Testing of the SB349, a 32x32 CTIA readout multiplexer for far IR focal-plane arrays

The SB349 is a 32x32 readout multiplexer specifically designed for far IR photodetectors and is capable of operating at cryogenic temperatures at least as low as 1.8K. This readout is a capacitive-transimpedance amplifier multiplexed to eight outputs and is buttable on two sides to form a 64x64 mosaic array. It features eight selectable gain settings, auto zero for better input uniformity, sample-and-hold circuitry, and provisions to block the readout glow. A special, 2-micron cryo-CMOS process was adopted to prevent freeze out and ensure low noise and proper operation at deep cryogenic temperatures. An overview of the design and the results of the tests performed on this device are reported in this paper.