US4442408A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Differential amplifier with auto bias adjust
Assignee: International Business Machines Corp
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Filing: 1982-05-13
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Granted: 1984-04-10
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Expires: 2002-05-13
Abstract
Abstract In a differential amplifier circuit a closed loop bias adjustment circuit samples the lower of the output levels of the differential amplifier output stages to control a variable current source. This variable current source draws current from the amplifier to bias the output transistors thereof to provide optimum speed, maximum voltage swing, and minimum power dissipation.
Inventors
- 👤 Trung Le
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 04:17
CPC Classifications
H; H03; H03F; H03F3/00; H03F3/45; H03F3/45071; H03F3/45076; H03F3/4508; H03F3/45085; H03F1/00; H03F1/02; H03F1/0205; H03F1/0261; H03F2203/00; H03F2203/45; H03F2203/45454; H03F2203/45702
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
57 words
In a differential amplifier circuit having first and second complimentary outputs, the improvement comprising; means for individually sensing the voltages of both differential amplifier outputs; and means responsive to the minimum of said sensed differential amplifier output voltages for controlling current flow out of said amplifier to maintain said minimum voltage value at a predetermined, constant level.
Claim 2
Dependent Claim
57 words
In a differential amplifier circuit having first and second complimentary outputs, the improvement comprising; means for individually sensing the voltages of both differential amplifier outputs; and means responsive to the minimum of said sensed differential amplifier output voltages for controlling current flow out of said amplifier to maintain said minimum voltage value at a predetermined, constant level.
Claim 3
Dependent Claim
39 words
In the differential amplifier circuit of claim 1 wherein said means for controlling current flow further comprises a current source transistor connected between a first voltage source and the emitters of a pair of transistors in said differential amplifier.
Claim 4
Dependent Claim
28 words
In the differential amplifier of claim 2 wherein said means for controlling current further comprises an operational amplifier for controlling the relative conductivity of said current source transistor.
Claim 5
Dependent Claim
31 words
In the differential amplifier of claim 3 wherein a first input of said operational amplifier is connected to sense a bias voltage of at least one transistor in said differential amplifier.
Claim 6
Dependent Claim
27 words
In the differential amplifier of claim 4 wherein a second input of said operational amplifier is connected to sense said minimum voltage value of said differential amplifier.
Claim 7
Dependent Claim
40 words
In the differential amplifier of claim 5 wherein said second input of said operational amplifier is connected to each of the outputs of said differential amplifier through separate diodes which are back biased with respect to a second voltage source.
Claim 8
Dependent Claim
47 words
In the differential amplifier of claim 6 further comprising a voltage divider connected between said second voltage source and ground, said voltage divider having its divider terminal connected to said second input of said operational amplifier to cause one of said diodes to conduct at all times.
Claim 9
Dependent Claim
28 words
In the differential amplifier circuit of claim 7 wherein said means for controlling current flow includes capacitive means for stabilizing operation of said controlling means during amplifier switching.
Claim 10
Dependent Claim
25 words
In the differential amplifier of claim 8 wherein the emitter of said current source transistor is connected to said first voltage source through a resistor.
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) | 1987-04-10 | 1987-10-10 | 1988-04-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-04-10 | 1991-10-10 | 1992-04-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-04-10 | 1995-10-10 | 1996-04-10 | $7700.00 | Window Closed / Lapsed |