Frequency and phase locked loop synthesizer
First Claim
1. A radio frequency (RF) circuit comprising:
- a first frequency-locked loop (FLL), which during a first FLL operating mode is adapted to;
receive a first reference signal having a first reference frequency;
provide a first frequency-reduced output signal having a first reduced output frequency, which is approximately equal to a first output frequency divided by a first constant; and
provide a first output signal having the first output frequency, which is based on a difference between the first reduced output frequency and the first reference frequency;
a first phase-locked loop (PLL), which during a first PLL operating mode is adapted to;
receive a second reference signal; and
provide the first output signal, which is based on a phase difference between the first output signal and the second reference signal, wherein the first FLL provides coarse tuning of a frequency of the first output signal during the first FLL operating mode and the first PLL provides fine tuning of a frequency of the first output signal during the first PLL operating mode;
a first variable frequency oscillator adapted to;
receive a first control signal and a second control signal; and
provide the first output signal having the first output frequency, which is based on at least one of the first control signal and the second control signal;
a first frequency reduction circuit, which during the first FLL operating mode is adapted to;
receive the first output signal; and
provide the first frequency-reduced output signal;
a first frequency detector circuit, which during the first FLL operating mode is adapted to;
receive the first frequency-reduced output signal and the first reference signal; and
provide a first frequency error signal, which is based on the difference between the first reduced output frequency and the first reference frequency;
a first loop filter circuit, which during the first FLL operating mode is adapted to;
receive and filter the first frequency error signal to create a first filtered frequency error signal; and
provide the first control signal based on the first filtered frequency error signal; and
PLL circuitry, which during the first PLL operating mode is adapted to;
receive one of the first output signal and the first frequency-reduced output signal, and a second reference signal having a second reference frequency; and
provide the second control signal based on the one of the first output signal and the first frequency-reduced output signal, and further based on the second reference signal.
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Abstract
The present invention is a frequency and phase locked loop (FPLL) synthesizer having a frequency-locked loop (FLL) operating mode and a phase-locked loop (PLL) operating mode. The FLL operating mode is used for rapid coarse tuning of the FPLL synthesizer and is followed by the PLL operating mode for fine tuning and stabilization of the frequency of an output signal from the FPLL synthesizer. The FPLL synthesizer includes a variable frequency oscillator, which is controlled by FLL circuitry during the FLL operating mode or by PLL circuitry during the PLL operating mode. The FLL circuitry includes frequency division circuitry for reducing the frequency of the output signal, frequency detection circuitry for measuring the frequency error of the frequency reduced output signal, and a loop filter to control the bandwidth of an FLL control loop formed by the FLL circuitry and the variable frequency oscillator.
28 Citations
21 Claims
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1. A radio frequency (RF) circuit comprising:
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a first frequency-locked loop (FLL), which during a first FLL operating mode is adapted to; receive a first reference signal having a first reference frequency; provide a first frequency-reduced output signal having a first reduced output frequency, which is approximately equal to a first output frequency divided by a first constant; and provide a first output signal having the first output frequency, which is based on a difference between the first reduced output frequency and the first reference frequency; a first phase-locked loop (PLL), which during a first PLL operating mode is adapted to; receive a second reference signal; and provide the first output signal, which is based on a phase difference between the first output signal and the second reference signal, wherein the first FLL provides coarse tuning of a frequency of the first output signal during the first FLL operating mode and the first PLL provides fine tuning of a frequency of the first output signal during the first PLL operating mode; a first variable frequency oscillator adapted to; receive a first control signal and a second control signal; and provide the first output signal having the first output frequency, which is based on at least one of the first control signal and the second control signal; a first frequency reduction circuit, which during the first FLL operating mode is adapted to; receive the first output signal; and provide the first frequency-reduced output signal; a first frequency detector circuit, which during the first FLL operating mode is adapted to; receive the first frequency-reduced output signal and the first reference signal; and provide a first frequency error signal, which is based on the difference between the first reduced output frequency and the first reference frequency; a first loop filter circuit, which during the first FLL operating mode is adapted to; receive and filter the first frequency error signal to create a first filtered frequency error signal; and provide the first control signal based on the first filtered frequency error signal; and PLL circuitry, which during the first PLL operating mode is adapted to; receive one of the first output signal and the first frequency-reduced output signal, and a second reference signal having a second reference frequency; and provide the second control signal based on the one of the first output signal and the first frequency-reduced output signal, and further based on the second reference signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A radio frequency (RF) circuit comprising:
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a first frequency-locked loop (FLL) comprising discrete tuning elements, and during a first FLL operating mode is adapted to; receive a first reference signal having a first reference frequency; select at least one of the discrete tuning elements based on a first output frequency and the first reference frequency; and provide a first output signal having the first output frequency, which is based on the select at least one of the discrete tuning elements; a first phase-locked loop (PLL), which during a first PLL operating mode is adapted to; receive a second reference signal; and provide the first output signal, which is based on a phase difference between the first output signal and the second reference signal, wherein the first FLL provides coarse tuning of a frequency the first FLL operating mode and the first PLL provides fine tuning of a frequency of the first output signal during the first PLL operating mode; a first variable frequency oscillator; comprising the discrete tuning elements; and adapted to; receive a first control signal and a second control signal; and provide the first output signal having the first output frequency, which is based on at least one of the first control signal and the second control signal, wherein the select at least one of the discrete tuning elements is based on the first control signal; a first frequency detector circuit, which during the first FLL operating mode is adapted to; receive one of a derived signal based on the first output signal having a derived output frequency and the first output signal; receive the first reference signal; and provide a first frequency error signal, which is based on a difference between one of the derived output frequency and the first output frequency, and the first reference frequency; a first loop filter circuit, which during the first FLL operating mode is adapted to; receive and filter the first frequency error signal to create a first filtered frequency error signal; and provide the first control signal based on the first filtered frequency error signal; and PLL circuitry, which during the first PLL operating mode is adapted to; receive one of the first output signal and the derived output signal, and the second reference signal having a second reference frequency; and provide the second control signal based on the one of the first output signal and the derived output signal, and further based on the second reference signal. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21)
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Specification