US4225829A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Local oscillator circuit having two phase locked loops having respective frequency dividers with a common division ratio
Assignee: Alps Alpine Co Ltd
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Filing: 1978-11-24
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Granted: 1980-09-30
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Expires: 1998-11-24
Abstract
Abstract A first phase locked loop produces a local oscillator signal. The output of a second phase locked loop is connected to the input of the first phase locked loop. A first variable frequency divider is connected in the first phase locked loop. A second variable frequency divider having the same frequency division ratio as the first frequency divider is connected between a variable frequency oscillator and the input of the second phase locked loop. An adder adds a base frequency of preferably 1 MHz to the output frequency of the second frequency divider. With the frequency of the variable frequency oscillator set at a center frequency, the frequency of the local oscillator signal is equal to the frequency division ratio of the frequency dividers multiplied by 1 MHz. Any variation in the frequency of the variable frequency oscillator from the center frequency is algebraically added to the local oscillator frequency, regardless of the frequency division ratio, as an offset frequency. The frequency range of the variable frequency oscillator is low compared to the frequency range of the local oscillator signal, thereby enabling low frequency drift. A gate disables the first phase locked loop when the second phase locked loop is not in lock.
Inventors
- 👤 Tadashi Kumagai
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 06:27
CPC Classifications
H; H03; H03L; H03L7/00; H03L7/06; H03L7/16; H03L7/22; H03L7/23; H03J; H03J5/00; H03J5/02; H03J5/0245; H03J5/0272; H03J5/0281
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
106 words
An oscillator circuit including a first phase locked loop having a first voltage controlled oscillator and a first phase comparator, the improvement comprising: a second phase locked loop having a second phase comparator and having an output connected to an input of said first phase comparator; a first frequency divider provided in said first phase locked loop for dividing an output frequency of said first voltage controlled oscillator; a variable frequency oscillator; and a second frequency divider having the same frequency division ratio as said first frequency divider and connected between an output of the variable frequency oscillator and an input of said second phase comparator.
Claim 2
Dependent Claim
106 words
An oscillator circuit including a first phase locked loop having a first voltage controlled oscillator and a first phase comparator, the improvement comprising: a second phase locked loop having a second phase comparator and having an output connected to an input of said first phase comparator; a first frequency divider provided in said first phase locked loop for dividing an output frequency of said first voltage controlled oscillator; a variable frequency oscillator; and a second frequency divider having the same frequency division ratio as said first frequency divider and connected between an output of the variable frequency oscillator and an input of said second phase comparator.
Claim 3
Dependent Claim
15 words
An oscillator circuit according to claim 1, said first and second frequency dividers being variable.
Claim 4
Dependent Claim
32 words
An oscillator circuit according to claim 1, the output frequency of said variable frequency oscillator being lower than the lower limit of the output frequency range of said first phase locked loop.
Claim 5
Dependent Claim
45 words
An oscillator circuit according to claim 1, further comprising a base frequency oscillator and adder means connected to the input of said second phase comparator for combining the base frequency of said base frequency oscillator and the output frequency of said second phase locked loop.
Claim 6
Dependent Claim
35 words
An oscillator circuit according to claim 4, said adder means being provided in said second phase locked loop and arranged to subtract said base frequency from the output frequency of said second phase locked loop.
Claim 7
Dependent Claim
54 words
An oscillator circuit according to claim 1, further comprising a base frequency oscillator and adder means connected between the output of said second phase locked loop and an input of said first phase locked loop for combining the base frequency of said base frequency oscillator with the output of said second phase locked loop.
Claim 8
Dependent Claim
47 words
An oscillator circuit according to claim 1, 4 or 6 said variable frequency oscillator having a center frequency AK, the frequency division ratio of said first and second frequency dividers being N-A, wherein K is said base frequency, A and K are constants and N is variable.
Claim 9
Dependent Claim
12 words
An oscillator circuit according to claim 7, wherein K equals 1 MHz.
Claim 10
Dependent Claim
53 words
An oscillator circuit according to claim 1, said second phase locked loop producing a lock signal, the oscillator circuit further comprising gate means provided in said first phase locked loop and having an input connected to an output of said first frequency divider, said lock signal being adapted to enable said gate means.
Claim 11
Dependent Claim
95 words
An oscillator circuit according to claim 1, said first phase locked loop further comprising a first low pass filter connected between said first phase comparator and said first voltage controlled oscillator, said first frequency divider being connected between said first voltage controlled oscillator and said first phase comparator, said second phase locked loop comprising a second voltage controlled oscillator and a second low pass filter connected between said second phase comparator and said second voltage controlled oscillator, an output of said second voltage controlled oscillator being connected to an input of said first phase comparator.
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) | 1983-09-30 | 1984-03-31 | 1984-09-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-09-30 | 1988-03-31 | 1988-09-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-09-30 | 1992-03-31 | 1992-09-30 | $7700.00 | Window Closed / Lapsed |