Automation of design of charge preamplifiers for radiation detection

A low noise charge preamplifier is an important component of any radiation detection system. These preamplifiers, although commercially available, are very expensive because they are targeted to meet a wide spectrum of applications. Automation of design of preamplifiers offers a possibility of lower cost and better performance because of design simplification and an application specific design approach. A knowledge based approach has been used to develop a synthesis program for the design of charge preamplifiers and shapers. The synthesis is done by choosing among three different preamplifier topologies and a library of more than hundred JFETs to arrive at a design that offers the minimum equivalent input noise charge for the specified detector characteristics. An example of a design is presented and the results obtained are compared with PSPICE simulations.