US5256985A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Current compensation technique for an operational amplifier
Assignee: Avago Technologies International Sales Pte Ltd
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Filing: 1992-08-11
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Granted: 1993-10-26
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Expires: 2012-08-11
Abstract
Abstract An apparatus and method is disclosed for minimizing the loading effect of the feedback network on the output voltage of an op-amp circuit. A single current source is coupled to the output of the op-amp to provide a predetermined current. By properly selecting the current source to be equal to the current demanded by the feedback network, the output current of the op-amp is significantly reduced. In turn, the loading effects of the feedback network resistors on the op-amp are significantly reduced and the accuracy of the op-amp circuit gain is improved.
Inventors
- 👤 Charles A. Brown
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 06:27
CPC Classifications
H; H03; H03F; H03F1/00; H03F1/34
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
102 words
An op-amp circuit comprising: an op-amp having a positive input, a negative input, and an output for providing an output voltage; a feedback network having a first input for receiving a fixed input reference voltage, a second input for receiving a reference voltage and first, second, and third nodes respectively coupled to the positive input, negative input, and output of the op-amp, the third node having a known operating current requirement; and a current source coupled to the output of the op-amp for providing a predetermined current for supplying at least a portion of the operating current requirement of the feedback network.
Claim 2
Dependent Claim
102 words
An op-amp circuit comprising: an op-amp having a positive input, a negative input, and an output for providing an output voltage; a feedback network having a first input for receiving a fixed input reference voltage, a second input for receiving a reference voltage and first, second, and third nodes respectively coupled to the positive input, negative input, and output of the op-amp, the third node having a known operating current requirement; and a current source coupled to the output of the op-amp for providing a predetermined current for supplying at least a portion of the operating current requirement of the feedback network.
Claim 3
Dependent Claim
25 words
The op-amp circuit of claim 1 in which the current source provides a current substantially equal to an operating current required by the feedback network.
Claim 4
Dependent Claim
46 words
The op-amp circuit of claim 1 in which the feedback network further comprises: an input voltage coupled to the positive input; a first resistor coupled between the negative input and a reference voltage source; and a second resistor coupled between the negative input and the output.
Claim 5
Dependent Claim
30 words
The op-amp circuit of claim 3 in which the predetermined current is substantially equal to the output voltage minus the input voltage divided by the value of the second resistor.
Claim 6
Dependent Claim
46 words
The op-amp circuit of claim 1 in which the feedback network further comprises: a reference voltage coupled to the positive input; a first resistor coupled between the negative input and an input voltage source; and a second resistor coupled between the negative input and the output.
Claim 7
Dependent Claim
30 words
The op-amp circuit of claim 5 in which the predetermined current is substantially equal to the output voltage minus the reference voltage divided by the value of the second resistor.
Claim 8
Dependent Claim
39 words
The op-amp circuit of claim 1 in which the current source comprises a P-channel FET having a source coupled to a supply voltage source, a gate coupled to a predetermined bias voltage, and a drain coupled to the output.
Claim 9
Dependent Claim
39 words
The op-amp circuit of claim 1 in which the current source comprises a PNP transistor having an emitter coupled to a supply voltage source, a base coupled to a predetermined bias voltage, and a collector coupled to the output.
Claim 10
Dependent Claim
22 words
The op-amp circuit of claim 1 in which the current source comprises a resistor coupled between a supply voltage and the output.
Claim 11
Dependent Claim
39 words
The op-amp circuit of claim 1 in which the current source comprises an N-channel FET having a source coupled to a supply voltage source, a gate coupled to a predetermined bias voltage, and a drain coupled t the output.
Claim 12
Dependent Claim
39 words
The op-amp circuit of claim 1 in which the current source comprises an NPN transistor having an emitter coupled to a supply voltage source, a base coupled to a predetermined bias voltage, and a collector coupled to the output.
Claim 13
Independent Claim
85 words
A method of accurately amplifying a voltage signal comprising: providing an op-amp having a positive input, a negative input, and an output for providing an output voltage; coupling a feedback network to the positive input, negative input and output of the op-amp, the feedback network having a known operating current requirement; coupling an input voltage to the feedback network; and coupling a current source to the output of the op-amp to provide at least a portion of the operating current requirement of the feedback network.
Claim 14
Independent Claim
85 words
A method of accurately amplifying a voltage signal comprising: providing an op-amp having a positive input, a negative input, and an output for providing an output voltage; coupling a feedback network to the positive input, negative input and output of the op-amp, the feedback network having a known operating current requirement; coupling an input voltage to the feedback network; and coupling a current source to the output of the op-amp to provide at least a portion of the operating current requirement of the feedback network.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1996-10-25 | 1997-04-26 | 1997-10-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-10-25 | 2001-04-26 | 2001-10-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-10-25 | 2005-04-26 | 2005-10-26 | $7700.00 | Window Closed / Lapsed |