Patent US4818903A successfully refreshed from Google Patents.
US4818903A
Expired / Lapsed
US
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Time constant automatic adjustment circuit for a filter circuit
Assignee: Toshiba Corp
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Filing: 1987-07-17
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Granted: 1989-04-04
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Expires: 2007-07-17
Abstract
Abstract An automatic adjustment circuit for adjusting the time constant of a filter circuit. The adjustment circuit includes a source of reference frequency signal, an oscillator for generating an oscillation signal, and a detector for detecting the difference in one of phase and frequency between the reference frequency signal and the oscillation signal and generating a control signal for automatically adjusting the time constant of the filter circuit.
Inventors
- 👤 Mitsumo Kawano
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 11:19
CPC Classifications
H; H03; H03H; H03H11/00; H03L; H03L7/00; H03L7/06; H03L7/08; H03L7/0805; H03J; H03J7/00; H03J7/02; H03L7/099
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
93 words
An automatic adjustment circuit for adjusting a filter circuit, the filter circuit having a time constant, the adjustment circuit adjusting the time constant and receiving a reference frequency signal, said adjustment circuit comprising: oscillation means for generating an oscillation signal, said oscillation means including a time constant variable filter and a feedback amplifier connected to said variable filter for positive feedback; and means for detecting a difference in phase between said reference frequency signal and said oscillation signal and generating a control signal for automatically adjusting the time constant of the filter circuit.
Claim 2
Dependent Claim
93 words
An automatic adjustment circuit for adjusting a filter circuit, the filter circuit having a time constant, the adjustment circuit adjusting the time constant and receiving a reference frequency signal, said adjustment circuit comprising: oscillation means for generating an oscillation signal, said oscillation means including a time constant variable filter and a feedback amplifier connected to said variable filter for positive feedback; and means for detecting a difference in phase between said reference frequency signal and said oscillation signal and generating a control signal for automatically adjusting the time constant of the filter circuit.
Claim 3
Dependent Claim
36 words
The adjustment circuit of claim 1 wherein the detecting means includes a phase detector and a frequency detector and means for supplying the control signal both to the filter circuit and the time constant variable filter.
Claim 4
Dependent Claim
28 words
The adjustment circuit of claim 1 wherein the filter circuit includes a main filter and the time constant variable filter has the same configuration as the main filter.
Claim 5
Dependent Claim
14 words
The adjustment circuit of claim 2 wherein the detecting means includes a frequency divider.
Claim 6
Independent Claim
85 words
A method for adjusting a time constant of a filter circuit comprising the steps of: generating an oscillation signal using a combination of a variable filter and an amplifier connected to provide positive feedback to said filter; comparing the phase of said oscillation signal with the phase of a reference frequency signal; generating a control signal in response to a difference in phase between said oscillation signal and said reference frequency signal; and adjusting said time constant of said filter circuit with said control signal.
Claim 7
Independent Claim
85 words
A method for adjusting a time constant of a filter circuit comprising the steps of: generating an oscillation signal using a combination of a variable filter and an amplifier connected to provide positive feedback to said filter; comparing the phase of said oscillation signal with the phase of a reference frequency signal; generating a control signal in response to a difference in phase between said oscillation signal and said reference frequency signal; and adjusting said time constant of said filter circuit with said control signal.
Claim 8
Dependent Claim
22 words
The method of claim 5 also including the step of adjusting the time constant of the variable filter with the control signal.
Claim 9
Dependent Claim
93 words
An automatic adjustment circuit for adjusting a filter circuit, the filter circuit having a time constant, the adjustment circuit adjusting the time constant and receiving a reference frequency signal, said adjustment circuit comprising: oscillation means for generating an oscillation signal, said oscillation means including a time constant and variable filter, a feedback amplifier connected to said variable filter for positive feedback; and means for detecting a difference in frequency between said reference frequency signal and said oscillation signal and generating a control signal for automatically adjusting the time constant of said filter circuit.
Claim 10
Dependent Claim
93 words
An automatic adjustment circuit for adjusting a filter circuit, the filter circuit having a time constant, the adjustment circuit adjusting the time constant and receiving a reference frequency signal, said adjustment circuit comprising: oscillation means for generating an oscillation signal, said oscillation means including a time constant and variable filter, a feedback amplifier connected to said variable filter for positive feedback; and means for detecting a difference in frequency between said reference frequency signal and said oscillation signal and generating a control signal for automatically adjusting the time constant of said filter circuit.
Claim 11
Independent Claim
85 words
A method for adjusting a time constant of the filter circuit comprising the steps of: generating an oscillation signal using a combination of a variable filter and an amplifier connected to provide positive feedback to said filter; comparing the frequency of said oscillation signal with the frequency of a reference frequency signal; generating a control signal in response to a difference in frequency between said oscillation signal and said reference frequency signal; and adjusting said time constant of said filter circuit with said control signal.
Claim 12
Independent Claim
85 words
A method for adjusting a time constant of the filter circuit comprising the steps of: generating an oscillation signal using a combination of a variable filter and an amplifier connected to provide positive feedback to said filter; comparing the frequency of said oscillation signal with the frequency of a reference frequency signal; generating a control signal in response to a difference in frequency between said oscillation signal and said reference frequency signal; and adjusting said time constant of said filter circuit with said control signal.
Claim 13
Dependent Claim
22 words
The method of claim 8 also including the step of adjusting the time constant of the variable filter with the control signal.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-04-03 | 1992-10-03 | 1993-04-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-04-03 | 1996-10-03 | 1997-04-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-04-03 | 2000-10-03 | 2001-04-04 | $7700.00 | Window Closed / Lapsed |