Method and apparatus for highly accurate higher frequency signal generation and related level gauge
First Claim
1. An apparatus comprising:
- a stable local oscillator comprising a first control loop, the first control loop comprising (i) a first voltage-controlled oscillator configured to generate a first output signal and (ii) a first phase-locked loop module;
a frequency up-converter configured to increase a frequency of the first output signal;
a second control loop configured to receive the up-converted first output signal, the second control loop comprising (i) a second voltage-controlled oscillator configured to generate a second output signal, (ii) a second phase-locked loop module, and (iii) a mixer having a first input coupled to the frequency up-converter, a second input coupled to the second voltage-controlled oscillator, and an output coupled to the second phase-locked loop module;
a buffer coupled between the stable local oscillator and the frequency up-converter; and
a filter coupled between the frequency up-converter and the mixer.
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Abstract
An apparatus includes a stable local oscillator, which includes a first control loop. The first control loop includes a first voltage-controlled oscillator configured to generate a first output signal and a first phase-locked loop. The apparatus also includes a frequency up-converter configured to increase a frequency of the first output signal. The apparatus further includes a second control loop configured to receive the up-converted first output signal. The second control loop includes a second voltage-controlled oscillator configured to generate a second output signal and a second phase-locked loop. The second control loop may further include a mixer having a first input coupled to the frequency up-converter, a second input coupled to the second voltage-controlled oscillator, and an output coupled to the second phase-locked loop. A reference frequency source may be configured to generate a signal identifying a reference frequency and to provide that signal to the phase-locked loops.
84 Citations
21 Claims
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1. An apparatus comprising:
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a stable local oscillator comprising a first control loop, the first control loop comprising (i) a first voltage-controlled oscillator configured to generate a first output signal and (ii) a first phase-locked loop module; a frequency up-converter configured to increase a frequency of the first output signal; a second control loop configured to receive the up-converted first output signal, the second control loop comprising (i) a second voltage-controlled oscillator configured to generate a second output signal, (ii) a second phase-locked loop module, and (iii) a mixer having a first input coupled to the frequency up-converter, a second input coupled to the second voltage-controlled oscillator, and an output coupled to the second phase-locked loop module; a buffer coupled between the stable local oscillator and the frequency up-converter; and a filter coupled between the frequency up-converter and the mixer. - View Dependent Claims (2)
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3. An apparatus comprising:
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a stable local oscillator comprising a first control loop, the first control loop comprising (i) a first voltage-controlled oscillator configured to generate a first output signal and (ii) a first phase-locked loop module; a frequency up-converter configured to increase a frequency of the first output signal; and a second control loop configured to receive the up-converted first output signal, the second control loop comprising; a second voltage-controlled oscillator configured to generate a second output signal; a second phase-locked loop module; a mixer having a first input coupled to the frequency up-converter, a second input coupled to the second voltage-controlled oscillator, and an output coupled to the second phase-locked loop module; a first amplifier coupled between the mixer and the second phase-locked loop module; a filter coupled to the second phase-locked loop module; and a second amplifier coupled between the filter and the second voltage-controlled oscillator.
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4. An apparatus comprising:
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a stable local oscillator comprising a first control loop, the first control loop comprising (i) a first voltage-controlled oscillator configured to generate a first output signal, (ii) a first phase-locked loop module, (iii) a filter coupled to the first phase-locked loop module, and (iv) an amplifier coupled between the filter and the first voltage-controlled oscillator; a frequency up-converter configured to increase a frequency of the first output signal; and a second control loop configured to receive the up-converted first output signal, the second control loop comprising (i) a second voltage-controlled oscillator configured to generate a second output signal and (ii) a second phase-locked loop module.
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5. An apparatus comprising:
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a stable local oscillator comprising a first control loop, the first control loop comprising (i) a first voltage-controlled oscillator configured to generate a first output signal and (ii) a first phase-locked loop module; a frequency up-converter configured to increase a frequency of the first output signal; a second control loop configured to receive the up-converted first output signal, the second control loop comprising (i) a second voltage-controlled oscillator configured to generate a second output signal and (ii) a second phase-locked loop module; an amplifier configured to receive and amplify the second output signal; and a variable attenuator configured to receive and attenuate the amplified second output signal. - View Dependent Claims (6, 7)
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8. An apparatus comprising:
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a stable local oscillator comprising a first control loop, the first control loop comprising (i) a first voltage-controlled oscillator configured to generate a first output signal and (ii) a first phase-locked loop module; a frequency up-converter configured to increase a frequency of the first output signal; a second control loop configured to receive the up-converted first output signal, the second control loop comprising (i) a second voltage-controlled oscillator configured to generate a second output signal and (ii) a second phase-locked loop module, wherein the second control loop forms part of a first stage; and a second stage configured to receive the second output signal and generate a higher-frequency third output signal, the second stage comprising a third control loop, the third control loop comprising (i) a third voltage-controlled oscillator configured to generate the third output signal and (ii) a third phase-locked loop module.
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9. A level gauge comprising:
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a sensor configured to transmit radio frequency wireless signals towards material in a tank and receive wireless signals reflected off the material in the tank; and a processing system configured to identify a level of the material in the tank based on the wireless signals transmitted towards and reflected off the material in the tank; wherein the sensor comprises; a phase-locked loop based stable local oscillator configured to generate a first output signal; and a phase-locked loop based control loop configured to generate a second output signal based on the first output signal. - View Dependent Claims (10, 11, 12, 13, 14, 15)
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16. A method comprising:
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generating a first signal using a stable local oscillator that comprises a first control loop, the first control loop comprising a first voltage-controlled oscillator and a first phase-locked loop module; increasing a frequency of the first signal to generate an up-converted first signal; generating a second signal based on the up-converted first signal using a second control loop, the second control loop comprising a second voltage-controlled oscillator and a second phase-locked loop module; amplifying the second signal; attenuating the amplified second signal; and at least one of; transmitting outgoing radio frequency wireless signals using the attenuated second signal; and processing incoming radio frequency wireless signals using the attenuated second signal. - View Dependent Claims (17)
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18. An apparatus comprising:
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a stable local oscillator comprising a first control loop, the first control loop comprising (i) a first voltage-controlled oscillator configured to generate a first output signal and (ii) a first phase-locked loop module; a frequency up-converter configured to increase a frequency of the first output signal to generate an up-converted first output signal; a second control loop configured to receive the up-converted first output signal, the second control loop comprising (i) a second voltage-controlled oscillator configured to generate a second output signal that has a frequency higher than the frequency of the first output signal, (ii) a second phase-locked loop module, and (iii) a mixer having a first input coupled to an output of the frequency up-converter, a second input coupled to an output of the second voltage-controlled oscillator, and an output coupled to the second phase-locked loop module and configured to provide a mixed signal to the second phase-locked loop module; and a stable reference frequency source configured to generate a reference signal having a reference frequency and to provide the reference signal to the first and second phase-locked loop modules; wherein the first phase-locked loop module is configured to compare a phase of the first output signal to a phase of the reference signal; and wherein the second phase-locked loop module is configured to compare a phase of the mixed signal to the phase of the reference signal. - View Dependent Claims (19)
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20. A level gauge comprising:
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a sensor configured to transmit radio frequency wireless signals towards material in a tank and receive wireless signals reflected off the material in the tank; and a processing system configured to identify a level of the material in the tank based on the wireless signals transmitted towards and reflected off the material in the tank; wherein the sensor comprises; a stable local oscillator comprising a first control loop, the first control loop comprising (i) a first voltage-controlled oscillator configured to generate a first output signal and (ii) a first phase-locked loop module; a frequency up-converter configured to increase a frequency of the first output signal to generate an up-converted first output signal; a second control loop configured to receive the up-converted first output signal, the second control loop comprising (i) a second voltage-controlled oscillator configured to generate a second output signal that has a frequency higher than the frequency of the first output signal, (ii) a second phase-locked loop module, and (iii) a mixer having a first input coupled to an output of the frequency up-converter, a second input coupled to an output of the second voltage-controlled oscillator, and an output coupled to the second phase-locked loop module and configured to provide a mixed signal to the second phase-locked loop module; and a stable reference frequency source configured to generate a reference signal having a reference frequency and to provide the reference signal to the first and second phase-locked loop modules; wherein the first phase-locked loop module is configured to compare a phase of the first output signal to a phase of the reference signal; and wherein the second phase-locked loop module is configured to compare a phase of the mixed signal to the phase of the reference signal.
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21. A method comprising:
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generating a first signal using a stable local oscillator that comprises a first control loop, the first control loop comprising (i) a first voltage-controlled oscillator and (ii) a first phase-locked loop module; increasing a frequency of the first signal to generate an up-converted first signal; generating a second signal based on the up-converted first signal using a second control loop, the second signal having a frequency higher than the frequency of the first signal, the second control loop comprising (i) a second voltage-controlled oscillator, (ii) a second phase-locked loop module, and (iii) a mixer having a first input coupled to an output of the frequency up-converter, a second input coupled to an output of the second voltage-controlled oscillator, and an output coupled to the second phase-locked loop module and providing a mixed signal to the second phase-locked loop module; and generating a reference signal having a reference frequency using a stable reference frequency source and providing the reference signal to the first and second phase-locked loop modules; wherein the first phase-locked loop module compares a phase of the first signal to a phase of the reference signal; and wherein the second phase-locked loop module compares a phase of the mixed signal to the phase of the reference signal.
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Specification