US 7,046,093 B1Granted

Dynamic phase-locked loop circuits and methods of operation thereof

AssigneeIntergrated Device Technology, Inc.

InventorsDeclan McDonagh, Paul Murtagh

Life of this patent

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Abstract

A phase locked loop (PLL) circuit includes a controlled oscillator circuit that is operative to generate an output clock signal responsive to an oscillator control signal according to a plurality of selectable transfer functions, and an oscillator control signal generator circuit that is operative to generate the oscillator control signal responsive to the output clock signal and a reference clock signal. The PLL circuit further includes a transfer function control circuit operative to transition operation of the controlled oscillator from a first one of the transfer functions to a second one of the transfer functions responsive to the oscillator control signal. For example, the transfer function control circuit may step the controlled oscillator circuit through a succession of the transfer functions in response to a change in a frequency of the reference clock signal and may enable a closed loop including the oscillator control signal generator circuit and the controlled oscillator circuit upon selection of each of the succession of transfer functions.

Claims16

Dependent claims

A phase locked loop (PLL) circuit, comprising:

a controlled oscillator circuit operative to generate an output clock signal responsive to an oscillator control voltage according to a plurality of selectable transfer functions;
an oscillator control signal generator circuit that generates the oscillator control signal responsive to the output clock signal and a reference clock signal, wherein the oscillator control signal generator circuit comprises:
a loop filter;
and
a charge pump circuit operative to charge and discharge the loop filter responsive to the output clock signal and the reference clock signal to generate the oscillator control voltage;
a transfer function control circuit operative to transition operation of the controlled oscillator circuit from a first one of the transfer functions to a second one of the transfer functions responsive to the oscillator control voltage, wherein the transfer function control circuit is operative to transition operation of the controlled oscillator circuit from the first transfer function to the second transfer function responsive to a voltage range criterion for the oscillator control voltage and wherein the transfer function control circuit is operative to enable and disable the charge pump circuit based on the voltage range criterion for the oscillator control voltage.

3 more elements

A PLL circuit, comprising:

a voltage-controlled oscillator (VCO) circuit that is configured to generate an output clock signal responsive to an oscillator control voltage according to a plurality of selectable transfer functions;
a loop filter coupled to an oscillator control voltage input of the VCO circuit;
a charge pump circuit coupled to the loop filter;
a PFD circuit that controls the charge pump responsive to the output clock signal and a reference clock signal;
a transfer function control circuit operative to transition operation of the VCO circuit from a first one of the transfer functions to a second one of the transfer functions responsive to the oscillator control voltage;
and
a common mode feedback (CMFB) circuit operative to receive a CMFB signal from the loop filter and to responsively control a common mode voltage of the oscillator control voltage, and wherein the transfer function control circuit is operative to transition operation of the VCO circuit from the first transfer function to the second transfer function responsive to the common mode voltage.

4 more elements

Dependencies are inferred from the claim text.

Facts

Application: 10/649,493Filed 27 Aug 2003
Granted: 16 May 2006
Term ends: Not estimatedThe source records don’t support an estimate.

Classification7 codes

H03L 7/10
Details of the phase-locked loop: for assuring initial synchronisation or for broadening the capture range
H03L 7/102
Using an additional control signal to the controlled loop oscillator derived from a signal generated in the loop: the additional signal being…
H03L 7/107
For assuring initial synchronisation or for broadening the capture range: using a variable transfer function for the loop, e.g. low pass filter…
H03L 7/095
Concerning mainly the frequency- or phase-detection arrangement including the filtering or amplification of its output signal: using a lock detector