高性能微处理器中一种改进的高扇入多米诺电路设计与实现

设计实现了一种改进的高扇入多米诺电路结构. 该电路的nMOS下拉网络分为多个块,有效降低了动态节点的电容,同时每一块只需要一个小尺寸的保持管. 由于省去了标准多米诺逻辑中的尾管,有效地提升了该电路的性能. 在0.13μm工艺下对该结构实现的一个64位或门进行模拟,延迟为63.9ps,功耗为32.4μW,面积为115μm2. 与组合多米诺逻辑相比,延迟和功耗分别降低了55%和38%.     

150Ms/s、6bit CMOS数字工艺折叠、电流插值A/D转换器

在1.2μm SPDM标准数字CMOS工艺条件下,实现6bit CMOS折叠、电流插值A/D转换器;提出高速度再生型电流比较器的改进结构,使A/D转换器(ADC)总功耗下降近30%;提出一种逻辑简单易于扩展的解码电路,以多米诺(Domino)逻辑实现.整个ADC电路中只使用单一时钟.在5V电压条件下,仿真结果为采样频率150-Ms/s时功耗小于185mW,输入模拟信号和二进制输出码之间延迟小于2个时钟周期.     

150Ms/s、6bit CMOS数字工艺折叠、电流插值A/D转换器

在1.2μm SPDM标准数字CMOS工艺条件下,实现6bit CMOS折叠、电流插值A/D转换器;提出高速度再生型电流比较器的改进结构,使A/D转换器(ADC)总功耗下降近30%;提出一种逻辑简单易于扩展的解码电路,以多米诺(Domino)逻辑实现.整个ADC电路中只使用单一时钟.在5V电压条件下,仿真结果为采样频率150-Ms/s时功耗小于185mW,输入模拟信号和二进制输出码之间延迟小于2个时钟周期.     

DSP中低功耗全加器的改进设计

在充分研究现有典型全加器结构的基础上,提出了一种结合传输管逻辑和传输门逻辑特点的新型全加器。该全加器采用对称的XOR/XNOR结构,减少了电路延迟,降低了功耗。基于0.18μm CMOS工艺,采用HSPICE对电路进行仿真。结果表明,与典型结构全加器相比,提出的全加器在电路功耗和延迟功耗积(PDP)方面的改进分别为22%和27%。     

64位超前进位对数加法器的设计与优化

设计一个应用于高性能微处理器的快速64位超前进位对数加法器.通过分析超前进位对数加法器原理,提出了改进四进制Kogge-Stone树算法的64位超前进位对数加法器结构,并结合使用多米诺动态逻辑、时钟延迟多米诺逻辑和传输门逻辑等技术来设计和优化电路.该加法器采用SMIC 0.18 μm CMOS工艺实现,在最坏情况下完成一次加法运算时间为486.1 ps,与相同工艺和相同电路结构采用静态CMOS实现相比,大大减少了加法器各级门的延迟时间,取得良好的电路性能.     

改进结构的64位CMOS并行加法器设计与实现

介绍了一个用于高性能的微处理器和 DSP处理器的快速 6 4位二进制并行加法器 .为了提高速度 ,改进了加法器结构 ,该结构大大减少了加法器各级门的延迟时间 .基于改进的加法器结构 ,有效地使用动态复合门、时钟延迟多米诺逻辑和场效应管尺寸缩小技术 ,可以取得良好的电路性能 .该加法器采用 U MC 2 .5 V 0 .2 5μm 1层多晶 5层金属的 CMOS工艺实现 .完成一次加法运算的时间是 70 0 ps,比传统结构的加法器快 2 0 % ;面积和功耗分别是0 .16 m m2和 2 0 0 m W@5 0 0 MHz,与传统结构加法器相当 .     

亚70nm CMOS工艺低漏电流、高噪声容限的低功耗多输入多米诺或门的设计

提出了两种新的电路技术,在降低多输入多米诺"或门"的动态功耗的同时减小了漏电流,并提高了电路的噪声容限.采用新的电路技术设计了八输入多米诺"或门"并基于45nm BSIM4 SPICE 模型对其进行了模拟.模拟结果表明,设计的两种新多米诺电路在同样的噪声容限下有效地降低了动态功耗,减小了总的漏电流,同时提高了工作速度.与双阈值多米诺电路相比,设计的两种电路动态功耗分别降低了8.8%和11.8%,电路速度分别提高了9.5%和13.7%,同时总的漏电流分别降低了80.8%和82.4%.基于模拟结果,也分析了双阈值多米诺电路中求值点的不同逻辑状态对总的漏电流的影响.     

亚70nm CMOS工艺低漏电流、高噪声容限的低功耗多输入多米诺或门的设计

提出了两种新的电路技术,在降低多输入多米诺"或门"的动态功耗的同时减小了漏电流,并提高了电路的噪声容限.采用新的电路技术设计了八输入多米诺"或门"并基于45nm BSIM4 SPICE 模型对其进行了模拟.模拟结果表明,设计的两种新多米诺电路在同样的噪声容限下有效地降低了动态功耗,减小了总的漏电流,同时提高了工作速度.与双阈值多米诺电路相比,设计的两种电路动态功耗分别降低了8.8%和11.8%,电路速度分别提高了9.5%和13.7%,同时总的漏电流分别降低了80.8%和82.4%.基于模拟结果,也分析了双阈值多米诺电路中求值点的不同逻辑状态对总的漏电流的影响.     

改进结构的64位CMOS并行加法器设计与实现

介绍了一个用于高性能的微处理器和DSP处理器的快速64位二进制并行加法器.为了提高速度,改进了加法器结构,该结构大大减少了加法器各级门的延迟时间.基于改进的加法器结构,有效地使用动态复合门、时钟延迟多米诺逻辑和场效应管尺寸缩小技术,可以取得良好的电路性能.该加法器采用UMC 2.5V 0.25μm 1层多晶5层金属的CMOS工艺实现.完成一次加法运算的时间是700ps,比传统结构的加法器快20%;面积和功耗分别是0.16mm2和200mW@500MHz,与传统结构加法器相当.     

对数跳跃加法器的静态CMOS实现

介绍了一种32位对数跳跃加法器结构.该结构采用ELM超前进位加法器代替进位跳跃结构中的组内串行加法器,同ELM相比节约了30%的硬件开销.面向该算法,重点对关键单元进行了晶体管级的电路设计.其中的进位结合结构利用Ling算法,采用支路线或电路结构对伪进位产生逻辑进行优化;求和逻辑的设计利用传输管结构,用一级逻辑门实现"与-民或"功能;1.0μm CMOS工世实现的32位对数跳跃加法器面积为0.62mm2,采用1μm和0.25μm 工世参数的关键路径延迟分别为6ns和0.8ns,在100MHz下功耗分别为23和5.2mW.     

Domino logic with variable threshold voltage keeper

A variable threshold voltage keeper circuit technique is proposed for simultaneous power reduction and speed enhancement of domino logic circuits. The threshold voltage of a keeper transistor is dynamically modified during circuit operation to reduce contention current without sacrificing noise immunity. The variable threshold voltage keeper circuit technique enhances circuit evaluation speed by up to 60% while reducing power dissipation by 35% as compared to a standard domino (SD) logic circuit. The keeper size can be increased with the proposed technique while preserving the same delay or power characteristics as compared to a SD circuit. The proposed domino logic circuit technique offers 14% higher noise immunity as compared to a SD circuit with the same evaluation delay characteristics. Forward body biasing the keeper transistor is also proposed for improved noise immunity as compared to a SD circuit with the same keeper size. It is shown that by applying forward and reverse body biased keeper circuit techniques, the noise immunity and evaluation speed of domino logic circuits are simultaneously enhanced.     

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.     

High speed wide fan‐in designs using clock controlled dual keeper domino logic circuits

Clock Controlled Dual keeper Domino logic structures (CCDD_1 and CCDD_2) for achieving a high‐speed performance with low power consumption and a good noise margin are proposed in this paper. The keeper control circuit comprises an additional PMOS keeper transistor controlled by the clock and foot node voltage. This control mechanism offers abrupt conditional control of the keeper circuit and reduces the contention current, leading to high‐speed performance. The keeper transistor arrangement also reduces the loop gain associated with the feedback circuitry. Hence, the circuits offer less delay variability. The design and simulation of various wide fan‐in designs using 180 nm CMOS technology validates the proposed CCDD_1 and CCDD_2 designs, offering an increased speed performance of 7.2% and 8.5%, respectively, over a conventional domino logic structure. The noise gain margin analysis proves good robustness of the CCDD structures when compared with a conventional domino logic circuit configuration. A Monte Carlo simulation for 2,000 runs under statistical process variations demonstrates that the proposed CCDD circuits offer a significantly reduced delay variability factor.     

Speed enhancement techniques for Clock-Delayed Dual Keeper Domino logic style

ABSTRACT

Domino circuit topology for high-speed operation, robustness and lower power consumption is quintessential in design of digital systems. In this paper, various high speed and robust mechanisms are proposed to enhance the speed of Clock-Delayed Dual Keeper Domino (CDDK) circuit. Delayed enabling of keeper circuit in CDDK domino circuit reduces contention between keeper circuit and Pull-Down network (PDN). The speed of transition at the dynamic node of the CDDK domino circuit is enhanced through imposing techniques namely (i) controlled clock delay time in enabling the keeper transistor, (ii) keeper control signal voltage swing variation, (iii) sizing of keeper transistors and (iv) deploying an additional conditional discharge path. The robustness of CDDK circuit is increased by upsizing the keeper transistor without degrading the speed by stack arrangement of dual keeper transistors. The simulation of enhancement techniques has been performed using Cadence® Virtuoso ADEL and ADEXL environments employing UMC 90nm technology library. The simulation results of wide fan-in 64-input OR gate demonstrate that CDDK technique with additional discharge path offer 38% increase in speed and CDDK technique with keeper transistor upsizing offers 52% increase in noise gain margin without speed degradation while comparing with the conventional domino logic circuit.     

GaAs trickle transistor dynamic logic

A GaAs dynamic logic gate is proposed which uses a trickle transistor to compensate for leakage from the precharged node. This trickle transistor dynamic logic (TTDL) circuit is configured as a domino logic gate and a differential cascode voltage switch logic (CVSL) gate. Delay chains were implemented in a 1-μm GaAs enhancement/depletion (E/D) process where the depletion-mode FETs (DFETs) and the enhancement-mode FETs (EFETs) have threshold voltages of -0.6 and 0.15 V, respectively, in order to obtain an experimental characterization of these gates. In addition, the TTDL gates were used to implement a 4-b carry-lookahead adder. The adder has a critical delay of 0.8 ns and a power dissipation of 130 mW     

Impact of NBTI on performance of domino logic circuits in nano-scale CMOS

Negative Bias Temperature Instability (NBTI) in pMOS transistors has become a major reliability concern in the state-of-the art digital circuit design. This paper discusses the effects of NBTI on 32 nm technology high fan-in dynamic OR gate, which is widely used in high-performance circuits. The delay degradation and power dissipation of domino logic, as well as the Unity Noise Gain (UNG), are analyzed in the presence of NBTI degradation. We have shown the degradation in the output inverter pMOS transistor of the domino gate has a dominant impact on the delay in comparison with the keeper impact. Based on this analysis we have proposed that upsizing just the output inverter pMOS transistor can compensate for the NBTI degradation. Moreover, the impact of tuning the duty cycle of the clock has been investigated. It has been shown that although the keeper and the precharge transistors experience more NBTI degradation by increasing the low level in the clock signal, the total performance of the circuit will improve. We have also proposed an adaptive compensation technique based on Forward Body Biasing (FBB), to recover the performance of the aged circuit.     

FinFET domino logic with independent gate keepers

Scaling of single-gate MOSFET faces great challenges in the nanometer regime due to the severe short-channel effects that cause an exponential increase in the sub-threshold and gate-oxide leakage currents. Double-gate FinFET technology mitigates these limitations by the excellent control over a thin silicon body by two electrically coupled gates. In this paper a variable threshold voltage keeper circuit technique using independent-gate FinFET technology is proposed for simultaneous power reduction and speed enhancement in domino logic circuits. The threshold voltage of a keeper transistor is dynamically modified during circuit operation to reduce contention current without sacrificing noise immunity. The optimum independent-gate keeper gate bias conditions are identified for achieving maximum savings in delay and power while maintaining identical noise immunity as compared to the standard tied-gate FinFET domino circuits. With the variable threshold voltage double-gate keeper circuit technique the evaluation speed is enhanced by up to 49% and the power consumption is reduced by up to 46% as compared to the standard domino logic circuits designed for similar noise margin in a 32 nm FinFET technology.     

Bus encoder design for reduced crosstalk,power and area in coupled VLSI interconnects

This research work presents a novel circuit for simultaneous reduction of power, crosstalk and area using bus encoding technique in RC modeled VLSI interconnect. Bus-invert method is used to reduce inter-wire coupling, which is actually responsible for crosstalk, delay and power dissipation in coupled interconnects. The proposed method focuses on simplified and improved encoder circuit for 4, 8 and 16 coupled lines. In past, the researchers developed encoders that usually focused on minimizing power dissipation and/or crosstalk, thereby paying heavy penalty in terms of chip area. However, the proposed encoder and decoder while significantly reducing crosstalk demonstrates an overall reduction of power dissipation by 68.76% through drastically limiting switching activity. Furthermore, while reducing the complexity, chip area and transistor count of the circuit is reduced by more than 57%.     

Analysis of ATPMOS configurations-based 4 × 1 multiplexer with estimation of power and delay

In this article, two consecutive augmenting transistor P-channel metal oxide semiconductor (ATPMOS) configurations are proposed. These two ATPMOS configurations (ST ATPMOS and DT ATPMOS) are implemented on a 4 × 1 (multiplexer) mux circuit. Leakage power dissipation, dynamic power dissipation and delay performance parameters are calculated for both (ST ATPMOS and DT ATPMOS) ATPMOS configurations-based 4 × 1 mux circuits at different values of transistor’s width. Due to simulation, it is realised that the leakage power dissipation and dynamic power dissipation are reduced and delay is improved (delay is reduced) in the DT ATPMOS configuration-based mux circuit compared to the ST ATPMOS configuration-based mux circuit. The whole simulation process was carried out in 45-nm technology. The circuits were operated at 1-V power supply.     

Logical effort based dynamic power estimation and optimization of static CMOS circuits

This paper introduces a simple and yet accurate closed-form expression to estimate the switching power dissipation of static CMOS gates. The developed model depends on normalizing a gate switching power to that of the unit standard inverter and it accounts for the effect of internodal capacitances. For different loads, gates, sizes and processes, the developed model shows a good agreement with Hspice simulations using BSIM3v3 and BSIM4 models for UMC 0.13 μm and Predictive high-k 45 nm processes, respectively. The average error introduced by the model for the considered scenarios is about 3.1%. Depending on the normalized switching power model, two power optimization techniques have been proposed in this paper. The first deals with transistor sizing problem and presents a scheme to size transistors according to a specific design goal. The second technique relies on the joint transistor sizing and supply voltage scaling for reducing the switching power dissipation under specific delay requirements. This technique exhibits superiority over the first for the considered technology processes: UMC 0.13 μm and the Predictive high-k 45 nm.