FAST SETTLING SAWTOOTH RAMP GENERATION IN A PHASE-LOCKED LOOP
First Claim
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1. A phase-locked loop comprising:
- a loop filter configured to provide a sawtooth ramp signal, wherein the sawtooth ramp signal has a settling time of less than 1 microsecond; and
an oscillator coupled to the loop filter, the oscillator configured to generate an oscillating signal based on the sawtooth ramp signal.
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Abstract
Aspects of this disclosure relate to reducing settling time of a sawtooth ramp signal in a phase-locked loop. Information from a loop filter of the phase-locked loop can be stored and used within the loop filter so as to improve the settling time of the sawtooth ramp signal. In certain embodiments, the settling time of a periodic sawtooth ramp signal can be reduced to less than one microsecond. An output frequency at the end of the sawtooth chirp can be brought back to an initial value without significantly modifying phase error in disclosed embodiments.
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Citations
20 Claims
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1. A phase-locked loop comprising:
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a loop filter configured to provide a sawtooth ramp signal, wherein the sawtooth ramp signal has a settling time of less than 1 microsecond; and an oscillator coupled to the loop filter, the oscillator configured to generate an oscillating signal based on the sawtooth ramp signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A phase-locked loop comprising:
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a loop filter comprising a proportional path and a sampling circuit configured to sample a value from the proportional path, wherein the loop filter is configured to provide a sawtooth ramp signal based on an output of the sampling circuit and an output of the proportional path; and an oscillator coupled to the loop filter, the oscillator configured to generate an oscillating signal based on the sawtooth ramp signal. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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17. A method of generating a sawtooth ramp signal in a phase-locked loop, the method comprising:
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sampling a signal from a loop filter of the phase-locked loop; and adjusting an output of the loop filter based on a value from said sampling such that the output of the loop filter is a sawtooth ramp signal with a reduced settling time. - View Dependent Claims (18, 19, 20)
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Specification