Low power ADC with fast zero suppression for balloon-borne experiment

A low power CAMAC analog-to-digital converter (ADC) module with fast zero suppression is described. The module is developed to improve data acquisition rate for a balloon-borne detector. The module is of a single CAMAC width and includes sixteen charge-to-voltage converter (QVC) channels. Each channel has its own A/D converter. The QVC outputs are digitized simultaneously. The A/D converter continues digitization for 15 μs at longest. A microprogrammed sequencer, which is installed in the module, scans the channels, comparing the outputs of the A/D converters with prescribed thresholds. The outputs are stored together with channel numbers into data memory when the outputs are greater than the thresholds. The zero suppression completes in 3 μs, and zero-suppressed data become ready within 18 μs. The operation of the QVC circuit is repeatedly simulated on a workstation in order that the temperature dependence of the QVC circuit can be reduced without sacrificing performance