US 6,806,786 B1Granted

Phase-locked loop with self-selecting multi-band VCO

AssigneeRF Micro Devices, Inc.

InventorsChristopher Lam, Thai Nguyen, Chet Sooraparth

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Abstract

Techniques to select the proper frequency band for use in a PLL from among multiple frequency bands of a multi-band VCO. The PLL comprises a detector, a loop filter, the multi-band VCO, and a control unit. The detector receives a first signal to be locked to and a second signal that is related to a VCO signal and provides a detector output. The loop filter filters the detector output to provide a control signal. The multi-band VCO selects one of the multiple frequency bands based on a select signal and provides the VCO signal at a frequency determined by the control signal. The control unit derives the select signal for the multi-band VCO based on information extracted from a third signal (e.g., a filtered version of the control signal) and a timing signal from a timer unit.

Claims23

Dependent claims

A phase-lock loop (PLL) comprising:

a detector configured to receive first and second signals and provide a detector output, wherein the first signal is related to a reference signal to be locked to and the second signal is related to a VCO signal;
a loop filter configured to received and filter the detector output to provide a control signal;
a multi-band voltage controlled oscillator (VCO) configured to receive the control signal and a select signal, select one of a plurality of frequency bands based on the select signal, and provide the VCO signal at a frequency within the selected frequency band based on the control signal;
and
a control unit configured to receive a third signal and provide the select signal, wherein the third signal is related to the control signal, the control unit comprising:
a first comparator configured to receive the third signal and a first threshold value and provide a first status signal indicative of whether or not the frequency of the VCO signal is too high, and
a second comparator configured to receive the third signal and a second threshold value and provide a second status signal indicative of whether or not the frequency of the VCO signal is too low, and
wherein the select signal is derived based on the first and second status signals.

5 more elements

Dependencies are inferred from the claim text.