US4813272A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Semiconductor pressure sensor
Assignee: Hitachi Ltd
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Filing: 1987-07-31
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Granted: 1989-03-21
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Expires: 2007-07-31
Abstract
Abstract There is a bridge circuit which is driven by a constant-current including a thermistor. The bridge circuit is constituted by strain gages defined by P-type diffused layers. Strain gages which constitute in combination the bridge circuit are defined by diffused resistor layers having a surface impurity concentration which is set so as to fall within the range from 2.3×10 18 to 2.5×10 18 atoms/cm 3 . The B constant of the thermistor is selected so as to fall within the range from 1400K to 2400K.
Inventors
- 👤 Atsushi Miyazaki
- 👤 Ryoichi Kobayashi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 23:23
CPC Classifications
G; G01; G01L; G01L9/00; G01L9/0041; G01L9/0051; G01L9/0052; G01L9/0054; G01L9/0042; G01L9/02; G01L9/06; G01L9/065
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
156 words
In a semiconductor pressure sensor including a silicon single crystal elastic substrate whose surface tension changes in accordance with the pressure applied thereto, a strain gage defined by a P-type diffused layer formed on the surface of said substrate, a bridge circuit including said strain gage, a constant-current circuit for supplying a driving current to said bridge circuit, and an amplifier circuit for amplifying an output from the output terminals of said bridge circuit to form an output signal, the improvement comprising: strain gages in said bridge circuit which are diffused resistor layers having a surface impurity concentration within the range from 2.3×10 18 to 2.5×10 18 atoms/cm 3 ; and thermistor means in said constant-current circuit, the thermistor means having a temperature-resistance characteristic for cancelling a temperature-resistance characteristic of said diffused resistor layers by selection of a B constant of the thermistor within the range from 1400K to 2400K, thereby effecting temperature compensation of sensitivity.
Claim 2
Dependent Claim
156 words
In a semiconductor pressure sensor including a silicon single crystal elastic substrate whose surface tension changes in accordance with the pressure applied thereto, a strain gage defined by a P-type diffused layer formed on the surface of said substrate, a bridge circuit including said strain gage, a constant-current circuit for supplying a driving current to said bridge circuit, and an amplifier circuit for amplifying an output from the output terminals of said bridge circuit to form an output signal, the improvement comprising: strain gages in said bridge circuit which are diffused resistor layers having a surface impurity concentration within the range from 2.3×10 18 to 2.5×10 18 atoms/cm 3 ; and thermistor means in said constant-current circuit, the thermistor means having a temperature-resistance characteristic for cancelling a temperature-resistance characteristic of said diffused resistor layers by selection of a B constant of the thermistor within the range from 1400K to 2400K, thereby effecting temperature compensation of sensitivity.
References Cited (Backward Citations)
US4173148A
Cited
JPH113379A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-03-20 | 1992-09-19 | 1993-03-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-03-20 | 1996-09-19 | 1997-03-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-03-20 | 2000-09-19 | 2001-03-21 | $7700.00 | Window Closed / Lapsed |