低功耗绝热SRAM

文章提出了一种新的绝热电路,并以该绝热电路为驱动,设计了一种低功耗绝热SRAM.由于所提出的绝热电路能以完全绝热的方式回收位线和字线上大开关电容的电荷,因此使该SRAM的功耗大大减小.我们采用0.25μm TSMC工艺,在时钟频率25～200MHz范围内对绝热SRAM进行了能耗和功能的HSPICE仿真,结果显示,与用传统的CMOS电路设计的SRAM相比,可节能80%左右.     

三值钟控绝热静态随机存储器设计

通过对多值逻辑、绝热电路和三值SRAM结构的研究,提出一种新颖的三值钟控绝热静态随机存储器(SRAM)的设计方案。该方案利用NMOS管的自举效应,以绝热方式对SRAM的行列地址译码器、存储单元、敏感放大器等进行充放电,有效恢复储存在字线、位线、行列地址译码器等大开关电容上的电荷,实现三值信号的读出写入和能量回收。PSPICE模拟结果表明,所设计的三值钟控绝热SRAM具有正确的逻辑功能和低功耗特性,在相同的参数和输入信号情况下,与三值常规SRAM相比,节约功耗达68%。     

一种新的基于SRAM的快速综合技术

对静态随机存储器(SRAM)全定制设计过程中的版图设计工作量大、重复性强的问题进行了分析,并在此基础上提出了一种新的应用于SRAM设计的快速综合技术。这种技术充分利用SRAM电路重复单元多的特点,在设计过程中尽可能把电路版图的硬件设计转换为使用软件来实现,节省了大量的版图设计和验证的时间,从而提高了工作效率。这种技术在龙芯Ⅱ号CPU的SRAM设计中得到了应用;芯片采用的是中芯国际0.18μm CM O S工艺。流片验证表明,该技术对于大容量的SRAM设计是较为准确而且有效的。     

开关信号理论与绝热CMOS电路设计

重新定义了钟控信号的表示方法,发展了适用于绝热电路的开关级设计理论.设计了实现全部钟控信号的基本单元电路,这些电路包括单轨和双轨结构,并给出了它们的多种级联方式.所提出电路的功耗与其他绝热电路相当,并工作于二相正弦功率时钟,因此可降低时钟电路的设计难度.这些电路可分别应用于需要基0信号和基1信号的绝热电路设计中.与以往大部分绝热电路不同的是,应用所提出的电路结构可以实现在同一时钟相位有多级电路同时参加运算.这一特性可以有效减少实现复杂逻辑电路时的等待时间以及实现流水结构时所需插入的缓冲器数目.通过对基0信号2∶1数据选择器     

开关信号理论与绝热CMOS电路设计

重新定义了钟控信号的表示方法,发展了适用于绝热电路的开关级设计理论.设计了实现全部钟控信号的基本单元电路,这些电路包括单轨和双轨结构,并给出了它们的多种级联方式.所提出电路的功耗与其他绝热电路相当,并工作于二相正弦功率时钟,因此可降低时钟电路的设计难度.这些电路可分别应用于需要基0信号和基1信号的绝热电路设计中.与以往大部分绝热电路不同的是,应用所提出的电路结构可以实现在同一时钟相位有多级电路同时参加运算.这一特性可以有效减少实现复杂逻辑电路时的等待时间以及实现流水结构时所需插入的缓冲器数目.通过对基0信号2∶1数据选择器和基1信号全加器的设计及SPICE模拟,验证了所提出设计技术的有效性以及电路的低功耗特性.     

一种用于SRAM快速仿真的模型

根据静态随机存储器(SRAM)电路及版图的设计特点,提出了一种新的可用于SRAM设计的快速仿真计算模型.该模型仿真快速准确,能克服Spice仿真软件对大容量SRAM版图后仿真速度较慢的缺点,在很大程度上缩短了设计周期.同时,它的仿真结果同Synopsys公司的Nanosim软件仿真结果相比偏差小于5%.该模型在龙芯Ⅱ号CPU的SRAM设计中得到了应用;芯片采用的是中芯国际0.18μm CMOS工艺.流片验证了该模型对于大容量的SRAM设计是准确而有效的.     

组合逻辑电路自动合成算法的硬件实现

根据FPGA的并行工作方式以及高速、高集成度的特点,采用Handel-C语言对改进型基因表达式克隆选择算法(IGE-CSA)进行编程.在基于FPGA的硬件平台上,实现了组合逻辑电路的自动合成.实验结果表明,采用基于FPGA硬件平台自动合成组合逻辑电路的方法,能获得更好更新颖的组合逻辑电路,同时减轻了设计者的负担,降低了组合逻辑电路的设计成本,为组合逻辑电路的自动合成方法得到实际应用提供了可能.     

兼有SRAM块和反熔丝逻辑的新型FPGA——一种有3584位双端口RAM的密集FPGA系列可以用来集成系统功能

系统设计人员经常在探索使用各种方法来满足日益增长的高工作速度的需求.一种看来似乎显而易见的答案就是使用较快的逻辑电路,但是CMOS逻辑本身有时不能按所要求的时钟速度运行.那些使用门阵列和标准单元库的设计人员常常要另外增加SRAM块用作缓冲器、FIFO寄存器和双端口存储器.这可使他们增强系统体系结构,提高系统速度.但是,在FPGA中实施成千上万位的存储器,不是大大减少可用的门数,就是效率低下,以致不能将FPGA逻辑用于大量存储器.最近,几家基于SRAM的FPGA供应商已把额外的SRAM加到其阵列中,从而使它们能取代掩模门阵列或基于单元的门阵列.事实上,Actel公司的设计人员还增加了存储器.就这家公司而言,它是把存储器加到做在0.6μm双     

采用三相电源的互补传输管绝热逻辑电路

提出了一种由三相电源驱动的新绝热逻辑电路--complementary pass-transistor adiabatic logic(CPAL).电路由CPL电路完成相应的逻辑运算,由互补传输门对输出负载进行绝热驱动,电路的整体功耗较小.指出选取合适的输出驱动管的器件尺寸可进一步减小CPAL电路的总能耗.设计了仅由一个电感和简单控制电路组成的三相功率时钟产生电路.为了验证提出的CPAL电路和时钟产生电路,设计了8bit全加器进行模拟试验.采用MOSIS的0.25μm CMOS工艺,在50～200MHz频率范围内,CPAL全加器的功耗仅为PFAL电路和2N-2N2P电路的50%和35%.     

45nm体硅工艺下使用双-栅氧化层厚度降低SRAM的泄漏功耗

提出了一种在45nm体硅工艺下使用双-栅氧化层厚度来降低整体泄漏功耗的方法.所提方法具有不增加面积和延时、改善静态噪声边界、对SRAM设计流程的改动很小等优点.提出了三种新型的SRAM单元结构,并且使用这些单元设计了一个32kb的SRAM,仿真结果表明,整体泄漏功耗可以降低50%以上.     

Design of ternary adiabatic multiplier on switch-level

The design of ternary adiabatic multiplier adopting switch-level design techniques is proposed in this paper. First by using the theory of three essential circuit elements, the switch-level functional expressions of the carry and product circuit models, which compose one bit ternary adiabatic multiplier, are derived. Consequently, the corresponding circuit structures can be obtained, and the evaluation and energy recovery for ternary circuit can be realized by bootstrapped NMOS transistors and cross-memory structure. Based on the designed circuits, the four bits ternary adiabatic multiplier is further realized by adopting the ripple carry manner. The PSPICE simulation results indicate that the designed circuits have correct logic function and are characterized with distinctive low power consumption.     

A 32×32-b adiabatic register file with supply clock generator

A 32×32-b adiabatic register file with one read port and one write port is designed. A four-phase clock generator is also designed to provide supply clocks for adiabatic circuits. All the word line and bit line charge on the capacitive interconnections is recovered to save energy. Adiabatic circuits are based on efficient charge recovery logic (ECRL) and are integrated using 0.8 μm complimentary metal-oxide-semiconductor (CMOS) technology. Measurement results show that power consumption of the core is significantly reduced by a factor of up to 3.5 compared with a conventional circuit     

An efficient charge recovery logic circuit

Efficient charge recovery logic (ECRL) is proposed as a candidate for low-energy adiabatic logic circuit. Power comparison with other logic circuits is performed on an inverter chain and a carry lookahead adder (CLA). ECRL CLA is designed as a pipelined structure for obtaining the same throughput as a conventional static CMOS CLA. Proposed logic shows four to six times power reduction with a practical loading and operation frequency range. An inductor-based supply clock generation circuit is proposed. Circuits are designed using 1.0-μm CMOS technology with a reduced threshold voltage of 0.2 V     

一种超低功耗、容错的静态随机存储器设计

为了减轻辐射环境中静态随机存储器（SRAM）受单粒子翻转（SEU）的影响以及解决低功耗和稳定性的问题,采用TSMC 90nm工艺,设计了一款可应用于辐射环境中的超低功耗容错静态随机存储器。该SRAM基于双互锁存储单元（DICE）结构,以同步逻辑实现并具有1KB（1K×8b）的容量,每根位线上有128个标准存储单元,同时具有抗SEU特性,提高并保持了SRAM在亚阈值状态下的低功耗以及工作的稳定性。介绍了这种SRAM存储单元的电路设计及其功能仿真,当电源电压VDD为0.3V时,该SRAM工作频率最大可达到2.7MHz,此时功耗仅为0.35μW;而当VDD为1V时,最大工作频率为58.2MHz,功耗为83.22μW。     

Adiabatic-CMOS/CMOS-adiabatic logic interface circuit

This paper describes the design of an adiabatic-CMOS/CMOS-adiabatic logic interface circuit for a group of low-power adiabatic logic families with a similar clocking scheme. The circuit provides interfacing between several recently proposed low-power adiabatic logic circuits and traditional digital CMOS circuits. One advantage of this design is that it is insensitive to clock overlap. With the proposed interface circuit, both adiabatic and CMOS logic circuits are able to co-exist on a single chip, taking advantage of the strengths of each approach in the design of low power systems.     

nMOS reversible energy recovery logic for ultra-low-energyapplications

We propose a new fully reversible adiabatic logic, nMOS reversible energy recovery logic (nRERL), which uses nMOS transistors only and a simpler 6-phase clocked power. Its area overhead and energy consumption are smaller, compared with the other fully adiabatic logics. We employed bootstrapped nMOS switches to simplify the nRERL circuits. With the simulation results for a full adder, we confirmed that the nRERL circuit consumed substantially less energy than the other adiabatic logic circuits at low-speed operation. We evaluated a test chip implemented with 0.8-μm CMOS technology, which included a chain of nRERL inverters integrated with a clocked power generator. The nRERL inverter chain of 2400 stages consumed the minimum energy at V_dd=3.5 V at 55 kHz, where the adiabatic and leakage losses are about equal, which is only 4.50% of the dissipated energy of its corresponding CMOS circuit at V_dd=0.9 V. In conclusion, nRERL is more suitable than the other adiabatic logic circuits for the applications that do not require high performance but low energy consumption     

DESIGN OF TWO-PHASE SINUSOIDAL POWER CLOCK AND CLOCKED TRANSMISSION GATE ADIABATIC LOGIC CIRCUIT

First the research is conducted on the design of the two-phase sinusoidal power clock generator in this paper. Then the design of the new adiabatic logic circuit adopting the two-phase sinusoidal power clocks--Clocked Transmission Gate Adiabatic Logic （CTGAL） circuit is presented. This circuit makes use of the clocked transmission gates to sample the input signals, then the output loads are charged and discharged in a fully adiabatic manner by using bootstrapped N-Channel Metal Oxide Semiconductor （NMOS） and Complementary Metal Oxide Semiconductor （CMOS） latch structure. Finally, with the parameters of Taiwan Semiconductor Manufacturing Company （TSMC） 0.25um CMOS device, the transient energy consumption of CTGAL, Bootstrap Charge-Recovery Logic （BCRL） and Pass-transistor Adiabatic Logic （PAL） including their clock generators is simulated. The simulation result indicates that CTGAL circuit has the characteristic of remarkably low energy consumption.     

Design of replica bit line control circuit to optimize power for SRAM

A design of a replica bit line control circuit to optimize power for SRAM is proposed. The proposed design overcomes the limitations of the traditional replica bit line control circuit, which cannot shut off the word line in time. In the novel design, the delay of word line enable and disable paths are balanced. Thus, the word line can be opened and shut off in time. Moreover, the chip select signal is decomposed, which prevents feedback oscillations caused by the replica bit line and the replica word line. As a result, the switch power caused by unnecessary discharging of the bit line is reduced. A 2-kb SRAM is fully custom designed in an SMIC 65-nm CMOS process. The traditional replica bit line control circuit and the new replica bit line control circuit are used in the designed SRAM, and their performances are compared with each other. The experimental results show that at a supply voltage of 1.2 V, the switch power consumption of the memory array can be reduced by 53.7%.