodiments herein provide a four input multiplexer Integrated circuit (MXT4) for improving (or, alternatively, optimizing) area and power of an integrated circuit (IC). The MXT4 includes a complementary signal generator circuit to receive two selection input signals and generate corresponding complementary selection output signals for the received two selection input signals. Further, the MXT4 includes a p-type metal oxide semiconductor (PMOS) and a n-type metal oxide semiconductor (NMOS) stack switch circuit to transmit at least one input signal to an output based on the received two selection input signals and the generated corresponding two complementary selection output signals.

[0030] Referring now to the drawings, and more particularly to FIGS. 3 through 6, where similar reference characters denote corresponding features consistently throughout the figures, there are shown some example embodiments.

[0031] FIG. 3 illustrates a full adder (ADDF) 300 circuit for high density standard cell libraries, according to at least one example embodiments, and FIG. 4 illustrates a circuit layout of the ADDF 300 circuit for high density standard cell libraries.

[0032] Referring to FIGS. 3 and 4, in an example embodiment, the ADDF 300 may include a complementary signal generator circuit 302, an internal signal generator circuit 304, a summation (SUM) output signal generator circuit 306 and a carryout (CO) signal generator circuit 308.

[0033] The complementary signal generator circuit 302 includes one or more inverters. The one or more inverters can be configured to receive three input signals A, B and CI, wherein the three input signals A, B and CI are adapted to take values either high logic level or low logic level. Further, the one or more inverters can be configured to generate three corresponding complementary output signals AN, BN and CIN based on the three input signals A, B and CI.

[0034] The internal signal generator circuit 304 includes combination of transmission gates, PMOS and NMOS stack and an inverter. The internal signal generator circuit 304 can be configured to generate an internal signal AXORB using two complementary output signals (e.g., AN and BN) out of the three corresponding complementary output signals AN, BN and CIN and one of the three input signals (e.g., B). Further, the internal signal generator circuit 304 can be configured to generate a complementary internal signal (e.g., AXNORB).

[0035] The SUM output signal generator circuit 306 includes combination of transmission gates, a PMOS and a NMOS stack and an inverter. Further, the SUM output signal generator circuit 306 can be configured to generate an output SUM signal using one complementary output signal (e.g., CIN) out of the generated three corresponding complementary output signals AN, BN and CIN, the generated internal signal and the generated complementary internal signal of the generated internal signal.

[0036] The CO signal generator circuit 308 includes two inverter drivers for driving output signals. The CO signal generator circuit 308 can be configured to generate a carry-out signal (CO) using two complementary output signals (e.g., BN and CIN) out of the generated three corresponding complementary output signals AN, BN and CIN, the internal signal (e.g., AXORB) and the complementary internal signal (e.g., AXNORB) of the generated internal signal.

[0037] For example, the ADDF 300 can be configured to take 3-Input signals A, B and CI which can take values either high (Logic 1) or low (Logic 0). Hence, the ADDF 300 can be configured to receive a total of 8 input signal combinations. Further, the ADDF 300 can be configured to generate three complementary output signals depending on the input signals A, B and CI. The three complementary output signals includes AN, BN and CIN signals, which are complementary version of the input signals A, B and CI respectively. Further, the ADDF 300 can be configured to generate an internal signal for example, AXORB signal, which is generated based on the complementary output signals AN, BN and the input signal B. Further, the AXORB signal can be transmitted through an inverter and generates AXNORB signal, which is a complementary internal signal generated based on the internal signal. Further, a signal Z can be generated based on the signals CIN, AXORB and AXNORB. Further, the generated signal Z can be transmitted through the inverter and generates an output summation (SUM) signal. The output SUM signal has proper driver which provide glitch-less signal and which can be easily scalable. Similarly signal X is generated depending on the signals BN, CIN, AXORB and AXNORB. Further, the signal X can be transmitted through the inverter and generate output carry-out signal (CO).

[0038] FIG. 5 illustrates 4-input multiplexer (MXT4) circuit 500 for high density standard cell libraries, according to at least one example embodiment, and FIG. 6 illustrates a circuit layout of the MXT4 circuit for high density standard cell libraries.

[0039] Referring to FIGS. 5 and 6, in an example embodiment, the MXT4 circuit 500 includes a complementary signal generator circuit 502 and a PMOS and a NMOS stack switch circuit 504.

[0040] The complementary signal generator circuit 502 of the MXT4 circuit 500 can be configured to receive two selection input signals S0 and S1, and to generate corresponding complementary selection output signals NS0 and NS1 based on respective ones of the two selection input signals S0 and S1.

[0041] Further, depending on the selection input signal S0 and S1, the PMOS and the NMOS stack switch circuit 504 can be configured to transmit at least one of input signal A, B C and D as an output signal Y. The selection signals S0, S1, NS0 and NS1 are used as a control signals for the NMOS's and the PMOS's stack.

[0042] In an example embodiment, based on the combination of S0 and S1, the NMOS's and the PMOS's stack conducts and then the output signal Y can be pulled-down (goes to logic 0) or pulled-up (goes to logic 1) depending upon the at least one of input signals A,B, C and D.

[0043] The MXT4 circuit 500 doesn't use any of the input inverters, which is required only because of transmission gates (TGs). Since, the TGs are not used in the MXT4 design, which helps in closing the layout in lesser area.

[0044] FIG. 7 is a block diagram illustrating various unit of the ADDF 300 circuit, according to at least one example embodiment.

[0045] Referring to FIG. 7, The ADDF 300 includes the complementary signal generator circuit 302, the internal signal generator circuit 304, the SUM output signal generator circuit 306 and the CO signal generator circuit 308.

[0046] The complementary signal generator circuit 302 can be configured to receive three input signals A, B and C and generate three corresponding complementary output signals AN, BN and CIN based on respective ones of the three input signals A, B and C. The three input signals A, B and C each have one of the high logic level and the low logic level.

[0047] Further, the internal signal generator circuit 304 can be configured to generate an internal signal AXORB, BXORB or CXORB using two complementary output signals out of the three corresponding complementary output signals AN, BN and CIN, and one of the three input signals A, B and C.

[0048] The SUM output signal generator circuit 306 can be configured to generate an output SUM signal using one complementary output signal out of the three corresponding complementary output signals AN, BN and CIN, the internal signal AXORB, BXORB or CXORB and the complementary internal signal AXNORB, BXNORB or CXNORB associated with the internal signal AXORB, BXORB or CXORB.

[0049] The CO signal generator circuit 308 can be configured to generate a carry-out signal (CO) using two complementary output signals out of the three corresponding complementary output signals AN, BN and CIN, the generated internal signal AXORB, BXORB or CXORB and the complementary internal signal AXNORB, BXNORB or CXNORB associated with the internal signal AXORB, BXORB or CXORB.

[0050] The ADDF 300 can use less number of transmission gates (TGs) in the internal signal generator circuit 304 and the SUM output signal generator circuit 306, thereby reduces surface area of the IC.

[0051] FIG. 8 is a block diagram illustrating various unit of the MXT4 circuit 500, according to at least one example embodiment.

[0052] Referring to FIG. 8, the MXT4 circuit 500 includes the complementary signal generator circuit 502 and the PMOS and the NMOS stack switch circuit 504.

[0053] The complementary signal generator circuit 502 can be configured to receive two selection input signals S0 and S1 and generate two corresponding complementary selection output signals NS0 and S1 based on respective ones of the two selection input signals S0 and S1.

[0054] Further, the PMOS and the NMOS stack switch circuit 504 can be configured to transmit at least one of input signals A, B, C or D as an output signal Y based on the two selection input signals S0, S1 and the two corresponding complementary selection output signals NS0 and NS1.

[0055] The MXT4 500 does not use any transmission gates (TGs), thereby reduces surface area of the IC.

[0056] The example embodiments disclosed herein can be implemented through at least one software program running on at least one hardware device and performing network management functions to control the elements. The elements shown in FIG. 3 and FIG. 5 can be at least one of a hardware device, or a combination of hardware device and software module.

[0057] A standard cell included in an IC may be selected from a standard cell library including information about a plurality of standard cells, based on a physical characteristic of the standard cell such as a function and a timing characteristic. By placing an instance of the selected standard cell, a layout of the IC may be generated.

[0058] The standard cell library may include a high density standard cell library that includes the full adder (ADDF) circuit 300 for high density standard cell libraries according to at least one example embodiment and/or the 4-input multiplexer (MXT4) circuit 500 for high density standard cell libraries according to at least one example embodiment.

[0059] The high density standard cell library may include information about characteristics of a plurality of standard cells having different characteristics. For example, the high density standard cell library may include information about a power characteristic, a timing characteristic, or a shape characteristic of the ADDF circuit 300 and/or the 4-input multiplexer (MXT4) circuit 500 according example embodiments.

[0060] According to an example embodiment, a computing system for designing an IC may generate layout data of an IC with reference to the standard cell library.

[0061] The computing system may include the processor, the memory, an input/output (I/O) device, a storage device and a bus.

[0062] The processor may be configured, through a layout design or execution of computer readable instructions stored in the memory, as a special purpose computer to perform at least one of various operations of designing the IC.

[0063] The processor may communicate with the memory, the I/O device, and the storage device through the bus. The processor may design a layout of the IC by performing a logic synthesis operation, a design for testability (DFT) logic insertion operation, a placement and routing (P&R) operation, a parasitic component extraction operation and/or a static timing analysis (STA) operation.

[0064] The logic synthesis operation may generate a netlist from data defining functions of the IC in a hardware description language (HDL). The placing and routing (P&R) operation may generate layout data for the IC by placing and routing standard cells that define the IC according to the netlist. The static timing analysis (STA) operation may be performed on the layout data, and if the analysis passes, a mask may be generated based on the layout data.

[0065] The IC may be manufactured using the mask by performing various semiconductor processes on a semiconductor substrate such as a wafer to form the semiconductor device in which the IC is implemented. For example, a process using a mask may refer to a patterning process through a lithography process. Through such a patterning process, a desired pattern may be formed on a semiconductor substrate or a material layer. Meanwhile, the semiconductor processes may include a deposition process, an etching process, an ion process, a cleaning process, and the like. In addition, the semiconductor process may include a packaging process for mounting the semiconductor device on a printed circuit board (PCB) and sealing it with a sealing material, and may include a test process for testing the semiconductor device or a package.

[0066] The memory may be a volatile memory such as static random access memory (SRAM) or dynamic random access memory (DRAM), or may be a non-volatile memory such as phase-change random access memory (PRAM), magnetoresistive random access memory (MRAM), resistive random access memory (ReRAM), ferroelectric random access memory (FRAM), or NOR flash memory.

[0067] The I/O device may control a user input and an output performed through user interface devices. For example, the I/O device may include one or more input devices such as a keyboard, a mouse device, and a touch pad and may receive input data which defines the IC. For example, the I/O device may include output devices such as a display and a speaker and may display a placement result, a routing result, an STA result, etc.

[0068] The storage device may include a memory card (for example, multimedia card (MMC), an embedded multi-media card (eMMC), a secure digital (SD) card, a MicroSD card, etc.), a solid state drive (SSD), a hard disk drive (HDD), and/or the like.

[0069] The foregoing description of some of the example embodiments will so fully reveal the general nature of the example embodiments herein that others can, by applying current knowledge, readily modify and/or adapt such specific example embodiments without departing from the example embodiments, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed example embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the example embodiments herein have been described in terms of some example embodiments, those skilled in the art will recognize that the example embodiments herein can be practiced with modification within the spirit and scope of the example embodiments as described herein.