Patent ID: 7224212

Claim:
Apparatus for filtering glitch, said apparatus comprising: an input terminal inverting device for generating a first inverted input signal responding to an input signal, the first inverted input signal and the input signal being complementary; an output buffer set for generating a first feedback signal and a second feedback signal, the first feedback signal and the second feedback signal being complementary; a low pass filter comprising a capacitor and a first inverter, wherein the first inverter is coupled to the output terminal of the input terminal inverting device, one terminal of the capacitor being grounded; a first glitch reset circuit having a first terminal grounded and a second terminal and a third terminal thereof coupled with an input terminal and an output terminal, respectively, of the low pass filter; and a second glitch reset circuit having a fourth terminal connected to a power and having a fifth terminal and a sixth terminal thereof coupled with the input terminal and the output terminal, respectively, of the low pass filter, furthermore, the first glitch reset circuit performing responding to the first feedback signal and the second feedback signal, so that the capacitor is rapidly charged through the second glitch reset circuit when the capacitor is charging and has a voltage thereof exceeding a threshold voltage of the output buffer set resulted in exchanging logic levels of the first feedback signal and the second feedback signal, furthermore, the first glitch reset circuit performing responding to the first feedback signal and the second feedback signal, the capacitor being rapidly discharged through the first glitch reset circuit when the capacitor is charging but has the voltage thereof lower than the threshold voltage of the output buffer set to keep the logic levels of the first feedback signal and the second feedback signal the same.