Calibration techniques for frequency synthesizers
First Claim
1. A frequency synthesizer comprising:
- an oscillator including configurable circuitry that defines an initial frequency of the oscillator for an initial input parameter;
a first divider that generates a signal indicative of the oscillator by scaling an oscillator frequency defined by the initial input parameter;
a second divider that generates a signal indicative of a reference by scaling a reference frequency; and
a calibration unit coupled directly to the first and second dividers, the calibration unit being configured to adjust the configurable circuitry based on a comparison of the signal indicative of the oscillator and the signal indicative of the reference, wherein the calibration unit initializes the signals indicative of the oscillator and the reference so that the signals are substantially in phase.
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Abstract
In one embodiment, this disclosure describes a frequency synthesizer for use in a wireless communication device, or similar device that requires precision frequency synthesis but small amounts of noise. In particular, the frequency synthesizer may include a phase locked loop (PLL) and an integrated voltage controlled oscillator (VCO). The frequency synthesizer may implement one or more calibration techniques to quickly and precisely calibrate the VCO. In this manner, the analog gain of the VCO can be significantly reduced, which may improve performance of the wireless communication device. Also, the initial state of the PLL may be improved to reduce lock time of the PLL, which may enhance performance of the wireless communication device.
59 Citations
29 Claims
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1. A frequency synthesizer comprising:
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an oscillator including configurable circuitry that defines an initial frequency of the oscillator for an initial input parameter; a first divider that generates a signal indicative of the oscillator by scaling an oscillator frequency defined by the initial input parameter; a second divider that generates a signal indicative of a reference by scaling a reference frequency; and a calibration unit coupled directly to the first and second dividers, the calibration unit being configured to adjust the configurable circuitry based on a comparison of the signal indicative of the oscillator and the signal indicative of the reference, wherein the calibration unit initializes the signals indicative of the oscillator and the reference so that the signals are substantially in phase. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A frequency synthesizer comprising:
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an oscillator including configurable circuitry that defines an initial frequency of the oscillator for an initial input parameter; a first divider means that generates a signal indicative of the oscillator by scaling an oscillator frequency defined by the initial input parameter; a second divider means that generates a signal indicative of a reference by scaling a reference frequency; and means for adjusting the configurable circuitry based on a comparison of the signal indicative of the oscillator and the signal indicative of a reference, wherein the means for adjusting initializes the signals indicative of the oscillator and the reference so that the signals are substantially in phase and is coupled directly to the first and second divider means. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. A method for calibrating a frequency synthesizer comprising:
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defining an initial frequency of an oscillator for an initial input parameter; initializing a first divider and a second divider by sending a signal from a calibration unit to each of the first and second dividers; generating, in the first divider, a signal indicative of the oscillator by scaling an oscillator frequency defined by the initial input parameter; generating, in the second divider, a signal indicative a reference by scaling a reference frequency; comparing the signal indicative of the oscillator and the signal indicative of the reference in the calibration unit; and adjusting configurable circuitry connected to the oscillator based on the comparison of the signal indicative of the oscillator and the signal indicative of the reference. - View Dependent Claims (16, 17, 18, 19)
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20. An apparatus for calibrating a frequency synthesizer comprising:
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means for defining an initial frequency of an oscillator for an initial input parameter; means for initializing a first divider and a second divider by sending a signal from a calibration unit to each of the first and second dividers; means for generating, in the first divider, a signal indicative of the oscillator by scaling an oscillator frequency defined by the initial input parameter; means for generating, in the second divider, a signal indicative a reference by scaling a reference frequency; means for comparing the signal indicative of the oscillator and the signal indicative of the reference in the calibration unit; and means for adjusting configurable circuitry connected to the oscillator based on the comparison of the signal indicative of the oscillator and the signal indicative of the reference. - View Dependent Claims (21, 22, 23, 24)
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25. A non-transitory computer readable storage medium having stored thereon processor-executable software instructions configured to cause a processor to perform operations for calibrating a frequency synthesizer, the operations comprising:
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defining an initial frequency of an oscillator for an initial input parameter; initializing a first divider and a second divider by sending a signal from a calibration unit to each of the first and second dividers; generating, in the first divider, a signal indicative of the oscillator by scaling an oscillator frequency defined by the initial input parameter; generating, in the second divider, a signal indicative a reference by scaling a reference frequency; comparing the signal indicative of the oscillator and the signal indicative of the reference in the calibration unit; and adjusting configurable circuitry connected to the oscillator based on the comparison of the signal indicative of the oscillator and the signal indicative of the reference. - View Dependent Claims (26, 27, 28, 29)
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Specification