| 摘要 |
The present invention provides a method and mechanism for adapting a single phase-locked loop (PLL) for a wider range of frequencies than has been possible with prior art solutions. An analog comparator circuit that senses the output of the charge pump voltage and provides an signal to a control circuit to choose a suitable load circuit for the PLL voltage controlled oscillator (VCO). This analog comparator with the digital control circuit is used to cause a change in the VCO loads, from a multiplicity of loads, and select the best VCO range to achieve the incoming signal frequency lock. The use of a single PLL with the analog comparator output to control the VCO load selection, in addition to the phase and frequency feedback of the prior art, allows multiple overlapping frequency ranges of the multiple tunable loads of the VCO to be covered with one PLL. This reduces the die size and power consumption compared to a circuit implementation using the standard PLL for the wider frequency range of operation.
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