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Patent US3600683A successfully refreshed from Google Patents.
US3600683A
Expired / Lapsed
US
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Frequency synthesizers
Assignee: Plessey Overseas Ltd
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Filing: 1969-06-20
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Granted: 1971-08-17
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Expires: 1989-06-20
Abstract
Abstract A frequency synthesizer comprising two control loops wherein the frequency of a slave oscillator is coarsely controlled in accordance with the setting of a variable divider contained in one loop having a short time constant and wherein fine frequency control is achieved in accordance with the setting of a further variable divider which is contained within the other loop having a long time constant (narrow bandwidth) thereby to provide the advantages of wide tuning range associated with LC oscillators with the stability of a crystal oscillator.
Inventors
- 👤 David John Martin
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 05:03
CPC Classifications
H; H03; H03L; H03L7/00; H03L7/06; H03L7/16; H03L7/22; H03L7/23; H03L7/235
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
206 words
A frequency synthesizer comprising in a primary control loop a slave oscillator, first phase detector means, a controlled oscillator and a first variable divider, the frequency of said slave oscillator being controlled by a correction signal provided by the first phase detector means in the presence of a frequency or phase difference between a signal derived from the controlled oscillator and a signal derived from the slave oscillator via the first variable divider, the sense of the correction signal being such as to nullify the said difference, and additionally comprising in association with a secondary control loop, second phase detector means, a second variable divider and a stable master oscillator, the said second phase detector means being responsive to a frequency or phase difference between a signal derived from the master oscillator and a signal derived from the slave oscillator via the said second variable divider for providing a control signal for controlling the frequency of said controlled oscillator, in a sense such as to nullify the frequency or phase difference between the signals presented to the said second phase detector means, an output signal of said synthesizer being provided by said slave oscillator which is selectable in accordance with the setting of said variable dividers.
Claim 2
Dependent Claim
206 words
A frequency synthesizer comprising in a primary control loop a slave oscillator, first phase detector means, a controlled oscillator and a first variable divider, the frequency of said slave oscillator being controlled by a correction signal provided by the first phase detector means in the presence of a frequency or phase difference between a signal derived from the controlled oscillator and a signal derived from the slave oscillator via the first variable divider, the sense of the correction signal being such as to nullify the said difference, and additionally comprising in association with a secondary control loop, second phase detector means, a second variable divider and a stable master oscillator, the said second phase detector means being responsive to a frequency or phase difference between a signal derived from the master oscillator and a signal derived from the slave oscillator via the said second variable divider for providing a control signal for controlling the frequency of said controlled oscillator, in a sense such as to nullify the frequency or phase difference between the signals presented to the said second phase detector means, an output signal of said synthesizer being provided by said slave oscillator which is selectable in accordance with the setting of said variable dividers.
Claim 3
Dependent Claim
30 words
A frequency synthesizer as claimed in claim 1, comprising fixed divider means via which an output signal from said controlled oscillator is applied to the said first phase detector means.
Claim 4
Dependent Claim
16 words
A frequency synthesizer as claimed in claim 1 wherein the controlled oscillator is a crystal oscillator.
References Cited (Backward Citations)
US3130376A
Cited
US3163823A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-08-16 | 1975-02-15 | 1975-08-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-08-16 | 1979-02-15 | 1979-08-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-08-16 | 1983-02-15 | 1983-08-17 | $7700.00 | Window Closed / Lapsed |