Patent US3828265A successfully refreshed from Google Patents.
US3828265A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Low frequency power amplifier
Assignee: STMicroelectronics SRL
•
Filing: 1972-02-04
•
Granted: 1974-08-06
•
Expires: 1992-02-04
Abstract
Abstract A power amplifier for low-frequency oscillations, realizable by integrated-circuit technique, comprises a number of cascaded transistors forming a high-impedance input stage, an intermediate or driver stage and a balanced power stage feeding a central output terminal 12. A control transistor T2 constituting part of a composite input transistor T1, T2 has its collector grounded through a current-limiting transistor T4 paired with an identical transistor T5 producing an image current which duplicates the collector current of the control transistor T2 and passes through a voltage divider composed of a pair of resistors R6, R7 each of the same magnitude as a feedback resistor R8 inserted between the output terminal 12 and the emitter of transistor T2. A controlled transistor T3 at the entrance of the intermediate stage, of the same conductivity type (PNP) as the control transistor T2 and susbtantially identical therewith, has its base connected to the collector of transistor T2 and has its emitter energized through an ancillary transistor T9 of opposite conductivity type whose base is tied to the junction of resistors R6 and R7. The emitters of transistors T9 and T3 are interconnected via a further resistor R9 of the same magnitude; with the bases of twin transistors T4 and T5 jointly connected to a d-c supply terminal 1 through a biasing transistor T10 and a low resistance (e.g. diodes D'', D'''') equaling the overall emitter/base resistance of composite transistor T1, T2, this arrangement stabilizes the means voltage of output terminal 12 at substantially half the voltage of the ungrounded supply terminal 4.
Inventors
- 👤 A Romano
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 21:11
CPC Classifications
G; G05; G05F; G05F3/00; G05F3/02; G05F3/08; G05F3/10; G05F3/16; G05F3/20; G05F3/26; G05F3/265; H; H03; H03F; H03F3/00; H03F3/30; H03F3/3083; H03F3/3086; H03F3/3091
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
330 words
A power amplifier comprising an input stage including a control transistor, an intermediate stage including a controlled transistor of the same conductivity type as said control transistor, and a power stage including a pair of final transistors serially connected in balanced relationship between a central output terminal and respective supply terminals of a source of direct current, each of said transistors being provided with an emitter, a base and a collector, said output terminal being connected to the emitter of one and to the collector of the other of said final transistors, the collector of said controlled transistor being connected to one of said supply terminals; coupling means in said power stage for connecting the bases of said final transistors in push-pull to said intermediate stage; a resistive direct-current feedback connection extending from said output terminal to the emitter of said control transistor, the base of said control transistor being connected to receive an a-c signal to be amplified, the collector of said control transistor being connected to the base of said controlled transistor; a current-limiting transistor connected in series with said control transistor between the collector of the latter and said one of said supply terminals for maintaining an emitter current in said control transistor holding the mean voltage of said output terminal substantially at a median value between the potentials of said supply terminals, the emitter of said control transistor being conductively joined to the other of said supply terminals by way of said feedback connection; an ancillary transistor connected in series with said controlled transistor between the emitter thereof and said other of said supply terminals; a matching transistor duplicating said current-limiting transistor and generating an image current equal to the collector current of said control transistor, said currentlimiting transistor and said matching transistor having interconnected bases and having their emitters connected to said one of said supply terminals; and biasing means for said ancillary transistor connecting the base thereof to the collector of said matching transistor.
Claim 2
Dependent Claim
330 words
A power amplifier comprising an input stage including a control transistor, an intermediate stage including a controlled transistor of the same conductivity type as said control transistor, and a power stage including a pair of final transistors serially connected in balanced relationship between a central output terminal and respective supply terminals of a source of direct current, each of said transistors being provided with an emitter, a base and a collector, said output terminal being connected to the emitter of one and to the collector of the other of said final transistors, the collector of said controlled transistor being connected to one of said supply terminals; coupling means in said power stage for connecting the bases of said final transistors in push-pull to said intermediate stage; a resistive direct-current feedback connection extending from said output terminal to the emitter of said control transistor, the base of said control transistor being connected to receive an a-c signal to be amplified, the collector of said control transistor being connected to the base of said controlled transistor; a current-limiting transistor connected in series with said control transistor between the collector of the latter and said one of said supply terminals for maintaining an emitter current in said control transistor holding the mean voltage of said output terminal substantially at a median value between the potentials of said supply terminals, the emitter of said control transistor being conductively joined to the other of said supply terminals by way of said feedback connection; an ancillary transistor connected in series with said controlled transistor between the emitter thereof and said other of said supply terminals; a matching transistor duplicating said current-limiting transistor and generating an image current equal to the collector current of said control transistor, said currentlimiting transistor and said matching transistor having interconnected bases and having their emitters connected to said one of said supply terminals; and biasing means for said ancillary transistor connecting the base thereof to the collector of said matching transistor.
Claim 3
Dependent Claim
41 words
A power amplifier as defined in claim 1 further comprising a voltage divider extending between the collector of said matching transistor and said other supply terminal, the base of said ancillary transistor being tied to a junction of said voltage divider.
Claim 4
Dependent Claim
33 words
A power amplifier as defined in claim 2 wherein said voltage divider comprises two identical resistors forming said junction, the resistance of each of said resistors equaling that of said resistive feedback connection.
Claim 5
Dependent Claim
47 words
A power amplifier as defined in claim 3 wherein said ancillary transistor is of a conductivity type opposite that of said controlled transistor and has its emitter connected to the emitter of said controlled transistor through a further resistor of the same magnitude as said identical resistors.
Claim 6
Dependent Claim
47 words
A power amplifier as defined in claim 4 wherein said current-limiting and matching transistors are provided with a common biasing transistor having an emitter connected to their bases, a collector connected to said other supply terminal and a base tied to the collector of said matching transistor.
Claim 7
Dependent Claim
42 words
A power amplifier as defined in claim 5, further comprising resistance means between said interconnected bases and the emitter of said biasing transistor, said resistance means having a magnitude which is small compared with that of the resistance of said feedback connection.
Claim 8
Dependent Claim
38 words
A power amplifier as defined in claim 6 wherein said control transistor is part of a composite transistor connected in a Darlington configuration with an overall forward emitter/base resistance substantially equal to the magnitude of said resistance means.
Claim 9
Dependent Claim
47 words
A power amplifier as defined in claim 5, further comprising a voltage-dropping resistor inserted between said other supply terminal and the collector of said biasing transistor, the bases of said final transistors being provided with biasing circuits extending through said voltage-dropping resistor to said other supply terminal.
Claim 10
Dependent Claim
24 words
A power amplifier as defined in claim 8, further comprising a capacitive shunt between the collector of said biasing transistor and said output terminal.
Claim 11
Dependent Claim
36 words
A power amplifier as defined in claim 8, further comprising diode means inserted between said voltage divider and said other of said supply terminals with a forward resistance of substantially the magnitude of said resistance means.
Claim 12
Dependent Claim
31 words
A power amplifier as defined in claim 1 wherein said intermediate and power stages are connected to provide negative feedback through said resistive connection to the emitter of said control transistor.
Claim 13
Dependent Claim
73 words
A power amplifier as defined in claim 1 wherein said coupling means comprises a first pilot transistor of one conductivity type in cascade with said one of said final transistors, and a second pilot transistor of the opposite conductivity type in cascade with said other of said final transistors, said pilot transistors having bases connected to an output lead of said intermediate stage, said final transistors being both of said one conductivity type.
Claim 14
Dependent Claim
21 words
A power amplifier as defined in claim 12, furTher comprising a biasing diode connected between the bases of said pilot transistors.
Claim 15
Dependent Claim
47 words
A power amplifier as defined in claim 12 wherein said power stage further includes an additional transistor in series with said second pilot transistor having a base/emitter circuit connected between said output terminal and the emitter of said second pilot transistor for preventing saturation of the latter.
Claim 16
Dependent Claim
26 words
A power amplifier as defined in claim 14 wherein said first pilot transistor and said one of said final transistors are connected in an emitter-follower circuit.
Claim 17
Dependent Claim
36 words
A power amplifier as defined in claim 14 wherein said additional transistor is of the same conductivity type as said first pilot transistor and has an emitter connected to the emitter of said second pilot transistor.
Claim 18
Dependent Claim
39 words
A power amplifier as defined in claim 12 wherein said output lead is connected to a collector of a transistor in said intermediate stage, further comprising another current-limiting transistor connected between the last-mentioned collector and said other supply terminal.
Claim 19
Dependent Claim
23 words
A power amplifier as defined in claim 1 wherein said intermediate stage includes a composite transistor of Darlington configuration following said controlled transistor.
Claim 20
Dependent Claim
21 words
A power amplifier as defined in claim 1 wherein said input, intermediate and power stages form part of an integrated module.
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) | 1977-08-05 | 1978-02-04 | 1978-08-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-08-05 | 1982-02-04 | 1982-08-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-08-05 | 1986-02-04 | 1986-08-06 | $7700.00 | Window Closed / Lapsed |