32-bit ALU with Clockless Gates for RSFQ Bit-Parallel Processor

Abstract

A32-bit arithmetic logic unit (ALU) is designed for a rapid single flux quantum (RSFQ) bit-parallel processor. In the ALU, clocked gates are partially replaced by clockless gates. This reduces the number of D flip flops (DFFs) required for path balancing. The number of clocked gates, including DFFs, is reduced by approximately 40 %, and size of the clock distribution network is reduced. The number of pipeline stages becomes modest. The layout design of the ALU and simulation results show the effectiveness of using clockless gates in wide datapath circuits.