VHF Josephson Arbitrary Waveform Synthesizer, IEEE Transactions On Applied Superconductivity

These data will appear in [1]. The abstract for that paper is given below:We report on the design, fabrication, and measurement of a Very High Frequency band Josephson Arbitrary Waveform Synthesizer (VHF-JAWS) at frequencies from 1~kHz to 50.05~MHz. The VHF-JAWS chip is composed of a series array of 12,810 Josephson junctions (JJs) embedded in a superconducting coplanar waveguide. Each JJ responds to a pattern of current pulses by creating a corresponding pattern of voltage pulses, each with a time-integrated area related to fundamental constants as $ extit{ extbf{h/2e}}$. The pulse patterns are chosen to produce quantum-based single-tone voltage waveforms with an open-circuit voltage of 50~mV~rms (\mbox{-19.03~dBm} output power into 50~$\Omega$ load impedances) at frequencies up to 50.05~MHz, which is more than twice the voltage that has been generated by previous RF-JAWS designs at 1~GHz. The VHF-JAWS is "quantum-locked", that is, it generates one quantized output voltage pulse per input current pulse per JJ while varying the dc current through the JJ array by at least 0.4~mA and the amplitude of the bias pulses by at least 10~%. We use the large bias pulse quantum-locking range to investigate one source of error in detail: the direct feedthrough of the current bias pulses into the DUT at VHF frequencies. We reduce this error by high-pass filtering the current bias pulses and measure the error as a function of input pulse amplitude using two techniques: by measuring small changes over the quantum-locking range and by passively attenuating the input pulse amplitude so that the nonlinear JJs no longer generate voltage pulses while the error is only linearly scaled.
Organization: National Institute of Standards and Technology
Last updated: 2024-03-12T23:56:27.774396
Tags: digital-analog-conversion, josephson-junction-arrays, power-measurement-standards, signal-synthesis, superconducting-integrated-circuits, superconducting-microwave-devices