20Â GHz Operation of an Asynchronous Wave-Pipelined RSFQ Arithmetic-Logic Unit

We have designed and tested at high frequency an RSFQ-based Arithmetic-Logic Unit (ALU), the critical component of an 8-bit RSFQ processor datapath. The ALU design is based on a Kogge-Stone adder and employs an asynchronous wave-pipelined approach scalable for wide datapath processors. The 8-bit ALU circuit was fabricated with HYPRES' standard 4.5 kA/cm2 process and consists of 7,950 Josephson junctions, including input and output interfaces. In this paper, we present chip design and high-speed test results for the 8-bit ALU circuit.