Encoders and decimation filters for superconductor oversampling ADCs

Modulators of superconductor ADCs can operate at very high sampling rates, ranging from 20 GHz (today's technologies) to 400 GHz (prospective sub-micr on technologies). Such devices are too fast and therefore impractical witho ut other superconductor devices capable of processing the data streams at s uch rates. We discuss various structures of such devices, in particular dem ultiplexers and decimation filters. We also analyze possible hybrid devices , in which only the front stages contain superconductor components, Encoder s and decimation comb filters for single-comparator and time-interleaved mo dulators were designed, fabricated (at HYPRES, Inc.) and successfully teste d. The most recent designs of the decimation filters have a unique modular structure, which allows an assembly of various comb filters handling clock frequencies of about 20 GHz (for a 1 kA/cm(2) fabrication technology).