Applications of the Josephson based spectrum analyzer

The Josephson spectrum analyzer exploits the programmable frequency spectrum in a Josephson Arbitrary Waveform Generator (JAWS) to measure a signal. The waveform to be measured is copied by the JAWS system. A conventional spectrum analyzer is used as a multi frequency null detector when the waveform and its JAWS copy are cancelled. We report the comparison of the Josephson spectrum analyzer with the classical approach used to measure harmonics present in waveforms, using a state of the art notch filter and a low noise amplifier. We also report measurements of the theoretically predicted-quantization harmonics, at -129 dBc, in a JAWS sinewave when a first order delta sigma modulator is used.