80-GHz Operation of an 8-Bit RSFQ Arithmetic Logic Unit

We have designed and demonstrated an arithmetic logic unit (ALU) based on rapid single-flux-quantum (RSFQ) technology. The ALU has been developed toward demonstration of high-performance information processing using a general purpose microprocessor CORE e4. The target operation frequency of the ALU is 50 GHz. In this paper, we present the design and high- speed functionality test results of the ALU. The ALU can execute 10 instructions. We aimed at high frequency operation with precise timing design using logic gates synchronized to the clock signal. The ALU contains 1555 Josephson junctions (JJs) and occupies a circuit area of 0.53mm². We have demonstrated the correct operation of the ALU using on-chip high-speed test. The estimated maximum operating frequency based on measurement results is 80 GHz.