Tuning circuit with distributed tunnel junction elements and superconductor integrated circuit comprising the tuning circuit

摘要

It is an object to provide a tuning circuit which has large fractional frequency band width, for example frequency band of the return loss of less than −10 dB. The tuning circuit is composed of a superconductor microstrip lines, a superconductor distributed tunnel junction elements, a signal input part and a signal output part. It comprises at least a superconductor microstrip line and at least two superconductor tunnel junction elements, wherein the microstrip line and the tunnel junction element are connected alternately. The microstrip line and the tunnel junction element are half-wavelength of an input signal at a center frequency. A quarter-wavelength impedance transformer is comprised between a signal input part and a half-wavelength tunnel junction which is nearest to the signal input part.