US3706937A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Gain controlled amplifier for integrated circuit applications
Assignee: National Semiconductor Corp
•
Filing: 1970-12-03
•
Granted: 1972-12-19
•
Expires: 1990-12-03
Abstract
Abstract A gain controlled amplifier circuit in which the amplifying element, such as a transistor, has its emitter-collector circuit connected to a gain control circuit which supplies a constant operating current and changes its AC impedance in accordance with an AGC signal. The gain control circuit includes a first branch having an impedance which varies with the externally applied AGC signal and a second branch having an impedance which varies with the current flow therethrough and which is connected to ground through an AC bypass. These two branches are connected in parallel to a constant current source so that the impedance of the first branch controls the current flow in the second branch and thereby its impedance.
Inventors
- 👤 John E Hanna
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 08:26
CPC Classifications
H; H03; H03G; H03G3/00; H03G3/20; H03G3/30; H03G3/3052; H03G1/00; H03G1/0005; H03G1/0017; H03G1/0023; H03G3/3005
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
136 words
A gain controlled amplifier comprising: an amplifier transistor; a current source for supplying operating current to said amplifier transistor; and gain control circuit means coupling said amplifier transistor to said current source to couple said operating current into said amplifier transistor, said gain control circuit means including a first transistor having an emitter-collector circuit coupled between said amplifier transistor and said current source and a base to which a gain control signal is applied to vary the impedance of said first transistor, and a diode coupled in parallel with the emitter-collector circuit of said first transistor between said amplifier transistor and said current source, said operating current being directed through said diode as the impedance of said first transistor is changed to thereby change the impedance of said diode and the gain of said amplifier transistor.
Claim 2
Dependent Claim
136 words
A gain controlled amplifier comprising: an amplifier transistor; a current source for supplying operating current to said amplifier transistor; and gain control circuit means coupling said amplifier transistor to said current source to couple said operating current into said amplifier transistor, said gain control circuit means including a first transistor having an emitter-collector circuit coupled between said amplifier transistor and said current source and a base to which a gain control signal is applied to vary the impedance of said first transistor, and a diode coupled in parallel with the emitter-collector circuit of said first transistor between said amplifier transistor and said current source, said operating current being directed through said diode as the impedance of said first transistor is changed to thereby change the impedance of said diode and the gain of said amplifier transistor.
Claim 3
Dependent Claim
25 words
A gain controlled amplifier as recited in claim 1 which further includes means for providing a low impedance AC current path by-passing said current source.
Claim 4
Dependent Claim
44 words
A gain controlled amplifier as recited in claim 1 wherein said amplifier transistor includes a first electrode for receiving an input signal, a second electrode coupled to said gain control circuit means and a third electrode from which an output signal can be obtained.
Claim 5
Dependent Claim
62 words
A gain controlled amplifier as recited in claim 1 wherein said amplifier transistor includes a base, an emitter and a collector, and said diode comprises a transistor having a collector, emitter, and base, the emitter of said amplifier transistor being coupled to the base and collector of said diode transistor, and the diode transistor emitter being coupled to said current source means.
Claim 6
Dependent Claim
41 words
A gain controlled amplifier as recited in claim 4 wherein the collector of said first transistor is coupled to the emitter of said amplifier transistor and the emitter of said first transistor is coupled to the emitter of said diode transistor.
Claim 7
Dependent Claim
170 words
A gain controlled differential amplifier comprising a first amplifier transistor and a second amplifier transistor in parallel with said first amplifier transistor, a current source for supplying operating current to said two parallel coupled amplifier transistors, and a pair of gain control circuit means, one for each of said amplifier transistors and coupling said associated amplifier transistor to said current source to couple operating current into the associated amplifier transistor, each of said gain control circuit means including a first transistor having an emitter-collector circuit coupled between said associated amplifier transistor and said current source and a base to which a gain control signal is applied to vary the impedance of said first transistor, and a diode coupled in parallel with the emitter-collector circuit of said first transistor between said associated amplifier transistor and said current source, said operating current being directed through said diode as the impedance of said associated first transistor is changed to thereby change the impedance of said diode and the gain of said amplifier transistors.
Claim 8
Dependent Claim
170 words
A gain controlled differential amplifier comprising a first amplifier transistor and a second amplifier transistor in parallel with said first amplifier transistor, a current source for supplying operating current to said two parallel coupled amplifier transistors, and a pair of gain control circuit means, one for each of said amplifier transistors and coupling said associated amplifier transistor to said current source to couple operating current into the associated amplifier transistor, each of said gain control circuit means including a first transistor having an emitter-collector circuit coupled between said associated amplifier transistor and said current source and a base to which a gain control signal is applied to vary the impedance of said first transistor, and a diode coupled in parallel with the emitter-collector circuit of said first transistor between said associated amplifier transistor and said current source, said operating current being directed through said diode as the impedance of said associated first transistor is changed to thereby change the impedance of said diode and the gain of said amplifier transistors.
Claim 9
Dependent Claim
39 words
A gain controlled differential amplifier as claimed in claim 6 including an additional transistor with its emitter-collector circuit coupled between the two diodes and the current source and having a base to which said gain control signal is coupled.
Claim 10
Dependent Claim
67 words
A gain controlled differential amplifier as recited in claim 6 wherein said amplifier transistors each include a base, an emitter and a collector, and said diodes each comprise a transistor having a collector, emitter, and base, the emitters of said two amplifier transistors being coupled to the base and collector of the associated diode transistor, and the diode transistor emitters being coupled to said current source means.
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) | 1975-12-19 | 1976-06-19 | 1976-12-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-12-19 | 1980-06-19 | 1980-12-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-12-19 | 1984-06-19 | 1984-12-19 | $7700.00 | Window Closed / Lapsed |