Superconducting modulators for high dynamic range delta-sigma analog-to-digital converters

Superconducting digital circuits are capable of producing high dynamic rang e analog-to-digital converters (ADCs). We present sigma-delta architectures using large (>100) oversampling ratios to give signal-to-noise ratios of g reater than 100 dB in simulation. Three distinct designs, using two distinc t mechanisms for feedback, are presented. All of the designs use only shunt ed junctions, and are therefore compatible with HTS SNS junctions. Simulati ons are presented for a modulator which creates feedback pulses by SQUID lo be-crossings, a modulator which uses the transresistance of a SQUID for fee dback, and a modulator which uses threshold crossings in both the first and second loops for feedback.