A semi-custom multi-channel preamplifier integrated circuit for spaceborne nuclear instrumentation

A monolithic eight-channel preamplifier for spaceborne nuclear instrumentation is being developed using a semicustom application specific integrated circuit (ASIC) based on bipolar tile-array technology. This general-purpose charge-sensitive bipolar octal preamplifier (BOP) was designed using a complementary current mirror approach so that it would be useful for amplifying both positive-going and negative-going input pulses while consuming low to moderate power. The input stages use a common-collector/common-base topology for good bandwidth and slew characteristics. The output stages use power devices configured as class AB and are capable of driving 50- Omega loads. Each of the eight channels can be biased or enabled separately. The design is implemented with dielectrically isolated, vertical geometry transistors. Such devices are inherently radiation-hard and have PNP transistors whose performance is superior to that of the lateral geometry types. The availability of dielectrically isolated topologies allows such devices to be usable in an environment where total dosages can be as high as 1 Mrad. Computer simulations of the BOP in various configurations show that design requirements were met.<
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