Low-noise Charge Preamplifier Research Articles

Low noise voltage and charge preamplifiers for phonon and ionization detectors at very low temperature

We have developed voltage and charge sensitive FET preamplifiers which feature ultra low noise, convenience and flexibility for phonon and ionization detectors operated at 20 mK. With an NJ132L J-FET, the white noise of the voltage amplifier is 1.1 nV/√Hz at room temperature and 0.9 nV/√Hz when the FET is cooled to ≈120 K; the 1 f knee is below 100 Hz. The power dissipation of the FET, about 7 mW in our application, allows it to be used in a 4 K environment. With the same cooled FET, the charge amplifier has shown a noise of 120 e − rms with a total input capacitance of 45 pF.

An HEMT input charge preamplifier for nanoseconds signal processing time

The capabilities of the high electron mobility transistor (HEMT) as front end device in charge preamplifiers for radiation detectors have been experimentally tested. We present the design and performance of a fast low-noise charge preamplifier having an HEMT as input transistor. An equivalent noise charge of 139 rms electrons, i.e., 1.13 keV FWHM in silicon detectors, has been measured at room temperature with 10 ns RC-CR shaping and 1 pF input capacitance.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Design of a high-performance, low-noise charge preamplifier

A high-performance, low-noise charge preamplifier integrated circuit is designed and tested for the Superconducting Super Collider. The amplifier is fabricated in a new dielectrically isolated (DI), radiation-hardened, very-high-frequency (VHF) BIFET IC process technology from Harris Corporation. This new process provides n-p-n, p-n-p, and p-channel JFET devices which are both radiation-hardened, tested to 3 Mrad of total gamma ray exposure and 3*10/sup 14//cm/sup 2/ neutron dosage, and provides high-frequency performance. The new charge preamplifier provides improved performance with an output rise time of 65 ns, input inferred noise of 28.6 mu V, or 3575 electrons, and power dissipation less than 33.7 mW. The circuit design is discussed with attention given to those design characteristics needed to specifically accommodate low noise with the new radiation-hardened process.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Hybrid low-noise charge preamplifiers for heavy-ion detectors

The characteristics of hybrid low-noise general-purpose preamplifiers are described. The basic performances are reported. They have been used in connection with ionization chambers, large-area Si detectors and photodiodes.

A Fast Low-Noise Charge Preamplifier

A wideband low-noise charge preamplifier was designed for energy and time spectroscopy with silicon surface barrier detectors. With a 0 pF detector capacitance the rise time is less than 4 ns, and the noise is 1.4 keV at 2 μs. With a 1000 pF detector capacitance the rise time is 19 ns, and the noise is 15.9 keV. FWHM time resolution values as low as 90 ps for 1 MeV signals are possible. A detailed investigation of factors affecting transient response is given. Root locus techniques are used to study loop transient response, and the problems with cable connection at the input are considered using transmission line theory.

Overload Recovery Circuit for Charge Amplifiers

In this paper the operation of low noise charge preamplifiers under high instantaneous pulse rates - "bursts" - is considered. An overload recovery circuit employing a field-effect transistor as the switch for the recovery current is described. The overload charge generated in the detector by the radiation burst in a time short compared to the small signal resolving time of the spectrometer may be 105 or more times larger than the charge due to a single particle to be measured between the bursts. The recovery time of the charge amplifier with the recovery circuit is less than 10 μsec. With a conventional amplifier-filter, the recovery time of the system to within the noise level is 50 to 100 μsec. The increase in noise due to the recovery circuit corresponds to an increase in the input capacitance of the charge amplifier of 2 pF.