RATIO STANDARD FOR DC RESISTANCE USING A JOSEPHSON POTENTIOMETER

A Josephson potentiometer for the comparison of two-terminal dc resist ors in the range from about 10 kOMEGA to at least 10 MOMEGA is describ ed. It is based on a three-terminal Josephson junction series array. R esistance ratios from 1:1 to 1:10 can be compared with a single device . Measurements with a prototype instrument have already shown a relati ve reproducibility of 1 part in 10(7). Besides standard Josephson junc tion series arrays with a characteristic impedance of the stripline Z almost-equal-to 3 OMEGA, high-impedance arrays with Z almost-equal-to 77 OMEGA have also been realized.