Cryogenic Phase Detector for Superconducting Integrated Receiver

New superconducting element, a cryogenic phase detector (CPD) has been proposed and preliminary tested. The CPD is based on a superconductor-insulator-superconductor junction and initially intended for phase locking of a flux-flow oscillator in a superconducting integrated receiver. First results of the CPD development and study are very encouraging; a sinusoidal response of the CPD has been measured at the variation of the phase shift between input signals. Dependences of the output signal and phase response on the CPD bias voltage have been studied; main parameters of this new device are estimated. Important that the CPD output current well above 10 has been measured at the input signal provided by the harmonic mixer of the integrated receiver and amplified by the existing HEMT-amplifier. Due to the large conversion coefficient this current being supplied to the flux-flow oscillator (FFO) control line is sufficient to directly tune FFO frequency. Obtained data demonstrate that the CPD intrinsically could operate with effective bandwidth more than 100 MHz. Preliminary results of the CPD implementation for the FFO phase locking are presented; possible advantages of such combination are discussed.