A Josephson-array calculable-waveform generator

This paper proposes a new method for using a Josephson array to create a voltage waveform with a root-mean-square value calculable to better than 2 in 10⁶ at frequencies below 50 Hz. A novel method of reliably switching the dc voltage from one known voltage step to another at precisely defined time intervals is investigated. In this method, transients in the microwave voltage driving the array are used to induce switching between steps. We consider two possible implementations of this concept. The first is for an array similar to that used in conventional dc voltage standards. The second uses the binary sequence of individually biased arrays introduced by Hamilton et al [1995]. Computer simulation and theoretical analysis are used to demonstrate that the uncertainties in switching times are potentially limited only by the speed of the available microwave attenuators, which is currently of the order of a nanosecond