We have studied software-defined radios (SDRs) based on superconducting devices. The increasing data rate in mobile communications will require a band-width of up to a few hundred MHz in the future. We have confirmed numerically the broad-band characteristic of oversampled analog-to-digital converters including a lowpass and bandpass modulator. Furthermore, the bandpass modulator constructed without a resistor is found to have sensitivity improved by two orders of magnitude compared to that of the lowpass modulator. This result means that the digital RF radio architecture based on a bandpass ADC is better suited for a future SDR receiver.Index Termsanalog-to-digital converter, RF-sampling, software-defined radio, wide-band receiver.

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