Superconducting Bandpass ADC Technology for Digitization at RF

HYPRES proposes to develop a superconducting digital-RF receiver with very high signal-to-noise ratio (SNR) and spur-free dynamic range (SFDR) to meet the requirements of future software radios for both military and commercial wireless communications. Thisrequires direct digitization of the RF signal, followed by down-conversion in the digital domain, replacing the nonlinear analog mixer in a conventional receiver. Superconductor ADCs, sampled up to 20 GHz rates, have already demonstrated superiorperformance in low-pass architectures. New circuit designs are needed to enhance performance. Our objective is to achieve at least 100 dB (16 effective bits) of SNR and SFDR over a 10-100 MHz bandwidth at frequencies up to 2 GHz, which is not achievable byconventional electronics. During Phase I, several alternative circuit architectures were investigated, new ADCs were designed and a development plan was established. In Phase II we will follow this plan to build three different wideband second-orderdelta-sigma ADC modulators, each sampled at 40 GHz, that are tailored for different sections of the communications spectrum. Starting with the Phase I Option, ADC circuits will be fabricated and integrated with programmable digital mixer and decimationfilters in Phase II. A complete receiver will be built and demonstrated.An improved bandpass analog-to-digital converter is an essential enabling component for next generation software radio. Elimination of frequency and protocol-specific analog componentsby broadband digitization, followed by digital processing, enables agile, inter-operable, reconfigurable communication transceivers as required by the Joint Tactical Radio System (JTRS). While the performance demands of commercial wireless communicationssystems lag well behind those of the military, software radio will pervade the commercial world in the next few years. Finally, in addition to communication systems, superconductive digital-RF technology will improve other military RF systems, such asradar and electronic warfare.