Author/Authors :
Yvon، نويسنده , , D and Sushkov، نويسنده , , V and Bernard، نويسنده , , R and Bret، نويسنده , , J.L and Cahan، نويسنده , , B and Cloue، نويسنده , , O and Maillard، نويسنده , , O and Mazeau، نويسنده , , B and Passerieux، نويسنده , , J.P and Paul، نويسنده , , B and Veyssiere، نويسنده , , C، نويسنده ,
Abstract :
We implemented a low noise current preamplifier for the readout of resistive bolometers. We tested the apparatus on thermometer resistances ranging from 10 to 500 MΩ. The use of current preamplifier overcomes constraints introduced by the readout time constant due to the thermometer resistance and the input capacitance. Using cold JFETs, this preamplifier board is shown to have very low noise: the Johnson noise of the source resistor (1 fA/Hz1/2) dominated in our noise measurements. We also implemented a lock-in chain using this preamplifier. Due to fast risetime, compensation of the phase shift may be unnecessary. If implemented, no tuning is necessary when the sensor impedance changes. Transients are very short, and thus low-passing or sampling of the signal is simplified. In case of spurious noise, the modulation frequency can be chosen in a much wider frequency range, without requiring a new calibration of the apparatus.
