Design and High-Speed Testing of a Superconducting Delta-Sigma Oversampled Converter

A delta-sigma Modulator with a lowpass filter can achieve the same signal-to-noise ratio (SNR) and dynamic range as a delta-sigma modulator with an integrator by adjusting the cut-off frequency of its lowpass filter. A lowpass filter modulator in superconducting niobium technology was designed and tested up to a 1 GHz sampling rate and was shown to be operating correctly. The bits of a pseudo-random bit stream digital output are acquired individually by a high-speed logic analyzer. The acquired data show 6 bits of modulator dynamic range, which is limited below the simulated value of 11 bits, at least in part, by errors in the test equipment. © 1995 IEEE