A Linear, Wideband, Low-Noise Amplifier Stage for Use in Nuclear Pulse Amplifiers

The design evolution of a wideband voltage-sensitive amplifier stage is presented. For the basic stage, including a new driver configuration and overload control circuit, three basic input sections are considered; the first section consists of differentially connected bipolar transistors for use with low generator impedances, the second consists of medium-transconductance FETs to allow larger coupling time constants, and the third consists of high-transconductance FETs for low-noise performance with large coupling time constants. Large-and small-signal bandwidth analysis is given for each configuration. From this analysis, criteria are established for allowing equal large-and small-signal rise times. Also, for each type of input section, expressions of equivalent noise voltage are derived. A table of experimental results is presented, summarizing data obtained for several important performance parameters. Typical measurements for the medium-transconductance FET input section for a voltage gain of 16 include small-and large-signal rise times of 10 nsec, overload recovery times from a 5-v input of ~20 nsec, and integral nonlinearity of <0.05%.