Superconducting High-Resolution Low-Pass Analog-to-Digital Converters

HYPRES has developed a high-resolution, dynamically programmable analog-to-digital converter (ADC) for radar and communications applications. The ADC uses the phase modulation-demodulation low-pass architecture and on-chip digital filtering. Detailed experimental results at 20 GHz clock frequency of the ADC chip fabricated with a 1 kA/cm² Nb process are presented and discussed. In addition to the standard ADC configuration, different ADC modifications are described. In the multi-rate ADC, the modulator sampling frequency is the twice the clock frequency for the time-interleaved digital filter. In addition to the standard parallel-output ADC, a serial output ADC and its interface to room temperature electronics are developed. This serial ADC chip fabricated with the advanced HYPRES 4.5 kA/cm² process operated up to 34 GHz clock. As a major step toward commercialization of superconducting electronics, an ADC chip was successfully packaged on a cryocooler where it showed reduced performance up to 11.52 GHz clock.