Readout of a 176 pixel FDM system for SAFARI TES arrays
Richard A. Hijmering (SRON–Netherlands Institute for Space Research)
R den Hartog (SRON–Netherlands Institute for Space Research)
M. Ridder (SRON–Netherlands Institute for Space Research)
A. J. van der Linden (SRON–Netherlands Institute for Space Research)
J. Van Der Kuur (SRON–Netherlands Institute for Space Research)
J.R. Gao (TU Delft - QN/Gao Lab, SRON–Netherlands Institute for Space Research)
B. Jackson (SRON–Netherlands Institute for Space Research)
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Abstract
In this paper we present the results of our 176-pixel prototype of the FDM readout system for SAFARI, a TES-based focal-plane instrument for the far-IR SPICA mission. We have implemented the knowledge obtained from the detailed study on electrical crosstalk reported previously. The effect of carrier leakage is reduced by a factor two, mutual impedance is reduced to below 1 nH and mutual inductance is removed. The pixels are connected in stages, one quarter of the array half of the array and the full array, to resolve intermediate technical issues. A semi-automated procedure was incorporated to find all optimal settings for all pixels. And as a final step the complete array has been connected and 132 pixels have been read out simultaneously within the frequency range of 1-3.8MHz with an average frequency separation of 16kHz. The noise was found to be detector limited and was not affected by reading out all pixels in a FDM mode. With this result the concept of using FDM for multiplexed bolometer read out for the SAFARI instrument has been demonstrated.