Performance of fast monolithic ECL voltage comparators in constant-fraction discriminators and other timing circuits

Timing errors caused by voltage comparator operation are investigated in detail for constant-fraction discriminators and other timing circuits. These errors result from changing comparator response time for input signals with different slopes (voltage/time) and different levels. Comparator response time is analyzed for a modern high-speed ECL voltage comparator using the SPICE circuit analysis program, which models the complex nonlinearities present in comparator operation. The simulated response time for a -90-mV to 10-mV step input is slightly larger than the specified comparator performance, indicating a conservative analysis. Response time is presented for a variety of input signals and supports a comparator response-time model that consists of a charge-sensitivity (variable-time) delay component and a fixed-delay component SPICE circuit simulation is extended to simulate comparator operation in a constant-fraction discriminator circuit.<>