US3924159A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Amplifier protection system
Assignee: RCA Corp
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Filing: 1974-10-04
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Granted: 1975-12-02
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Expires: 1994-10-04
Abstract
Abstract An emulating amplifier stage, that can be lower in power capability but otherwise has the same electrical operating parameters as the amplifier output stage being protected, forms a bridge network with this output stage. A resistor is connected between two nodes of the bridge (between the output terminals of these stages). When a fault occurs, such as a short circuit across the load being driven by the amplifier, the bridge network becomes unbalanced and current flows through the resistor. In response thereto, the drive signal and bias voltage are removed from the input circuit of the output stage.
Inventors
- 👤 Merle Vincent Hoover
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 20:20
CPC Classifications
H; H02; H02H; H02H3/00; H02H3/26; H02H3/36; H03; H03F; H03F1/00; H03F1/52
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
211 words
A protection circuit for protecting the output stage of an amplifier from damage when a ground or voltage fault is connected to an output terminal of said output stage, said output stage having at least one input terminal receptive of a drive signal and bias voltages, the output terminal of said output stage being coupled to a load impedance, said protection circuit including: an emulating output stage having substantially the same operating characteristics as and connected in parallel with said output stage of said amplifier, said emulating output stage having an output terminal; current sensing means connected between said output terminal of said emulating output stage and said output terminal of said output stage of said amplifier, respectively, whereupon a zero voltage differential exists across and no current flows through said sensing resistor during normal operation of said amplifier, whereas when a ground or voltage fault occurs at the output terminal of said amplifier, current will flow through and cause a voltage differential to exist across said sensing means; means coupled across said current sensing means for producing a signal manifestation indicative of a voltage differential existing across said current sensing means; and means responsive to said signal manifestation for removing the drive signal from said output stage of said amplifier.
Claim 2
Dependent Claim
211 words
A protection circuit for protecting the output stage of an amplifier from damage when a ground or voltage fault is connected to an output terminal of said output stage, said output stage having at least one input terminal receptive of a drive signal and bias voltages, the output terminal of said output stage being coupled to a load impedance, said protection circuit including: an emulating output stage having substantially the same operating characteristics as and connected in parallel with said output stage of said amplifier, said emulating output stage having an output terminal; current sensing means connected between said output terminal of said emulating output stage and said output terminal of said output stage of said amplifier, respectively, whereupon a zero voltage differential exists across and no current flows through said sensing resistor during normal operation of said amplifier, whereas when a ground or voltage fault occurs at the output terminal of said amplifier, current will flow through and cause a voltage differential to exist across said sensing means; means coupled across said current sensing means for producing a signal manifestation indicative of a voltage differential existing across said current sensing means; and means responsive to said signal manifestation for removing the drive signal from said output stage of said amplifier.
Claim 3
Dependent Claim
76 words
The protection circuit of claim 1, wherein said signal manifestation producing means includes a differential amplifier having a pair of input terminals connected across said current sensing means, and an output terminal coupled to a control electrode of said means responsive to said signal manifestation, whereupon said differential amplifier is responsive to the occurrence of a voltage differential across said current sensing means to produce said signal manifestation at the output terminal of said differential amplifier.
Claim 4
Dependent Claim
106 words
The protection circuit of claim 1, wherein said means responsive to said signal manifestation includes a crowbar circuit having a control electrode receptive of said signal manifestation, a first main current carrying electrode coupled to at least one of said input terminals of said output stage of said amplifier, and a second main current carrying electrode connected to a reference voltage, whereupon said crowbar circuit is operated by said signal manifestation to shunt said drive signal and bias voltages to said reference voltage in the event of a fault at said output terminal of either said output stage of said amplifier or said emulating output stage.
Claim 5
Dependent Claim
23 words
The protection circuit of claim 1, wherein said emulating output stage is of lower power capability than the output stage of said amplifier.
Claim 6
Dependent Claim
205 words
A circuit for protecting an output stage of a first amplifier, said output stage having an output terminal, and at least one input terminal receptive of a drive signal, said output terminal of said output stage being connected to a load impedance, said protection circuit comprising: a second amplifier substantially identical to the output stage of said first amplifier connected in parallel with said output stage, said second amplifier having an output terminal; a current sensor connected between said output terminals of said output stage of said first amplifier and said second amplifier, whereupon a zero voltage differential exists across and no current flows through said current sensors during normal operation of said first amplifier, whereas upon the occurrence of a ground or voltage fault at the output terminal of said first amplifier, current will flow through and cause a voltage differential to exist across said current sensor; means coupled across said current sensor for producing a signal manifestation indicative of a voltage differential existing across said current sensor; and means responsive to said signal manifestation for removing the drive signal and bias voltages from said output stage of said first amplifier whenever said signal manifestation is indicative of a fault in said first amplifier.
Claim 7
Dependent Claim
205 words
A circuit for protecting an output stage of a first amplifier, said output stage having an output terminal, and at least one input terminal receptive of a drive signal, said output terminal of said output stage being connected to a load impedance, said protection circuit comprising: a second amplifier substantially identical to the output stage of said first amplifier connected in parallel with said output stage, said second amplifier having an output terminal; a current sensor connected between said output terminals of said output stage of said first amplifier and said second amplifier, whereupon a zero voltage differential exists across and no current flows through said current sensors during normal operation of said first amplifier, whereas upon the occurrence of a ground or voltage fault at the output terminal of said first amplifier, current will flow through and cause a voltage differential to exist across said current sensor; means coupled across said current sensor for producing a signal manifestation indicative of a voltage differential existing across said current sensor; and means responsive to said signal manifestation for removing the drive signal and bias voltages from said output stage of said first amplifier whenever said signal manifestation is indicative of a fault in said first amplifier.
Claim 8
Dependent Claim
70 words
The protection circuit of claim 5, wherein said signal manifestation means includes a differential amplifier having a pair of input terminals connected across said current sensor, and an output terminal coupled to a control electrode of said means responsive to said signal manifestation, whereupon said differential amplifier is responsive to a voltage differential across said current sensor to produce said signal manifestation at the output terminal of said differential amplifier.
Claim 9
Dependent Claim
98 words
The protection circuit of claim 5, wherein said means responsive to said signal manifestation includes a crowbar circuit having a control electrode receptive of said signal manifestation, a first main current carrying electrode coupled to at least one of said input terminals of said output stage of said first amplifier, and a second main current carrying electrode connected to a reference voltage, whereupon said crowbar circuit is operated by said signal manifestation to shunt said drive signal to said reference voltage in the event of a fault at said output terminal of said output stage of said amplifier.
Claim 10
Dependent Claim
23 words
The protection circuit of claim 5, wherein said second amplifier is of lower power capability than the output stage of said first amplifier.
Claim 11
Dependent Claim
152 words
A circuit for protecting the output stage of an amplifier from an overload condition, the output stage comprising an output amplifier having an input terminal means to which an input signal may be applied, and an output terminal, and a load coupled between said output terminal and a point of reference voltage comprising: a second amplifier having substantially the same electrical operating characteristics for the input signal, as said output amplifier, said second amplifier having an output terminal, an input terminal means connected to the input terminal means of said output amplifier and receptive of the same signal, and in other respects also connected in parallel with said output amplifier; current sensing means connected between the output terminals of said two amplifiers, and means responsive to said current sensing means for effectively placing a low impedance path between said input terminal means of said output amplifier and a point of reference voltage.
Claim 12
Dependent Claim
152 words
A circuit for protecting the output stage of an amplifier from an overload condition, the output stage comprising an output amplifier having an input terminal means to which an input signal may be applied, and an output terminal, and a load coupled between said output terminal and a point of reference voltage comprising: a second amplifier having substantially the same electrical operating characteristics for the input signal, as said output amplifier, said second amplifier having an output terminal, an input terminal means connected to the input terminal means of said output amplifier and receptive of the same signal, and in other respects also connected in parallel with said output amplifier; current sensing means connected between the output terminals of said two amplifiers, and means responsive to said current sensing means for effectively placing a low impedance path between said input terminal means of said output amplifier and a point of reference voltage.
Claim 13
Dependent Claim
13 words
The circuit of claim 9, wherein said current sensing means comprises a resistor.
Claim 14
Dependent Claim
30 words
The circuit of claim 10, wherein said means responsive to said current sensing means comprises means connected across said current sensing means for sensing the voltage produced across said resistor.
Claim 15
Dependent Claim
58 words
A circuit as set forth in claim 9, wherein said output stage and second amplifier comprises complementary-symmetry amplifiers, each amplifier comprising two transistors of different conductivity types, each transistor having a conduction path, the two conduction paths connected in series between operating voltage terminals, and each amplifier output terminal being at the connection of the two conduction paths.
Claim 16
Dependent Claim
28 words
A circuit as set forth in claim 9, wherein said load is capacitively coupled between said output terminal of said output stage and said point of reference potential.
Claim 17
Dependent Claim
122 words
A circuit for protecting the output stage of an amplifier from an overload condition comprising, in combination: a protective amplifier stage having substantially the same operating characteristics for an identical input signal as said output stage forming a bridge with said output stage and connected to receive the same input signals as said output stage, said bridge having two nodes at opposite points of the bridge which, in normal operation, in view of the balanced condition of the bridge, operate at the same voltage levels; current sensing means connected to said nodes for sensing an imbalance in the bridge, and means responsive to said current sensing means for effectively removing said input signals from said output stage when said bridge becomes imbalanced.
Claim 18
Dependent Claim
122 words
A circuit for protecting the output stage of an amplifier from an overload condition comprising, in combination: a protective amplifier stage having substantially the same operating characteristics for an identical input signal as said output stage forming a bridge with said output stage and connected to receive the same input signals as said output stage, said bridge having two nodes at opposite points of the bridge which, in normal operation, in view of the balanced condition of the bridge, operate at the same voltage levels; current sensing means connected to said nodes for sensing an imbalance in the bridge, and means responsive to said current sensing means for effectively removing said input signals from said output stage when said bridge becomes imbalanced.
Claim 19
Dependent Claim
25 words
A circuit as set forth in claim 14, further including a load capacitively coupled between one of said nodes and a point of reference potential.
Claim 20
Dependent Claim
70 words
A circuit as set forth in claim 15, wherein said output stage and said protective stage comprise CMOS amplifiers, each amplifier comprising a P type MOS transistor, the conduction path of which is connected in series with the conduction path of an N type MOS transistor, between two operating voltage terminals, the nodes of the bridge being located at the connections between conduction paths of the P and N transistors.
Claim 21
Dependent Claim
26 words
A circuit as set forth in claim 16, further including a load capacitively coupled between one of said nodes and one of said operating voltage terminals.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-12-01 | 1979-06-02 | 1979-12-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-12-01 | 1983-06-02 | 1983-12-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-12-01 | 1987-06-02 | 1987-12-02 | $7700.00 | Window Closed / Lapsed |