A 1 GOPs 8 b Josephson digital signal processor

A 6.3 K-gate digital signal processor (DSP) that performs 8-b*8-b multiplication in 240 ps and 13-b addition in 410 ps contains 23000 Josephson junctions, and is fabricated using 1.5- mu m all-niobium Josephson technology is described. The DSP attains a nonparallel processing speed of 1 gigaoperation per second (GOPS) with 12-mW dissipation. Digital signal processing devices, such as FIR (finite-impulse-response) and IIR (infinite-impulse-response) filters, for video signal processing must be capable of handling high-speed multiply and add operations. For the FIR filter, parallel processing allows high-speed operation, but it is hard to use in an IIR filter which operates with previously processed data. Speed is a great asset in nonparallel data processing. Josephson gates offer high-speed operation and low power dissipation. A block diagram and the three-stage pipeline processing sequence of the DSP are shown. Both the 8-b*8-b multiplier and the 13-b ALU (arithmetic logic unit) are active in the third stage. Consequently, the DSP can complete once every machine cycle not only a series of multiply-add operations, but also a multiply-add operation using the previously added data. With this design, the data-processing rate using the previous data is the same as the internal machine rate.<>