US4558242A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Extended reference range, voltage-mode CMOS D/A converter
Assignee: Analog Devices Inc
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Filing: 1983-02-11
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Granted: 1985-12-10
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Expires: 2003-02-11
Abstract
Abstract A CMOS D/A converter for use in a voltage-mode and having complementary-driven switch pairs for V ref and A gnd respectively. The "ON" gate voltage of the A gnd switch is adjusted in accordance with the value of V ref , to give switch V GS equality and therefore "ON" resistance matching with the V ref switch over a wide range of reference voltage. Circuits are shown for developing the A gnd gate voltage varying with V ref .
Inventors
- 👤 Michael G. Tuthill
- 👤 Paschal Minogue
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 09:20
CPC Classifications
H; H03; H03M; H03M1/00; H03M1/66; H03M1/74
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
84 words
In a digital-to-analog converter of the type comprising a plurality of complementary-driven MOS switch pairs for V ref (reference voltage) and A gnd (analog ground) respectively; that improvement for assuring a close match between the "ON" resistances of the switch pairs over an extended range of values of V ref , comprising: a gate-voltage generator having means producing an A gnd switch gate voltage which varies with changes in V ref ; and means coupling said switch gate voltage to said A gnd switches.
Claim 2
Dependent Claim
84 words
In a digital-to-analog converter of the type comprising a plurality of complementary-driven MOS switch pairs for V ref (reference voltage) and A gnd (analog ground) respectively; that improvement for assuring a close match between the "ON" resistances of the switch pairs over an extended range of values of V ref , comprising: a gate-voltage generator having means producing an A gnd switch gate voltage which varies with changes in V ref ; and means coupling said switch gate voltage to said A gnd switches.
Claim 3
Dependent Claim
37 words
Apparatus as in claim 1, wherein said generator is connected to the supply voltage V DD and the reference voltage V ref , and includes means to produce a voltage corresponding to V DD -V ref .
Claim 4
Dependent Claim
77 words
Apparatus as in claim 1, wherein said generator includes an output circuit having a transistor the V be of which appears as a component of the output signal; and a compensation circuit for said generator including a second transistor applying to said first transistor an input signal including the V be of said second transistor as a component thereof, thereby tending to compensate for the effect of said first V be component on the generated gate voltage.
Claim 5
Dependent Claim
50 words
Apparatus as in claim 1, wherein said generator includes circuits to develop both V ref and A gnd switch gate voltages; said circuits including transistor means introducing in each of said gate voltages a signal component proportional to the V be of at least one transistor of said transistor means.
Claim 6
Dependent Claim
23 words
Apparatus as in claim 1, wherein the V ref and A gnd switches of each pair have identical channel widths and channel lengths.
Claim 7
Dependent Claim
41 words
Apparatus as in claim 5, wherein the "ON" gate voltage of the A gnd switch is V DD -V ref (where V DD is a supply voltage), and the "ON" gate voltage of the V ref switch is V DD .
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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) | 1988-12-09 | 1989-06-10 | 1989-12-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-12-09 | 1993-06-10 | 1993-12-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-12-09 | 1997-06-10 | 1997-12-10 | $7700.00 | Window Closed / Lapsed |