Patent attributes
A superconducting Analog-to-Digital Converter (ADC) employing rapid-single-flux-quantum (RSFQ) logic is disclosed. The ADC has only superconductor active components, and is characterized as being an Nth-order bandpass sigma-delta ADC, with the order “N” being at least 2. The ADC includes a sequence of stages, which stages include feedback loops and resonators. The ADC further includes active superconducting components which directionally couple resonator pairs of adjacent stages. The active superconducting components electrically shield the higher order resonator from the lower order resonator. These active superconductor components include a superconducting quantum interference device (SQUID) amplifier, which is inductively coupled to the higher order resonator, and may include a Josephson transmission line (JTL), which is configured to electrically connect the SQUID amplifier to the lower order resonator. The first stage of ADC may employ an implicit feedback loop.