The Bias Generator System for the CUORE Large Mass Bolometer Detectors

We present a Bias Generator System designed for Large Mass Bolometric Detectors. The bias current, 100 pA ÷ 200 pA range, for these detectors is provided by large value resistors, that can be located at cold or at room temperature. To improve the precision and the stability of the bias current we developed a system based on a custom resistive network to take advantage of the good tolerance ratio and TCR (Temperature Coefficient of Resistance) of these devices. This custom network design exploits a geometry optimized to obtain a small 1/f noise. The presented system is also programmable thanks to the adoption of a digital potentiometer. The final feature is the availability of a double selectable range useful to produce the large bias current typically needed during the DC detector characterization phase. The system and the results from its characterizations, noise properties, precision, programmability, thermal and humidity sensitivity will be shown in details.