Cypress Semiconductor Corporation

Ahmet Akyildiz

Greg J Richmond

Alex Shkidt

An apparatus and a method to initiate spread spectrum modulation have been presented. In one embodiment, a spread spectrum off to spread spectrum on transition circuit is used to start spread spectrum modulation. The spread spectrum off to spread spectrum on transition circuit may include a phase lock loop (PLL) to output a clock signal. The spread spectrum off to spread spectrum on transition circuit may further include a control block coupled to the PLL to cause the PLL to lock the clock signal to a predetermined center frequency before transitioning from a non-spread spectrum mode into a spread spectrum mode.

Initiating spread spectrum modulation

Embodiments of the present invention provide for generating a sampled differential pattern signal with reduced jitter. In one embodiment of the present invention, a seed frequency generator provides a differential seed frequency signal. The differential seed frequency signal is converted to a single ended seed frequency signal by a differential-to-single ended converter. The pattern generation logic utilizes the single ended seed frequency signal to generate single ended pattern signals. Single ended-to-differential samplers then generate a sampled differential pattern signal by sampling the single ended pattern signal according to the differential seed frequency signal.

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Santa Clara, CA, United States of America

Ahmet Akyildiz