US3928813A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Device for synthesizing frequencies which are rational multiples of a fundamental frequency
Assignee: HP Inc
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Filing: 1974-09-26
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Granted: 1975-12-23
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Expires: 1994-09-26
Abstract
Abstract A frequency synthesizer is disclosed which can provide frequencies which are rational multiples of a fundamental reference frequency. The synthesizer includes a voltagecontrolled oscillator in a phase-locked loop with the reference frequency. A modulo-N counter is included to allow synthesis of harmonics of the reference frequency. To obtain rational fractional frequencies between harmonics a ''''cycle swallower'''' is provided to occasionally abruptly shift the phase of the oscillator output. The swallowing rate is determined by the contents of a storage register which is pre-loaded with a representation of the desired frequency. The contents of this storage register are periodically loaded into and accumulated in an accumulator which generates an overflow signal to the cycle swallower whenever the accumulated value exceeds its maximum storage capacity. In response to the average rate of phase shifting by the swallower, the loop stabilizes when the oscillator frequency is equal to the desired rational multiple of the reference frequency.
Inventors
- 👤 Charles A Kingsford-Smith
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 17:25
CPC Classifications
H; H03; H03L; H03L7/00; H03L7/06; H03L7/16; H03L7/18; H03L7/197; H03L7/1974; H03L7/1976; H03L7/1978
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
262 words
An electronic frequency synthesizer of the phase-locked loop type for generating frequencies which are desired rational multiples of the frequency of a reference signal, said synthesizer comprising: frequency generating means for producing an output signal of a frequency responsive to the level of an input signal; counting means responsive to the output signal of the frequency generating means for producing a wave-train output whose pulse spacing is equal to the total spacing of N pulses of a signal appearing at the input of the counting means, where N is a predetermined integer; phase comparison means for comparing the phases of the wave train output from the counting means and the reference signal and generating an error signal indicative of a phase difference therebetween, said error signal serving as the input signal to the frequency generating means to thereby vary the frequency of the output signal from the frequency generating means; digital storage means for storing a representation of a rational fractional interval indicative of the fractional part of said desired rational multiple of said refErence frequency; digital accumulating means for periodically receiving the contents of the digital storage means and accumulating said contents and generating a carryover signal output whenever the accumulated contents exceed the storage capacity of the accumulating means; and cycle swallowing means interconnected between the frequency generating means and the counter means and being responsive to said carryover signal to alter by one cycle the output of the frequency generating means, for altering the phase of the signal directed to the counting means and phase comparison means by 360*.
Claim 2
Dependent Claim
262 words
An electronic frequency synthesizer of the phase-locked loop type for generating frequencies which are desired rational multiples of the frequency of a reference signal, said synthesizer comprising: frequency generating means for producing an output signal of a frequency responsive to the level of an input signal; counting means responsive to the output signal of the frequency generating means for producing a wave-train output whose pulse spacing is equal to the total spacing of N pulses of a signal appearing at the input of the counting means, where N is a predetermined integer; phase comparison means for comparing the phases of the wave train output from the counting means and the reference signal and generating an error signal indicative of a phase difference therebetween, said error signal serving as the input signal to the frequency generating means to thereby vary the frequency of the output signal from the frequency generating means; digital storage means for storing a representation of a rational fractional interval indicative of the fractional part of said desired rational multiple of said refErence frequency; digital accumulating means for periodically receiving the contents of the digital storage means and accumulating said contents and generating a carryover signal output whenever the accumulated contents exceed the storage capacity of the accumulating means; and cycle swallowing means interconnected between the frequency generating means and the counter means and being responsive to said carryover signal to alter by one cycle the output of the frequency generating means, for altering the phase of the signal directed to the counting means and phase comparison means by 360*.
Claim 3
Dependent Claim
39 words
An electronic frequency synthesizer as in claim 1 wherein the cycle swallowing means alters the phase of the signal directed to the counting means by minus 360* by removing one cycle from the output of the frequency generating means.
Claim 4
Dependent Claim
56 words
An electronic frequency synthesizer as in claim 1 wherein: the digital storage means comprises means for storing a representation of the desired rational multiple of said reference frequency including both the integer N and the desired fractional interval; and the counting means is interconnected with the digital storage means for receiving therefrom the predetermined integer N.
Claim 5
Dependent Claim
21 words
An electronic frequency synthesizer as in claim 3 including loop filter means for suppressing undesired signal components in the phase-locked loop.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-12-22 | 1979-06-23 | 1979-12-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-12-22 | 1983-06-23 | 1983-12-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-12-22 | 1987-06-23 | 1987-12-23 | $7700.00 | Window Closed / Lapsed |