Patent ID: 6671652
Filing Date: 2003-12-30
Classification: G01R,G06F,H03K

Abstract:
A method of measuring an uncertainty window within which a target clock signal of an electronic device makes state transitions, the method comprising:defining a time window between features of a first and second reference clock signals; and comparing within the electronic device a plurality of cycles of the target clock signal to the reference clock signals to determine whether the target clock signal makes state transitions within the time window; wherein comparing the reference clock signals to the target clock signal comprises: phase detecting the first reference clock signal against the target clock signal to determine whether the target clock signal makes its state transition before or after the first reference clock signal; and phase detecting the second reference clock signal against the target clock signal to determine whether the target clock signal makes its state transition before or after the second reference clock signal, and wherein the target clock signal makes state transitions within the time window if those transitions are detected to be after the first reference clock signal and before the second reference clock signal.