Component test toward single-flux-quantum processors

We have developed essential components for most of microarchitectures based on the single-flux-quantum (SFQ) logic. The circuit under test is composed of two registers, an ALU and a control unit, and made up of about 540 cells, 1600 Josephson junctions on 1.5 x 2.4 mm area. We have obtained the correct results by a sequence of several instructions, in which two integers are written into the registers with the LOAD and COPY operations, and then execute the ADD operation. Some of their functions were tested at both low and high frequencies. As a result, we found that the designed components could work at 15 GHz for the designed bias current and up to 18 GHz for higher bias currents