US4354162A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Wide dynamic range control amplifier with offset correction
Assignee: National Semiconductor Corp
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Filing: 1981-02-09
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Granted: 1982-10-12
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Expires: 2001-02-09
Abstract
Abstract A unity gain amplifier circuit has a control characteristic which permits a variation of the high frequency roll off as a function of a control voltage. Means are provided to prevent a change of output voltage resulting from the control voltage variation.
Inventors
- 👤 John W. Wright
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 04:08
CPC Classifications
H; H03; H03G; H03G5/00; H03F; H03F1/00; H03F1/08; H03F1/083; H03F1/32; H03F1/3211; H03G1/00; H03G1/04
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
114 words
A control amplifier circuit having a frequency response that can be varied in response to a control voltage, said circuit comprising: a variable transconductance amplifier having a differential input; means responsive to said control voltage for varying the current in said transconductance amplifier; a pair of back to back diodes coupled in series across said differential input; means for forward biasing said diodes whereby the linearity of said amplifier is enhanced; negative feedback means coupled to the noninverting input of said amplifier to limit the gain thereof; and a resistor coupled in series with the inverting input of said amplifier whereby the offset introduced into said amplifier by said means for varying is compensated.
Claim 2
Dependent Claim
114 words
A control amplifier circuit having a frequency response that can be varied in response to a control voltage, said circuit comprising: a variable transconductance amplifier having a differential input; means responsive to said control voltage for varying the current in said transconductance amplifier; a pair of back to back diodes coupled in series across said differential input; means for forward biasing said diodes whereby the linearity of said amplifier is enhanced; negative feedback means coupled to the noninverting input of said amplifier to limit the gain thereof; and a resistor coupled in series with the inverting input of said amplifier whereby the offset introduced into said amplifier by said means for varying is compensated.
Claim 3
Dependent Claim
19 words
The circuit of claim 1, wherein the value of said resistor approximates the resistance of said pair of diodes.
Claim 4
Dependent Claim
25 words
The circuit of claim 2, wherein said means for varying comprise a variable tail current source in the input stage of said variable transconductance amplifier.
Claim 5
Dependent Claim
34 words
The circuit of claim 3, wherein an integrator is coupled to the output of said transconductance amplifier whereby the frequency response of said amplifier circuit can be varied by controlling said variable tail current.
References Cited (Backward Citations)
US4292597A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1985-10-11 | 1986-04-12 | 1986-10-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-10-11 | 1990-04-12 | 1990-10-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-10-11 | 1994-04-12 | 1994-10-12 | $7700.00 | Window Closed / Lapsed |