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Patent US3587091A successfully refreshed from Google Patents.
US3587091A
Expired / Lapsed
US
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Digital to analogue conversion
Assignee: Allard Way Holdings Ltd
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Filing: 1968-07-15
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Granted: 1971-06-22
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Expires: 1988-07-15
Abstract
Abstract A digital to analogue converter comprises a resistor ladder which produces an intermediate analogue signal dependent on a digital input signal. A comparator compares the intermediate analogue signal with the charge on a capacitor in a selected output channel, and adjusts the charge, by means of a current source and a current sink, until the charge represents the value of the intermediate analogue signal.
Inventors
- 👤 John J L Cooper
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 23:29
CPC Classifications
H; H03; H03M; H03M1/00; H03M1/12; H03M1/124
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
202 words
A digital to analogue converter system comprising input means for receiving a digital signal, means responsive to the digital signal to produce on intermediate analogue signal representative thereof, a plurality of output means each comprising respective capacitive storing means producing a variable output signal representing the charge in the capacitive storing means, current source means connected to the capacitive storing means and operative when activated to increase the said charge, and current sink means connected to the capacitive storing means and operative when activated to decrease the said charge, comparing means responsive to the intermediate analogue signal, selecting means responsive to an address signal representative of any particular one of said output means and operative to connect the said comparing means to the selected output means so that the comparing means is responsive also to the variable output signal therefrom and produces an error signal dependent on the difference between the two signals compared, and control means responsive to the error signal to activate such one of the current source means and the current sink means in the selected output means as tends to reduce the error signal to zero whereby the output signal is the analogue of the said digital signal.
Claim 2
Dependent Claim
202 words
A digital to analogue converter system comprising input means for receiving a digital signal, means responsive to the digital signal to produce on intermediate analogue signal representative thereof, a plurality of output means each comprising respective capacitive storing means producing a variable output signal representing the charge in the capacitive storing means, current source means connected to the capacitive storing means and operative when activated to increase the said charge, and current sink means connected to the capacitive storing means and operative when activated to decrease the said charge, comparing means responsive to the intermediate analogue signal, selecting means responsive to an address signal representative of any particular one of said output means and operative to connect the said comparing means to the selected output means so that the comparing means is responsive also to the variable output signal therefrom and produces an error signal dependent on the difference between the two signals compared, and control means responsive to the error signal to activate such one of the current source means and the current sink means in the selected output means as tends to reduce the error signal to zero whereby the output signal is the analogue of the said digital signal.
Claim 3
Dependent Claim
43 words
A system according to claim 1, including means operative to increase the rate of charging of the current source means and the rate of discharge of the current sink means for a period during which the said error signal tends to be high.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-06-21 | 1974-12-21 | 1975-06-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-06-21 | 1978-12-21 | 1979-06-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-06-21 | 1982-12-21 | 1983-06-22 | $7700.00 | Window Closed / Lapsed |