US4088963A — Gain control circuit

Claim 1

Independent Claim 536 words

A gain control circuit comprising (a) a sound amplifier circuit including an audio signal input terminal and an audio signal output terminal, said sound amplifier circuit amplifying and introducing to said sound output terminal the audio signal applied to said audio signal input terminal; (b) gain control voltage means including an input terminal and an output terminal, said input terminal being connected to said audio signal output terminal, said means detecting part of the audio signal when said audio signal appears at said audio signal output terminal, said means producing a gain control voltage on the basis of said detected signal; (c) an attenuator circuit connected between the output terminal of the gain control voltage-generating means and said audio signal input terminal of said sound amplifier circuit, said attenuator circuit comprising a current control circuit controlled by the gain control voltage so as to be in a conducting state when said audio signal is applied to said audio signal input terminal and a gain control voltage above a predetermined voltage level is produced at the output terminal of said gain control voltage-generating means, and controlled so as to be in a nonconducting state when no audio signal exists on said audio signal input terminal, and further comprising a signal attenuator circuit controlled in accordance with the conducting state of said current control circuit, said signal attenuator circuit comprising a first transistor of a first conductivity type and a second transistor of a second conductivity type connected to each other in such a manner that the collector and emitter currents thereof flow in the same conducting direction; and said current control circuit comprising a third transistor controlled so as to be in a conducting state when the gain control voltage is above a predetermined voltage level and a current control semiconductor circuit controlled so as to be in a conducting state in accordance with the conducting state of said third transistor, and the current thereof being controlled by said third transistor, where said current control semiconductor circuit is provided with first and second current control semiconductor elements respectively having at least one junction electrode of a first type semiconductor and a second type semiconductor, the first type electrode of said first current control semiconductor element being connected to the base electrode of said first transistor, the second type electrode of said second current control semiconductor element being connected to the base electrode of said second transistor, and the remaining first and second type electrodes of said first and second current control semiconductor elements being connected commonly so that said first and second current control semiconductor elements control the current of said first and second transistors; (d) circuit means for connecting the commonly connected electrodes of said first and second current control semiconductor elements in said current control circuit to a point of the same DC potentials as that of said audio signal input terminal of said sound amplifier circuit and for connecting the commonly connected electrodes to ground with a low impedance with respect to AC frquencies; (e) means for connecting the common emitter of said first and second transistors in said signal attenuator circuit directly to said audio signal input terminal of said sound amplifier circuit.

Claim 2

Dependent Claim 536 words

A gain control circuit comprising (a) a sound amplifier circuit including an audio signal input terminal and an audio signal output terminal, said sound amplifier circuit amplifying and introducing to said sound output terminal the audio signal applied to said audio signal input terminal; (b) gain control voltage means including an input terminal and an output terminal, said input terminal being connected to said audio signal output terminal, said means detecting part of the audio signal when said audio signal appears at said audio signal output terminal, said means producing a gain control voltage on the basis of said detected signal; (c) an attenuator circuit connected between the output terminal of the gain control voltage-generating means and said audio signal input terminal of said sound amplifier circuit, said attenuator circuit comprising a current control circuit controlled by the gain control voltage so as to be in a conducting state when said audio signal is applied to said audio signal input terminal and a gain control voltage above a predetermined voltage level is produced at the output terminal of said gain control voltage-generating means, and controlled so as to be in a nonconducting state when no audio signal exists on said audio signal input terminal, and further comprising a signal attenuator circuit controlled in accordance with the conducting state of said current control circuit, said signal attenuator circuit comprising a first transistor of a first conductivity type and a second transistor of a second conductivity type connected to each other in such a manner that the collector and emitter currents thereof flow in the same conducting direction; and said current control circuit comprising a third transistor controlled so as to be in a conducting state when the gain control voltage is above a predetermined voltage level and a current control semiconductor circuit controlled so as to be in a conducting state in accordance with the conducting state of said third transistor, and the current thereof being controlled by said third transistor, where said current control semiconductor circuit is provided with first and second current control semiconductor elements respectively having at least one junction electrode of a first type semiconductor and a second type semiconductor, the first type electrode of said first current control semiconductor element being connected to the base electrode of said first transistor, the second type electrode of said second current control semiconductor element being connected to the base electrode of said second transistor, and the remaining first and second type electrodes of said first and second current control semiconductor elements being connected commonly so that said first and second current control semiconductor elements control the current of said first and second transistors; (d) circuit means for connecting the commonly connected electrodes of said first and second current control semiconductor elements in said current control circuit to a point of the same DC potentials as that of said audio signal input terminal of said sound amplifier circuit and for connecting the commonly connected electrodes to ground with a low impedance with respect to AC frquencies; (e) means for connecting the common emitter of said first and second transistors in said signal attenuator circuit directly to said audio signal input terminal of said sound amplifier circuit.

Claim 3

Dependent Claim 474 words

A gain control circuit for a sound amplifier comprising: a sound amplifier circuit including an input terminal to which an audio signal to be amplified is applied and an output terminal, said sound amplifier circuit amplifying the audio signal applied to the input terminal and introducing the thus amplified audio signal to said output terminal, and further comprising detecting means, connected to the output terminal of said amplifier circuit, for detecting the signal appearing at the output terminal of the amplifier circuit and generating a gain control voltage depending on the detection intensity of the amplified audio signal, and gain control circuit also comprising an attenuator circuit comprising: a signal attenuator circuit comprising a first transistor of first conductivity type and a second transistor of second conductivity type with emitters thereof connected together so that a current flows from a collector of the first transistor to that of the second transistor; a current control circuit comprising first transistor means having a base to which the gain control voltage is applied for controlling said means so as to render it non-conductive or conductive in dependence upon whether the gain control voltage has exceeded a predetermined level, and a variable impedance device having a second transistor means comprising third and fourth transistors of different conductivity types, one of either the emitters or the bases of said third and fourth transistors being connected together and the remaining bases or emitters of said third and fourth transistors being connected to the bases of said first and second transistors respectively such that the PN emitter-base junctions of said third and fourth transistors are serially connected together in the same conducting direction and that the thus serially connected circuit of the PN emitter-base junctions is connected in parallel across the bases of said first and second transistors so as to allow current to flow in the thus connected parallel circuit in the same conducting direction, and said first transistor means being connected with said second transistor means so as to control the conduction of said second transistor means in response to its conductive state; and means for applying to the commonly connected emitters or bases of said third and fourth transistors a reference potential having the same potential as the DC potential at the input terminal of said sound amplifier circuit, and means for connecting the commonly connected emitters of said first and second transistors directly to the input terminal of said sound amplifier circuit, whereby the audio signal applied to the input terminal of sound amplifier circuit is attenuated in accordance with the magnitude of the output impedance of said attenuator circuit, which magnitude is controlled by the conduction of said current control circuit under condition of same current flow in the emitter-collector circuits of said first and second transistors, thereby to control the gain of said sound amplifier.

Claim 4

Dependent Claim 474 words

A gain control circuit for a sound amplifier comprising: a sound amplifier circuit including an input terminal to which an audio signal to be amplified is applied and an output terminal, said sound amplifier circuit amplifying the audio signal applied to the input terminal and introducing the thus amplified audio signal to said output terminal, and further comprising detecting means, connected to the output terminal of said amplifier circuit, for detecting the signal appearing at the output terminal of the amplifier circuit and generating a gain control voltage depending on the detection intensity of the amplified audio signal, and gain control circuit also comprising an attenuator circuit comprising: a signal attenuator circuit comprising a first transistor of first conductivity type and a second transistor of second conductivity type with emitters thereof connected together so that a current flows from a collector of the first transistor to that of the second transistor; a current control circuit comprising first transistor means having a base to which the gain control voltage is applied for controlling said means so as to render it non-conductive or conductive in dependence upon whether the gain control voltage has exceeded a predetermined level, and a variable impedance device having a second transistor means comprising third and fourth transistors of different conductivity types, one of either the emitters or the bases of said third and fourth transistors being connected together and the remaining bases or emitters of said third and fourth transistors being connected to the bases of said first and second transistors respectively such that the PN emitter-base junctions of said third and fourth transistors are serially connected together in the same conducting direction and that the thus serially connected circuit of the PN emitter-base junctions is connected in parallel across the bases of said first and second transistors so as to allow current to flow in the thus connected parallel circuit in the same conducting direction, and said first transistor means being connected with said second transistor means so as to control the conduction of said second transistor means in response to its conductive state; and means for applying to the commonly connected emitters or bases of said third and fourth transistors a reference potential having the same potential as the DC potential at the input terminal of said sound amplifier circuit, and means for connecting the commonly connected emitters of said first and second transistors directly to the input terminal of said sound amplifier circuit, whereby the audio signal applied to the input terminal of sound amplifier circuit is attenuated in accordance with the magnitude of the output impedance of said attenuator circuit, which magnitude is controlled by the conduction of said current control circuit under condition of same current flow in the emitter-collector circuits of said first and second transistors, thereby to control the gain of said sound amplifier.

Claim 5

Dependent Claim 65 words

A gain control circuit according to claim 2, wherein said first and third transistors are of opposite conductivity types and said second and fourth transistors are of opposite conductivity types, the bases of said third and fourth transistors being commonly connected to each other, and the emitters of said third and fourth transistors being connected with the bases of the first and second transistors, respectively.

Claim 6

Dependent Claim 121 words

A gain control circuit according to claim 3, wherein said first transistor means comprises: a fifth transistor serially connected with emitter of said fourth transistor, with the gain control voltage being applied to the base of said fifth transistor; a first impedance element connected between said fifth transistor and ground; sixth and seventh transistors whose bases are commonly connected to each other as well as to the collector of the seventh transistor, and the collectors of said sixth and seventh transistors being connected with the emitter and collector of the third and fourth transistors, respectively; and second and third impedance elements connected with emitters of said sixth and seventh transistors respectively for supplying power to the sixth and seventh transistors therethrough.

Claim 7

Dependent Claim 33 words

A gain control circuit according to claim 2, which further comprises a current correcting circuit coupled with the current control circuit for equalizing the currents flowing through the respective third and fourth transistors.

Claim 8

Dependent Claim 76 words

A gain control circuit according to claim 2, wherein said first and third transistors are of the same conductivity type as well as said second and fourth transistors are of the same conductivity type, respectively, the emitters of said third and fourth transistors being commonly connected to each other, with the base and collector of the respective third and fourth transistors commonly connected and also connected with the bases of said first and second transistors, respectively.

Claim 9

Dependent Claim 99 words

A gain control circuit according to claim 6, wherein said first transistor means comprises: fifth and sixth transistors with the gain control voltage being applied to the bases thereof, said fifth transistor being serially connected between collector of said fourth transistor and ground; and seventh and eighth transistors whose bases are commonly connected to each other and connected in series with the sixth transistor, with the emitter-collector circuit of said eighth transistor being also connected in series with said sixth transistor, the emitter-collector circuit of said seventh transistor being connected in series with the collector of said third transistor.

Claim 10

Dependent Claim 352 words

A gain control circuit comprising: a sound amplifier means, having input and output terminals, for amplifying an audio signal applied to its input terminal and providing said amplified signal at its output terminal; a gain control means connected to said sound amplifier means for detecting the audio signal at the output terminal of said sound amplifier means and producing a gain control voltage in dependence upon the magnitude of said detected audio signal; an attenuator means connected to the input terminal of said sound amplifier means for controlling the amplitude of the output of said sound amplifier means by shunting part of the audio input signal to ground, said attenuation means controlled by said gain control voltage; said attenuation means comprising a first transistor of a first conductivity type and a second transistor of a second conductivity type; the emitters of said first and second transistors both being connected to the input terminal of said sound amplifier means; the collector of said first transistor connected to a DC power source and the collector of said second transistor connected to ground; said attenuation means further comprising a third transistor of the first conductivity type, the emitter of which being grounded, the collector of which connected to the base of said second transistor and the base of which receives the gain control voltage; said attenuator means further comprising a fourth transistor of the second conductivity type and a fifth transistor of the first conductivity type, the collector of which connected together and to the base of said fourth transistor, the emitter of said fourth transistor connected to the DC power source, the emitter of said fifth transistor connected to the base of said second transistor and the base of said fifth transistor connected to an AC ground; said attenuator means further comprising sixth and seventh transistors of the second conductivity type, the collector of said sixth transistor connected to the base of said first transistor and the emitter of said seventh transistor, the emitter of said sixth transistor connected to the DC power source and the collector of said seventh transistor connected to ground.

Claim 11

Dependent Claim 352 words

A gain control circuit comprising: a sound amplifier means, having input and output terminals, for amplifying an audio signal applied to its input terminal and providing said amplified signal at its output terminal; a gain control means connected to said sound amplifier means for detecting the audio signal at the output terminal of said sound amplifier means and producing a gain control voltage in dependence upon the magnitude of said detected audio signal; an attenuator means connected to the input terminal of said sound amplifier means for controlling the amplitude of the output of said sound amplifier means by shunting part of the audio input signal to ground, said attenuation means controlled by said gain control voltage; said attenuation means comprising a first transistor of a first conductivity type and a second transistor of a second conductivity type; the emitters of said first and second transistors both being connected to the input terminal of said sound amplifier means; the collector of said first transistor connected to a DC power source and the collector of said second transistor connected to ground; said attenuation means further comprising a third transistor of the first conductivity type, the emitter of which being grounded, the collector of which connected to the base of said second transistor and the base of which receives the gain control voltage; said attenuator means further comprising a fourth transistor of the second conductivity type and a fifth transistor of the first conductivity type, the collector of which connected together and to the base of said fourth transistor, the emitter of said fourth transistor connected to the DC power source, the emitter of said fifth transistor connected to the base of said second transistor and the base of said fifth transistor connected to an AC ground; said attenuator means further comprising sixth and seventh transistors of the second conductivity type, the collector of said sixth transistor connected to the base of said first transistor and the emitter of said seventh transistor, the emitter of said sixth transistor connected to the DC power source and the collector of said seventh transistor connected to ground.

Claim 12

Dependent Claim 124 words

A gain control circuit according to claim 8, wherein said sound amplifier circuit comprises: a differential amplifier transistor circuit comprising in its first stage a bias circuit; said bias circuit comprising an additional first transistor with the base thereof connected to the audio signal input terminal, and an additional second transistor with the base thereof so grounded as to lower the AC impedance, said first and second additional transistors having the emitters thereof connected to each other; said first additional transistor having the base thereof connected in DC fashion to the output terminal of said signal attenuator circuit, said second additional transistor having the base thereof connected in DC mode to the base of said fourth and fifth transistors of said current control circuit.

Claim 13

Dependent Claim 147 words

A gain control circuit according to claim 8, wherein said sound amplifier circuit comprises: a differential amplifier transistor circuit comprising in its first stage a bias circuit; said bias circuit comprising an additional first transistor with the base thereof connected to the audio signal input terminal, and an additional said transistor with the base thereof so grounded as to lower the AC impedance, said first and second additional transistors having the emitters thereof connected to each other; and means for grounding the base of said first additional transistor through part of said bias circuit in such a manner as to lower the AC impedance; said first additional transistor having the base thereof connected in DC mode to the output terminal of said signal attenuator circuit, said grounding means being connected in DC mode to the bases of said fourth and fifth transistors of said circuit control circuit.

Claim 14

Dependent Claim 51 words

A gain control circuit as in claim 8, wherein the attenuator means further comprises an eighth transistor of the second conductivity type with the emitter of which connected to the base of said first transistor, the collector of which grounded and the base of which connected to a fixed reference voltage.

Claim 15

Dependent Claim 102 words

A gain control circuit as in claim 8, wherein the attenuator means further comprises ninth, tenth and eleventh transistors of the first conductivity type, the base of said ninth transistor connected to the base of said fifth transistor, the collectors of said ninth and tenth transistors connected to the emitters of said sixth and fourth transistors, respectively, the base of said tenth transistor connected to a fixed DC voltage, the emitters of said ninth and tenth transistors both connected to the collector of the eleventh transistor, the emitter of which is grounded and the base of which receives said gain control voltage.

Claim 16

Dependent Claim 85 words

A gain control circuit as in claim 8, wherein the attenuator means further comprises a twelfth transistor of the first conductivity type and a thirteenth transistor of the second conductivity type, the emitters of which connected together, the collector of said twelfth transistor connected to the emitter of said fourth transistor, the base of said twelfth transistor connected to a fixed reference voltage, the base of said thirteenth transistor connected to the base of said second transistor and the collector of said thirteenth transistor grounded.

Claim 17

Dependent Claim 363 words

A gain control circuit comprising: a sound amplifier means, having input and output terminals, for amplifying an audio signal applied to its input terminal and providing said amplified signal at its output terminal; a gain control means connected to said sound amplifier means for detecting the audio signal at the output terminal of said sound amplifier means and producing a gain control voltage in dependence upon the magnitude of said detected audio signal; an attenuator means connected to the input terminal of said sound amplifier means for controlling the amplitude of the output of said sound amplifier means by shunting part of the audio input signal to ground, said attenuation means controlled by said gain control voltage; said attenuator means comprising a first transistor of a first conductivity type and a second transistor of a second conductivity type; the emitters of said first and second transistors both being connected to the input terminal of said sound amplifier means; the collector of said first transistor connected to a DC power source and the collector of said second transistor connected to ground; said attenuator means further comprising a third transistor of the first conductivity type, the emitter of which being grounded, the collector of which connected to the base of said second transistor and the base of which receives the gain control voltage; said attenuator means further comprising fourth and fifth transistors of the second conductivity type, the bases of which connected to the collectors of said third and fourth transistors, the emitters of which connected to a DC power source, the collector of said fifth transistor connected to the base of said first transistor; said attenuator means further comprising sixth, seventh, and eighth transistors of the first, second and first conductivity type, respectively, the emitters of the sixth and seventh transistors connected together and connected to an AC ground, the collectors of the seventh and eighth transistors connected together and also connected to the bases of the second and seventh transistors, the collector and base of the sixth transistor connected to the base of the first transistor, the base of the eighth transistor receiving the gain control voltage and the emitter connected to ground.

Claim 18

Dependent Claim 363 words

A gain control circuit comprising: a sound amplifier means, having input and output terminals, for amplifying an audio signal applied to its input terminal and providing said amplified signal at its output terminal; a gain control means connected to said sound amplifier means for detecting the audio signal at the output terminal of said sound amplifier means and producing a gain control voltage in dependence upon the magnitude of said detected audio signal; an attenuator means connected to the input terminal of said sound amplifier means for controlling the amplitude of the output of said sound amplifier means by shunting part of the audio input signal to ground, said attenuation means controlled by said gain control voltage; said attenuator means comprising a first transistor of a first conductivity type and a second transistor of a second conductivity type; the emitters of said first and second transistors both being connected to the input terminal of said sound amplifier means; the collector of said first transistor connected to a DC power source and the collector of said second transistor connected to ground; said attenuator means further comprising a third transistor of the first conductivity type, the emitter of which being grounded, the collector of which connected to the base of said second transistor and the base of which receives the gain control voltage; said attenuator means further comprising fourth and fifth transistors of the second conductivity type, the bases of which connected to the collectors of said third and fourth transistors, the emitters of which connected to a DC power source, the collector of said fifth transistor connected to the base of said first transistor; said attenuator means further comprising sixth, seventh, and eighth transistors of the first, second and first conductivity type, respectively, the emitters of the sixth and seventh transistors connected together and connected to an AC ground, the collectors of the seventh and eighth transistors connected together and also connected to the bases of the second and seventh transistors, the collector and base of the sixth transistor connected to the base of the first transistor, the base of the eighth transistor receiving the gain control voltage and the emitter connected to ground.

Claim 19

Dependent Claim 124 words

A gain control circuit according to claim 14, wherein said sound amplifier circuit comprises: a differential amplifier transistor circuit comprising in its first stage a bias circuit; said bias circuit comprising an additional first transistor with the base thereof connected to the audio signal input terminal, and an additional second transistor with the base thereof so grounded as to lower the AC impedance, said first and second additional transistors having the emitters thereof connected to each other; said first additional transistor having the base thereof connected in DC mode to the output terminal of said signal attenuator circuit, said second additional transistor having the base thereof connected in DC mode to the emitters of said fourth and eighth transistors of said current control circuit.

Claim 20

Dependent Claim 147 words

A gain control circuit according to claim 14, wherein said sound amplifier circuit comprises: a differential amplifier transistor circuit comprising in its first stage a bias circuit; said bias circuit comprising an additional first transistor with the base thereof connected to the audio signal input terminal, and an additional second transistor with the base thereof so grounded as to lower the AC impedance, said first and second additional transistors having the emitters thereof connected to each other; and means for grounding the base of said first additional transistor through part of said bias circuit in such a manner as to lower the AC impedance; said first additional transistor having the base thereof connected in DC mode to the output terminal of said signal attenuator circuit, said grounding means being connected in DC mode to the emitters of said fourth and eighth transistors of said current control circuit.

Claim 21

Dependent Claim 94 words

A gain control circuit as in claim 14, wherein said attenuator means further comprises ninth, tenth and eleventh transistors, the emitters of the ninth and tenth transistors both connected to the collector of the eleventh transistor, the bases of the ninth and tenth transistor connected to the emitter of the sixth transistor and a fixed reference voltage, respectively, the collectors of the ninth and tenth transistors connected to the emitters of the fifth and fourth transistors, respectively, the base of the eleventh transistor receiving the gain control voltage and the emitter connected to ground.

Claim 22

Dependent Claim 78 words

A gain control circuit as in claim 14, wherein the attenuator means further comprises twelfth and thirteenth transistors of first and second conductivity types, respectively, the emitters of which are connected together, the collector of the twelfth transistor connected to the emitter of the fourth transistor, the collector of the thirteenth transistor connected to ground, and the bases of the twelfth and thirteenth transistors connected to a fixed reference voltage and the base of the second transistor, respectively.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1981-05-08	1981-11-07	1982-05-09	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1985-05-08	1985-11-07	1986-05-09	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1989-05-08	1989-11-07	1990-05-09	$7700.00	Window Closed / Lapsed

Gain control circuit

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