Amplifying compensation circuit for semiconductor

• US 5,042,307 A
• Filed: 07/17/1990
• Issued: 08/27/1991
• Est. Priority Date: 07/19/1989
• Status: Expired due to Term

• Current Assignee: Fuji Electric Company Limited (Fuji Electric Systems Company Limited)
• Original Assignee: Fuji Electric Company Limited (Fuji Electric Systems Company Limited)
• Inventors: Kato, Kazuyuki
• Primary Examiner(s): WOODIEL, DONALD
• Application Number:
  US07/553,339
• Time in Patent Office: 406 Days
• Field of Search: 73/708, 73/720, 73/721, 73/726, 73/727, 73/766, 338/4, 338/3
• US Class Current: 73/708
• CPC Class Codes: G01L 1/2281 for temperature variations
• CPC Class Codes: G01L 19/02 Arrangements for preventing, or for compensating for, effects of inclination or acceleration of the measuring device; Zero-setting means for aneroid barometers G01L7/14
• CPC Class Codes: G01L 9/045 with electric temperature compensating means non electric temperature compensating means G01L19/04

Abstract

A pressure sensor circuit has a bridge circuit of strain gauges formed on a silicon diaphragm with two output terminals. The difference in the voltage between the two output terminals is dependent on the pressure applied to the strain gauges. A differential amplifier circuit having an operational amplifier and a feedback circuit amplifies the difference between the two output terminals. A temperature dependent resistor in the feedback circuit provides temperature compensation. An adjustable resistor adjusts the sensitivity of the pressor sensor circuit. Temperature dependent resistors connected between the operational amplifier and reference voltages compensate for zero point temperature fluctuations, and adjustable resistors connected between the operational amplifier and the reference voltages adjust the zero point.

Claims

1. A pressure sensor circuit, comprising:

first and second terminals connected respectively to first and second potentials;

means for sensing a pressure and generating first and second voltages interconnected with the first and second terminals, the difference of the first and second voltages being dependent on at least one pressure to be sensed;

means for converting impedance comprising a voltage follower circuit which receives the first voltage;

means for amplifying the difference between the first and second voltages comprising an operational amplifier with first and second inputs and a feedback circuit with a temperature dependent resistor;

means for adjusting the sensitivity of the pressure sensor circuit comprising a resistor with adjustable resistance connected between the pressure sensing means and the first input of the operational amplifier;

means for compensating for temperature induced fluctuations in the zero point of the pressure sensor circuit comprising at least one temperature dependent resistor connected between the first input of the operational amplifier and the first terminal; and

means for adjusting the zero point of the pressure sensor circuit comprising at least one resistor with an adjustable resistance connected between the first input of the operational amplifier and the first terminal.

2. A pressure sensor circuit as claimed in claim 1, wherein the first input of the operational amplifier is the inversion input.

3. A pressure sensor circuit as claimed in claim 2, wherein the pressure sensor means is a bridge circuit having strain gauges formed on a silicon diaphragm.

4. A pressure sensor circuit as claimed in claim 3, wherein the feedback circuit further comprises a resistor with adjustable resistance connected in parallel to the temperature dependent resistor.

5. A pressure sensor circuit as claimed in claim 4, wherein the means for compensating for the temperature induced fluctuations further comprises a resistor with adjustable resistance connected in series with the at least one temperature dependent resistor.

6. A pressure sensor circuit, comprising:

first and second terminals connected respectively to first and second potentials;

means for sensing a pressure and generating first and second voltages interconnected with the first and second terminals, the difference of the first and second voltages being dependent on at least one pressure to be sensed;

means for converting impedance comprising a voltage follower circuit which receives the first voltage;

means for amplifying the difference between the first and second voltages comprising an operational amplifier with first and second inputs and a feedback circuit with a temperature dependent resistor;

means for adjusting the sensitivity of the pressure sensor circuit comprising a resistor with adjustable resistance connected between the pressure sensing means and the first input of the operational amplifier;

means for compensating for temperature induced fluctuations in the zero point of the pressure sensor circuit comprising at least one temperature dependent resistor connected between the first input of the operational amplifier and the first terminal, and at least one temperature dependent resistor connected between the first input of the operational amplifier and the second terminal; and

means for adjusting the zero point of the pressure sensor circuit comprising at least one resistor with an adjustable resistance connected between the first input of the operational amplifier and the first terminal, and at least one resistor with an adjustable resistance connected between the first input of the operational amplifier and the second terminal.

7. A pressure sensor circuit as claimed in claim 6, wherein the first input of the operational amplifier is the inversion input.

8. A pressure sensor circuit as claimed in claim 7, wherein the pressure sensor means is a bridge circuit having strain gauges formed on a silicon diaphragm.

9. A pressure sensor circuit as claimed in claim 8, wherein the feedback circuit further comprises a resistor with adjustable resistance connected in parallel to the temperature dependent resistor.

10. A pressure sensor circuit as claimed in claim 9, wherein the means for compensating for the temperature induced fluctuations further comprises a resistor with adjustable resistance connected in series with the at least one temperature dependent resistor connected between the first input of the operational amplifier and the first terminal, and a resistor with adjustable resistance connected in series with the at least one temperature dependent resistor connected between the first input of the operational amplifier and the second terminal.