One kind of apporoach is presented,which combined the hysteresis comparison and timer comparison tracing control,and the analytical expression of track error,everage switching frequency and fluctuate of switchig frequency are obtained.

In the aspect of time distinction, the circuit of fixed propagation delay and high comparator were used whether not to make a fixed threshold voltage to judge the signals which was back.

To reduce the measurement error caused by the constant threshold of pulse laser fuze,a high precision threshold circuit for laser fuze is proposed based on the principle of constant fraction discrimination.