Veljko Radeka: Notes on the origin of charge amplifiers

July2, 2014

1

The first record of a Charge-Sensitive Amplifier Circuit

Classical “integrator” known from WWII (1941-5,) appears as charge amplifier in ~1950-ies (Gatti, et al.):

Input capacitance ~ open-loop gain x Cf

1948

Vacuum tube at the input until ~1963 when the first JFET is used …

Cf

Cf

The “last word” from vacuum tubes – introducing Ge detectors (Tavendale,1963)

3

Noise: ~200 e rms at 20pF, 1-2μs

The Cascode!

Feedback

Original charge preamp with JFET, 1968

From: V. Radeka“State of the art of low noise amplifiers for semiconductor radiation detectors”Proc. Intern. Symp. Nuclear electronics, vol. I (1968), p. 46.1, 28