Amplitude and time measurement ASIC with analog derandomization

A versatile 32-channel ASIC has been developed for accurate processing of high-rate pulse signals from highly segmented detectors. In contrast to conventional approaches, this circuit affords a dramatic reduction in data volume through the use of analog techniques (precision peak detectors and time-to-amplitude converters) together with fast arbitration and sequencing logic to concentrate the data before digitization. In operation the circuit functions like a data-driven analog first-in, first-out (FIFO) memory between the preamplifiers and the ADC. Peak amplitudes of pulses arriving at any one of the 32 inputs are sampled, stored, and queued for readout and digitization through a single output port. Hit timing, pulse risetime, and channel address are also available at the output. ype chips have been fabricated in 0.35 μm CMOS and tested. Amplitude accuracy of the peak detect and hold circuit is 0.2% (absolute) and 0.04% (nonlinearity) for signals within 0.3 V of either supply rail. Time walk is below 5 ns, droop rate is 250 mV/s, and power consumption is less than 2 mW/channel at pulse rates up to 500 kHz per channel.