基于遗传算法的低功耗有限状态机状态分配

提出一种通过状态分配来实现有限状态机的功耗和面积同时优化的方法．在分析现有成本函数的基础上，提出了一个新的成本函数，并利用遗传算法能进行多目标优化的能力来实现功耗和面积的同时优化．该算法用C语言实现，并对17个MCNC有限状态机标准电路进行测试．测试结果表明，与已有的功耗优化算法相比，文中算法在功耗和面积方面有一定的优势．     

面向多优化目标的有限状态机状态分配

针对有限状态机状态分配问题,提出一种不仅考虑面积,同时也考虑功耗的算法.借鉴接力跑算法的基本思想提出了全新的粗略搜索方法、聚焦搜索方法、指引操作和传递操作.为了克服局部最优和快速收敛的问题,算法中分成粗略搜索和聚焦搜索,粗略搜索采用旋转和非邻交换方法大幅度修改解,而聚焦搜索采用相邻交换方法小幅度修改解;指引操作利用概率计算来引导优化取得更佳解,传递操作则通过组合最优解和当前解产生新的解以克服局部最优解问题.实验结果表明,文中算法在面积、功耗和CPU时间三方面性能指标都获得了理想的结果.     

面向峰值电流优化的FSM状态分配

有限状态机(FSM)状态分配与峰值电流有密切关系.针对峰值电流过大易导致电路失效的问题,提出2种优化峰值电流的方法.1)提出一种考虑峰值电流和动态功耗的成本函数,采用遗传算法对两者进行同时优化;2)首先基于遗传算法得到功耗优化后的状态分配解,然后提出基于布尔可满足性(SAT)的启发式算法对功耗优化的状态分配进行重新编码,以降低峰值电流.将这2种方法应用于LGSynth93标准电路的实验结果表明,与传统的功耗优化算法相比,第1种方法虽然功耗略有增加,但能有效地降低峰值电流;第2种方法在实现不增加功耗额外开销的前提下能有效地降低峰值电流,并可将其有效地集成到不同的FSM功耗优化算法中,获得低功耗、低峰值电流的FSM状态分配解.     

划分有限状态机的低功耗实现模型

通过引入映射状态,使得单状态机的状态分配算法可直接应用于被划分的有限状态机,提出了实现划分有限状态机的通用物理模型.对13个MCNC基准电路,采用文中模型进行测试,实验结果与已发表的结果相比,文中模型在功耗和面积的改进方面有一定的优势.     

基于整体退火遗传算法的低功耗最佳极性搜索

针对n变量逻辑函数在不同极性下所对应的XNOR/OR电路功耗和面积不同的特点,首先用信号概率传递算法和多输入XNOR/OR(同或/或)门的低功耗分解算法建立了XNOR/OR电路的功耗估计模型.在此基础上,将基于列表技术的极性转换算法和整体退火遗传算法相结合,提出了一种针对大规模XNOR/OR电路的低功耗最佳极性搜索算法.对8个较大规模MCNC Benchmark电路测试表明,该算法搜索到的最佳极性所对应的XNOR/OR电路与极性0时的XNOR/OR电路相比,平均节省功耗和面积分别达到了84.4%和65.2%.     

基于Verilog和VHDL的状态机设计技术

对于数字逻辑工程师来说,设计一个同步有限状态机(FSM)是一项很常见的任务。该论文讨论了若干关于设计有限状态机方面的问题,包括用于状态分配的状态编码方法,状态机的输入输出等等。     

基于存储器映射的Flash高速低功耗驱动实现

针对高速大容量Flash芯片控制中面临的高速可靠性不高与动态功耗大的问题,研究了一种将复杂状态机操作映射到内嵌RAM上运行的方法。通过对内嵌RAM读地址的切换,实现了等延时的状态跳变与输出控制。同时采用加强时钟管理、分割组合逻辑来避免信号不必要的翻转,极大地提高了时序运行的可靠性并降低了其动态功耗。实践表明,该方法实现的Flash控制时序比传统的状态机在资源消耗和功耗方面均能降低50%以上,为复杂时序逻辑的实现提供了一个新思路。     

面向对象类测试的精简EFSM转换算法

EFSM是一个没有层次和并发结构的状态图,因此很难处理较复杂的软件系统,而且由于EFSM中存在前置条件,使得生成的测试序列有可能存在不可达性。该文提出一种将EFSM转化为精简有限状态机(FSM)的转换算法,很大程度上减少了中间产生的等价状态,并有效防止了组合间爆炸问题的出现,得到的精简FSM最小可达。     

基于Verilog HDL的高速可综合FSM设计

有限状态机（finite state machine,FSM）广泛应用于数字系统的控制器设计中,用Verilog设计的可综合状态机有多种编码风格,通常这些编码风格生成的状态机带有组合逻辑输出.时序分析指出组合逻辑输出型状态机不适合高速系统,提出了一种适合高速系统的寄存器输出型状态机.最后通过实例给出了寄存器输出型状态机的状态编码方法及其可综合Verilog编码风格.     

用STATECAD快速设计有限状态机

有限状态机设计的关键是如何把一个实际的时序逻辑关系抽象成一个时序逻辑函数，传统的电路图输入法通过直接设计寄存器组来实现各个状态之间的转换，而用硬件描述语言来描述有限状态机，往往是通过充分发挥硬件描述语言的抽象建模能力，通过对系统在系统级或寄存器传输级进行描述来建立有限状态机。随着EDA工具的快速发展，通过CAD快速设计有限状态机自动化成为可能。     

Sequential algorithm for low-power encoding internal states of finite state machines

A heuristic method for encoding internal states (state assignment) of finite state machines (FSMs) so as to reduce their power consumption is proposed. A feature of the proposed approach is that the state assignment procedure takes into account the activity function of the memory elements when the FSM transits from a current state to other states that have already been encoded. A procedure for determining the power consumption of the FSM based on the codes of its internal states and probabilities of appearance of units at each input of the FSM is described. Experiments showed that the proposed approach makes it possible to reduce the power consumption of the FSM by 39% on the average compared with the NOVA algorithm and sometimes by 68%. In conclusion, the possibilities of improving the performance of the proposed algorithm in the synthesis of a specific FSM are discussed and promising directions of further research are indicated.     

Low Power State Assignment Algorithm for FSMs Considering Peak Current Optimization

Finite state machine （FSM） plays a vital current which is drawn by state transitions can result in role in the sequential logic design. In an FSM, the high peak large voltage drop and electromigration which significantly affect circuit reliability. Several published papers show that the peak current can be reduced by post-optimization schemes or Boolean satisfiability （SAT）-based formulations. However, those methods of reducing the peak current either increase the overall power dissipation or are not efficient. This paper has proposed a low power state assignment algorithm with upper bound peak current constraints. First the peak current constraints are weighted into the objective function by Lagrangian relaxation technique with Lagrangian multipliers to penalize the violation. Second, Lagrangian sub-problems are solved by a genetic algorithm with Lagrangian multipliers updated by the subgradient optimization method. Finally, a heuristic algorithm determines the upper bound of the peak current, and achieves optimization between peak current and switching power. Experimental results of International Workshop on Logic and Synthesis （IWLS） 1993 benchmark suites show that the proposed method can achieve up to 45.27% reduction of peak current, 6.31% reduction of switching power, and significant reduction of run time compared with previously published results.     

Low power noise immune node voltage comparison keeper design for high speed architectures

The demand for high speed and area minimization has directed the designers towards dynamic CMOS logic design. The domino logic is one of the famous logic in dynamic CMOS logic. The designer needs to compromise the circuit speed and power consumption to reduce the impact of noise in domino logic circuit design. In this work, low power domino logic circuit is proposed to decrease power consumption with improvement in noise immunity. The low power consumption is achieved at the cost small sacrifice in delay. However, the proposed logic circuit has attained better Power Delay Product (PDP) as compared to existing noise tolerant circuits. The experimental simulation results shows the proposed logic exhibit 3.4% power reduction when compared with the low power domino logic circuit [10] for two input OR gates. The proposed logic had a little compromise with delay in the existing logics. However, the Power Delay Product (PDP) of proposed logic circuit has reduced as compared to existing techniques. The proposed logic also provides the better improvement in noise immunity parameters such as UNG and ANTE as compared to the existing logics. The proposed logic circuit based application circuit such as 4:1 multiplexer also provides better improvement in case of power consumption and noise immunity.     

基于加权数据通路的RTL级低功耗SoC设计

低功耗是SoC设计与评估的重要技术指标之一,现利用加权数据通路,提出一种新的低功耗SoC设计方法。该算法首先利用程序切片技术提取RTL级数据通路,然后采用贝叶斯网络训练获得各数据通路的权重(使用频率),以形成加权数据通路,最后根据各路径权值控制门控信号的产生,对权值小的通路优先插入门控逻辑或合并门控逻辑,从而有效降低系统功耗。实验结果表明,该算法与已有ODC低功耗算法相比功耗平均下降8. 38%,面积开销平均减少6.8%,同时数据通路的简化也使得算法计算负荷大幅下降。     

FSM状态间逻辑条件检验的算法研究

有限状态机(FSM)是VLSI控制结构的一种映射,它的自动综合成为设计自动化的一个十分重要的环节和途径。本文讨论在FSM自动综合中输入阶段的状态间逻辑条件检验的问题,研究分析状态间逻辑条件检验的相互关系及影响,并提出了FSM状态间逻辑条件检验的优化算法,从而使时间复杂度降低,实现更加简便。最后,本文给出了优化算法的流程和一些实验结果,结果令人满意。     

Dual threshold voltage and sleep switch dual threshold voltage DOIND approach for leakage reduction in domino logic circuits

Subthreshold leakage current becomes the major component of total power dissipation as scaling down the feature size. In this paper, two new circuit techniques are proposed for reducing the subthreshold leakage power consumption in domino logic circuit. Dual threshold voltage DOIND (Domino logic with clock and input dependent transistors) and NMOS sleep switch dual threshold voltage DOIND circuits for low leakage domino logic circuits are presented. High threshold voltage transistors are utilized to reduce the leakage current and a sleep transistor is added to the dynamic node that strongly turnoff all the high threshold voltage transistor and significantly reduce the subthreshold leakage power. The proposed circuit techniques, dual threshold voltage DOIND logic and sleep switch dual threshold voltage DOIND logic reduces the leakage current by 71.46 and 74.86% respectively as compared to standard domino logic circuit. Simulation results also shows that both the circuits are less affected by supply and temperature variations. The proposed sleep switch dual threshold voltage DOIND exhibits 19.95% less power consumption with 24% die area overhead for the buffer circuit as compared to standard domino logic circuit. The proposed sleep switch dual threshold voltage DOIND logic has improved normalized figure of merit of 1.17 as compared to standard domino logic circuit.

     

逻辑平衡与高速数字电路

在设计者进行系统和电路级设计时,时常会将要实现的逻辑功能或操作较为平均地分配到时序中的各个阶段,称之为逻辑平衡设计。该论文引用了逻辑平衡的方法,将其运用在高速数字部件设计中,以常用运算单元如计数器,有限状态机和乘法器的高性能设计方案为例,分析了逻辑平衡在高速集成电路设计中的应用;并分析了逻辑平衡的方法在减小电路面积,提高电路的性价比和降低电路功耗中的作用。     

基于Agent和FSM的细胞信号转导网络仿真

针对现有细胞信号转导网络仿真方法的不足,提出一种基于Agent和FSM的仿真方法,在宏观水平与微观水平之间构建多Agent系统,仿真复杂的细胞信号转导网络。融合了智能Agent技术和FSM模型实现分子建模,有效地模拟了信号传递的分子机制,并减少了外部通信。采用定性仿真建模分子构象,降低了组合复杂性。通过仿真实验证明了方法的有效性。     

Machine Learning-Based Pruning Technique for Low Power Approximate Computing

Approximate Computing is a low power achieving technique that offers an additional degree of freedom to design digital circuits. Pruning is one of the types of approximate circuit design technique which removes logic gates or wires in the circuit to reduce power consumption with minimal insertion of error. In this work, a novel machine learning (ML) -based pruning technique is introduced to design digital circuits. The machine-learning algorithm of the random forest decision tree is used to prune nodes selectively based on their input pattern. In addition, an error compensation value is added to the original output to reduce an error rate. Experimental results proved the efficiency of the proposed technique in terms of area, power and error rate. Compared to conventional pruning, proposed ML pruning achieves 32% and 26% of the area and delay reductions in 8*8 multiplier implementation. Low power image processing algorithms are essential in various applications like image compression and enhancement algorithms. For real-time evaluation, proposed ML optimized pruning is applied in discrete cosine transform (DCT). It is a basic element of image and video processing applications. Experimental results on benchmark images show that proposed pruning achieves a very good peak signal-to-noise ratio (PSNR) value with a considerable amount of energy savings compared to other methods.