Circuit techniques for CMOS low-power high-performance multipliers

In this paper we present circuit techniques for CMOS low-power high-performance multiplier design. Novel full adder circuits were simulated and fabricated using 0.8-μm CMOS (in BiCMOS) technology. The complementary pass-transistor logic-transmission gate (CPL-TG) full adder implementation provided an energy savings of 50% compared to the conventional CMOS full adder. CPL implementation of the Booth encoder provided 30% power savings at 15% speed improvement compared to the static CMOS implementation. Although the circuits were optimized for (16×16)-b multiplier using the Booth algorithm, a (6×6)-b implementation was used as a test vehicle in order to reduce simulation time. For the (6×6)-b case, implementation based on CPL-TG resulted in 18% power savings and 30% speed improvement over conventional CMOS     

A 32-bit carry lookahead adder using dual-path all-N logic

We have developed dual path all-N logic (DPANL) and applied it to 32-bit adder design for higher performance. The speed is significantly enhanced due to reduced capacitance at each evaluation node of dynamic circuits. The power saving is achieved due to reduced adder cell size and minimal race problem. Post-layout simulation results show that this adder can operate at frequencies up to 1.85 GHz for 0.35-/spl mu/m 1P4M CMOS technology and is 32.4% faster than the adder using all-N transistor (ANT). It also consumes 29.2% less power than the ANT adder. A 0.35-/spl mu/m CMOS chip has been fabricated and tested to verify the functionality and performance of the DPANL adder on silicon.     

准静态单相能量回收逻辑

提出了一种新的准静态单相能量回收逻辑,其不同于以往的能量回收逻辑,真正实现了单相功率时钟,且不需要任何额外的辅助控制时钟,不但降低了能耗,更大大简化了时钟树的设计.该逻辑还可以达到两相能量回收逻辑所具有的速度.设计了一个8位对数超前进位加法器,并分别用传统的静态CMOS逻辑、钟控CMOS绝热逻辑(典型的单相能量回收逻辑)和准静态单相能量回收逻辑实现.采用128组随机产生的输入测试向量的仿真结果表明:输入频率为10MHz时,准静态能量回收逻辑的能耗仅仅是传统静态CMOS逻辑的45%;当输入频率大于2MHz时,可以获得比时钟控CMOS绝热逻辑更低的能耗.     

准静态单相能量回收逻辑

提出了一种新的准静态单相能量回收逻辑,其不同于以往的能量回收逻辑,真正实现了单相功率时钟,且不需要任何额外的辅助控制时钟,不但降低了能耗,更大大简化了时钟树的设计.该逻辑还可以达到两相能量回收逻辑所具有的速度.设计了一个8位对数超前进位加法器,并分别用传统的静态CMOS逻辑、钟控CMOS绝热逻辑(典型的单相能量回收逻辑)和准静态单相能量回收逻辑实现.采用128组随机产生的输入测试向量的仿真结果表明:输入频率为10MHz时,准静态能量回收逻辑的能耗仅仅是传统静态CMOS逻辑的45%;当输入频率大于2MHz时,可以获得比时钟控CMOS绝热逻辑更低的能耗.     

A novel multiplexer-based low-power full adder

The 1-bit full adder circuit is a very important component in the design of application specific integrated circuits. This paper presents a novel low-power multiplexer-based 1-bit full adder that uses 12 transistors (MBA-12T). In addition to reduced transition activity and charge recycling capability, this circuit has no direct connections to the power-supply nodes, leading to a noticeable reduction in short-current power consumption. Intensive HSPICE simulation shows that the new adder has more than 26% in power savings over conventional 28-transistor CMOS adder and it consumes 23% less power than 10-transistor adders (SERF and 10T ) and is 64% faster.     

Compact four bit carry look-ahead CMOS adder in multi-output DCVSlogic

A four-bit carry look-ahead (CLA) CMOS adder based on transistor sharing in a multi-output differential cascode voltage switch (MODCVS) logic is presented. This adder uses a new enhanced CLA unit, which enables the generation of all output carries in one single compact gate structure. Simulation results using HSPICE with CMOS 1.0 μm technology designs show that the four-bit adder proposed has 15.7% less transistors, 27.2% less silicon area, ~14% speed improvement, and a 29.1% reduction in average power consumption compared to a standard DCVS implementation     

Design and analysis of low power high-speed 1-bit full adder cells for VLSI applications

This paper presents a low power and high speed two hybrid 1-bit full adder cells employing both pass transistor and transmission gate logics. These designs aim to minimise power dissipation and reduce transistor count while at the same time reducing the propagation delay. The proposed full adder circuits utilise 16 and 14 transistors to achieve a compact circuit design. For 1.2 V supply voltage at 0.18-μm CMOS technology, the power consumption is 4.266 μW was found to be extremely low with lower propagation delay 214.65 ps and power-delay product (PDP) of 0.9156 fJ by the deliberate use of CMOS inverters and strong transmission gates. The results of the simulation illustrate the superiority of the newly designed 1-bit adder circuits against the reported conservative adder structures in terms of power, delay, power delay product (PDP) and a transistor count. The implementation of 8-bit ripple carry adder in view of proposed full adders are finally verified and was observed to be working efficiently with only 1.411 ns delay. The performance of the proposed circuits was examined using Mentor Graphics Schematic Composer at 1.2 V single ended supply voltage and the model parameters of a TSMC 0.18-μm CMOS.     

采用交流能源的低功耗CPL电路

从改变CM O S电路中能量转换模式的观点出发,研究CPL电路在采用交流能源后的低功耗特性。在此基础上提出了一种仅由nM O S构成的低功耗绝热电路——nM O S Com p lem en tary Pass-trans istor A d iabaticLog ic(nCPAL)。该电路利用nM O S管自举原理对负载进行全绝热驱动,从而减小了电路整体功耗和芯片面积。nCPAL能耗几乎与工作频率无关,对负载的敏感程度也较低。采用TSM C的0.25μm CM O S工艺,设计了一个8-b it超前进位加法器和功率时钟产生器。版图后仿真表明,在50~200 MH z频率范围内,nCPAL全加器的功耗仅为PAL-2N电路和2N-2N 2P电路的50%和35%。研究表明nCAPL适合于在VLS I设计中对功率要求较高的应用场合。     

A GHz MOS adaptive pipeline technique using MOS current-mode logic

This paper describes an adaptive pipeline (APL) technique, which is a new pipeline scheme capable of compensating for device-parameter deviations and for operating-environment variations. This technique can also compensate for clock skew and eliminate excessive power dissipation in current-mode logic (CML) circuits. The APL technique is here applied to a 0.4-μm MOS 1.6-V 1-GHz 64-bit double-stage pipeline adder, and this paper shows that the adder can operate accurately on condition that the clock has 20% skew. The APL technique uses MOS current-mode logic (MCML) circuits, whose propagation delay time can be varied by the control ports. MCML circuits can operate with lower signal voltage swing and higher operating frequency at lower supply voltage than CMOS circuits can. This paper also shows that MCML circuits are suitable for a low-noise variable delay circuit. Measurement results show that jitter of MCML circuits is about 65% that of CMOS circuits     

Low-voltage adders for power-efficient arithmetic circuits

This paper presents the results of a study of alternative adder architectures, a full-swing Bipolar Double Pass-Transistor adder, a new full-swing BiNMOS adder, a reduced-swing Bipolar Double Pass-Transistor adder and a reduced-swing Double Pass-Transistor BiNMOS adder, that outperform a standard CMOS adder up to three times in power-efficiency at supply voltages 1.5–3 V. The Bipolar Double Pass-Transistor adder is more power-efficient than a standard CMOS adder even at a fanout of 1. All remaining proposed adders have a lower crossover capacitance with a standard CMOS adder than the previously reported low-voltage adders. Circuits were designed and fabricated in 0.8 μm BiCMOS technology.     

A Low Power Correlator for CDMA Wireless Systems

The complex valued matched filter correlators consume maximum power in the DS/SS CDMA receivers. These correlators accumulate 1024 samples lying in the range –7 to +7. This accumulation needs 3 data bits, 1 sign bit and 10 extra bits for overflow. Hence, the correlator can be implemented as a cascade of 4-bit full adder and a 10-bit incrementer. As a ripple carry adder (RCA) consumes the least power among all the existing adder architectures, we have implemented the 4-bit adder as a RCA. Previous incrementers were implemented as ripple counters. In this paper we propose a novel incrementer which is faster than a ripple counter based incrementer. Hence, it can be operated at a reduced voltage resulting in considerable power reduction. The incrementer is implemented using multiplexers, AND gates and TSPC registers. The ripple-counter correlator and the proposed incrementer correlator were laid out in MAGIC using 0.5 CMOS technology followed by power estimation using HSPICE. It is shown that the proposed architecture requires 50% less power than a ripple counter based design.     

A New Low-Power Architecture Design for Distributed Arithmetic Unit in FIR Filter Implementation

In this article, an improved Distributed Arithmetic (DA) architecture is proposed, in which the high power consumed by adder units is relocated in the system to reduce the switching activity and total power needed. We used the concept of Time Domain Activity Duration Function (ADF) in architectural-level modification of target units at dynamic operating conditions. The proposed DA exploits the circuit activity, and the adder units are used in minimum states. The proposed DA is a run-time reconfigurable and lets system change the coefficients of FIR filter dynamically. The design was simulated, and the results were verified via two-phase power calculation method. The power calculations are based on forward synthesis invariant points and backward synthesis oriented activity approach. This method was applied to calculate the power and area of the proposed DA and other well-known counterparts in the literature. In the experimental results on 180 nm CMOS ASIC synthesis, the maximum clock of 100 MHz is achieved. In the 32-tap FIR filter implementation of our proposed DA and best known DA2 in serial DA structure, the switching power and internal power improvements are about 21 % and 10 %, respectively, in approximately equal speed and 5 % area increment.     

A self-controllable voltage level (SVL) circuit and its low-power high-speed CMOS circuit applications

A self-controllable voltage level (SVL) circuit which can supply a maximum dc voltage to an active-load circuit on request or can decrease the dc voltage supplied to a load circuit in standby mode was developed. This SVL circuit can drastically reduce standby leakage power of CMOS logic circuits with minimal overheads in terms of chip area and speed. Furthermore, it can also be applied to memories and registers, because such circuits fitted with SVL circuits can retain data even in the standby mode. The standby power of an 8-bit 0.13-/spl mu/m CMOS ripple carry adder (RCA) with an on-chip SVL circuit is 8.2 nW, namely, 4.0% of that of an equivalent conventional adder, while the output signal delay is 786 ps, namely, only 2.3% longer than that of the equivalent conventional adder. Moreover, the standby power of a 512-bit memory cell array incorporating an SVL circuit for a 0.13-/spl mu/m 512-bit SRAM is 69.1 nW, which is 3.9% of that of an equivalent conventional memory-cell array. The read-access time of this 0.13-/spl mu/m SRAM is 285 ps, that is, only 2 ps slower than that of the equivalent SRAM.     

Design and simulation of an ultra-low power high performance CMOS logic: DMTGDI

An ultra-low power, high speed dual mode CMOS logic family called DMTGDI is introduced. This logic family takes over and improves main characteristics of Gate Diffusion Input (GDI) and Dual Mode Logic (DML). Simulations have been performed in 90 nm CMOS on a single bit full adder. DMTGDI shows 60% performance improvement over conventional DML, and significant reduction of power-delay product (PDP), of about 95% in static mode, and 75% in dynamic mode. Monte Carlo simulations reveal that DMTGDI is more robust under process variation comparing to conventional DML. Post layout simulation demonstrates negligible effect of parasitic elements on performance of the single bit adder.     

An area-efficient static CMOS carry-select adder based on a compact carry look-ahead unit

This paper presents a highly area-efficient CMOS carry-select adder (CSA) with a regular and iterative-shared transistor structure very suitable for implementation in VLSI. This adder is based on both a static and compact multi-output carry look-ahead (CLA) circuit and a very simple select circuit. Comparisons with other representative 32-bit CSAs show that the proposed adder reduces the area by between 25 and 16%, the number of transistors by between 43 and 30%, and the dynamic power supply between 35 and 16%, while maintaining a high speed.     

A 64-bit carry look ahead adder using pass transistor BiCMOS gates

This paper describes a 64-bit two-stage carry look ahead adder utilizing pass transistor BiCMOS gate. The new pass transistor BiCMOS gate has a smaller intrinsic delay time than conventional BiCMOS gates. Furthermore, this gate has a rail-to-rail output voltage. Therefore the next gate does not have a large degradation of its driving capability. The exclusive OR and NOR gate using the pass transistor BiCMOS gate shows a speed advantage over CMOS gates under a wide variance in load capacitance. The pass transistor BiCMOS gates were applied to full adders, carry path circuits, and carry select circuits. In consequence, a 64-bit two-stage carry look ahead adder was fabricated using a 0.5 μm BiCMOS process with single polysilicon and double-metal interconnections. A critical path delay time of 3.5 ns was observed at a supply voltage of 3.3 V. This is 25% better than the result of the adder circuit using CMOS technology. Even at the supply voltage of 2.0 V, this adder is faster than the CMOS adder     

DSP芯片中全加器电路的优化设计

全加器在DSP芯片中是一个非常重要的逻辑器件,在DSP芯片内部存在着大量的加法器,通过对加法器的优化设计,可以使DSP芯片的性能得到提高.在本文中以CPL结构(Complementary pass transistor logic)加法器为基础提出了一种优化的加法器结构.并且通过HSPICE仿真,对28个晶体管的CMOS加法器、传统的CPL加法器和改进型的CPL加法器进行了比较.仿真的结果表明:改进型CPL加法器在功耗和延时等特性上比传统的28-T CMOS结构加法器和一般的CPL结构加法器有较大的提高.     

3.3-V BiCMOS current-mode logic circuits for high-speed adders

New high-speed BiCMOS current mode logic (BCML) circuits for fast carry propagation and generation are described. These circuits are suitable for reduced supply voltage of 3.3-V. A 32-b BiCMOS carry select adder (CSA) is designed using 0.5-μm BiCMOS technology. The BCML circuits are used for the correct carry path for high-speed operation while the rest of the adder is implemented in CMOS to achieve high density and low power dissipation. Simulation results show that the BiCMOS CSA outperforms emitter coupled logic (ECL) and CMOS adders     

Clock-delayed domino for dynamic circuit design

Clock-delayed (CD) domino is a self-timed dynamic logic family developed to provide single-rail gates with inverting or noninverting outputs. CD domino is a complete logic family and is as easy to design with as static CMOS circuits from a logic design and synthesis perspective. Design tools developed for static CMOS are used as part of a methodology for automating the design of CD domino circuits. The methodology and CD domino's characteristics are demonstrated in the design of a 32-b carry look-ahead adder. The adder was fabricated with MOSIS's 0.8-μm CMOS process with scalable CMOS design rules that allow a 1.0-μm drawn gate length. Measurements of the adder show a worst case addition of 2.1 ns. The CD domino adder is 1.6× faster than a dual-rail domino adder designed with the same cell library and technology     

Design of CNTFET-based 2-bit ternary ALU for nanoelectronics

This article presents a hardware-efficient design of 2-bit ternary arithmetic logic unit (ALU) using carbon nanotube field-effect transistors (CNTFETs) for nanoelectronics. The proposed structure introduces a ternary adder–subtractor functional module to optimise ALU architecture. The full adder–subtractor (FAS) cell uses nearly 72% less transistors than conventional architecture, which contains separate ternary cells for addition as well as subtraction. The presented ALU also minimises ternary function expressions with utilisation of binary gates for optimisation at the circuit level, thus attaining a simple design. Hspice simulations results demonstrate that the ALU ternary circuits achieve great improvement in terms of power delay product with respect to their CMOS counterpart at 32 nm.