US3808545A
Expired / Lapsed
US
⏱️ 0.0 years remaining
High power bridge audio amplifier
Assignee: INT RADIO AND ELECTRONICS CORP
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Filing: 1972-10-04
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Granted: 1974-04-30
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Expires: 1992-10-04
Abstract
Abstract A high power audio amplifier includes four power amplifier sections connected in a bridge, with the power supply connected to one opposite pair of nodes and the load terminals connected to a second opposite pair of nodes. One of the load terminals may be connected to a ground reference potential and the power supply is floating with reference to ground. First and second drive amplifiers are provided, with each of the drive amplifiers being connected to the two power amplifier sections connected to one load terminal. The input signal to be amplified is applied to one input of the first drive amplifier and a feedback signal from the load terminal which is not connected to ground is connected to the second input thereof. The second drive amplifier receives either the input signal or the signal from the load terminal, and compares the same with the supply potential to balance the bridge. To protect the transistors of the power amplifier sections, the currents in the transistors of the amplifier sections driven by the second drive amplifier are sensed and used to control the first drive amplifier, to thereby protect the transistors in all of the power amplifier sections. Auxiliary protection circuits are provided for the transistors in the power amplifier sections coupled to each drive amplifier.
Inventors
- 👤 G Stanley
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 04:13
CPC Classifications
H; H03; H03F; H03F3/00; H03F3/30; H03F3/3081; H03F1/00; H03F1/52
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
182 words
A bridge audio amplifier circuit including in combination: first, second, third and fourth power amplifier sections, first and second load terminals, one of which is connected to a reference potential, power supply means including first and second supply terminals providing voltages of opposite polarities floating with respect to the reference potential, means connecting said amplifier sections to said power supply means and to said load terminals to form a bridge circuit, with said first and second supply terminals forming one opposite pair of nodes and said first and second load terminals forming a second opposite pair of nodes, and drive means for said amplifier sections including first and second drive amplifiers, and coupling means direct current coupling said first drive amplifier to said power amplifier sections connected to said first load terminal and direct current coupling said second drive amplifier to said power amplifier sections connected to said second load terminal, said coupling means applying signals to said power amplifier sections to cause the same to operate in a balanced manner to provide a high fidelity audio output at said load terminals.
Claim 2
Dependent Claim
182 words
A bridge audio amplifier circuit including in combination: first, second, third and fourth power amplifier sections, first and second load terminals, one of which is connected to a reference potential, power supply means including first and second supply terminals providing voltages of opposite polarities floating with respect to the reference potential, means connecting said amplifier sections to said power supply means and to said load terminals to form a bridge circuit, with said first and second supply terminals forming one opposite pair of nodes and said first and second load terminals forming a second opposite pair of nodes, and drive means for said amplifier sections including first and second drive amplifiers, and coupling means direct current coupling said first drive amplifier to said power amplifier sections connected to said first load terminal and direct current coupling said second drive amplifier to said power amplifier sections connected to said second load terminal, said coupling means applying signals to said power amplifier sections to cause the same to operate in a balanced manner to provide a high fidelity audio output at said load terminals.
Claim 3
Dependent Claim
88 words
A bridge amplifier circuit in accordance with claim 1 wherein said first and second drive amplifiers each includes an operational amplifier having two inputs, signal input means connected to one input of each of said drive amplifiers, feedback means connected from said load terminal which is not connected to a reference potential to the other input of said first drive amplifier for applying signals from said load terminal to said other input, and means connecting said power supply means to the other input of said second drive amplifier.
Claim 4
Dependent Claim
45 words
A bridge amplifier circuit in accordance with claim 1 wherein at least one of said power amplifier sections includes a pre-driver transistor, and including supplementary power supply means coupled to said transistor and providing a voltage therefor greater than the voltages at said supply terminals.
Claim 5
Dependent Claim
34 words
A bridge amplifier circuit in accordance with claim 1 wherein said power amplifier sections coupled to each of said first and second drive amplifiers include a pair of complementary pre-driver transistors providing push-pull outputs.
Claim 6
Dependent Claim
107 words
A bridge amplifier circuit in accordance with claim 1 wherein said first and second drive amplifiers each includes an operational amplifier, and wherein said power supply means includes a first portion connected to said first and second supply terminals for providing operating voltages to said power amplifier sections and a second portion connected to said operational amplifiers for providing operating voltages therefor, and control means for causing said second portion of said power supply means to be operative before said first portion thereof is operative so that said operational amplifiers are rendered operative before said power amplifier sections are energized by said first and second supply terminals.
Claim 7
Dependent Claim
57 words
A bridge amplifier circuit in accordance with claim 1 wherein said power supply means has a reference terminal which produces a potential which varies with the output signal, and control means coupled to said reference terminal and responsive to variations in such potential which are below a predetermined frequency for removing the potential from said supply terminals.
Claim 8
Dependent Claim
102 words
A bridge amplifier circuit in accordance with claim 1 wherein each of said power amplifier sections includes a pre-driver transistor, a power output transistor coupled to said pre-driver transistor and having output electrodes, and a sense resistor connected in series with said output electrodes, and including current limiter means for said power amplifier sections associated with each drive amplifier, said current limiter means being coupled to said sense resistors of said power amplifier sections and responsive to the voltages developed thereacross, and being connected to said pre-driver transistors of said power amplifier sections for controlling the same to limit the outputs thereof.
Claim 9
Dependent Claim
55 words
A bridge amplifier circuit in accordance with claim 7 wherein each of said current limiter means includes a pair of transistors individually coupled to said pre-driver transistors, and including means coupling said sense resistors of both of said amplifier sections coupled to each drive amplifier to each of said transistors of said current limiter means.
Claim 10
Dependent Claim
73 words
A bridge amplifier circuit in accOrdance with claim 8 wherein said transistors of each of said pairs are of complementary type, and each transistor of said current limiter means is of the same type as said pre-driver transistor to which it is coupled, and each of said current limiter means acts to reduce the output of the associated pre-driver transistor when the voltages across the sense resistors coupled thereto reach predetermined threshold values.
Claim 11
Dependent Claim
105 words
A bridge amplifier circuit in accordance with claim 1 wherein said first and second drive amplifiers each includes an operational amplifier having two inputs, signal input means connected to one input of said first drive amplifier, feedback circuit means connected from said load terminal not connected to the reference potential to the other input of said first drive amplifier for applying signals from said load terminal to said other input, means connecting said load terminal not connected to the reference potential to one input of said second drive amplifier and means connecting said power supply means to the other input of said second drive amplifier.
Claim 12
Dependent Claim
78 words
A bridge amplifier circuit in accordance with claim 10 wherein said amplifier sections coupled to said second drive amplifier each includes an output transistor and a sense resistor connected in series with such output transistor, and including current limiter means coupled to said sense resistors and to said first drive amplifier for controlling the drive of said first drive amplifier in accordance with the voltage across said sense resistors in response to voltages which exceed a predetermined threshold.
Claim 13
Dependent Claim
55 words
A bridge amplifier circuit in accordance with claim 10 wherein each of said power amplifier sections coupled to said first drive amplifier includes a pair of pre-driver transistors, and including a translating circuit coupling said operational amplifier to said first drive amplifier to said pre-driver transistors for increasing the level of the signals applied thereto.
Claim 14
Dependent Claim
83 words
A bridge amplifier circuit in accordance with claim 12 wherein said amplifier sections coupled to said second drive amplifier each includes an output transistor and a sense resistor connected in series with such output transistors, and said translating circuit includes a pair of transistors, and including current limiting means coupled to said sense resistors and to said transistors of said translating circuit for reducing the level of the signals in such transistors when the voltage across said sense resistors exceeds a predetermined threshold.
Claim 15
Dependent Claim
71 words
A bridge rectifier in accordance with claim 12 wherein said translating circuit includes a plurality of transistors, and further including supplementary power supply means having first and second portions bootstrapped to said first and second supply terminals for providing operating voltages greater than the voltages at said supply terminals, and means connecting said supplementary power supply means to said transistors of said translating circuit for providing the greater operating voltages thereto.
Claim 16
Dependent Claim
150 words
A bridge amplifier circuit in accordance with claim 10 wherein said power amplifier sections coupled to said first drive amplifier includes pre-driver transistors of complementary types, said pre-driver transistors having base electrodes for receiving signals, and a circuit for establishing a predetermined offset between the voltages of said base electrodes including first and second transistors of complementary types, each having base, emitter and collector electrodes, first, second and third resistors connected in series between said base electrodes of said pre-driver transistors, said emitter and collector electrodes of said first transistor being connected across said second and third resistors, and a fourth resistor connected in series with the emitter and collector electrodes of said second transistors, the common point between said second and third resistors being connected to the base electrode of said second transistor, and said collector of said second traNsistor being connected to said base of said first transistor.
Claim 17
Dependent Claim
139 words
A bridge amplifier circuit in accordance with claim 1 wherein each of said power amplifier sections includes a first transistor having an emitter-collector path connected in series with a resistor between one of said supply terminals and one of said load terminals, and at least one output transistor having base, emitter and collector electrodes, with said base electrode connected to the junction of said collector-emitter path of said first transistor and said resistor, and means connecting said emitter and collector electrodes of said output transistor between said one supply terminal and said one load terminal, with said first transistor of each amplifier section providing the output current to said one load terminal at relatively low signal levels and providing a voltage across said resistor to render said output transistor conducting to provide output current at relatively high signals levels.
Claim 18
Dependent Claim
42 words
The bridge amplifier in accordance with claim 16 wherein each of said power amplifier sections includes a plurality of output transistors connected between the associated supply and load terminals which operate in parallel to provide the output current at high signal levels.
Claim 19
Dependent Claim
111 words
A bridge amplifier in accordance with claim 1 wherein said first drive amplifier is coupled to said power amplifier sections connected to the load terminal which is connected to the reference potential and said second drive amplifier is connected to the other load terminal, said second drive amplifier including an operational amplifier having first and second inputs, first means coupled to said first input for applying thereto signals to be amplified, and second means coupled to said second input for applying thereto feedback signals from said other load terminal, said second means including a circuit portion for receiving signals and providing a unity gain inverted output at said other load terminal.
References Cited (Backward Citations)
US2821639A
Cited
US3383613A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-04-29 | 1977-10-29 | 1978-04-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-04-29 | 1981-10-29 | 1982-04-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-04-29 | 1985-10-29 | 1986-04-30 | $7700.00 | Window Closed / Lapsed |