Design of a finite impulse response filter for rapid single-flux-quantum signal processors based on stochastic computing

Rapid-Single-Flux-Quantum (RSFQ) circuit technology is well known for its low power consumption and latency, which enables digital signal processing up to tens of GHz. As a fundamental digital filter, the Finite Impulse Response (FIR) filter has wide applications in communication systems. A design of an FIR filter based on RSFQ circuit technology is proposed. However, the FIR filter consumes large amounts of adders and multipliers. Based on Stochastic Computing (SC) theory with which adder and multiplier are much simpler, the hardware cost of FIR filter is dramatically reduced. A novel stochastic number generator (SNG), a stochastic-tobinary converter (SBC), and the FIR filter were designed and verified via logic simulation with a target frequency of 10 GHz. The results indicated the FIR filter performs correct operations. The proposed FIR filter consists of 2255 Josephson junctions (JJs) without wiring cells (i.e., Josephson Transmission Lines (JTLs), Passive Transmission Lines (PTLs)), which is acceptable, making it possible to be used in RSFQ digital signal processors.