A very simple method to measure the input capacitance and the input current of transistors

We report on the front-end electronics designed for the readout of the CUORICINO experiment's array of 60 large-mass bolometers. The front end consists of a preamplifier and a bias system for the bolometer. A significant feature of our design is its capability for in situ DC characterization of each bolometer as a function of applied bias. The principal front-end operating parameters, low-noise bias selection, load resistor selection, offset compensation, and gain are remotely programmable.Index Terms-Detector biasing, electronics for bolometric detectors, front-end readout, high-input impedance circuit, low noise, low noise amplifier, low thermal drift, programmable system.

Section: The Preamplifiermentioning

confidence: 99%

The programmable front-end system for CUORICINO, an array of large-mass bolometers

Arnaboldi¹,

Bucci²,

Campbell³

et al. 2002

“…A much better condition is obtained if the optimum filter is applied, since its transfer, or weighting, function is given by the ratio between the signal and the noise [11]- [13]. In this case the importance of the improvement in the S/N is marginal with respect to the very small Gate area needed to obtain this result [13].…”

Section: A System Set-up and Requirementsmentioning

confidence: 99%

A Front-End Readout for Micro Bolometers Having Sub Nano Volt Noise Floor

Arnaboldi

Pessina

2006

We present our circuit solution for the second stage of the front-end readout of an array of -bolometers, cryogenic detectors having Si or Ge thermistor as sensing element. The front-end consists in a cold unity gain buffer stage (with single sided input connection) followed by a room temperature second differential amplifying stage. The optimization of the input transistor of the set-up has been determined by comparing the performances obtained applying a low pass filter or the optimum filter at output of the front-end. To minimize EMI interference the output of the cold buffer stage and its ground reference signal, taken close to the buffer itself, are readout in differential way from the second stage. To minimize noise, in our circuit solution the differential amplifier has an input stage with a noise that is 1.6 times smaller (1.27 times smaller if we consider the Square Root noise, SRn) than in a standard differential solution. Since the series noise is inversely proportional to the Gate area, to further reduce the noise the input JFET of the second stage has a large Gate area, of about 1 nF, and a very small feedback resistance. The performances of the presented second differential stage amplifier are about 0.194 (nV) 2 /Hz (440 pV/ Hz for the SRn), and a figure of less than 1.21 (nV) 2 /Hz (or 1100 pV/ Hz SRn) at 1 Hz. Parallel noise is completely negligible over the ranges of the expected output impedances of the cold stage. Dynamic input impedance is a few tens of pF. The voltage gain is 500 V/V, AC coupled down to 80 mHz.

“…The description of the B bandgap narrowing action is easily understood from the equation that gives the current gain, the ratio between the C and B currents, of a bipolar transistor: (1) In (1), is the smaller value between the width of the E region and the diffusion length of holes within the E region; is the width of the Base B;…”

Section: A Si-ge Hbt Principle Of Operation At Coldmentioning

confidence: 99%

“…The minimization of the connections results in a reduction of the parasitic shunting impedance that can deteriorate the signal to noise ratio and/or the dynamic performances [1].…”

Section: Introductionmentioning

confidence: 99%

Dynamic and low-frequency noise characterization of Si-Ge heterojunction-bipolar transistors at cryogenic temperatures

Arnaboldi

Boella

Pessina

2003