Patent US3825850A successfully refreshed from Google Patents.
US3825850A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Direct-coupled audio amplifier having unbypassed emitter resistor stages
Assignee: Electrospace Corp
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Filing: 1972-11-28
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Granted: 1974-07-23
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Expires: 1992-11-28
Abstract
Abstract A single-ended high-voltage gain, direct-coupled audio amplifier has unbypassed emitter resistor stages. Two common-emitter NPN amplifying stages are followed by an inverted PNP emitterfollower output stage. The second amplifying stage has an unbypassed, low valued emitter resistor through which the collector current of the output stage passes to develop sufficient bias on the emitter of the second stage. Decoupled DC feedback is provided between the unbypassed resistor and the input base of the first amplifying stage.
Inventors
- 👤 K Meri
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 01:44
CPC Classifications
H; H03; H03F; H03F1/00; H03F1/34; H03F1/347; H03F1/30; H03F1/302
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
102 words
A direct-coupled amplifier having unbypassed emitter resistor stages comprising an even number of amplifying stages each having a transistor of the same polarity; an output stage coupled to said series of stages and having a transistor of opposite polarity, the last stage of the series being provided with a resistor of relatively low resistance unbypassed by a low impedance network, said output stage transistor having the collector thereof connected to said unbypassed resistor, whereby the collector current of said output stage is arranged to pass through said unbypassed resistor to establish sufficient bias potential for said last amplifying stage of said series.
Claim 2
Dependent Claim
102 words
A direct-coupled amplifier having unbypassed emitter resistor stages comprising an even number of amplifying stages each having a transistor of the same polarity; an output stage coupled to said series of stages and having a transistor of opposite polarity, the last stage of the series being provided with a resistor of relatively low resistance unbypassed by a low impedance network, said output stage transistor having the collector thereof connected to said unbypassed resistor, whereby the collector current of said output stage is arranged to pass through said unbypassed resistor to establish sufficient bias potential for said last amplifying stage of said series.
Claim 3
Dependent Claim
33 words
An audio amplifier as defined in claim 1, further comprising temperature stabilizing means including DC feedback means provided between the resistor and the first stage of the series for temperature stabilizing the amplifier.
Claim 4
Dependent Claim
21 words
An audio amplifier as defined in claim 1, wherein two amplifying stages are provided in addition to the one output stage.
Claim 5
Dependent Claim
31 words
An audio amplifier as defined in claim 1, wherein the transistors of said amplifying stages are of NPN polarity, and wherein the transistor of said output stage is of PNP polarity.
Claim 6
Dependent Claim
62 words
An audio amplifier as defined in claim 1, wherein said output stage comprises an emitter-follower stage, the collector of the transistor of said latter stage being connected to said unbypassed resistor, whereby the collector current of said output stage is arranged to pass through said unbypassed resistor to thereby establish an emitter bias potential for said last amplifying stage of said series.
Claim 7
Dependent Claim
59 words
An audio amplifier as defined in claim 2, wherein the audio amplifier has an input terminal and a ground potential reference point, and wherein said DC feedback means comprises resistor means connected between said unbypassed resistor and the base of said first amplifying stage, and further comprising AC decoupling means connected between said resistor means and said reference point.
Claim 8
Dependent Claim
33 words
An audio amplifier as defined in claim 6, wherein said AC decoupling means comprises a capacitor having a capacitance sufficiently large so as to substantially prevent AC feedback through said DC feedback means.
Claim 9
Dependent Claim
40 words
An audio amplifier as defined in claim 1, further comprising AC feedback means connected between the output electrode of the output stage transistor and an electrode of the transistor of the first amplifying stage of said series of amplifying stages.
Claim 10
Dependent Claim
43 words
An audio amplifier as defined in claim 1, wherein the values of conventional emitter resistors in audio amplifying stages are typically within a predetermined range, and wherein said unbypassed resistor has a value approximately one-two hundreth of the values of said predetermined range.
Claim 11
Dependent Claim
22 words
An audio amplifier as defined in claim 1, wherein said unbypassed resistor has a value approximately in the range of 100-200 ohms.
Claim 12
Dependent Claim
27 words
An audio amplifier as defined in claim 1, wherein all said amplifying stages are common emitter stages while said output stage is an inverted emitter follower stage.
Claim 13
Dependent Claim
32 words
An audio amplifier as defined in claim 1, wherein said output stage comprises an inverted emitter-follower stage, and further comprises transformer output coupling means connected to the emitter of said inverted stage.
Claim 14
Dependent Claim
18 words
An audio amplifier as defined in claim 1, wherein the audio amplifier is constructed as an integrated circuit.
Claim 15
Dependent Claim
14 words
An audio amplifier as defined in claim 1, wherein said output stage is single-ended.
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) | 1977-07-22 | 1978-01-21 | 1978-07-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-07-22 | 1982-01-21 | 1982-07-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-07-22 | 1986-01-21 | 1986-07-23 | $7700.00 | Window Closed / Lapsed |