US3786200A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Amplifier for use in communication systems
Assignee: Plantronics Inc
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Filing: 1972-05-17
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Granted: 1974-01-15
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Expires: 1992-05-17
Abstract
Abstract An amplifier for use in communication systems in which the output lines supply power to the amplifier which can operate from either polarity of supply voltage which may also be a relatively low voltage. The amplifier receives an input signal and applies the signal to said pair of lines. In one embodiment of the amplifier it can operate at high gain in response to an input signal and low gain in absence of an input signal to provide suppression of background noise. Another embodiment provides control of the amplifier gain as a function of operating current to more closely match the output characteristics of carbon microphones. The amplifier disclosed is particularly suitable for integration into a silicon monolithic bipolar circuit.
Inventors
- 👤 H Camenzind
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 18:09
CPC Classifications
H; H04; H04M; H04M9/00; H04M9/08; H04M9/10; H04M1/00; H04M1/60; H04M1/6008
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
181 words
An amplifier for use in communication systems of the type in which d.c. power is supplied to the amplifier from the communication lines to which the amplifier delivers its output comprising signal processing circuit means for receiving and processing an input signal to provide a processed signal, first and second output amplifiers each connected each to receive and amplify the processed signal and each apply their output to said communication lines, said first output amplifier connected to said output lines to receive power therefrom and operate when voltage of one polarity appears across said lines and being inoperative when a voltage of the other polarity appears across said lines and said second output amplifier being connected to operate when voltage of the other polarity appears across said lines and being inoperative when voltage of one polarity appears across said lines, and steering means connected between said communication lines and said signal processing means to apply voltage of predEtermined polarity to said signal processing means regardless of whether the voltage which appears across said lines is of one or the other polarity.
Claim 2
Dependent Claim
181 words
An amplifier for use in communication systems of the type in which d.c. power is supplied to the amplifier from the communication lines to which the amplifier delivers its output comprising signal processing circuit means for receiving and processing an input signal to provide a processed signal, first and second output amplifiers each connected each to receive and amplify the processed signal and each apply their output to said communication lines, said first output amplifier connected to said output lines to receive power therefrom and operate when voltage of one polarity appears across said lines and being inoperative when a voltage of the other polarity appears across said lines and said second output amplifier being connected to operate when voltage of the other polarity appears across said lines and being inoperative when voltage of one polarity appears across said lines, and steering means connected between said communication lines and said signal processing means to apply voltage of predEtermined polarity to said signal processing means regardless of whether the voltage which appears across said lines is of one or the other polarity.
Claim 3
Dependent Claim
137 words
An amplifier as in claim 1 in which said signal processing means includes a pair of terminals connected to receive the line voltage and said steering means comprises a first NPN transistor having its emitter connected to one of said communication lines and a second NPN transistor having its emitter connected to the other communication line with the collectors of said first and second NPN transistors connected to one terminal of the signal processing circuit, a first PNP transistor having its emitter connected to the other communication line and a second PNP transistor having its emitter terminal connected to the one communication line with the collectors of said first and second PNP transistors connected to the other terminal of the signal processing network, and means interconnecting the bases of said first transistors and of said second transistors.
Claim 4
Dependent Claim
17 words
An amplifier as in claim 2 wherein a plurality of resistances interconnect the bases of the transistors.
Claim 5
Dependent Claim
36 words
An amplifier as in claim 2 wherein each of the bases of the current steering transistors is connected through resistance means to the opposite line than that to which the emitter of said transistors is connected.
Claim 6
Dependent Claim
83 words
An amplifier as in claim 1 in which the first and second output amplifiers each comprise a first transistor having its base connected to receive the processed signal and providing a substantially constant current source, and a second transistor connected to receive the processed signal and having its emitter and collector connected across said communication lines to amplify and apply the signal to the communication lines with the second transistor of each amplifier having its collector and emitter connected to opposite communication lines.
Claim 7
Dependent Claim
42 words
An amplifier as in claim 5 including a diode connected in series with the collector of said second transistor to prevent application of power to one of the two transistors depending upon the polarity of the supply voltage on the communication lines.
Claim 8
Dependent Claim
99 words
An amplifier as in claim 1 wherein said signal processing circuit includes a preamplifier adapted to receive and amplify the input signal, a signal controlled attenuator connected to receive the output of said preamplifier, a control circuit connected to said attenuator and providing its output to said first and second output amplifiers, and an amplifier-detector having an input connected to receive the preamplifier output signal and having its output connected to said signal controlled attenuator to control said attenuator to reduce the attenuation when the preamplifier output signal applied to the amplifier-detector circuit input is above a predetermined amplitude.
Claim 9
Dependent Claim
102 words
An amplifier as in claim 7 in which said signal operated attenuator comprises first and second series connected resistors in the emitter-collector path of a transistor connected to receive the output of the preamplifier, said control circuit being connected to the common terminal of said resistors, said amplifier-detector connected to the base of said transistor to turn it on when the input signal is below said predetermined amplitude and turn it off when the input signal is above said predetermined amplitude, said resistors acting as a voltage divider to attenuate the signal applied to said control circuit when the transistor is on.
Claim 10
Dependent Claim
95 words
An amplifier as in claim 7 in which said control circuit includes a transistor having its base connected to receive signal from said signal controlled attenuator and its collector connected to apply signal to output amplifiers each comprising transistors having base, emitter and collector electrodes, the emitter electrodes of said amplifiers being connected to a resistance network, means for reducing the resistance of said network when the output current from the amplifiers is high to increase the gain and increasing the resistancE of said network to decrease the gain when the output current is low.
Claim 11
Dependent Claim
62 words
An amplifier as in claim 7 wherein said control circuit includes a transistor having its base terminal connected to receive the output of said signal controlled attenuator and having its output connected to the output of said output amplifiers together with circuit means connected to said transistor for providing a substantially constant output as a function of current to said output amplifiers.
Claim 12
Dependent Claim
80 words
An amplifier as in claim 7 wherein said amplifier-detector comprises means for deriving reference voltages, a differential amplifier connected to said means and to receive the output signal from the preamplifier which is unbalanced until the preamplifier signal reaches a predetermined amplitude, a control transistor connected to said signal controlled attenuator, and means connected to the output of said differential amplifier for controlling said control transistor whereby the same is conducting when the amplifier is unbalanced to attenuate the signal.
References Cited (Backward Citations)
US3733441A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-01-14 | 1977-07-16 | 1978-01-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-01-14 | 1981-07-16 | 1982-01-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-01-14 | 1985-07-16 | 1986-01-15 | $7700.00 | Window Closed / Lapsed |