US3855540A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Push-pull transistor amplifier with driver circuits providing over-current protection
Assignee: RCA Licensing Corp
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Filing: 1973-12-13
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Granted: 1974-12-17
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Expires: 1993-12-13
Abstract
Abstract An amplifier having output transistors with collector-to-emitter paths connected in series for application of operating potential and connected in push-pull for signal, is afforded over-current protection by limiting the sum of the base currents available to the output transistors. This sum current is applied to a node to which the base electrode of one of the output transistors is connected, and the distribution of this current between the base electrodes of two output transistors is controlled by a signalresponsive variable-conduction device connected between the base electrodes of the two output transistors. Class AB operation of the output transistor may be obtained by connecting separate nonlinear resistance networks in parallel with each of their base emitter junctions.
Inventors
- 👤 A Leidich
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 16:26
CPC Classifications
H; H03; H03F; H03F1/00; H03F1/52; H03F3/00; H03F3/30; H03F3/3083; H03F3/3086; H03F3/3096; H03F3/45; H03F3/45071; H03F3/45479
Claims Analysis
Total Claims: 25
Claim 1
Independent Claim
201 words
An amplifier comprising: an interconnection point adapted for coupling to a load circuit; first and second transistors of the same conductivity type, each having a principal conduction path between first and second electrodes and having a control electrode, the conductance of said conduction path of each of said first and said second transistors respectively increasing and decreasing as the potential appearing between said first and said control electrodes is respectively increased and decreased, said first transistor first electrode and said second transistor second electrode being connected to said interconnection point adapted for coupling to a load circuit; means for applying an operating potential between said first transistor second electrode and said second transistor first electrode; a source of substantially constant quiescent biasing current; a variable conduction device with a control electrode and a variable conduction path between first and second electrodes thereof, the conductance of said conduction path varying in response to a control signal applied to said control electrode, said first electrode of said device being connected to said source of a substantially constant quiescent biasing current and having said firsT transistor control electrode coupled thereto, said second electrode of said device having said second transistor control electrode coupled thereto.
Claim 2
Dependent Claim
201 words
An amplifier comprising: an interconnection point adapted for coupling to a load circuit; first and second transistors of the same conductivity type, each having a principal conduction path between first and second electrodes and having a control electrode, the conductance of said conduction path of each of said first and said second transistors respectively increasing and decreasing as the potential appearing between said first and said control electrodes is respectively increased and decreased, said first transistor first electrode and said second transistor second electrode being connected to said interconnection point adapted for coupling to a load circuit; means for applying an operating potential between said first transistor second electrode and said second transistor first electrode; a source of substantially constant quiescent biasing current; a variable conduction device with a control electrode and a variable conduction path between first and second electrodes thereof, the conductance of said conduction path varying in response to a control signal applied to said control electrode, said first electrode of said device being connected to said source of a substantially constant quiescent biasing current and having said firsT transistor control electrode coupled thereto, said second electrode of said device having said second transistor control electrode coupled thereto.
Claim 3
Dependent Claim
201 words
An amplifier comprising: an interconnection point adapted for coupling to a load circuit; first and second transistors of the same conductivity type, each having a principal conduction path between first and second electrodes and having a control electrode, the conductance of said conduction path of each of said first and said second transistors respectively increasing and decreasing as the potential appearing between said first and said control electrodes is respectively increased and decreased, said first transistor first electrode and said second transistor second electrode being connected to said interconnection point adapted for coupling to a load circuit; means for applying an operating potential between said first transistor second electrode and said second transistor first electrode; a source of substantially constant quiescent biasing current; a variable conduction device with a control electrode and a variable conduction path between first and second electrodes thereof, the conductance of said conduction path varying in response to a control signal applied to said control electrode, said first electrode of said device being connected to said source of a substantially constant quiescent biasing current and having said firsT transistor control electrode coupled thereto, said second electrode of said device having said second transistor control electrode coupled thereto.
Claim 4
Dependent Claim
201 words
An amplifier comprising: an interconnection point adapted for coupling to a load circuit; first and second transistors of the same conductivity type, each having a principal conduction path between first and second electrodes and having a control electrode, the conductance of said conduction path of each of said first and said second transistors respectively increasing and decreasing as the potential appearing between said first and said control electrodes is respectively increased and decreased, said first transistor first electrode and said second transistor second electrode being connected to said interconnection point adapted for coupling to a load circuit; means for applying an operating potential between said first transistor second electrode and said second transistor first electrode; a source of substantially constant quiescent biasing current; a variable conduction device with a control electrode and a variable conduction path between first and second electrodes thereof, the conductance of said conduction path varying in response to a control signal applied to said control electrode, said first electrode of said device being connected to said source of a substantially constant quiescent biasing current and having said firsT transistor control electrode coupled thereto, said second electrode of said device having said second transistor control electrode coupled thereto.
Claim 5
Dependent Claim
69 words
An amplifier as set forth in claim 1 wherein said source of biasing current includes means for constraining the magnitude of said biasing current such that current flow through either of said first and said second transistors even when substantially all of said operating potentials appears across its principal conduction path will not cause sufficient internal heating of the transistor to lead to its being seriously and permanently damaged.
Claim 6
Dependent Claim
150 words
An amplifier as set forth in claim 1 wherein said first and said second transistors are bipolar transistors, each having base and emitter and collector electrodes corresponding respectively to said control and said first and said second electrodes, each having a base-emitter junction between its said base and emitter electrodes, said amplifier further including: first and second semiconductor junction diodes; first and second linear resistive elements; means connecting said first semiconductor junction diode and said first linear resistive element in a first serial combination, between said first transistor base and emitter electrodes with said junction poled in the same direction as said first transistor base-emitter junction; and means connecting said second semiconductor junction diode and said second linear resistive element in a second serial combination, connected between said second transistor base and emitter electrodes and with said second junction poled in the same direction as said second transistor base-emitter junction.
Claim 7
Dependent Claim
33 words
An amplifier as set forth in claim 3 wherein said first and said second semiconductor junction diodes each consists of: a further transistor having an emitter electrode and interconnected base and collector electrodes.
Claim 8
Dependent Claim
67 words
An amplifier as set forth in claim 3 wherein: a third transistor corresponds to said variable conduction device, said third transistor having collector and emitter electrodes corresponding respectively to its said first and said second electrodes, having a base electrode and having a common emitter forward current gain hfe; a source of input signal; and means for coupling said input signal to said third transistor base electrode.
Claim 9
Dependent Claim
98 words
An amplifier as set forth in claim 5 having: means for providing selective collector-to-base feedback to said third transistor including a phase-compensation capacitor for introducing a dominant single-pole high-frequency roll-off into the overall gain characteristic of the complete amplifier and an input amplifier with transconductance which varies substantially inversely with the hfe of said third transistor said input amplifier being included within said means for coupling said input signal to said third transistor base electrode thereby causing the phase margin for the complete amplifier to be less dependent upon the value of the hfe of said third transistor.
Claim 10
Dependent Claim
187 words
An amplifier as set forth in claim 3 having: a third transistor having base and emitter and collector electrodes and having a common emitter forward current gain hfe; means connecting said third transistor in an intermediate amplifier with an input circuit and an output circuit and with a forward current gain therebetween substantially proportional to the hfe of said third transistor, said intermediate amplifier output circuit being connected to the control electrode of said variable conduction device to supply it said control signal; means for providing collector-to-base selective feedback to said third transistor including a phase-compensation capacitor for introducing a dominant single time constant high-frequency roll-off into the overall gain characteristics of the complete amplifier; a source of input signal; and an input amplifier with transconductance which varies substantially inversely with the hfe of said third transistor, said input amplifier having an input circuit connected to said source of input signal and an output circuit connected to the input circuit of said intermediate amplifier, thereby causing the phase margin for the complete amplifier to be less dependent upon the value of the hfe of said third transistor.
Claim 11
Dependent Claim
91 words
An amplifier as set forth in claim 3 wherein said source of substantially constant quiescent biasing current comprises: a third transistor of a conductivity type complementary to said first and said second transistors, having an output electrode connected to said first electrode of said variable conduction device and having an input electrode and a common electrode; and means for applying forward bias potential between the input and common electrodes of said third transistor for causing said third transistor to provide said substantially constant quiescent biasing current from its said output electrode.
Claim 12
Dependent Claim
77 words
An amplifier as set forth in claim 8 wherein: said third transistor has a transconductance which varies as a function of the potential between its common and output electrodess and wherein said first linear resistive element has larger resistance than said second linear resistive element to compensate for this variation of the transconductance of said third transistor, such that a more symmetrical gain characteristic is obtained for the push-pull operation of said first and said second transistor.
Claim 13
Dependent Claim
72 words
An amplifier as set forth in claim 3 wherein said source of substantially constant quiescent biasing current includes: means for constraining the magnitude of said biasing current such that current flow through either of said first and said second transistors even when substantially all of said operating potential appears across its principal conduction path will not cause sufficient internal heating of the transistor to lead to its being seriously and permanently damaged.
Claim 14
Dependent Claim
133 words
An amplifier as set forth in claim 1 wherein: said first and said second transistors are bipolar transistors, each having base and emitter and collector electrodes corresponding respectively to said control and said first and said second electrodes, and each having a base-emitter junction; a third bipolar transistor of the same conductivity type as that of said first and said second transistors corresponds to said variable conduction device, and its collector and emitter and base electrodes correspond respectively to the first and second and control electrodes of said variable conduction device; and a unilaterally conductive semiconductor junction device is connected between the collector electrode of said third transistor and the base electrode of said first transistor, said junction device being poled for simultaneous easy conduction with the base-emitter junction of said first transistor.
Claim 15
Dependent Claim
132 words
An amplifier as set forth in claim 1 wherein: said first and said second transistors are bipolar transistors, each having base and emitter and collector electrodes corresponding respectively to said control and said first and said second electrodes, and each having a base-emitter junction; a third bipolar transistor of a conductivity type opposite from that of said first and said second transistors corresponding to said variable conduction device, and its emitter and collector and base electrodes corresponding respectively to the first and second and control electrodes of said variable conduction device; a unilaterally variable semiconductor conduction device is connected between the emitter electrode of said third transistor and the base electrode of said first transistor, said junction device being poled for simultaneous easy conduction with the base-emitter junction of said first transistor.
Claim 16
Dependent Claim
39 words
An amplifier as claimed in claim 13 wherein: said first and said second bipolar transistors are of the same conductivity type; and the emitter electrode of said first transistor is connected to the collector electrode of said second transistor.
Claim 17
Dependent Claim
134 words
An amplifier as claimed in claim 14 wherein said means responsive to input signal thereto applied to supply first and second currents, respectively, to said first and said second parallel combinations comprises: a supply of substantially constant current; means for connecting said supply of substantially constant current to the end of said first parallel combination at the base electrode of said first transistor; and a variable conduction device with a control electrode and a variable conduction path between first and second electrodes thereof, the conductance of said conduction path varying in response to said input signal applied to its said control electrode, said first and said second electrodes thereof being connected respectively to said supply of substantially constant current and to the end of said second parallel combination at said second transistor base electrode.
Claim 18
Dependent Claim
34 words
An amplifier as claimed in claim 15 wherein the amplitude of the substantially constant current supplied from said source thereof is constrained thereby to provide over-current protection for said first and said second transistors.
Claim 19
Dependent Claim
47 words
An amplifier as claimed in claim 15 wherein said variable conduction device is a transistor of the same conductivity type as said first and said second transistors; its base, collector and emitter electrodes corresponding to the aforeclaimed control, first and second electrodes of said variable conduction device.
Claim 20
Dependent Claim
42 words
An amplifier as claimed in claim 17 wherein said means for connecting said supply of substantially constant current to the end of said first parallel combination is a semiconductor junction device poled for simultaneous easy current conduction with said first parallel combination.
Claim 21
Dependent Claim
48 words
An amplifier as claimed in claim 15 wherein said variable conduction device is a transistor of opposite conductivity type from that of said first and said second transistors; its base, emitter and collector electrodes corresponding to the aforeclaimed control, first and second electrodes of said variable conduction device.
Claim 22
Dependent Claim
42 words
An amplifier as claimed in claim 19 wherein said means for connecting said supply of substantially constant current to the end of said first parallel combination is a semiconductor junction device poled for simultaneous easy current conduction with said first parallel combination.
Claim 23
Dependent Claim
55 words
An amplifier as set forth in claim 21 wherein said means including said signal responsive variable conductance means comprises a connection from said current source to one of said control electrodes, and said variable conductance means being connected between said control electrodes for diverting a portion of said constant current to the other control electrode.
Claim 24
Dependent Claim
45 words
An amplifier as set forth in claim 22 wherein said semiconductor devices comprise first and second bipolar transistors, each having base and emitter electrodes with a base-emitter junction therebetween and each having a collector electrode, said conduction paths comprising the emitter-to-collector paths of said transistors.
Claim 25
Dependent Claim
136 words
An amplifier as set forth in claim 23 further including first and second non-linear resistive means, said first non-linear resistive means being connected between the base and emitter electrodes of said first transistor to parallel its base-emitter junction and said second non-linear resistance means being connected between the base and emitter electrodes of the second transistor to parallel its base-emitter junction, said first and said second non-linear resistance means each being conductive under quiescent conditions to divert base current from the base-emitter junction with which it is parallelled, the respective conductances of said first and said second non-linear resistance means increasing less rapidly with increasing potentials respectively thereacross than do the conductances of the base-emitter junctions of said first and said second transistors, respectively, for conditioning said first and said second transistors for Class AB amplification.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-12-16 | 1978-06-17 | 1978-12-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-12-16 | 1982-06-17 | 1982-12-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-12-16 | 1986-06-17 | 1986-12-17 | $7700.00 | Window Closed / Lapsed |