Patent US3750030A successfully refreshed from Google Patents.
US3750030A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Frequency switching circuitry for varactor tuned radio receivers
Assignee: RCA Licensing Corp
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Filing: 1970-12-29
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Granted: 1973-07-31
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Expires: 1990-12-29
Abstract
Abstract In a varactor tuned radio receiver which utilizes scan circuitry to tune the receiver, frequency switching circuitry is provided for developing a voltage across a scan control capacitor for application to the scan circuitry to tune the receiver to within a particular range of the desired frequency within one of a plurality of spreadbands. The frequency switching circuitry includes first, second, and third variable resistances connected in circuit with the scan control capacitor. Adjustment of the first variable resistance tunes the receiver to within a first relatively broad range within a desired spreadband. Adjustment of the second variable resistance tunes the receiver to within a second narrower range within the first range. The third variable resistance is ganged to the first variable resistance and is simultaneously adjusted to compensate for small nonlinearities in the voltage versus capacitance characteristic of the varactor.
Inventors
- 👤 J Worcester
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 13:27
CPC Classifications
H; H03; H03J; H03J5/00; H03J5/02; H03J5/0209; H03J7/00; H03J7/18; H03J7/20; H03J7/24
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
236 words
A varactor tuned receiver utilizing scan circuitry and a scan control capacitor to tune the receiver by selectively impressing predetermined voltages on the varactors of said receiver, comprising: a. first variable resistance means for providing a coarse tuning adjustment of said receiver, b. second variable resistance means for providing a fine tuning adjustment of said receiver, c. first means for digitally setting the value of said first resistance means, d. second means for digitally setting the value of said second resistance means and for coupling together said first and second resistance means, e. third variable resistance means having a resistance characteristic matched to that of said first resistance means for providing compensation for the nonlinear voltage versus frequency properties of said varactors, f. third means for digitally setting the value of said third resistance means and for coupling together said second and third resistance means, said third means being coupled in cooperative relationship with said first means so that the values of said first and third resistance means are set together, and g. switching means for momentarily coupling said first, second and third resistance means in circuit with a voltage source and said scan capacitor so as to apply a voltage to said capacitor that is in accordance with the combined values of said first, second and third resistance means, thereby selecting a particular range of frequencies within a given spreadband for tuning of the receiver.
Claim 2
Dependent Claim
236 words
A varactor tuned receiver utilizing scan circuitry and a scan control capacitor to tune the receiver by selectively impressing predetermined voltages on the varactors of said receiver, comprising: a. first variable resistance means for providing a coarse tuning adjustment of said receiver, b. second variable resistance means for providing a fine tuning adjustment of said receiver, c. first means for digitally setting the value of said first resistance means, d. second means for digitally setting the value of said second resistance means and for coupling together said first and second resistance means, e. third variable resistance means having a resistance characteristic matched to that of said first resistance means for providing compensation for the nonlinear voltage versus frequency properties of said varactors, f. third means for digitally setting the value of said third resistance means and for coupling together said second and third resistance means, said third means being coupled in cooperative relationship with said first means so that the values of said first and third resistance means are set together, and g. switching means for momentarily coupling said first, second and third resistance means in circuit with a voltage source and said scan capacitor so as to apply a voltage to said capacitor that is in accordance with the combined values of said first, second and third resistance means, thereby selecting a particular range of frequencies within a given spreadband for tuning of the receiver.
Claim 3
Dependent Claim
107 words
A varactor tuned receiver as in claim 1 wherein said first variable resistance means comprises a first pair of resistor segments coupled between one side of said voltage source and said second means, said first pair of resistor segments having a first set of multiple taps, and wherein said first means selectively connects one of said multiple taps to said switching means so as to place said first pair of resistor segments in a voltage divider arrangement, the connection being made so that as the value of one of said first pair of resistor segments is changed, the value of the other changes in reciprocal relationship therewith.
Claim 4
Dependent Claim
111 words
A varactor tuned receiver as in claim 2 wherein said second variable resistance means comprises a second pair of resistor segments coupled between the other side of said voltage source and said third means, said second pair of resistor segments having a second set of multiple taps, and wherein said second means selectively connects one of said second set of multiple taps to said first resistance means so as to place said second pair or resistor segments in a parallel arrangement, the connection being made so that as the value of one of said second pair of resistor segments is changed, the value of the other changes in reciprocal relationship therewith.
Claim 5
Dependent Claim
36 words
A varactor tuned receiver as in claim 3 wherein said first and second means each comprise a multiple contact switch for connecting, respectively, to the multiple taps of said first and second pair of resistor segments.
Claim 6
Dependent Claim
60 words
A varactor tuned receiver as in claim 4 wherein said third variable resistance means comprises a plurality of resistor segments joined together at one end and coupled to said other side of said voltage source, and said third means connects the other ends of said plurality of resistor segments in serieS with one of said second pair of resistor segments.
Claim 7
Dependent Claim
36 words
A varactor tuned receiver as in claim 5 wherein said third means comprises a multiple contact switch ganged together with the multiple contact switch of said first means for connecting to said plurality of resistor segments.
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) | 1976-07-30 | 1977-01-29 | 1977-07-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-07-30 | 1981-01-29 | 1981-07-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-07-30 | 1985-01-29 | 1985-07-31 | $7700.00 | Window Closed / Lapsed |