Clock filter device, clock filter and pulse generator

Abstract

A clock filter device for finding an optimal cut-off frequency of a clock filter through a controller to achieve an effective clock filtering is illustrated. Further, in the calibration mode, a reference clock that has not passed the clock filter and a reference clock that has passed the clock filter make a first counter and a second counter count respectively. After the first counter counts to a specific value, a count value of the second counter is obtained. The count values of the first counter and the second counter are compared to each other to determine whether the two values are approximate or not. When the two values are not approximate, the previous cut-off frequency of the clock filter is taken as the optimal cut-off frequency. Therefore, the clock filter can adopt the optimal cut-off frequency in a working mode to effectively filter out the noise an input clock.