US Patent 10234505 Clock generation for integrated circuit testing

A disclosed integrated circuit includes first and second clock generation circuits, a stagger circuit, and a plurality of scan chains. The first clock generation circuit receives a first clock signal and generates a first set of clock pulses having a first frequency in response to receipt of a first clock trigger signal and a first enable signal. The second clock generation circuit receives a second clock signal and generates a second set of clock pulses having a second frequency in response to receipt of a second clock trigger signal and a second enable signal. The stagger circuit generates the first and second clock trigger signals from the global trigger signal at different times. The first set of clock pulses are staggered relative to the second set of clock pulses. The plurality of scan chains test functionality of logic circuitry within the IC chip using the first and second set of clock pulses.