US3609414A
Expired / Lapsed
US
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Apparatus for stabilizing field effect transistor thresholds
Assignee: International Business Machines Corp
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Filing: 1968-08-20
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Granted: 1971-09-28
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Expires: 1988-08-20
Abstract
Abstract Apparatus is disclosed which permits the adjustment and stabilization of field effect transistor threshold voltages so that the variation in threshold voltages due to fabrication nonuniformities are reduced to a minimum. This is accomplished by utilizing one of a plurality of field effect devices on a semiconductor chip as a sensor to detect changes in the characteristics of the devices, from whatever cause. A feedback circuit provides a signal which adjusts the voltage applied to the semiconductor chip or substrate and returns the threshold voltage to some nominal value. Several circuit arrangements are shown which accomplish the desired result. A plurality of chips each having a sensor and associated feedback circuitry is also disclosed indicating the environment in which the concept of the present invention is used most advantageously.
Inventors
- 👤 Peter Pleshko
- 👤 Lewis M Terman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 16:19
CPC Classifications
H; H03; H03K; H03K17/00; H03K17/14; H03K17/145; G; G05; G05F; G05F3/00; G05F3/02; G05F3/08; G05F3/10; G05F3/16; G05F3/20; G05F3/205; H03F; H03F1/00; H03F1/30; H03F1/301; H03F3/00; H03F3/34; H03F3/343; H03F3/345; H10; H10D; H10D84/00; H10D84/80; H10D84/811; H10D84/817; H10D84/82; H10D84/83; H10D84/83125; H10D89/00; H10D89/211; H10D89/213
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
72 words
Stabilization and control apparatus comprising; a semiconductor substrate containing a plurality of field effect transistors, means for applying a voltage to said substrate to establish a desired value of threshold voltage, and means including at least a field effect transistor integral with said substrate having characteristics representative of said plurality of field effect transistors for counteracting a departure from said desired value of threshold voltage connected to said means for applying voltage.
Claim 2
Dependent Claim
130 words
Stabilization and control apparatus according to claim 2 wherein said means for counteracting includes, a reference voltage connected to said at least a field effect transistor which coacting with said means for applying a voltage to said substrate controls the flow of current through said at least said field effect transistor, means connected to said transistor for detecting a change in current through said transistor by a corresponding voltage drop, comparison means including another reference voltage coupled to said means for detecting to compare said voltage drop with said another reference voltage to provide an output voltage when said voltage drop and said another voltage differ, and means interconnecting said comparison means and said means for applying a voltage to said substrate to apply said output voltage to said substrate.
Claim 3
Dependent Claim
93 words
Stabilization and control apparatus comprising; a plurality of semiconductor substrates each containing a plurality of field effect transistors, a plurality of voltage sources each coupled to a respective substrate to establish a desired value of threshold voltage for each plurality of field effect transistors, sensing means integral with each said substrate for detecting a departure from said desired value of threshold voltage, and means resPonsive to each said sensing means for adjusting each of said plurality of voltage sources to maintain said threshold voltage of each of said substrates at said desired value.
Claim 4
Dependent Claim
95 words
Stabilization and control apparatus comprising; a plurality of semiconductor substrates each containing a plurality of field effect transistors each substrate differing from all others electrically, means for applying a voltage to each of said plurality of substrates to establish a desired value of threshold voltages for all the pluralities of field effect transistors, and means including at least a field effect transistor integral with each said substrate having characteristics representative of its associated plurality of transistors for counteracting a departure from said desired value of threshold voltage connected to each said means for applying voltage.
Claim 5
Dependent Claim
136 words
Stabilization and control apparatus according to claim 5 wherein each said means for counteracting includes, a reference voltage connected to said at least a field effect transistor which coacting with said means for applying a voltage to said substrate controls the flow of current through said at least said field effect transistor, means connected to said transistor for detecting a change in current through said transistor by a corresponding voltage drop, comparison means including a common reference voltage source coupled to each said means for detecting to compare said voltage drop with said common reference voltage to provide an output voltage when said voltage drop and said common reference voltage differ, and means interconnecting said comparison means and said means for applying a voltage to said substrate to apply said output voltage to its associated substrate.
Claim 6
Dependent Claim
202 words
Stabilization and control apparatus comprising: a plurality of substrates each containing a plurality of field effect transistors each substrate having electrical characteristics different from all others, means for applying a voltage to each of said substrates, a sensing transistor integral with each of said substrates said sensing transistor being characteristic of each of its associated plurality of field effect transistors, a reference voltage electrically coupled to each said sensing transistor to establish a given threshold voltage, a voltage source and a resistance disposed in series with each said sensing transistor, a field effect transistor connected to each said voltage source the gate electrode of which is connected between said sensing transistor and said resistance to apply a voltage to said gate electrode inversely proportional to the current through said sensing transistor, and another resistance connected in series with each said field effect transistor and with said means for applying a voltage to each of said substrates, the current flow through said another resistance being directly proportional to the voltage on said gate of said field effect transistor said current flow through said means for applying a voltage resulting in the variation of said means for applying a voltage to each said substrate.
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) | 1974-09-27 | 1975-03-29 | 1975-09-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-09-27 | 1979-03-29 | 1979-09-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-09-27 | 1983-03-29 | 1983-09-28 | $7700.00 | Window Closed / Lapsed |