Apple Inc.
Reconfigurable clock flipping scheme for duty cycle measurement

Abstract:

A clock test system included in a computer system includes a clock generator circuit that generates multiple clock signals. A switch circuit selects different ones of the multiple clock signals during different time periods to generate an output clock signal. A measurement circuit measures a duty cycle of the output clock signals during the different time periods to generate multiple duty cycle measures. The measurement circuit uses the multiple duty cycle measurements to cancel a portion of duty cycle distortion in the output clock signal to determine an adjusted duty cycle value.