Design and Implementation of a 16-Word by 1-Bit Register File Using Adiabatic Quantum Flux Parametron Logic

We have been developing extremely energy-efficient microprocessors using the adiabatic quantum flux parametron (AQFP) logic. In this study, we designed and fabricated an AQFP register file, which is one of the key building blocks in the microprocessor. The 16-word by 1-bit register file with dual output ports and a single input port was designed by using an AQFP cell library with a minimalist design. The circuit is composed of three decoders and feedback delay latches (D-latches), which are clocked by fourphase excitation currents. The circuits were fabricated using the AIST 10 kA/cm² Nb process. The total junction number and circuit area are 2544 and 3.1 mm × 5.4 mm, respectively. The estimated energy consumption is 18 aJ per clock cycle for 5 GHz operation. The latency is 1600 ps for 5 GHz operation. In the low-speed test, we confirmed the correct operations across 15 addresses.