Comparator with smooth start-up for high frequencies

摘要

A comparator has a simple high frequency signal path from input to output formed by two differentially connected transistors with an output transistor connected to each. A current control circuit maintains a constant total current flowing through the differentially connected transistors. The ratio of currents flowing through the differentially connected transistors is initially set by a control circuit, so that the output of the comparator is predictable when powered up. The control circuit then gradually releases control, so that there is a smooth transfer to control by a reference signal input to the comparator.