US Patent 7365663 Flux-quantizing superconducting analog to digital converter (ADC)

A superconducting analog-to-digital converter includes a superconducting input loop to which is applied an analog voltage to be converted to a digital format. The superconducting loop includes two Josephson junctions for converting said analog input voltage into a single flux quantum (SFQ) pulse stream having a frequency f1 which is directly proportional to the amplitude of the analog input voltage. The loop includes two outputs for distributing the pulse stream in a cyclical and staggered fashion onto the two loop outputs such that the frequency of the pulses along each one of the loop outputs is f½. Additional frequency divider circuits may be coupled to the loop outputs to produce pulse streams on N output lines having a frequency of f1/N.