Method for improving voltage modulation depth of high T/sub c/ DC SQUID with large inductance

Two methods are proposed in order to improve the voltage modulation depth of high-T/sub c/ DC SQUIDs in the case of large inductances. One is a damping resistance parallel to the inductance, and the other is a new SQUID using three junctions, which we call 3J-SQUID. Numerical simulation shows the usefulness of the present method. Moreover. It is shown that the improvement of the voltage modulation depth results in the improvement of magnetic flux noise in the white noise region. Therefore, the present method will enable the use of large inductances. The usefulness of the present method is also confirmed partly by experimental results.<
>