On-chip high-frequency diagnostic of RSFQ logic cells

Hilbert Transform spectroscopy is described as a method to analyze the spectrum of pulse trains generated by RSFQ circuits. Simulations are carried out using parameters appropriate for NbN Josephson junctions for both generation and detection of SFQ pulse trains. It is shown that the pulse shape along with the pulse train repetition rate can be extracted through the use of a Josephson junction, used as a spectrometer, and located on-chip with the RSFQ circuit to test.