FREQUENCY ACQUISITION

On the rising edge of CE the VCO goes through a frequency

acquisition mode which coarse locks the PLL to the approxi-

mate final frequency. This portion of the lock digitally sets the

frequency such that the final tuning voltage on the CPin line

of the VCO is approximately Vdd/2. Benefits of this system is

the maximum required charge pump voltage is reduced as

large frequency ranges may be tuned with a small tuning

voltage. This makes the digitally tuned VCO different from

conventional analog VCOs.

Frequency Acquisition Timing Diagram

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