US3900801A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Gain controlled differential amplifier
Assignee: Sony Corp
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Filing: 1974-07-29
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Granted: 1975-08-19
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Expires: 1994-07-29
Abstract
Abstract A gain controlled differential amplifier comprised of amplifying transistors connected in differential amplifier configuration whereby respective emitter electrodes are connected in a common current path. The common current path includes a first control transistor whose conductivity is regulated in accordance with an AGC voltage applied thereto so as to control the gain of the differential amplifier. A second control transistor is connected to the base electrode of one of the amplifying transistors so as to provide a variable conducting path for an input signal applied to such base electrode. The conductivity of the second control transistor is determined in accordance with the AGC voltage applied thereto, whereby the conductivity of both control transistors is regulated by the AGC voltage when the differential amplifier input signal exceeds a predetermined level so as to provide a large range of gain variation for the differential amplifier.
Inventors
- 👤 Hiroshi Furuno
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 14:10
CPC Classifications
H; H03; H03F; H03F3/00; H03F3/45; H03F3/45071; H03G; H03G1/00; H03G1/0005; H03G1/0017; H03G1/0023; H03G3/00; H03G3/20; H03G3/30; H03G3/3052
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
175 words
A differential amplifier, comprising: first and second amplifying transistor means connected in differential amplifier configuration and having respective emitter electrodes connected in common, one of said first and second amplifying transistor means being provided with a signal input terminal and the other of said first and second amplifying transistor means being provided with a signal output terminal; a control input terminal for receiving a control signal; first control means connected to said Common connected emitter electrodes and coupled to said control input terminal for receiving said control signal, said first control means being responsive to said control signal applied thereto for varying the currents flowing through said first and second amplifying transistor means; and second control means connected to the base electrode of said one amplifying transistor means provided with said input terminal and coupled to said control input terminal for receiving said control signal, said second control means being responsive to said control signal applied thereto to vary the voltage at said base electrode and to thereby vary the gain of said differential amplifier.
Claim 2
Dependent Claim
175 words
A differential amplifier, comprising: first and second amplifying transistor means connected in differential amplifier configuration and having respective emitter electrodes connected in common, one of said first and second amplifying transistor means being provided with a signal input terminal and the other of said first and second amplifying transistor means being provided with a signal output terminal; a control input terminal for receiving a control signal; first control means connected to said Common connected emitter electrodes and coupled to said control input terminal for receiving said control signal, said first control means being responsive to said control signal applied thereto for varying the currents flowing through said first and second amplifying transistor means; and second control means connected to the base electrode of said one amplifying transistor means provided with said input terminal and coupled to said control input terminal for receiving said control signal, said second control means being responsive to said control signal applied thereto to vary the voltage at said base electrode and to thereby vary the gain of said differential amplifier.
Claim 3
Dependent Claim
67 words
A differential amplifier in accordance with claim 1 wherein said second control means includes means to which said control signal is applied to cause said second control means to operate at a control signal level that differs from the operating level of said first control means such that one of said first and second control means operates before the other in response to the same control signal.
Claim 4
Dependent Claim
42 words
A differential amplifier in accordance with claim 2 wherein said means included in said second control means comprises voltage divider means to which said control signal is applied, the output of said voltage divider means causing said second control means to operate.
Claim 5
Dependent Claim
82 words
A differential amplifier in accordance with claim 3 wherein said first control means comprises a first control transistor having its collector-emitter circuit connected in series with said common connected emitter electrodes and its base electrode supplied with said control signal; and wherein said second control means includes a second control transistor having its collector-emitter circuit connected in shunt relationship with said base electrode of said one amplifying transistor means and its base electrode supplied with the output of said voltage divider means.
Claim 6
Dependent Claim
93 words
A differential amplifier in accordance with claim 1, further comprising an AGC signal input terminal for receiving an AGC signal; and wherein said first control means comprises a first control transistor having its collector-emitter circuit connected in series with said common connected emitters and its base electrode coupled to said AGC signal input terminal; and wherein said second control means comprises a second control transistor having its collector-emitter circuit connected in a shunt circuit coupled to said differential amplifier signal input terminal and its base electrode coupled to said AGC signal input terminal.
Claim 7
Dependent Claim
66 words
A differential amplifier in accordance with claim 5 wherein said second control means further comprises AGC voltage divider means coupled to said AGC signal input terminal and means for supplying the output of said voltage divider means to the base electrode of said second control transistor such that, as said AGC signal varies, said first control transistor is activated before said second control transistor is activated.
Claim 8
Dependent Claim
40 words
A differential amplifier in accordance with claim 6 wherein said shunt circuit includes a first diode connected in the collector circuit of said second control transistor and a second diode connected in the emitter circuit of said second control transistor.
Claim 9
Dependent Claim
52 words
A differential amplifier in accordance with claim 1 further comprising a bias circuit formed of resistance means connected in series with diode means to form a junction at which a bias voltage is produced, said bias voltage being supplied to the respective base electrodes of said first and second amplifying transistor means.
Claim 10
Dependent Claim
151 words
A differential amplifier, comprising: first and second amplifying transistors connected in differential amplifier configuration and having their respective emitter electrodes connected in common, the base electrode of said first amplifying transistor being connected to a signal input terminal and the collector electrode of said second amplifying transistor being connected to a signal output electrode; a fiRst control transistor having its collector-emitter circuit connected in series with said common connected emitter electrodes; a second control transistor having its collector-emitter circuit connected in a series circuit between said first amplifying transistor base electrode and a reference potential; and means for supplying an AGC voltage to said first and second control transistors such that said first control transistor is conductive when an input signal supplied to said signal input terminal is less than a predetermined level and both said first and second control transistors are conductive when said input signal exceeds said predetermined level.
Claim 11
Dependent Claim
151 words
A differential amplifier, comprising: first and second amplifying transistors connected in differential amplifier configuration and having their respective emitter electrodes connected in common, the base electrode of said first amplifying transistor being connected to a signal input terminal and the collector electrode of said second amplifying transistor being connected to a signal output electrode; a fiRst control transistor having its collector-emitter circuit connected in series with said common connected emitter electrodes; a second control transistor having its collector-emitter circuit connected in a series circuit between said first amplifying transistor base electrode and a reference potential; and means for supplying an AGC voltage to said first and second control transistors such that said first control transistor is conductive when an input signal supplied to said signal input terminal is less than a predetermined level and both said first and second control transistors are conductive when said input signal exceeds said predetermined level.
References Cited (Backward Citations)
US3538448A
Cited
US3641450A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-08-18 | 1979-02-17 | 1979-08-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-08-18 | 1983-02-17 | 1983-08-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-08-18 | 1987-02-17 | 1987-08-19 | $7700.00 | Window Closed / Lapsed |