Superconductive convolver

Concepts for realizing superconductive convolvers capable of processing analog signals having bandwidths up to 10 GHz have been developed and are being implemented. A preliminary convolver structure with 19 taps and a 14-ns interaction length has recently been demonstrated. This device employs a superconductive transmission line as a low-loss delay element and superconductive tunnel junctions as nonlinear mixing elements. The niobium delay line provides the relative shifting of signal and reference waveforms, niobium/niobium-oxide/lead mixers with proximity taps provide local multiplication of the two waveforms, and a short output transmission line provides coherent summation of the local products. The principles of device operation, design tradeoffs and experimental results will be presented. Convolvers can provide the essential programmable matched-filter component for extremely wide-bandwidth spread-spectrum communication systems. It appears feasible to produce a convolver with an interaction time of about 100 ns and signal processing gains of up to 1000. This superconductive analog device offers the potential of providing a real-time programmable signal processing function with the digital equivalent of about 10¹²operations/sec.