Robust low leakage controlled keeper by current-comparison domino for wide fan-in gates

In this paper, a new design for low leakage and noise immune wide fan-in domino circuits is presented. The proposed technique uses the difference and the comparison between the leakage current of the OFF transistors and the switching current of the ON transistors of the pull down network to control the PMOS keeper transistor, yielding reduction of the contention between keeper transistor and the pull down network from which previously proposed techniques have suffered. Moreover, using the stacking effect, leakage current is reduced and the performance of the current mirror is improved. Results of simulation in high performance 16 nm predictive technology model (PTM) demonstrate that the proposed circuit exhibits about 39% less power consumption, and nearly 2.57 times improvement in noise immunity with a 41% die area overhead for a 64-bit OR gate compared to a standard domino circuit.     

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.     

VSF:CMOS组合电路的静态功耗评估模型

为了解决利用晶体管级电路模拟分析CMOS电路静态功耗时模拟时间随电路规模增大迅速增加的问题,在分析晶体管堆叠效应对标准单元泄漏电流影响的基础上,定义了归一化堆叠系数和电路等效堆叠系数的概念,提出了基于电路有效堆叠系数的静态功耗评估模型.该模型可用于CMOS组合电路静态功耗估算和优化.实验结果表明使用该模型进行静态功耗估算时,不需要进行Hspice模拟.针对ISCAS85基准电路的静态功耗优化结果表明,利用该模型能够取得令人满意的静态功耗优化效果,优化速度大大提高.     

Process variation aware dual-Vth assignment technique for low power nanoscale CMOS design

This paper presents a novel sensitivity-based, transistor-level, dual threshold voltage (V_th) assignment technique for the design of low power nanoscale CMOS circuits. The proposed technique is based on the Plackett-Burman Design of Experiment method (PB-DOE) in which sensitivity of each transistor to delay variation due to change in its V_th is obtained. The various paths in the circuit are categorized into process sensitive and process-insensitive paths. Transistors in the process sensitive paths are assigned a high V_th to reduce the leakage power without affecting performance. The application of the proposed technique to ISCAS-85 C17 benchmark circuit shows 20% reduction in the leakage power as compared to conventional gate-level dual-V_th assignment technique. Moreover, it is shown that the proposed algorithm can be easily extended to assign dual gate length circuits to achieve a further 20% reduction in the leakage power. The robustness of the proposed technique against process variations is demonstrated with extensive Monte Carlo Simulations. The versatility of the proposed approach to reduce the leakage power for a general CMOS circuit is demonstrated using a Manchester carry chain adder.     

Sleep switch dual threshold voltage domino logic with reduced subthreshold and gate oxide leakage current

A circuit technique is proposed in this paper for simultaneously reducing the subthreshold and gate oxide leakage power consumption in domino logic circuits. PMOS-only sleep transistors and a dual threshold voltage CMOS technology are utilized to place an idle domino logic circuit into a low leakage state. Sleep transistors are added to the dynamic nodes in order to reduce the subthreshold leakage current by strongly turning off all of the high threshold voltage transistors. Similarly, the sleep switches added to the output nodes suppress the voltages across the gate insulating layers of the transistors in the fan-out gates, thereby minimizing the gate tunneling current. The proposed circuit technique lowers the total leakage power by 88 to 97% as compared to the standard dual threshold voltage domino logic circuits. Similarly, a 22 to 44% reduction in the total leakage power is observed as compared to a previously published sleep switch scheme in a 45 nm CMOS technology.     

A 4.1-ns compact 54×54-b multiplier utilizing sign-selectBooth encoders

A 54×54-b multiplier with only 60 K transistors has been fabricated by 0.25-μm CMOS technology. To reduce the total transistor count, we have developed two new approaches: sign-select Booth encoding and 48-transistor 4-2 compressor circuits both implemented with pass transistor logic. The sign-select Booth algorithm simplifies the Booth selector circuit and enables us to reduce the transistor count by 45% as compared with that of the conventional one. The new compressor reduces the count by 20% without speed degradation. By using these new circuits, the total transistor count of the multiplier is reduced by 24%. The active size of the 54×54-b multiplier is 1.04×1.27 mm and the multiplication time is 4.1 ns at a 2.5-V power supply     

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.     

2.5 V 43–45 Gb/s CDR Circuit and 55 Gb/s PRBS Generator in SiGe Using a Low-Voltage Logic Family

An alternative design approach for implementing high-speed digital and mixed-signal circuits is proposed. It is based on a family of low-voltage logic gates with reduced transistor stacking compared to series-gated emitter-coupled logic. It includes a latch, an xor gate, and a MUX with mutually compatible interfaces. Topologies and characteristics of the individual gates are discussed. Closed-form propagation delay expressions are introduced and verified with simulations. The proposed design style was used to implement a 43–45 Gb/s CDR circuit with a 600MHz locking range and a 55 Gb/s PRBS generator with a$2^7!-!1$sequence length. The circuits were fabricated in a SiGe BiCMOS technology with$f _T = 120~hboxGHz$. Corresponding measurement results validate the proposed design style and establish it as a viable alternative to emitter-coupled logic in high-speed applications. Both circuits operate from a 2.5 V nominal power supply and consume 650 mW and 550 mW, respectively.     

Distributed sleep transistor network for power reduction

Sleep transistors are effective to reduce leakage power during standby modes. The cluster-based design was proposed to save sleep transistor area by clustering gates to minimize the simultaneous switching current per cluster and inserting a sleep transistor per cluster. In this paper, we propose a novel distributed sleep transistor network (DSTN), and show that DSTN is intrinsically better than the cluster-based design in terms of the sleep transistor area and circuit performance. We reveal properties of optimal DSTN designs, and then develop an efficient algorithm for gate level DSTN synthesis. The algorithm obtains DSTN designs with up to 70.7% sleep transistor area reduction compared to cluster-based designs. Furthermore, we present custom layout designs to verify the area reduction by DSTN.     

INDEP approach for leakage reduction in nanoscale CMOS circuits

Complementary metal oxide semiconductor (CMOS) technology scaling for improving speed and functionality turns leakage power one of the major concerns for nanoscale circuits design. The minimization of leakage power is a rising challenge for the design of the existing and future nanoscale CMOS circuits. This paper presents a novel, input-dependent, transistor-level, low leakage and reliable INput DEPendent (INDEP) approach for nanoscale CMOS circuits. INDEP approach is based on Boolean logic calculations for the input signals of the extra inserted transistors within the logic circuit. The gate terminals of extra inserted transistors depend on the primary input combinations of the logic circuits. The appropriate selection of input gate voltages of INDEP transistors are reducing the leakage current efficiently along with rail to rail output voltage swing. The important characteristic of INDEP approach is that it works well in both active as well as standby modes of the circuits. This approach overcomes the limitations created by the prevalent current leakage reduction techniques. The simulation results indicate that INDEP approach mitigates 41.6% and 35% leakage power for 1-bit full adder and ISCAS-85 c17 benchmark circuit, respectively, at 32 nm bulk CMOS technology node.     

Graphene nanoribbon crossbar architecture for low power and dense circuit implementations

Crossbar array is a promising nanoscale architecture which can be used for logic circuit implementation. In this work, a graphene nanoribbon (GNR) based crossbar architecture is proposed. This design uses parallel GNRs as device channel and metal as gate, source and drain contacts. Schottky-barrier type graphene nanoribbon field-effect transistors (SB-GNRFETs) are formed at the cross points of the GNRs and the metallic gates. Benchmark circuits are implemented using the proposed crossbar, Si-CMOS and multi-gate Si-CMOS approaches to evaluate the performance of the crossbar architecture compared to the conventional CMOS logic design. The compact SPICE model of SB-GNRFET was used to simulate crossbar-based circuits. The CMOS circuits are also simulated using 16 nm technology parameters. Simulation results of benchmark circuits using SIS synthesis tool indicate that the GNR-based crossbar circuits outperform conventional CMOS circuits in low power applications. Area optimized cell libraries are implemented based on the asymmetric crossbar architecture. The area of the circuit can be more reduced using this architecture at the expense of higher delay. The crossbar cells can be combined with CMOS cells to exhibit better performance in terms of EDP.     

PMOS-Only Sleep Switch Dual-Threshold Voltage Domino Logic in Sub-65-nm CMOS Technologies

A circuit technique is proposed in this paper for simultaneously reducing the subthreshold and gate oxide leakage power consumption in domino logic circuits. Only p-channel sleep transistors and a dual-threshold voltage CMOS technology are utilized to place an idle domino logic circuit into a low leakage state. Sleep transistors are added to the dynamic nodes in order to reduce the subthreshold leakage current by strongly turning off all of the high-threshold voltage transistors. Similarly, the sleep switches added to the output nodes suppress the voltages across the gate insulating layers of the transistors in the fan-out gates, thereby minimizing the gate tunneling current. The proposed circuit technique lowers the total leakage power by up to 77% and 97% as compared to the standard dual-threshold voltage domino logic circuits at the high and low die temperatures, respectively. Similarly, a 22% to 44% reduction in the total leakage power is observed as compared to a previously published sleep switch scheme in a 45-nm CMOS technology. The energy overhead of the circuit technique is low, justifying the activation of the proposed sleep scheme by providing a net savings in total energy consumption during short idle periods.     

Threshold voltage-minimum gate length trade-off in buried channelPMOS devices for scaled supply voltage CMOS technologies

The trade-off between threshold voltage (V_th) and the minimum gate length (L_min) is discussed for optimizing the performance of buried channel PMOS transistors for low voltage/low power high-speed digital CMOS circuits. In a low supply voltage CMOS technology it is desirable to scale V_th and L_min for improved circuit performance. However, these two parameters cannot be scaled independently due to the channel punch-through effect. Statistical process/device modeling, split lot experiments, circuit simulations, and measurements are performed to optimize the PMOS transistor current drive and CMOS circuit speed. We show that trading PMOS transistor V_th for a smaller L_min results in faster circuits for low supply voltage (3.3 to 1.8 V) n⁺-polysilicon gate CMOS technology, Circuit simulation and measurements are performed in this study. Approximate empirical expressions are given for the optimum buried channel PMOS transistor V _th for minimizing CMOS circuit speed for cases involving: (1) constant capacitive load and (2) load capacitance proportional to MOS gate capacitance. The results of the numerical exercise are applied to the centering of device parameters of a 0.5 μm 3.3 V CMOS technology that (a) matches the speed of our 0.5 μm 5 V CMOS technology, and (b) achieves good performance down to 1.8 V power supply. For this process the optimum PMOS transistor V_th (absolute value) is approximately 0.85-0.90 V     

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.     

Characterizing,modeling, and analyzing soft error propagation in asynchronous and synchronous digital circuits

Soft errors, due to cosmic radiations, are one of the major challenges for reliable VLSI designs. In this paper, we present a symbolic framework to model soft errors in both synchronous and asynchronous designs. The proposed methodology utilizes Multiway Decision Graphs (MDGs) and glitch-propagation sets (GP sets) to obtain soft error rate (SER) estimation at gate level. This work helps mitigate design for testability (DFT) issues in relation to identifying the controllable and the observable circuit nodes, when the circuit is subject to soft errors. Also, this methodology allows designers to apply radiation tolerance techniques on reduced sets of internal nodes. To demonstrate the effectiveness of our technique, several ISCAS89 sequential and combinational benchmark circuits, and multiple asynchronous handshake circuits have been analyzed. Results indicate that the proposed technique is on average 4.29 times faster than the best contemporary state-of-the-art techniques. The proposed technique is capable to exhaustively identify soft error glitch propagation paths, which are then used to estimate the SER. To the best of our knowledge, this is the first time that a decision diagram based soft error identification approach is proposed for asynchronous circuits.     

基于SET/MOS混合结构的译码器电路的设计

基于SET的I-V特性以及SET与MOS管互补的特性,以MOS管的逻辑电路为设计思想,首先提出了一个SET/MOS混合结构的反相器,进而推出或非门电路,并最终实现了一个唯一地址译码器.通过SET和MOS管两者的混合构建的电路与纯SET实现的电路相比,电路的带负载能力增强;与纯MOS晶体管实现的电路相比,电路同样仅需要单电源供电,且元器件数目得到了减少,电路的静态功耗大大降低.仿真结果验证了电路设计的正确性.     

Series-parallel association of FET's for high gain and highfrequency applications

This paper presents a simple approach in the design of composite field effect transistors with low output conductance. These transistors consist of the series association of two transistors, with the transistor connected to the drain terminal wider than the transistor connected to the source terminal. It is shown that this composite transistor has the same DC characteristics as a long-channel transistor of uniform width. A composite transistor has two main advantages over its “DC equivalent” transistor of uniform width: significant area savings and a higher cutoff frequency. The main application is low-voltage, high-frequency analog circuits. The proposed technique is particularly suited for analog design in gate arrays     

Path sensitisation and gate sizing approach to low poweroptimisation

A powerful circuit optimisation solution for high-performance and low-power design is presented. The proposed method combines path sensitisation and gate resizing approaches to reduce the power dissipation under a given timing constraint. The algorithm is tested on ISCAS-85 benchmark circuits, and up to 30%, power reduction is achieved     

Characteristics analysis and optimization design of a new ESD power clamp circuit

As CMOS technology scales down, the design of ESD protection circuits becomes more challenging. There are some disadvantages for the actual power clamp circuit. In this paper, an optimization ESD power clamp circuit is proposed. The new clamp circuit adopts the edge triggering True Single Phase Clocked Logic (TSPCL) D flip-flop to turn on and time delay, it has the advantage of dynamic transmission structure. By adding a leakage transistor of small size, the clamp circuit can turn off effectively. By changing the W/L ratio, the clamp can safely protect the gate of ESD power clamp devices from thermoelectric breakdown. The results show that the circuit can reduce the false triggering and power supply noise more effectively, it can be widely used in high-speed integrated circuits. The proposed structure has the advantages of low power and low cost, and can be used to the system-level ESD protection.     

Petri net modeling of gate and interconnect delays for power estimation

Switching activity estimation is an important step in average power estimation of VLSI circuits at the gate level. In this paper, we present a novel approach based on Petri net modeling for real delay switching activity and power estimation of CMOS circuits, considering both gate and interconnect delays. We propose a new type of Petri net called hierarchical colored hardware Petri net (HCHPN), which accurately captures the spatial and temporal correlations in modeling switching activity. The logic circuit is first modeled as a gate signal graph (GSG) which is then converted into the corresponding HCHPN and simulated as a Petri net to obtain the switching activity estimates and the power values. The proposed method is accurate and fast compared to other simulative methods. Experimental results are provided for ISCAS '85 and ISCAS '89 benchmark circuits and compared with the commercial tools, PowerMill, and Prime Power.