We have designed and demonstrated a Superconducting Quantum Interference Device (SQUID) array linearized with cryogenic feedback. To achieve the necessary loop gain a 300 element series array SQUID is constructed from three monolithic 100-element series arrays. A feedback resistor completes the loop from the SQUID output to the input coil. The short feedback path of this Linearized SQUID Array (LISA) allows for a substantially larger flux-locked loop bandwidth as compared to a SQUID flux-locked loop that includes a room temperature amplifier. The bandwidth, linearity, noise performance, and dynamic range of the LISA are sufficient for its use in our target application: the multiplexed readout of transition-edge sensor bolometers.
@article{arxiv.0901.1919,
title = {Linearized SQUID Array (LISA) for High Bandwidth Frequency-Domain Readout Multiplexing},
author = {T. Lanting and M. Dobbs and H. Spieler and A. T. Lee and Y. Yamamoto},
journal= {arXiv preprint arXiv:0901.1919},
year = {2009}
}