Operating conditions for a pulse-quantized AC and DC bipolar voltage source

Abstract

We have developed an accurate ac and dc bipolar voltage source based on the quantized pulses of Josephson junctions. A factor-of-6 increase in output voltage over previous unipolar waveforms is achieved by generating bipolar waveforms where arrays of junctions are biased with both a broadband two-level digital code and a sine wave. We use simulations to determine the optimum operating conditions as a function of frequency and as a function of the phase difference between the digital code and the sinusoidal drive.