US4806883A
Expired / Lapsed
US
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Multifrequency oscillator circuit
Assignee: Sony Corp
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Filing: 1987-11-24
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Granted: 1989-02-21
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Expires: 2007-11-24
Abstract
Abstract Oscillation circuit that generates an oscillating signal by charging and discharging a capacitor between two reference voltages employs several constant current sources, with the number of constant current sources that are connected to the capacitor at any one time being controlled so that the oscillation frequency can be changed in a step-wise fashion, whereby the circuitry is relatively simplified compared with known step-wise changing oscillators.
Inventors
- 👤 Takahiko Tamura
- 👤 Hiroyuki Suzuki
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 03:20
CPC Classifications
H; H04; H04N; H04N3/00; H04N3/10; H04N3/16; H04N3/27; H03; H03L; H03L7/00; H03L7/06; H03L7/08; H03L7/099; H03K; H03K3/00; H03K3/02; H03K3/023; H03K3/0231
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
72 words
An oscillation circuit for generating an oscillation signal by charging and discharging a capacitor between two reference voltages, comprising: a plurality of constant current sources each having the same current value; and switching circuits connected between said plurality of constant current sources and said capacitor, wherein said switching circuits selectively change the number of said constant current sources connected to said capacitor, thereby to step-wise change the frequency of said oscillation signal.
Claim 2
Dependent Claim
72 words
An oscillation circuit for generating an oscillation signal by charging and discharging a capacitor between two reference voltages, comprising: a plurality of constant current sources each having the same current value; and switching circuits connected between said plurality of constant current sources and said capacitor, wherein said switching circuits selectively change the number of said constant current sources connected to said capacitor, thereby to step-wise change the frequency of said oscillation signal.
Claim 3
Dependent Claim
20 words
An oscillation circuit according to claim 1, further comprising current multiplier means connected between said switching circuits and said capacitor.
Claim 4
Dependent Claim
54 words
An oscillation circuit according claim 2, in which said oscillation circuit is used in a video system and further comprising means for comparing the phase of a voltage across said capacitor with the phase of a horizontal synchronizing pulse in a video signal and providing a phase comparison signal to said current multiplier means.
Claim 5
Dependent Claim
31 words
An oscillator circuit according to claim 2, wherein and said current multiplier circuit comprises three current multipliers mutually connected in series and in series between said capacitor and said switching circuits.
Claim 6
Dependent Claim
23 words
An oscillation circuit according to claim 1, wherein currents produced by respective ones of said plurality of constant current sources are substantially equal.
Claim 7
Dependent Claim
18 words
An oscillator circuit according to claim 1, wherein said switching circuits comprise a plurality of differentially connected transistors.
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) | 1992-02-21 | 1992-08-22 | 1993-02-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-02-21 | 1996-08-22 | 1997-02-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-02-21 | 2000-08-22 | 2001-02-21 | $7700.00 | Window Closed / Lapsed |