一种新型低功耗异步比较器的设计方法

摘要

Two types of low-power asynchronous comparators named asynchronous ripple comparator and pre-stop asynchronous comparator are proposed based on the statistical characteristic of input data in the paper. The asynchronous ripple comparator stops computing at the first unequal bit, but it has to deliver the result to the LSB. The pre-stop asynchronous comparator is proposed by revising the truth table based on the new 2-bit comparison unit and stop judgment circuit. It can stop comparing at the first unequal bit and obtain the result immediately. The proposed and contrasn've comparators (BCL comparator and clock-gating comparator) are implemented with SMIC 0.18μm process. Simulation results show that the proposed pre-stop asynchronous comparator features the lowest power.It saves 87.1% ,84.5% and 37.5% ,28.6% power respectively compared to the synchronous BCL comparator and clock-gating comparator with random data and data from LDPC decoder.%本文利用输入数据的统计特性,设计了两种低功耗异步比较器——异步行波比较器和提前终止异步比较器.异步行波比较器从第一个不相等的数位开始停止运算,但要把结果传到最低位,消耗部分功耗.提前终止异步比较器通过修改真值表,基于新的比较单元电路和终止判断电路,在第一个不相等的数位停止运算并立即输出比较结果,节省不必要的功耗.新设计的异步比较器和用于对比的同步比较器(BCL比较器和门控时钟比较器)均用SMIC0.18μm工艺实现.仿真结果表明,提前终止异步比较器功耗最低,与同步BCL比较器和门控时钟比较器相比,在随机数据和来自LDPC解码器的数据下,分别节省了87.1％、84.5％和37.5％、28.6％的功耗.