A minimum total power methodology for projecting limits on CMOS GSI

A circuit design methodology minimizing total power drain of a static complementary metal-oxide-semiconductor (CMOS) random logic network for a prescribed performance, operating temperature range, and short channel threshold voltage rolloff is investigated. Physical, continuous, smooth, and compact “transregional” MOSFET drain current models that consider high-field effects in scaled devices and permit tradeoffs between saturation drive current and subthreshold leakage current are employed to model CMOS circuit performance and power dissipation at low voltages. Transregional models are used in conjunction with physical short channel MOSFET threshold voltage rolloff models and stochastic interconnect distributions to project optimal supply voltages, threshold voltages, and device channel widths minimizing total power dissipated by CMOS logic circuits for each National Technology Roadmap for Semiconductors (NTRS) technology generation. Optimum supply voltage, corresponding to minimum total power dissipation, is projected to scale to 510 mV for the 50-nm 10-GHz CMOS generation in the year 2012. Techniques exploiting datapath parallelism to further scale the supply voltage are shown to offer decreasing reductions in power dissipation with technology scaling     

Full-chip subthreshold leakage power prediction and reduction techniques for sub-0.18-/spl mu/m CMOS

The driving force for the semiconductor industry growth has been the elegant scaling nature of CMOS technology. In future CMOS technology generations, supply and threshold voltages will have to continually scale to sustain performance increase, control switching power dissipation, and maintain reliability. These continual scaling requirements on supply and threshold voltages pose several technology and circuit design challenges. With threshold voltage scaling, subthreshold leakage power is expected to become a significant portion of the total power in future CMOS systems. Therefore, it becomes crucial to predict and reduce subthreshold leakage power of such systems. In the first part of this paper, we present a subthreshold leakage power prediction model that takes into account within-die threshold voltage variation. Statistical measurements of 32-bit microprocessors in 0.18-/spl mu/m CMOS confirm that the mean error of the model is 4%. In the second part of this paper, we present the use of stacked devices to reduce system subthreshold leakage power without reducing system performance. A model to predict the scaling nature of this stack effect and verification of the model through statistical device measurements in 0.18-/spl mu/m and 0.13-/spl mu/m are presented. Measurements also demonstrate reduction in threshold voltage variation for stacked devices compared to nonstack devices. Comparison of the stack effect to the use of high threshold voltage or longer channel length devices for subthreshold leakage reduction is also discussed.     

Level-shifter free design of low power dual supply voltage CMOS circuits using dual threshold voltages

Usage of dual supply voltages in a digital circuit is an effective way of reducing the dynamic power consumption due to the quadratic relation of supply voltage to dynamic power consumption. But the need for level shifters when a low voltage gate drives a high voltage gate has been a limiting factor preventing widespread usage of dual supply voltages in digital circuit design. The overhead of level shifters forces designers to increase the granularity of dual voltage assignment, reducing the maximum obtainable savings. We propose a method of incorporating voltage level conversion into regular CMOS gates by using a second threshold voltage. Proposed level shifter design makes it possible to apply dual supply voltages at gate level granularity with much less overhead compared to traditional level shifters. We modify the threshold voltage of the high voltage gates that are driven by low voltage gates in order to obtain the level shifting operation together with the logic operation. Using our method, we obtained an average of 20% energy savings for ISCAS'85 benchmark circuits designed using 180-nm technology and 17% when 70-nm technology is used.     

Power dissipation analysis and optimization of deep submicron CMOSdigital circuits

This paper introduces a simple analytical model for estimating standby and switching power dissipation in deep submicron CMOS digital circuits. The model is based on Berkeley Short-Channel IGFET model and fits HSPICE simulation results well. Static and dynamic power analysis for various threshold voltages is addressed. A design methodology to minimize the power-delay product by selecting the lower and upper bounds of the supply and threshold voltages is presented. The effects of the supply voltage, the threshold voltage, and η, which reflects the drain induced barrier lowering, are also addressed     

Reversed Temperature-Dependent Propagation Delay Characteristics in Nanometer CMOS Circuits

The supply voltage to threshold voltage ratio is reduced with each new technology generation. The gate overdrive variation with temperature plays an increasingly important role in determining the speed characteristics of CMOS integrated circuits. The temperature-dependent propagation delay characteristics, as shown in this brief, will experience a complete reversal in the near future. Contrary to the older technology generations, the speed of circuits in a 45-nm CMOS technology is enhanced when the temperature is increased at the nominal supply voltage. Operating an integrated circuit at the prescribed nominal supply voltage is not preferable for reliable operation under temperature fluctuations. A design methodology based on optimizing the supply voltage for temperature-variation-insensitive circuit performance is proposed in this brief. The optimum supply voltage is 45% to 53% lower than the nominal supply voltage in a 180-nm CMOS technology. Alternatively, the optimum supply voltage is 15% to 35% higher than the nominal supply voltage in a 45-nm CMOS technology. The speed and energy tradeoffs in the supply voltage optimization technique are also presented     

基于不同VTH值的新型CMOS电压基准

传统基准电路主要采用带隙基准方案,利用二级管PN结具有负温度系数的正向电压和具有正温度系数的yBE电压得出具有零温度系数的基准。针对BJT不能与标准的CMOS工艺兼容的缺陷,利用NMOS和PMOS管的两个阈值电压VTHN和VTHP具有相同方向但不同数量的温度系数,设计了一种基于不同VTH。值的新型CMOS基准。该电路具有没有放大器、没有BJT、结构简单等特点,适宜于标准CMOS工艺集成。在此给出了详细的原理分析和电路实现。该电路通过HSpice验证,其输出基准电压为1．22V,在-40～＋85℃内温度系数仅为30ppm／℃,电源电压为2．6～5．5V时,电源电压调整率为1．996mV／V。     

A sub-1 Volt 10-bit supply boosted SAR ADC design in standard CMOS

This paper presents a new very low-power, low-voltage successive approximation analog to digital converter (SAR ADC) design based on supply boosting technique. The supply boosting technique (SBT) and supply boosted (SB) circuits including level shifter, comparator, and supporting electronics are described. Supply boosting provides wide input common mode range and sub-1 Volt operation for the circuits designed in standard CMOS processes that have only high-V_t MOSFETs. A 10-bit supply boosted SAR ADC was designed and fabricated in a standard 0.5 μm, 5 V, 2P3M, CMOS process in which threshold voltages of NMOS and PMOS devices are +0.8 and −0.9 V, respectively. Fabricated SB-SAR ADC achieves effective number of bits (ENOB) of 8.04, power consumption of 147 nW with sampling rate of 1.0 KS/s on 1 Volt supply. Measured figure of merit (FOM) was 280 fJ/conversion-step. Proposed supply boosting technique improves input common mode range of both SB comparator and SAR ADC, allows sub-1 Volt operation when threshold voltages are in the order of the supply voltage, and achieves low energy operation. Thus, SBT is suitable for mixed-signal circuit designed for energy limited applications and systems in where supply voltage is in the order of threshold voltages of the process.     

Trading speed for low power by choice of supply and thresholdvoltages

The trading of speed for low power consumption in CMOS VLSI by using the supply voltage and the threshold voltage as variables was investigated. It is shown that it is desirable to minimize the supply voltage for minimizing the power consumption. The lower bound of the supply voltage and the possible decrease in power consumption without speed loss were investigated under different circuit constraints, and the consequences for circuit performance were calculated. Results show, for example, that power reductions of about 40 times can be obtained without speed loss by using supply voltages down to about 0.48 V     

Design of charge pump circuit with consideration of gate-oxide reliability in low-voltage CMOS processes

A new charge pump circuit with consideration of gate-oxide reliability is designed with two pumping branches in this paper. The charge transfer switches in the new proposed circuit can be completely turned on and turned off, so its pumping efficiency is higher than that of the traditional designs. Moreover, the maximum gate-source and gate-drain voltages of all devices in the proposed charge pump circuit do not exceed the normal operating power supply voltage (VDD). Two test chips have been implemented in a 0.35-/spl mu/m 3.3-V CMOS process to verify the new proposed charge pump circuit. The measured output voltage of the new proposed four-stage charge pump circuit with each pumping capacitor of 2 pF to drive the capacitive output load is around 8.8 V under 3.3-V power supply (VDD = 3.3 V), which is limited by the junction breakdown voltage of the parasitic pn-junction in the given process. The new proposed circuit is suitable for applications in low-voltage CMOS processes because of its high pumping efficiency and no overstress across the gate oxide of devices.     

1 V CMOS Subthreshold Log Domain PDM

A new CMOS circuit strategy for very low-voltage Pulse-Duration Modulators (PDM) is proposed. Optimization of voltage supply scaling below the sum of threshold voltages is based on Instantaneous Log Companding processing through the MOSFET operating in weak inversion. A 1 V VLSI PDM circuit for very low-voltage audio applications such as Hearing Aids is presented, showing good agreement between simulated and experimental data.     

High-voltage power delivery through charge recycling

In this paper, we describe a technique for delivering power to a digital integrated circuit at high voltages, reducing current demands and easing requirements on power-ground network impedances. The design approach consists of stacking CMOS logic domains to operate from a voltage supply that is a multiple of the nominal supply voltage. DC-DC downconversion is performed using charge recycling without the need for explicit downconverters. Experimental results are presented for the prototype system in a 0.18-/spl mu/m CMOS technology operating at both 3.6 V and 5.4 V. Peak energy efficiencies as high as 93% are demonstrated at 3.6 V.     

Low-voltage high-gain differential OTA for SC circuits

A new differential operational transconductance amplifier (OTA) for SC circuits that operates with a supply voltage of less than two transistor threshold voltages is presented. Its simplicity relies on the use of a low-voltage regulated cascode circuit, which achieves very high output impedance under low-voltage restrictions. The OTA has been designed to operate with a supply voltage of V/sub DD/=1.5 V, using a 0.6 /spl mu/m CMOS technology with transistor threshold voltages of V/sub TN/=0.75 V and V/sub TP/=-0.85 V. Post-layout simulation results for a load capacitance (C/sub L/) of 2 pF show a 75 MHz gain-bandwidth product and 100 dB DC gain with a quiescent power consumption of 750 /spl mu/W.     

A Low-Voltage Fully Differential Constant-Gm Rail-to-Rail CMOS Operational Amplifier

A low-voltage fully differential CMOS operational amplifier withconstant-g_mand rail-to-rail input and output stages ispresented. It is the fully differential version of a previously realizedsingle-ended operational amplifier where a novel circuit to ensure constanttransconductance has been implemented [1]. The input stage is a rail-to-railstructure formed by two symmetrical OTAs in parallel (the input transistorsare operating in weak inversion). The class-AB output stages have also afull voltage swing. A rail-to-rail input common mode feedback structureallows the output voltage control. Measurements in a 0.7 µ standardCMOS process with threshold voltages of about 0.7 V have been done. Theminimum experimental supply voltage is about 1.1 V. The circuit provides a60 dB low frequency voltage gain and about 1.5 MHz unity gain frequency fora total power consumption of about 0.72 mW at a 1.5 V supply voltage.     

CMOS PWM D类音频功率放大器的过流保护电路

基于Class-D音频功率放大器的应用,采用失调比较器及单边迟滞技术,提出了一种过流保护电路,其核心为两个CMOS失调比较器。整个电路基于CSMC0.5μmCMOS工艺的BSIM3V3Spice典型模型,采用Hspice对比较器的特性进行了仿真。失调比较器的直流开环增益约为95dB,失调电压分别为0.25V和0.286V。仿真和测试结果显示,当音频放大器输出短路或输出短接电源时,过流保护电路都能正常启动,保证音频放大器不会受到损坏,能完全满足D类音频放大器的设计要求。过流保护电路有效面积为291μm×59.5μm。     

Low-power CMOS with subvolt supply voltages

We first present a circuit taxonomy along the space and time dimensions, which is useful for classifying generic low-power techniques, followed by an analysis of optimal power supply and threshold voltages and transistor sizing for minimizing the energy-delay product of a class of complementary metal-oxide-semiconductor (CMOS) digital circuits     

Low-power CMOS digital design with dual embedded adaptive powersupplies

A low-power CMOS design methodology with dual embedded adaptive power supplies is presented. A variable supply-voltage scheme for dual power supplies, namely, the dual-VS scheme, is presented. It is found that the lower supply voltage should be set at 0.7 of the higher supply voltage to minimize chip power dissipation. This knowledge aids designers in the decision of the optimal supply voltages within a restricted design time. An MEPG-4 video codec chip is designed at 2.5 and 1.75 V for internal circuits that are generated from an external power supply of 3.3 V by the dual-VS circuits. Power dissipation is reduced by 57% without degrading circuit performance compared to a conventional CMOS design     

单片化低压低功耗Si CMOS运算放大器的实现

基于新型的折叠共栅共源PMOS差分输入级拓扑、轨至轨AB类低压CMOS推挽输出级模型、低压低功耗LV/LP技术特别考虑和EDA平台的实验设计与模拟仿真,并设计配置了先进的Si 2 mm P阱硅栅CMOS集成工艺技术。已经得到一种具有VT = 0.7 V、电源电压1.1~1.5 V、静态功耗典型值330 mW、75 dB开环增益和945 kHz单位增益带宽的LV/LP运算放大器。该运放可应用于ULSI库单元和诸多相关技术领域,其实践有助于Si CMOS低压低功耗集成电路技术的进一步开发与交流。     

A High-Swing, High-Speed CMOS WTA Using Differential Flipped Voltage Followers

A high-performance CMOS winner-take-all circuit based on the differential flipped voltage follower is introduced. Simulations demonstrate the potential of the circuit to operate at very high speed, with high precision even for close input values and with low supply voltages. Experimental verification of the circuit is provided in a 0.5-mum CMOS technology.     

ISFET threshold voltage programming in CMOS using hot-electron injection

The use of hot-electron injection as a method for programming the threshold voltages of CMOS based ion-sensitive field-effect transistors (ISFETs) in standard pH buffer solution is presented. This method allows compensation of large threshold voltage variations generally seen with ISFETs fabricated in unmodified CMOS due to the presence of trapped charge, enabling operation of the device using nominal supply voltage as well as reduction of mismatch between devices when fabricating ISFET arrays. Fabricated in a 0.35 m CMOS process, threshold voltage shifts of up to 2.8 V have been achieved in a pH 7 buffer solution.     

A low-voltage low-power threshold voltage monitor for CMOS process sensing

In this paper a low-voltage low-power threshold voltage monitor for CMOS process sensing is presented. This circuit works in weak inversion and it can be used as an elementary circuit block for on-chip compensation of the intra-die or inter-die threshold voltage variations in low-power analog and mixed-signal SoC, since it is robust to temperature and power supply voltage variations (similar to the bandgap voltage reference). The proposed threshold voltage monitor has been successfully verified in a standard 0.35-μm n-well CMOS TSMC process. Experimental results have confirmed that the circuit generates an average reference voltage of 758 mV (very close to the typical threshold voltage when extrapolated to absolute zero) for a 950 mV power supply voltage, with a variation of 39 ppm/°C for the −20 to 80°C temperature range.