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 ¿s. 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.