US3796945A
Expired / Lapsed
US
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Digital attenuator wherein transistor switch means are biased by rectifier circuit
Assignee: Beltone Electronics Corp
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Filing: 1973-05-15
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Granted: 1974-03-12
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Expires: 1993-05-15
Abstract
Abstract The disclosure describes a digital attenuator having nonisolated, L-type attenuator sections. The sections comprise shunt legs that are switched to ground potential by bipolar NPN transistors. An adder circuit and a decoder circuit provide switching signals that enable predetermined attenuator sections through PNP transistors that are connected to the NPN transistors. A rectifier circuit produces a half-wave signal that biases the NPN transistors during their off state to prevent audio signals having a large magnitude from switching on the NPN transistors.
Inventors
- 👤 S Feldman
- 👤 W Mellenthin
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 16:53
CPC Classifications
H; H03; H03G; H03G3/00; H03G3/001; H03H; H03H7/00; H03H7/24; H03H7/25
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
247 words
A digital attenuator for attenuating an audio signal comprising: an input terminal for receiving the audio signal; an output terminal for transmitting the audio signal to a load circuit; first attenuator means for attenuating the audio signal by a discrete predetermined magnitude; second attenuator means for attenuating the audio signal by a discrete predetermined magnitude; conductor means for connecting the first and second attenuator means between the input terminal and the output terminal; operating means for generating a first switching signal that enables the first attenuator means and for generating a second switching signal that enables the second attenuator means; first switching means having a first output circuit operatively connected to the first attenuator means and having a first input circuit operatively connected to the operating means for enabling the first attenuator means in response to the first switching signal; second switching means having a second output circuit operatively connected to the second attenuator means and having a second input circuit operatively connected to the operating means for enabling the second attenuator means in response to the second switching signal; and rectifier means for rectifying said audio signal to produce a half-wave signal and for transmitting the half-wave signal to the first and second input circuits so that an input signal of large magnitude is incapable of enabling said first attenuator means in the absence of said first switching signal and is incapable of enabling said second attenuator means in the absence of said second switching signal.
Claim 2
Dependent Claim
247 words
A digital attenuator for attenuating an audio signal comprising: an input terminal for receiving the audio signal; an output terminal for transmitting the audio signal to a load circuit; first attenuator means for attenuating the audio signal by a discrete predetermined magnitude; second attenuator means for attenuating the audio signal by a discrete predetermined magnitude; conductor means for connecting the first and second attenuator means between the input terminal and the output terminal; operating means for generating a first switching signal that enables the first attenuator means and for generating a second switching signal that enables the second attenuator means; first switching means having a first output circuit operatively connected to the first attenuator means and having a first input circuit operatively connected to the operating means for enabling the first attenuator means in response to the first switching signal; second switching means having a second output circuit operatively connected to the second attenuator means and having a second input circuit operatively connected to the operating means for enabling the second attenuator means in response to the second switching signal; and rectifier means for rectifying said audio signal to produce a half-wave signal and for transmitting the half-wave signal to the first and second input circuits so that an input signal of large magnitude is incapable of enabling said first attenuator means in the absence of said first switching signal and is incapable of enabling said second attenuator means in the absence of said second switching signal.
Claim 3
Dependent Claim
44 words
An attenuator, as claimed in claim 1, wherein the first attenuator means comprises: a first series resistor connected in series between the input terminal and the output terminal; and a first shunt resistor connected between the first series resistor and the first output circuit.
Claim 4
Dependent Claim
44 words
An attenuator, as claimed in claim 2, wherein the second attenuAtor means comprises: a second series resistor connected in series between the input terminal and the output terminal; and a second shunt resistor connected between the second series resistor and the second output circuit.
Claim 5
Dependent Claim
32 words
An attenuator, as claimed in claim 1, wherein the operating means comprises: an electronic adder circuit; and a decoder circuit connected between the adder circuit and the first and second switching means.
Claim 6
Dependent Claim
108 words
An attenuator, as claimed in claim 4, wherein the operating means further comprises: third switching means having a third output circuit connected to the first input circuit, a third input circuit connected to the decoder circuit and a fourth input circuit connected to a low impedance circuit; fourth switching means having a fourth output circuit connected to the second input circuit, a fifth input circuit connected to the decoder circuit and a sixth input circuit connected to the low impedance circuit; and bias means for biasing the third and fifth input circuits so that the half-wave signal is shunted to the low impedance circuit during said switching signals.
Claim 7
Dependent Claim
60 words
An attenuator, as claimed in claim 5, wherein the third switching means comprises a first PNP transistor, wherein the third output circuit comprises a collector element of the first PNP transistor, wherein the third input circuit comprises a base element of the first PNP transistor and wherein the fourth input circuit comprises an emitter element of the first PNP transistor.
Claim 8
Dependent Claim
60 words
An attenuator, as claimed in claim 6, wherein the fourth switching means comprises a second PNP transistor, wherein the fourth output circuit comprises a collector element of the second PNP transistor, wherein the fifth input circuit comprises a base element of the second PNP transistor and wherein the sixth input circuit comprises an emitter element of the second PNP transistor.
Claim 9
Dependent Claim
57 words
An attenuator, as claimed in claim 7, wherein the first switching means comprises a first NPN transistor, wherein the first output circuit comprises an emitter element of the first NPN transistor, wherein the first input circuit comprises a base element of the first NPN transistor and wherein said first NPN transistor further comprises a grounded collector element.
Claim 10
Dependent Claim
57 words
An attenuator, as claimed in claim 8, wherein the second switching means comprises a second NPN transistor, wherein the second output circuit comprises an emitter element of the second NPN transistor, wherein the second input circuit comprises a base element of the second NPN transistor and wherein the second NPN transistor further comprises a grounded collector element.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-03-11 | 1977-09-10 | 1978-03-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-03-11 | 1981-09-10 | 1982-03-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-03-11 | 1985-09-10 | 1986-03-12 | $7700.00 | Window Closed / Lapsed |