A cryogenic bolometer detector utilizing a NTD Ge temperature sensor operating at 10 mK is being developed to study neutrinoless double beta decay (NDBD) in 124Sn. In the present readout electronics, output signal from the sensor is amplified using a commercially available low noise differential amplifier kept at room temperature. To reduce the EMI pickups due to the long cables connecting the cold sensor with the amplifier at room temperature and to minimize the signal integration due to the cable capacitance, indigenous development of the front-end cryogenic stage has been initiated. In this talk, design, simulation and test results of a cryogenic low noise DC coupled source follower amplifier implemented with an active load resistor will be presented. The output signal of the front-end stage will be further amplified using a second stage low noise high gain differential amplifier, which will be kept at room temperature. The design aspects as well as the preliminary results of the second stage amplifier will also be presented.
In this talk, I will also present the detailed noise characterization, investigation of various noise sources and its mitigation to improve the performance of a cryogenic bolometer detector. The noise spectrum has been measured for a sapphire bolometer test setup and the effect of external noise, arising either from ground loops in the system or from the diagnostic and control electronics of the cryostat, on the performance of the bolometer will be discussed