Patent US3424700A successfully refreshed from Google Patents.
Patent US3810035A successfully refreshed from Google Patents.
US3810035A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Controlled resistance devices and attenuators
Assignee: DOLBY LABOR INC US
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Filing: 1972-09-28
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Granted: 1974-05-07
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Expires: 1992-09-28
Abstract
Abstract A controlled impedance device such as an attenuator is formed by parallel connected bipolar transistors and a network so applying a control signal to their bases that, as the control signal increases, the transistors commence to conduct progressively. A bootstrapped variable attenuator is formed by a variable attenuator connected in series with an impedance between the output and input of a high input impedance amplifier.
Inventors
- 👤 K Gundry
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 13:11
CPC Classifications
H; H03; H03G; H03G7/00; H03G7/06; H03G7/08; H03G1/00; H03G1/0005; H03G1/0035; H03G1/0082; H03H; H03H11/00; H03H11/02; H03H11/24
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
180 words
An audio attenuator comprising an amplifier with voltage gain and having an input and an output, a ladder network having a plurality of series impedances and a plurality of shunt arms connected between the ends of the series impedances and a common terminal, each shunt arm comprising an impedance and a transistor in series therewith, a control circuit connected between a control terminal and control electrodes of the individual transistors and responsive to an increasing control signal applied to the control terminal to render the transistors conductive in cumulative progression from one end of the ladder network to the other, the series impedances being connected between the output and input of the amplifier in a bootstrapped configuration to present an input impedance to the amplifier determined by the sum of the impedances multiplied by 1/(1-A) where A is the voltage gain of the amplifier, when no transistor is conducting, and the progressive conduction of the transistors progressively removing the series impedances from the bootstrapping action and progressively increasing the attenuation of the ladder network to progressively decrease said input impedance.
Claim 2
Dependent Claim
180 words
An audio attenuator comprising an amplifier with voltage gain and having an input and an output, a ladder network having a plurality of series impedances and a plurality of shunt arms connected between the ends of the series impedances and a common terminal, each shunt arm comprising an impedance and a transistor in series therewith, a control circuit connected between a control terminal and control electrodes of the individual transistors and responsive to an increasing control signal applied to the control terminal to render the transistors conductive in cumulative progression from one end of the ladder network to the other, the series impedances being connected between the output and input of the amplifier in a bootstrapped configuration to present an input impedance to the amplifier determined by the sum of the impedances multiplied by 1/(1-A) where A is the voltage gain of the amplifier, when no transistor is conducting, and the progressive conduction of the transistors progressively removing the series impedances from the bootstrapping action and progressively increasing the attenuation of the ladder network to progressively decrease said input impedance.
Claim 3
Dependent Claim
30 words
An audio attenuator according to claiM 1, further comprising a low output impedance amplifier followed by a complex impedance connected between the ladder network and the input of the amplifier.
Claim 4
Dependent Claim
17 words
An audio attenuator according to claim 2, wherein the impedance presented by the complex impedance is capacitive.
Claim 5
Dependent Claim
26 words
An audio attenuator according to claim 1, wherein the product of the voltage gain of the amplifier and the attenuation of the ladder network is negative.
Claim 6
Dependent Claim
89 words
An audio attenuator according to claim 1, wherein the ladder network comprises, in order from the input to the output of the amplifier, a first shunt arm followed by a first series impedance, a second shunt arm followed by a second series impedance, and so on to a last shunt arm followed by a last series impedance, and wherein the control circuit is constructed to render the transistors of the shunt arms cumulatively, progressively conductive starting with the transistor of the last shunt arm, as the control signal increases.
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) | 1977-05-06 | 1977-11-05 | 1978-05-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-05-06 | 1981-11-05 | 1982-05-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-05-06 | 1985-11-05 | 1986-05-07 | $7700.00 | Window Closed / Lapsed |