Mixed analog-digital niobium superconductive circuits for a 2-gigachip-per-second spread-spectrum modem

This paper describes the architecture and operation of a superconductive programmable matched filter that provides rapid synchronization information and data demodulation for a 2-GHz spread-spectrum modem. Results are reported for the first circuit fabrication runs using a new doubly planarized process. With the exception of circuits containing layout errors, all circuits have performed as intended and with characteristics that match well the predictions of JSIM simulations. The MVTL digital components and the buffer between the digital and analog circuits have been demonstrated for the first time. The seven-stage MVTL shift register in a complete prototype filter was operated at 1 GHz. In addition, combinations of (1) the MVTL digital shift register and the buffer and (2) the buffer and the T/H cell have been operated successfully, demonstrating that all of the components in the filter core will work together.