Pass transistor with dual threshold voltage domino logic design using standby switch for reduced subthreshold leakage current

Dual threshold voltages domino design methodology utilizes low threshold voltages for all transistors that can switch during the evaluate mode and utilizes high threshold voltages for all transistors that can switch during the precharge modes. We employed standby switch can strongly turn off all of the high threshold voltage transistors which enhances the effectiveness of a dual threshold voltage CMOS technology to reduce the subthreshold leakage current. Subthreshold leakage currents are especially important in burst mode type integrated circuits where the majority of the time for system is in an idle mode. The standby switch allowed a domino system enters and leaves a low leakage standby mode within a single clock cycle. In addition, we combined domino dynamic circuits style with pass transistor XNOR and CMOS NAND gates to realize logic 1 output during its precharge phase, but not affects circuits operation in its evaluation and standby phase. The first stage NAND gates output logic 1 can guarantee the second stage computation its correct logic function when system is in a cascaded operation mode. The processing required for dual threshold voltage circuit configuration is to provide an extra threshold voltage involves only an additional implant processing step, but performs lower dynamic power consumption, lower delay and high fan-out, high switching frequencies circuits characteristics. SPICE simulation for our proposed circuits were made using a 0.18 µm CMOS process from TSMC, with 10 fF capacitive loads in all output nodes, using the parameters for typical process corner at 25 °C, the simulation results demonstrated that our designed 8-bit carry look-ahead adders reduced chip area, power consumption and propagation delay time more than 40%, 45% and around 20%, respectively. Wafer based our design were fabricated and measured, the measured data were listed and compared with simulation data and prior works. SPICE simulation also manifested lower sensitivity of our design to power supply, temperature, capacitive load and process variations than the dynamic CMOS technologies.     

A 4:1 Multiplexer using dual chirality CNTFET-based domino logic in nano-scale technology

ABSTRACT

This paper proposes a 4:1 Multiplexer (MUX) designed using proposed Dual Chirality High-Speed Noise Immune Domino Logic (DCHSNIDL) technique for designing lower delay noise immune domino logic circuits in Carbon Nanotube Field Effect Transistors (CNTFETs) technology. Dynamic power consumption, speed and noise immunity of the circuit are improved by changing the threshold voltage of the CNTFETs. The chirality indices of the carbon nanotubes (CNTs) are varied to change the threshold voltage of the CNTFETs. Simulations are carried out for 32 nm Stanford CNTFET model in HSPICE for 2-, 4-, 8- and 16-input domino OR gates at a clock frequency of 200 MHz on a DC supply voltage of 0.9V. The proposed DCHSNIDL domino circuit reduces power consumption by a maximum of 61.77% and propagation delay by a maximum of 55.11% compared to Current-Mirror Based Process Variation Tolerant (CPVT) circuit in CNTFET technology. The proposed CNTFET-based domino technique shows a maximum reduction of 96.31% in power consumption compared to its equivalent circuit in CMOS technology for a 4-input OR gate. The proposed technique shows an improvement of 1.04× to 1.35× times in Unity Noise Gain (UNG) compared to various existing techniques in CNTFET technology. The 4:1 MUX designed using proposed technique has 48.91% lower propagation delay and consumes 52.80% lower power compared to MUX using CPVT technique.     

Skew-tolerant domino circuits

Domino circuits are widely used in high-performance CMOS microprocessors. However, textbook domino pipelines suffer significant timing overhead from clock skew, latch delay, and the inability to borrow time. To eliminate this overhead, some designers provide multiple overlapping clock phases such that domino gates are always ready for evaluation by the time critical inputs arrive and do not precharge until the next gate consumes the result. This paper describes a systematic framework, called skew-tolerant domino circuits, for understanding and analyzing domino circuits with overlapping clocks. Simulations confirm that a speedup of 25% or more can be achieved over textbook domino circuits in high-speed systems     

Single-Phase SP-Domino: A Limited-Switching Dynamic Circuit Technique for Low-Power Wide Fan-in Logic Gates

The high switching activity of wide fan-in dynamic domino gates introduces significant power overhead that poses a limitation on using these compact high-speed circuits. This paper presents a new limited-switching clock-delayed dynamic circuit technique, called SP-Domino, which achieves static-like switching behavior, while maintaining the low-area and high-performance characteristics of wide fan-in dynamic gates. SP-Domino is a single-phase footless domino that can be freely mixed with static gates and can provide inverting and non-inverting functions. Simulations on 8 and 16 inputs or gates show that SP-Domino reduces dynamic power by up to 63% compared to same-UNG and same-delay standard footless domino, and up to 56.9% compared to low-contention high-speed standard footless domino.     

Reduced clock swing domino logic

A reduced clock swing domino logic gate for 50% reduction in power consumption in clock networks is presented. The original full swing gate works properly at reduced swing with a better noise tolerance and small loss of performance while simple resizing allows the same speed, power and noise figures     

Low power wide gates for modern power efficient processors

In this paper, a low power register file and tag comparator is proposed which has lower leakage and higher noise immunity without dramatic speed degradation due to the wide fan-in gates. Simulation of register files and tag comparators designed is done using low-V_th 90 nm CMOS process technology model in all process corners. The results demonstrate 20% power reduction and 2× noise-immunity improvement in the implemented register file using the proposed circuit at the same delay compared to the standard domino circuits. On the other hand, simulation of tag comparators implemented using the other proposed circuit shows 41%, 22% and 7.5% reduction in power, delay and area, respectively compared to the standard footless domino at the same robustness condition. Moreover, the register file and the tag comparator designed with the proposed circuits respectively show 2.48 and 3 times improvement in the defined figure of merit compared to the counterpart circuits designed with the conventional domino circuit. Thus, the proposed are power efficient and suitable approaches for embedded processors with multi-ported register file and fully-associative caches with large number of tag comparators.     

Clock-Logic Domino Circuits for High-Speed and Energy-Efficient Microprocessor Pipelines

We present a design methodology for synchronous single-rail domino logic circuits, where inverting and nonmonotonic logic functions can be integrated into a pipeline with almost zero overhead relative to classic domino counterparts. This logic family, called clock-logic (CL) domino, is functionally complete while tolerating skew and minimizing the number of clock phases that must be distributed. Simulation results for a CL domino algorithmic logic unit (ALU) at 1 GHz under high skew conditions, shows a power reduction of 41% over the same ALU implemented in dual-rail skew-tolerant domino logic. This power reduction incurs no performance penalty over dual-rail techniques, although in some cases additional design effort is required     

An efficient scaling procedure for domain CMOS logic

The layout area required by a domino CMOS gate to support a specific response-time performance for a particular capacitive load can be substantially reduced by scaling the NFET chain. A scaling procedure that requires little execution time is described and illustrated by its application to AND, AOI, and OAI domino CMOS gates. The procedure is equally applicable to other forms of dynamics logic     

Designing leakage tolerant, low power wide-OR dominos for sub-130 nm CMOS technologies

In this paper, we discuss the design of leakage tolerant wide-OR domino gates for deep submicron (DSM), bulk CMOS technologies. Technology scaling is resulting in a 3×-5× increase in transistor I_OFF/μm per generation causing 15-30% degradation in the noise margin of high performance domino gates. We investigate several techniques that can improve the noise margin of domino logic gates and thereby ensure their reliable operation for sub-130 nm technologies. Our results indicate that, selective usage of dual V_TH transistors shows acceptable energy-delay tradeoffs for the 90 nm technology. However, techniques like supply voltage (V_cc) reduction or using non-minimum L_e transistors are required in order to ensure robust and low power operation of wide-OR domino designs for the 70 nm generation.     

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.     

Monte Carlo analysis of a low power domino gate under parameter fluctuation

Using the multiple-parameter Monte Carlo method, the effectiveness of the dual threshold voltage technique (DTV) in low power domino logic design is analyzed. Simulation results indicate that under significant temperature and process fluctuations, DTV is still highly effective in reducing the total leakage and active power consumption for domino gates with speed loss. Also, regarding power and delay characteristics, different structure domino gates with DTV have different robustness against temperature and process fluctuation.     

参数浮动下低功耗多米诺门的蒙特卡罗分析

Using the multiple-parameter Monte Carlo method, the effectiveness of the dual threshold voltage technique （DTV） in low power domino logic design is analyzed. Simulation results indicate that under significant temperature and process fluctuations, DTV is still highly effective in reducing the total leakage and active power consumption for domino gates with speed loss. Also, regarding power and delay characteristics, different structure domino gates with DTV have different robustness against temperature and process fluctuation.     

Fast Tag Comparator Using Diode Partitioned Domino for 64-bit Microprocessors

As the clock frequency and physical address space of 64-bit microprocessors continue to grow, one major critical path is the access to the on-die cache memory that includes a tag comparator, a tag SRAM and a data SRAM. To improve the delay of the tag comparator, a diode-partitioned (DP) domino circuit is proposed. DP domino reduces the parasitic capacitance and enables a smaller keeper in high fan-in gates. The diode circuit is also improved by an enhanced diode that boosts up the gate voltage of the nMOS diode. Delay of a 40-bit tag comparator using the proposed scheme is 33% faster than an optimized complex domino circuit in 1.8-V 180-nm CMOS technology     

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.     

45nm工艺pn混合下拉网络多米诺异或门设计

提出了一种pn混合下拉网络技术,即在多米诺门的下拉网络中混合使用pMOS管和nMOS管来降低电路的功耗并提高电路的性能. 首先,应用此技术设计了多米诺异或门,与标准的n型多米诺异或门相比,新型异或门的静态功耗和动态功耗分别减小了46%和3%. 然后,在此技术的基础上,综合应用多电源电压技术和双阈值技术设计了功耗更低的多米诺异或门,与标准的n型多米诺异或门相比,静态功耗和动态功耗分别减小了82%和21%. 最后分析并确定了4种多米诺异或门的最小漏电流状态和交流噪声容限.     

High performance low power CMOS dynamic logic for arithmetic circuits

This paper presents the design of high performance and low power arithmetic circuits using a new CMOS dynamic logic family, and analyzes its sensitivity against technology parameters for practical applications. The proposed dynamic logic family allows for a partial evaluation in a computational block before its input signals are valid, and quickly performs a final evaluation as soon as the inputs arrive. The proposed dynamic logic family is well suited to arithmetic circuits where the critical path is made of a large cascade of inverting gates. Furthermore, circuits based on the proposed concept perform better in high fanout and high switching frequencies due to both lower delay and dynamic power consumption. Experimental results, for practical circuits, demonstrate that low power feature of the propose dynamic logic provides for smaller propagation time delay (3.5 times), lower energy consumption (55%), and similar combined delay, power consumption and active area product (only 8% higher), while exhibiting lower sensitivity to power supply, temperature, capacitive load and process variations than the dynamic domino CMOS technologies.     

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.     

Impacts of NBTI/PBTI on performance of domino logic circuits with high-k metal-gate devices in nanoscale CMOS

Negative-bias temperature instability (NBTI) and positive-bias temperature instability (PBTI) weaken PFETs and high-k metal-gate NFETs, respectively. This paper provides comprehensive analyses on the impacts of NBTI and PBTI on wide fan-in domino gates with high-k metal-gate devices. The delay degradation and power dissipation of domino logic, as well as the Unity Noise Gain (UNG) are analyzed in the presence of NBTI/PBTI degradation. It has been shown that the main concern is the degradation impact on delay which can increase up to 16.2% in a lifetime of 3 years. We have also proposed a degradation tolerant technique to compensate for the NBTI/PBTI-induced delay degradation in domino gates with a negligible impact on UNG and power.     

A 9-GHz 65-nm Intel® Pentium 4 Processor Integer Execution Unit

This paper describes a fourth generation Intel Pentium 4 processor integer execution core operating at 9 GHz in a 1.3-V, 65-nm CMOS technology at 70degC. Low-voltage-swing circuits of the 90-nm design are replaced by: 1) 2times frequency fast clock (FCLK)-optimized domino clocking scheme; 2) segmented arithmetic and logic unit (ALU) front-end multiplexer; 3) sparse-tree ALU adder; 4) merged add/subtract sparse-tree address generation unit (AGU) design; 5) speculative RC-delay-optimized rotator; and 6) single-rail L0 cache and alignment multiplexer, resulting in 8.4% reduction in integer core normalized active power and 42% reduction in normalized leakage power. The use of standard domino/static tools and methodologies lowers design complexity, reducing development cost and time. The redesign also reduces integer core thermal density, resulting in an 8degC reduction in CPU operating temperature     

Dynamic latch for high speed GaAs domino circuits

A latch for use with GaAs domino logic gates is presented. A hybrid of a GaAs domino logic gate and a two-phase dynamic FET logic gate, the latch stores data during the precharge phase of domino logic operation. It enables the use of domino logic in large scale systems without the need for interfacing with power consumptive static latches. It is implemented with depletion mode MESFETs and dissipates 0.8 mW.<>