US4604584A
Expired / Lapsed
US
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Switched capacitor precision difference amplifier
Assignee: Motorola Solutions Inc
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Filing: 1985-06-10
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Granted: 1986-08-05
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Expires: 2005-06-10
Abstract
Abstract A circuit which can selectively sample and hold two real time input voltages and provide an output voltage indicating the difference value of the input voltages is provided. A switched capacitor structure which provides no parasitic capacitance output error component when the two input voltages are substantially equal is used.
Inventors
- 👤 Stephen H. Kelley
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 09:56
CPC Classifications
H; H03; H03F; H03F1/00; H03F1/30; H03F1/303; H03F3/00; H03F3/005
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
169 words
A precision difference amplifier comprising: first and second charge storage means, for selectively storing first and second input voltages, respectively, said first charge storage means being connected to a reference voltage terminal; first switching means for coupling the to the first charge storage means during a first time period; second switching means for coupling the second charge storage means between the second input voltage and the reference voltage terminal during a second time period successive to the first time period; integrating operational amplifier means having a first input connected to the reference voltage terminal, a second input, an output for providing a difference signal proportional to a differential voltage between the first and second inputs, and feedback charge storage means coupled between the second input and the output thereof; and third switching means for connecting the first and second charge storage means in series between the reference voltage terminal and the second input of the operational amplifier means during a third time period successive to the second time period.
Claim 2
Dependent Claim
169 words
A precision difference amplifier comprising: first and second charge storage means, for selectively storing first and second input voltages, respectively, said first charge storage means being connected to a reference voltage terminal; first switching means for coupling the to the first charge storage means during a first time period; second switching means for coupling the second charge storage means between the second input voltage and the reference voltage terminal during a second time period successive to the first time period; integrating operational amplifier means having a first input connected to the reference voltage terminal, a second input, an output for providing a difference signal proportional to a differential voltage between the first and second inputs, and feedback charge storage means coupled between the second input and the output thereof; and third switching means for connecting the first and second charge storage means in series between the reference voltage terminal and the second input of the operational amplifier means during a third time period successive to the second time period.
Claim 3
Dependent Claim
38 words
The precision difference amplifier of claim 1 wherein the first switching means further comprise: a first switch having a first terminal coupled to the first input voltage, and a second terminal connected to the first charge storage means.
Claim 4
Dependent Claim
24 words
The precision difference amplifier of claim 2 wherein the first switch is an MOS transmission gate which is controlled by a first control signal.
Claim 5
Dependent Claim
92 words
The precision difference amplifier of claim 2 wherein the second switching means further comprise: a second switch having a first terminal for receiving the second input voltage, and a second terminal connected to the second charge storage means, said second switch being an MOS transmission gate controlled by a second control signal; and a third switch having a first terminal connected to the second charge storage means and a second terminal connected to the reference voltage terminal, said third switch also being an MOS transmission gate controlled by the second control signal.
Claim 6
Dependent Claim
87 words
The precision difference amplifier of claim 4 wherein the third switching means further comprise: a fourth switch having a first terminal connected to both the second terminal of the first switch and the first charge storage means, and a second terminal connected to the second charge storage means; and a fifth switch having a first terminal connected to both the first terminal of the third switch and the second charge storage means, and a second terminal connected to the second input of the integrating operational amplifier means.
Claim 7
Dependent Claim
23 words
The precision difference amplifier of claim 5 wherein the fourth and fifth switches are MOS transmission gates controlled by a third control signal.
Claim 8
Independent Claim
154 words
A method of precisely measuring a difference in voltage potential, if any, between first and second input voltages, comprising the steps of: coupling a first capacitor between the first input voltage and a reference voltage terminal to charge the first capacitor to substantially the first input voltage during a first time period; coupling a second capacitor between the second input voltage and the reference voltage terminal to charge the second capacitor to substantially the second input voltage during a second time period; coupling the first and second capacitors in series between the reference voltage terminal and a first input of an integrating operational amplifier during a third time period, a second input of the integrating operational amplifier being at a voltage potential substantially equal to the reference voltage terminal; and providing at an output of the integrating operational amplifier a difference voltage which precisely indicates the difference between the first and second input voltages.
Claim 9
Independent Claim
154 words
A method of precisely measuring a difference in voltage potential, if any, between first and second input voltages, comprising the steps of: coupling a first capacitor between the first input voltage and a reference voltage terminal to charge the first capacitor to substantially the first input voltage during a first time period; coupling a second capacitor between the second input voltage and the reference voltage terminal to charge the second capacitor to substantially the second input voltage during a second time period; coupling the first and second capacitors in series between the reference voltage terminal and a first input of an integrating operational amplifier during a third time period, a second input of the integrating operational amplifier being at a voltage potential substantially equal to the reference voltage terminal; and providing at an output of the integrating operational amplifier a difference voltage which precisely indicates the difference between the first and second input voltages.
Claim 10
Dependent Claim
262 words
A switched capacitor precision difference amplifier comprising: a first analog switch having a first terminal for receiving a first input voltage, a second terminal, and a control input for receiving a first control signal; a second analog switch having a first terminal for receiving a second input voltage, a second terminal, and a control input for receiving a second control signal; a first capacitor having a first electrode connected to the second terminal of the second switch, and a second electrode connected to a reference voltage terminal; a second capacitor having a first electrode connected to the second terminal of the first switch, and a second electrode; a third analog switch having a first terminal connected to the first electrode of the first capacitor, a second terminal connected to a first electrode of the second capacitor, and a control input for receiving a third control signal; a fourth analog switch having a first terminal connected to the reference voltage terminal, a second terminal connected to the second electrode of the second capacitor, and a control input for receiving the first control signal; a fifth analog switch having a first terminal connected to the second electrode of the second capacitor, a second terminal, and a control input for receiving the third control signal; an operational amplifier having a first input connected to the second terminal of the fifth switch, a second input connected to the reference voltage terminal, and an output for providing an output difference signal; and a feedback capacitor connected between the output and the first input of the operational amplifier.
Claim 11
Dependent Claim
262 words
A switched capacitor precision difference amplifier comprising: a first analog switch having a first terminal for receiving a first input voltage, a second terminal, and a control input for receiving a first control signal; a second analog switch having a first terminal for receiving a second input voltage, a second terminal, and a control input for receiving a second control signal; a first capacitor having a first electrode connected to the second terminal of the second switch, and a second electrode connected to a reference voltage terminal; a second capacitor having a first electrode connected to the second terminal of the first switch, and a second electrode; a third analog switch having a first terminal connected to the first electrode of the first capacitor, a second terminal connected to a first electrode of the second capacitor, and a control input for receiving a third control signal; a fourth analog switch having a first terminal connected to the reference voltage terminal, a second terminal connected to the second electrode of the second capacitor, and a control input for receiving the first control signal; a fifth analog switch having a first terminal connected to the second electrode of the second capacitor, a second terminal, and a control input for receiving the third control signal; an operational amplifier having a first input connected to the second terminal of the fifth switch, a second input connected to the reference voltage terminal, and an output for providing an output difference signal; and a feedback capacitor connected between the output and the first input of the operational amplifier.
Claim 12
Dependent Claim
59 words
The switched capacitor precision difference amplifier of claim 8 wherein the first and fourth analog switches are conductive during a first time period, the second switch is conductive during a second time period, and the third and fifth switches are conductive during a third time period, said first, second and third time periods being non-overlapping, substantially successive time periods.
Claim 13
Dependent Claim
23 words
The switched capacitor precision difference amplifier of claim 8 wherein the first, second, third, fourth and fifth analog switches are MOS transmission gates.
References Cited (Backward Citations)
US4028558A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-08-04 | 1990-02-03 | 1990-08-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-08-04 | 1994-02-03 | 1994-08-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-08-04 | 1998-02-03 | 1998-08-05 | $7700.00 | Window Closed / Lapsed |