Asynchronous superconductor serial multiply-accumulator

Abstract

An oscillator/multiply-accumulator AID converter ( ) which simultaneously provides frequency downconversion, band pass filtering and analog-to-digital conversion of an analog signal, where the analog signal includes a carrier wave modulated with information by any known modulation technique. The converter ( ) uses a superconducting, Josephson single flux quantum circuit operating as a voltage controlled oscillator ( ). The voltage controlled oscillator ( ) receives the analog signal to be converted, and generates a series of sharp, high frequency pulses based on the characteristics of the carrier signal. The series of pulses are applied to a gate circuit ( ) that either passes or blocks the pulses depending on a gate control signal ( ). When the pulses are passed by the gate circuit ( ), a multiply-accumulator ( ) multiplies the pulse by a binary coefficient ( ) and accumulates the products ( ) resulting from the multiplication during a predetermined time period. The predetermined time period includes at least one sampling period. Each sample is multiplied by a different weight and their products ( ) are accumulated. This operation eliminates the DC response, and leads to an improved frequency response.