Spur-free sigma-delta modulator and multiple flux quanta feedback generator

Abstract

A spur-free sigma delta modulator analog-to-digital converter for converting an analog input signal to a digital output signal is provided. A race Josephson junction is provided between the pulse generator and the integrating inductor. The race Josephson junction emits a voltage pulse in response to every sampling pulse. This voltage pulse kills any retained persisting current in the integrating inductor. By adding the race Josephson junction, nonlinearities in the converter are eliminated. A multiple flux quanta feedback generator for creating a multiple digital pulse feedback in response to an input signal is provided. A quantizer connected to the input inductor produces a pulse when the current produced by the input inductor exceeds a predetermined amount. A splitter is connected to the quantizer for producing output pulses. In order to produce 2.sup.n output pulses, 2.sup.n -1 splitters are required. Each of the splitters produces two output pulses in response to a single pulse produced by the quantizer. Each of the 2.sup.n output pulses drives one of 2.sup.n feedback pulse generators. Each of the feedback pulse generators is connected to one of the output pulses to produce 2.sup.n +1 quanta feedback which is fed back to the input inductor.

Dependencies are inferred from the claim text.