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Silicon Clocks, Inc.

Colin Wai Mun Leong

Jagdeep Singh Bal

Richard Steven Miller

A hybrid frequency synthesizer includes an analog phase lock loop (PLL), a digital PLL, and a control circuit to control an output oscillator. The control circuit assigns control of the output oscillator between the analog PLL and/or the digital PLL depending on a state of lock of the analog PLL and/or the digital PLL. During a frequency acquisition mode, the digital PLL provides a coarse control of the output oscillator. During a phase capture mode, the analog PLL provides a fine control and the digital PLL provides a coarse control of the output oscillator. During the phase capture mode, the analog PLL control signal and the digital PLL control signal may be given a percentage of control over the output oscillator depending on the state of lock of the analog PLL and/or the digital PLL. During a phase lock mode, the analog PLL controls the output oscillator.

Method and apparatus for a hybrid phase lock loop frequency synthesizer

A hybrid frequency synthesizer includes an analog phase lock loop (PLL), a PLL, and a control circuit to control an output oscillator. The control circuit combines a control signal from the analog PLL with a control signal from the digital PLL to form a composite control signal. The composite control signal is conditioned depending on a state of lock of the analog PLL and/or the digital PLL. The composite signal controls the phase and frequency of the output oscillator. The analog control signal and the digital PLL control signal may be given a percentage of over the hybrid frequency synthesizer depending on the state of lock of the PLL and/or the digital PLL. The composite control signal provides both rapid, accurate, and robust acquisition by the digital PLL, and a smooth transition thereafter to low noise phase lock by the analog PLL.

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Livermore, CA, United States of America

Colin Wai Mun Leong