A low noise cryogenic CMOS preamplifier for high critical temperature superconducting IR and FIR sensors

YBaCuO thin films have shown their attractiveness for infrared and far-infrared sensors working at the superconducting transition temperature (/spl ap/85 K). We present a cryogenic CMOS preamplifier designed for working close to such a sensor at the same temperature. This preamplifier has been tested from room temperature (300 K) down to liquid nitrogen temperature (77 K). Simulation results show that an equivalent input noise of 2.7 nV//spl radic/Hz at 10 kHz can be obtained at room temperature, whereas measurement results are 3.2 nV//spl radic/Hz at 300 K and 2 nV//spl radic/Hz at 77 K. When coupled to the YBaCuO sensor, an improvement of the overall noise level of the detector, by cooling the preamplifier, could be observed.