Patent US4727309A successfully refreshed from Google Patents.
US4727309A
Expired / Lapsed
US
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Current difference current source
Assignee: Intel Corp
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Filing: 1987-01-22
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Granted: 1988-02-23
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Expires: 2007-01-22
Abstract
Abstract A current difference current source which provides a stable current as operating conditions change. Two MOS transistors operate as two current sources. A difference current is obtained by subtracting the two transistor currents. The two current sources are configured to vary similarly as conditions change, such that their difference remains constant. In the alternative the difference current is forced to decrease as current increases in the transistors, wherein a reverse compensated current is provided. The difference current is used to drive a current mirror which functions as a compensated current source.
Inventors
- 👤 Branislav Vajdic
- 👤 Stephen L. Smith
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 21:30
CPC Classifications
G; G05; G05F; G05F3/00; G05F3/02; G05F3/08; G05F3/10; G05F3/16; G05F3/20; G05F3/24; G05F3/242; G05F3/247; G05F3/245
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
126 words
A circuit for providing a compensated current which is substantially independent of operating condition changes, comprising: a first current source comprised of a first transistor and having a first current; a second current source comprised of a second transistor and coupled serially to said first current source and having a second current; a third transistor coupled serially to said first current source and parallel to said second current source for providing said compensated current, said compensated current determined by a difference of said first and second currents; said first and second current sources having characteristics, such that said first and second currents vary as operating conditions change, but said difference remains approximately constant; whereby a substantially uniform compensated current independant of operating condition variations is achieved.
Claim 2
Dependent Claim
126 words
A circuit for providing a compensated current which is substantially independent of operating condition changes, comprising: a first current source comprised of a first transistor and having a first current; a second current source comprised of a second transistor and coupled serially to said first current source and having a second current; a third transistor coupled serially to said first current source and parallel to said second current source for providing said compensated current, said compensated current determined by a difference of said first and second currents; said first and second current sources having characteristics, such that said first and second currents vary as operating conditions change, but said difference remains approximately constant; whereby a substantially uniform compensated current independant of operating condition variations is achieved.
Claim 3
Dependent Claim
17 words
The circuit of claim 1, wherein said first, second and third transistors are comprised of MOS transistors.
Claim 4
Dependent Claim
22 words
The circuit of claim 2, wherein said third transistor is coupled to a fourth MOS transistor to operate as a current mirror.
Claim 5
Dependent Claim
33 words
The circuit of claim 3, wherein said compensated current has a reverse compensation characteristic such that said difference decreases as said first and second currents increase due to changes of said operating condition.
Claim 6
Dependent Claim
94 words
A circuit for providing a compensated current which is substantially independent of operating condition changes, comprising: a first transistor; a second transistor coupled serially to said first transistor; a third transistor coupled serially to said first transistor and parallel to said second transistor; said compensated current is equivalent to a current flow through said third transistor and is determined by a subtraction of a second transistor current flowing through said second transistor from a first transistor current flowing through said first transistor; whereby said compensated current is substantially uniform as said operating conditions change.
Claim 7
Dependent Claim
94 words
A circuit for providing a compensated current which is substantially independent of operating condition changes, comprising: a first transistor; a second transistor coupled serially to said first transistor; a third transistor coupled serially to said first transistor and parallel to said second transistor; said compensated current is equivalent to a current flow through said third transistor and is determined by a subtraction of a second transistor current flowing through said second transistor from a first transistor current flowing through said first transistor; whereby said compensated current is substantially uniform as said operating conditions change.
Claim 8
Dependent Claim
11 words
The circuit of claim 5, wherein said transistors are MOS transistors.
Claim 9
Dependent Claim
46 words
The circuit of claim 6, wherein said first and second transistors respond characteristically to that of typical MOS transistors, such that said first and second currents vary according to said operating condition changes, but said difference of said first and second transistor currents remain substantially constant.
Claim 10
Dependent Claim
20 words
The circuit of claim 7, including a fourth transistor coupled to said third transistor to function as a current mirror.
Claim 11
Dependent Claim
66 words
The circuit of claim 8, further including feedback means coupled to said first transistor for providing feedback, so that said first transistor current varies at a slower rate to said operating condition changes than said second transistor current, wherein said compensated current has a reverse compensation characteristic such that said difference decreases as said first and second transistor currents increase due to said operating condition changes.
Claim 12
Dependent Claim
13 words
The circuit of claim 9, wherein said feedback means is a fifth transistor.
Claim 13
Dependent Claim
26 words
The circuit of claim 10, wherein said first, second and fifth transistors are depletion type transistors and said third and fourth transistors are enhancement type transistors.
Claim 14
Dependent Claim
15 words
The circuit of claim 9, wherein said first and second transistors are depletion type transistors.
Claim 15
Dependent Claim
15 words
The circuit of claim 12, wherein said third and fourth transistors are enhancement type transistors.
Claim 16
Dependent Claim
12 words
The circuit of claim 9, wherein said feedback means is a resistor.
Claim 17
Dependent Claim
13 words
The circuit of claim 14, wherein all four transistors are enhancement type transistors.
Claim 18
Dependent Claim
25 words
The circuit of claim 14, wherein said first and second transistors are depletion type transistors and said third and fourth transistors are enhencement type transistors.
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) | 1991-02-22 | 1991-08-24 | 1992-02-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-02-22 | 1995-08-24 | 1996-02-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-02-22 | 1999-08-24 | 2000-02-23 | $7700.00 | Window Closed / Lapsed |