Two SQUID amplifiers intended to alleviate the summing node inductance problem in multiplexed arrays of Transition Edge Sensors

Abstract

Frequency Domain Multiplexed detector arrays constructed of superconducting Transition Edge Sensors in the current-summing configuration suffer from the finite impedance of the summing node which should ideally be zero. We suggest two circuits to alleviate the effect. The first circuit uses a capacitive resonant transformer to increase the voltages and decrease the currents of TES signals to overcome the parasitic inductance of the interconnections. On the SQUID chip impedance transform to the opposite direction takes place. The second circuit implements a power combiner having a better branch-to-branch isolation than a simple T-junction. Two SQUID devices have been designed and fabricated for a proof-of-principle demonstration of the circuits.