Evaluation of dynamic range for an HTS sigma-delta modulator with 100-GHz sampling

Circuit simulations were used to study the capability of a high-temperature superconducting (HTS) sigma-delta modulator using interface-engineered-Josephson junctions (IEJ's). The dynamic range was calculated while varying the temperature (T) and input-signal frequency (f/sub 0/), and in the resultant power spectra, correct noise shaping (6 dB/oct) was found. Investigation of the dynamic range in terms of effective number of bits (ENOB) showed that ENOB was 6.7 for f/sub 0/<200 MHz and T<40 K. At higher input-signal frequencies, i.e., 400 MHz40 K.