JOSEPHSON JUNCTION A/D CONVERTERS USING DIFFERENTIAL CODING.

A Josephson junction A/D converter is proposed that allows the conversion accuracy (characterized by the output bit number N) to be increased without using high-precision ( delta lambda / lambda approximately equals congruent 2**-**N) components. This improvement is made possible by the structure of the device, including a fast low-bit (p less than less than N) input A/D converter and several digital differentiation/integration stages. The general properties of this device and the possible realization of its main components in Josephson technology are discussed. Estimates show that at relatively low signal frequencies an additional digital stage (IF filter) can greatly improve the converter performance, making it considerably more accurate than any existing A/D converter.