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US4387345A
Expired / Lapsed
US
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Precision gain AC coupled operational amplifier
Assignee: Motorola Solutions Inc
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Filing: 1981-03-24
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Granted: 1983-06-07
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Expires: 2001-03-24
Abstract
Abstract A precision gain AC coupled operational amplifier circuit utilizing an integrated resistor voltage divider network and switched capacitors is provided. Precise gain is obtained by the use of integrated capacitors, and a low frequency stabilizing pole in the order of 10 Hertz is created by proper selection of the ratio of the resistors in the divider network.
Inventors
- 👤 Stephen H. Kelley
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 09:52
CPC Classifications
H; H03; H03F; H03F3/00; H03F3/005; H03F1/00; H03F1/08; H03F1/083
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
116 words
An inverting operational amplifier circuit comprising: operational amplifier means having an inverting and a non-inverting input and an output, for developing an output voltage proportional to the difference in voltages applied to the inputs thereof; capacitive feedback means coupled between the output and the inverting input of the operational amplifier means; resistive feedback means coupled between the output of the operational amplifier means and the inverting input thereof, for providing a DC feedback voltage proportional to the amplifier's output voltage, comprising: voltage divider means coupled between the output of the operational amplifier means and a reference voltage; and switched capacitance means coupled between the voltage divider means and the inverting input of the operational amplifier means.
Claim 2
Dependent Claim
116 words
An inverting operational amplifier circuit comprising: operational amplifier means having an inverting and a non-inverting input and an output, for developing an output voltage proportional to the difference in voltages applied to the inputs thereof; capacitive feedback means coupled between the output and the inverting input of the operational amplifier means; resistive feedback means coupled between the output of the operational amplifier means and the inverting input thereof, for providing a DC feedback voltage proportional to the amplifier's output voltage, comprising: voltage divider means coupled between the output of the operational amplifier means and a reference voltage; and switched capacitance means coupled between the voltage divider means and the inverting input of the operational amplifier means.
Claim 3
Dependent Claim
36 words
The amplifier circuit of claim 1 wherein said voltage divider means comprise first and second series-connected resistors selected to provide a first divider voltage at the junction thereof having a predetermined relationship to the output voltage.
Claim 4
Dependent Claim
63 words
The amplifier circuit of claim 2 wherein said voltage divider means further comprise a third and fourth series-connected resistors coupled to the junction between the first and second resistors of the first divider voltage selected to provide a second divider voltage at the junction between said third and fouth resistors and having a predetermined relationship to the voltage of the first voltage divider.
Claim 5
Dependent Claim
40 words
The amplifier circuit of claims 1, 2 or 3 wherein said switched capacitance means comprise two series-connected switching means responsive to respective non-overlapping clock signals and capacitance means coupled between the node connecting the switching means and the reference voltage.
Claim 6
Dependent Claim
19 words
The amplier circuit of claim 4 wherein said capacitance means comprise the inherent parasitic capacitance of the switching means.
Claim 7
Dependent Claim
23 words
The amplifier circuit of claims 1, 2 or 3 wherein said inverting operational amplifier circuit comprises input capacitance means to provide AC coupling.
Claim 8
Dependent Claim
142 words
An inverting operational amplifier circuit having a low frequency pole comprising: an operational amplifier, having an inverting and a non-inverting input and an output, for developing an output voltage proportional to the difference in voltages applied to the inputs thereof; a feedback capacitor coupled between the inverting input and the output of the operational amplifier; a first and a second resistor connected in series between the output of the operational amplifier and a reference voltage, said first and second resistors selected to provide a first divider voltage at the junction therebetween; two series-connected switching means responsive to non-overlapping clock signals and having an inherent parasitic capacitance therewith coupled between the junction of the first and second resistors and the inverting input of the operational amplifier; and a coupling capacitor connected between the inverting input of the operational amplifier and an input signal.
Claim 9
Dependent Claim
142 words
An inverting operational amplifier circuit having a low frequency pole comprising: an operational amplifier, having an inverting and a non-inverting input and an output, for developing an output voltage proportional to the difference in voltages applied to the inputs thereof; a feedback capacitor coupled between the inverting input and the output of the operational amplifier; a first and a second resistor connected in series between the output of the operational amplifier and a reference voltage, said first and second resistors selected to provide a first divider voltage at the junction therebetween; two series-connected switching means responsive to non-overlapping clock signals and having an inherent parasitic capacitance therewith coupled between the junction of the first and second resistors and the inverting input of the operational amplifier; and a coupling capacitor connected between the inverting input of the operational amplifier and an input signal.
Claim 10
Dependent Claim
51 words
The amplifier circuit of claim 7 further comprising: third and fourth series-connected resistors coupled between the junction of the first and second resistors and a reference voltage, said third and fourth resistors selected to provide a second divider voltage at the junction therebetween which is coupled to the two switching means.
References Cited (Backward Citations)
US4210872A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-06-06 | 1986-12-06 | 1987-06-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-06-06 | 1990-12-06 | 1991-06-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-06-06 | 1994-12-06 | 1995-06-07 | $7700.00 | Window Closed / Lapsed |