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Patent US3836893A successfully refreshed from Google Patents.
US3836893A
Expired / Lapsed
US
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Capacitive computer circuits
Assignee: Ultra Electronics Ltd
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Filing: 1973-02-22
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Granted: 1974-09-17
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Expires: 1993-02-22
Abstract
Abstract A capacitive computer circuit comprises a field effect switch connected to a storage capacitor, means for applying a signal characteristic to or deriving a signal characteristic from the capacitor, and means for compensating for errors in the derived signal due to leakage current or stray capacitance in the circuit.
Inventors
- 👤 R Lamden
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 15:09
CPC Classifications
G; G11; G11C; G11C27/00; G11C27/02; G11C27/024; G11C27/026
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
112 words
A capacitive computer circuit comprising: a first field effect switch and a storage capacitor connected thereto; means for applying a signal characteristic to or deriving a signal characteristic from said capacitor; a dummy storage capacitor; and amplifier having inverting and noninverting inputs connected across said dummy storage capacitor, said non-inverting input being also connected to earth; a further field effect switch; and input of said amplifier connected through said further field effect switch to the inverting input of said amplifier, thereby providing negative feedback to resist any change in the voltage of said dummy capacitor, said amplifier also controlling said first field effect switch to compensate for leakage in said storage capacitor.
Claim 2
Dependent Claim
112 words
A capacitive computer circuit comprising: a first field effect switch and a storage capacitor connected thereto; means for applying a signal characteristic to or deriving a signal characteristic from said capacitor; a dummy storage capacitor; and amplifier having inverting and noninverting inputs connected across said dummy storage capacitor, said non-inverting input being also connected to earth; a further field effect switch; and input of said amplifier connected through said further field effect switch to the inverting input of said amplifier, thereby providing negative feedback to resist any change in the voltage of said dummy capacitor, said amplifier also controlling said first field effect switch to compensate for leakage in said storage capacitor.
Claim 3
Dependent Claim
73 words
The capacitive circuit of claim 1 in which said field effect switches are field effect transistors having their gate electrodes connected to said output of said amplifier, and in which a resistor is connected in series with the main current path of each field effect transistor for selecting the degree of compensation provided, each said resistor connecting each said capacitor to earth through said main current path of each said field effect transistor.
Claim 4
Dependent Claim
72 words
The capacitive computer circuit of claim 2, comprising further storage capacitors, each said storage capacitor having one electrode connected to earth and one electrode connected to earth through a respective field effect switch and a respective resistor, the control electrode of each said switch being connected to the output of said amplifier and each said transistor being selected to provide a predetermined degree of leakage compensation for each of said storage capacitors.
Claim 5
Dependent Claim
77 words
A capacitive computer circuit comprising: a field effect switch and a storage capacitor connected thereto; means for applying a signal characteristic to or deriving a signal characteristic from said capacitor; a voltage amplifier having an inverting input connected to said field effect switch; and a preset capacitor connected between the output and input of said voltage amplifier so as to resist any charge build-up in the stray capacitance in said circuit, the stray capacitance thereby being compensated.
Claim 6
Dependent Claim
77 words
A capacitive computer circuit comprising: a field effect switch and a storage capacitor connected thereto; means for applying a signal characteristic to or deriving a signal characteristic from said capacitor; a voltage amplifier having an inverting input connected to said field effect switch; and a preset capacitor connected between the output and input of said voltage amplifier so as to resist any charge build-up in the stray capacitance in said circuit, the stray capacitance thereby being compensated.
Claim 7
Dependent Claim
23 words
The capacitive computer circuit of claim 4, comprising switches connected to short circuit the stray capacitance and the feedback capacitor between each reading.
Claim 8
Dependent Claim
73 words
A capacitive computer circuit comprising: a first field effect switch and a storage capacitor connected thereto; means for applying a signal characteristic to or deriving a signal characteristic from said capacitor; means for compensating for stray capacitance in said circuit, said means including a fixed positive gain voltage amplifier having its input directly connected to said switch, and a preset capacitance connecting the output of said fixed gain voltage amplifier to said switch.
Claim 9
Dependent Claim
73 words
A capacitive computer circuit comprising: a first field effect switch and a storage capacitor connected thereto; means for applying a signal characteristic to or deriving a signal characteristic from said capacitor; means for compensating for stray capacitance in said circuit, said means including a fixed positive gain voltage amplifier having its input directly connected to said switch, and a preset capacitance connecting the output of said fixed gain voltage amplifier to said switch.
Claim 10
Dependent Claim
22 words
The circuit of claim 6 in which said fixed positive gain amplifier is non-linear to compensate for a voltage dependent stray capacitance.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-09-16 | 1978-03-18 | 1978-09-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-09-16 | 1982-03-18 | 1982-09-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-09-16 | 1986-03-18 | 1986-09-17 | $7700.00 | Window Closed / Lapsed |