Patent ID: 7209852

Claim:
A system that includes a first pulse train input to a switch having a repeating high value and low value at a first frequency, and a transition from the low value to the high value having a first edge sharpness; a second pulse train input to the switch in synchronization with the first pulse train having a repeating high value and low value at a second frequency lower than the first frequency; and a frequency changing circuit coupled between the input pulse train and the switch, the frequency changing circuit to one of multiply and divide the frequency of the second pulse train, wherein the output of the frequency changing circuit has substantially the frequency of the first pulse train, the switch selecting an output from one of the first pulse train and the second pulse train to create an output pulse train appropriate to transition fault test an integrated circuit, depending upon a selection signal having a determined pulse train input to the switch; the selection signal in synchronization with the first pulse train; wherein the switch switches from the second pulse train to the first pulse train and substantially maintains the first edge sharpness of the first pulse train, and from the first pulse train to the second pulse train, during a low value of both the first and the second pulse trains.