Superconducting bandpass /spl Delta//spl Sigma/ modulator with 2.23 GHz center frequency and 42.6 GHz sampling rate

A superconducting bandpass /spl Delta//spl Sigma/ modulator employing a 2.23 GHz microstrip resonator and a single flux quantum comparator clocked at 42.6 GHz achieves 49 dB peak SNR over a 20.8 MHz bandwidth. At 40.2 GHz clock rate, in-band noise over a 19.6 MHz bandwidth is -57 dBFS. The test chip with integrated acquisition memory contains 4065 Josephson junctions and dissipates 1.9 mW at T=4.2K.