Measuring and testing – Fluid pressure gauge – Diaphragm
Patent
1992-03-09
1994-01-18
Woodiel, Donald O.
Measuring and testing
Fluid pressure gauge
Diaphragm
73518, 73720, 73DIG4, 374143, 257 26, G01L 900, H01L 2984
Patent
active
052791629
ABSTRACT:
This invention relates to a semiconductor sensor for detecting external physical forces, such as acceleration, contact pressures, air pressures, mechanical vibrations, etc. The semiconductor sensor according to this invention is characterized by the use of compound semiconductors of high piezoelectricity, such as GaAs, etc. Conventionally sensors of the cantilever type, diaphragm type, etc. are made of silicon. These prior art sensors have low detection sensitivity, and their characteristics tend to deteriorate. The sensor according to this invention is made of GaAs, which has high piezoelectricity and can retain good characteristics of the semiconductor even at high temperatures and includes a field-effect transistor formed on the GaAs for sensing a stress. The FET is driven by a constant current or a constant voltage so as to detect a change of an electrical characteristic (e.g., threshold characteristic) due to a stress. The structure of the sensor according to this invention enables the sizes of the sensors not only to be diminished but also to reduce the fabrication costs. When a stress is applied to the FET, the transconductance changes, and the temperature changes, consequently the I-V characteristic changes. An a.c. signal biased by a direct current is supplied to the gate of the FET, and a drain current is detected in an a.c. component and a d.c. component so as to detect a temperature concurrently with a detection of a stress.
REFERENCES:
patent: 4633099 (1986-12-01), Tanabe et al.
patent: 4698657 (1987-10-01), Watanabe et al.
patent: 4873871 (1989-10-01), Bai et al.
Doi Mizuho
Hiyama Satoshi
Takebe Katsuhiko
Takehara Hiroyasu
Urabe Masanobu
Honda Giken Kogyo Kabushiki Kaisha
Woodiel Donald O.
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