Patent FR900246A successfully refreshed from Google Patents.
US4489282A
Expired / Lapsed
US
⏱️ 0.0 years remaining
CMOS Op amp bias circuit
Assignee: National Semiconductor Corp
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Filing: 1983-03-04
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Granted: 1984-12-18
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Expires: 2003-03-04
Abstract
Abstract A CMOS op amp is disclosed in which one op amp is programmed with a controlled offset voltage and a reference current. The amplifier is constructed so that its gain adjusts to where its output current equals the reference current. Thus its G m equals the reference current divided by the offset voltage. Other such amplifiers can be slaved to the programmed amplifier so that a plurality of amplifiers can be simultaneously programmed.
Inventors
- 👤 William B. Jett, Jr.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 18:35
CPC Classifications
H; H03; H03G; H03G1/00; H03G1/04
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
91 words
A programmed differential operational amplifier circuit having a pair of input terminals and an output terminal, said circuit comprising: means for generating a reference current; means for applying an offset potential between said pair of input terminals whereby an output current is created; means for comparing said reference current with said output current; and means responsive to said comparing to adjust the transconductance of said amplifier to where said output current equals said reference current whereby said amplifier has a transconductance equal to said reference current divided by said offset potential.
Claim 2
Dependent Claim
91 words
A programmed differential operational amplifier circuit having a pair of input terminals and an output terminal, said circuit comprising: means for generating a reference current; means for applying an offset potential between said pair of input terminals whereby an output current is created; means for comparing said reference current with said output current; and means responsive to said comparing to adjust the transconductance of said amplifier to where said output current equals said reference current whereby said amplifier has a transconductance equal to said reference current divided by said offset potential.
Claim 3
Dependent Claim
27 words
The circuit of claim 1 wherein said offset potential is poled so that said amplifier sinks current and said reference current is developed in a current source.
Claim 4
Dependent Claim
41 words
The circuit of claim 2 wherein said differential amplifier incorporates a differentially operated transistor pair in which the amplifier transconductance is related to the tail current of said pair and said means for comparing is combined with the transistor pair load.
Claim 5
Dependent Claim
18 words
The circuit of claim 3 wherein said load includes a differential to single ended output first current mirror.
Claim 6
Dependent Claim
41 words
The circuit of claim 4 further comprising a second current mirror having an input coupled to said first current mirror output and an output coupled to supply tail current to said transistor pair thereby creating a feedback loop around said pair.
Claim 7
Dependent Claim
35 words
The circuit of claim 5 wherein said second current mirror output is coupled to other similar operational amplifiers whereby the transconductance in said programmed operational amplifier is the same in all of said operational amplifiers.
Claim 8
Dependent Claim
50 words
The circuit of claim 6 wherein said operational amplifiers are constructed in integrated circuit chip form and said means for generating a reference current includes a resistor that is external to said chip whereby the transconductance of said operational amplifiers can be programmed by selecting the value of said resistor.
Claim 9
Dependent Claim
13 words
The circuit of claim 7 wherein said chip is constructed in CMOS form.
References Cited (Backward Citations)
US4383223A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-12-18 | 1988-06-18 | 1988-12-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-12-18 | 1992-06-18 | 1992-12-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-12-18 | 1996-06-18 | 1996-12-18 | $7700.00 | Window Closed / Lapsed |