APPARATUS AND METHODS FOR ADJUSTING PHASE-LOCKED LOOP GAIN
First Claim
1. A frequency synthesizer comprising:
- plurality of voltage-controlled oscillators (VCOs) of which a selected VCO provides a VCO output to a closed loop of a phase-locked loop;
a charge pump configured to adjust a loop gain of the phase-locked loop based on a charge pump current control value; and
a charge pump controller configured to select a VCO gain adjustment model corresponding to the selected VCO based on a VCO gain indicator, said charge pump controller further configured to obtain from a memory VCO gain model parameters corresponding to the selected VCO gain adjustment model and to adjust the charge pump current control value based on the VCO gain model parameters to thereby cause the loop gain of the phase-locked loop to be adjusted.
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Abstract
Apparatus and methods for adjusting a gain of an electronic oscillator, such as a voltage-controlled oscillator (VCO), are disclosed. In one aspect, an apparatus for compensating for VCO gain variations includes a charge pump controller. The charge pump controller can be configured to select a VCO gain model based on a comparison of a VCO gain indicator and a threshold value stored in a memory, obtain VCO gain model parameters from the memory corresponding to the selected VCO gain model, and compute a charge pump current control value using the VCO gain model parameters. The charge pump current control value can be used to compensate for VCO gain variations.
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Citations
20 Claims
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1. A frequency synthesizer comprising:
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plurality of voltage-controlled oscillators (VCOs) of which a selected VCO provides a VCO output to a closed loop of a phase-locked loop; a charge pump configured to adjust a loop gain of the phase-locked loop based on a charge pump current control value; and a charge pump controller configured to select a VCO gain adjustment model corresponding to the selected VCO based on a VCO gain indicator, said charge pump controller further configured to obtain from a memory VCO gain model parameters corresponding to the selected VCO gain adjustment model and to adjust the charge pump current control value based on the VCO gain model parameters to thereby cause the loop gain of the phase-locked loop to be adjusted. - View Dependent Claims (2, 3, 4)
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5. An apparatus comprising:
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a memory configured to store gain adjustment model parameters including slopes and offsets corresponding to frequency ranges of an electronic oscillator; and an arithmetic logic unit configured to select a slope and an offset of the gain adjustment model parameters stored in the memory based on an indicator of output frequency of the electronic oscillator and to cause a charge pump to adjust a gain of a phase-locked loop based on the selected slope and the selected offset. - View Dependent Claims (6, 7, 8, 9, 10, 11)
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12. An apparatus comprising a charge pump controller configured to select a slope and an offset associated with a selected voltage-controlled oscillator (VCO) of a plurality of VCOs each configured to generate an output within a different frequency band than the other of the plurality of VCOs, the selected VCO configured to provide a VCO output to a closed loop of a phase-locked loop;
- and to compute a charge pump control value based on the selected slope and the selected offset to cause a loop gain of the phase-locked loop to be adjusted.
- View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20)
Specification