Two-Stage SQUID Amplifier for the Frequency Multiplexed Readout of the X-IFU X-Ray Camera

The X-ray Integral Field Unit (X-IFU) is a cryogenic X-ray camera intended for the ATHENA space observatory. Its focal plane will contain a kilopixel array of Transition Edge Sensors (TESs), originally intended to be read out by a Frequency Domain Multiplexer involving 40 carrier frequencies in the 1-5 MHz range per readout channel. We review dimensioning principles and fabrication of a SQUID tandem, operating at 50 mK and 2 K temperatures, intended to amplify the multiplexed signal from the TES array. The first measurements indicate a 40 (sic) coupled energy resolution in the relevant frequency band, and sufficient linearity to reach the required 1% total harmonic distortion. Additionally, we describe the non-multiplexed amplifier SQUID for the X-IFU anti-coincidence detector.Peer reviewe

Noise Measurements of a Low-Noise Amplifier in the FDM Readout System for SAFARI

The SPICA-SAFARI instrument requires extremely sensitive transition edge sensor (TES) arrays with a noise equivalent power of 2×10-19W/Hz and a readout system with an output noise that is dominated by the detector noise. It is essential to ensure the frequency domain multiplexing (FDM) readout system in SAFARI meets the noise requirement. The FDM system in SAFARI consists essentially of LC filters, a superconducting quantum interference device, a room-temperature low-noise amplifier (LNA), and a demultiplexer. Here we present a noise study of the LNA from a laboratory amplifier chain. We found the equivalent current and voltage noise of the LNA to be 5.4pA/Hz and 315pV/Hz, respectively, which are low enough to read out SAFARI’s TES arrays