A DUAL SQUID LINEARIZATION CONCEPT USING A PHASE MODULATION SCHEME

A critical control system evaluation is presented of basic flux-locked loop systems. The development of a new superconducting quantum interf erence device (SQUID) linearization method is then described, where no magnetic flux feedback is necessary to cancel the applied flux. It is shown that a dual SQUID configuration will be able to produce a true phase modulation system that is easily demodulated with a phase-locked loop. The theoretical performance of the proposed configuration is ve rified by simulations, and the performance and limitations are discuss ed in detail. It is shown that small de correction voltages at the out put of the SQUID's significantly decrease output noise, as is the case with an increase in SQUID de bias currents. An optional feedback syst em is also described for optimal performance of the dual SQUID configu ration.