PHYSICAL QUANTITY DETECTION CIRCUIT AND PHYSICAL QUANTITY SENSOR DEVICE

• US 20100169028A1
• Filed: 10/28/2009
• Published: 07/01/2010
• Est. Priority Date: 12/25/2008
• Status: Abandoned Application

• Current Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: SHIRAKI, Yoshinori, TANIGUCHI, Motonori
• Application Number:
  US12/607,572
• Publication Number:
  US 20100169028A1
• Time in Patent Office: Days
• US Class Current: 702/56
• CPC Class Codes: G01C 19/5614 Signal processing
• CPC Class Codes: G01N 2291/0427 Flexural waves, plate waves, e.g. Lamb waves, tuning fork, cantilever
• CPC Class Codes: G01N 29/32 Arrangements for suppressing undesired influences, e.g. temperature or pressure variations , compensating for signal noise

Abstract

An analog-to-digital conversion circuit converts a monitor signal and a sensor signal from a physical quantity sensor to a digital monitor signal and a digital sensor signal, respectively. A correction circuit generates a digital correction signal by adjusting the amplitude of the digital monitor signal and the phase difference between the digital monitor signal and the digital sensor signal, and corrects the digital sensor signal using the digital correction signal. A detector circuit detects a physical quantity signal corresponding to the physical quantity given to the physical quantity sensor from the digital sensor signal corrected by the correction circuit.

Claims

1. A physical quantity detection circuit used for a physical quantity sensor that vibrates from self-excitation by application of a drive signal to output a monitor signal responsive to the self-excited vibration and also outputs a sensor signal according to a physical quantity given externally, the circuit comprising:

an analog-to-digital conversion circuit configured to convert the monitor signal and the sensor signal to a digital monitor signal and a digital sensor signal, respectively;

a correction circuit configured to generate a digital correction signal by adjusting the amplitude of the digital monitor signal and the phase difference between the digital monitor signal and the digital sensor signal and correct the digital sensor signal using the digital correction signal; and

a detector circuit configured to detect a physical quantity signal corresponding to the physical quantity from the digital sensor signal corrected by the correction circuit.

2. The physical quantity detection circuit of claim 1, wherein the analog-to-digital conversion circuit selectively executes first analog-to-digital conversion processing of converting the monitor signal to the digital monitor signal and second analog-to-digital conversion processing of converting the sensor signal to the digital sensor signal.

3. The physical quantity detection circuit of claim 2, wherein the correction circuit interpolates digital values of the digital correction signals.

4. The physical quantity detection circuit of claim 2, wherein the analog-to-digital conversion circuit switches between the first analog-to-digital conversion processing and the second analog-to-digital conversion processing in synchronization with a control clock that is based on the drive signal as the frequency reference, and

the detector circuit detects the physical quantity signal from the digital sensor signal corrected by the correction circuit using a detection signal that is based on the drive signal as the frequency reference.

5. The physical quantity detection circuit of claim 1, wherein the analog-to-digital conversion circuit includes:

a first analog-to-digital converter configured to convert the monitor signal to the digital monitor signal; and

a second analog-to-digital converter configured to convert the sensor signal to the digital sensor signal.

6. The physical quantity detection circuit of claim 1, wherein the detector circuit includes:

a detection signal generator configured to generate a digital detection signal in synchronization with a detection clock that is based on the drive signal as the frequency reference; and

a multiplier configured to multiply the digital sensor signal corrected by the correction circuit by the digital detection signal generated by the detection signal generator to thereby detect the physical quantity signal.

7. The physical quantity detection circuit of claim 4, wherein the detector circuit includes:

a detection signal generator configured to generate a digital detection signal in synchronization with a detection clock that is based on the drive signal as the frequency reference; and

a multiplier configured to multiply the digital sensor signal corrected by the correction circuit by the digital detection signal generated by the detection signal generator to thereby detect the physical quantity signal, and

the frequency of the control clock is at least twice as high as the frequency of the detection clock.

8. The physical quantity detection circuit of claim 1, wherein the detector circuit includes:

a digital-to-analog converter configured to convert the digital sensor signal corrected by the correction circuit to an analog sensor signal; and

an analog detector configured to synchronously detect the physical quantity signal from the analog sensor signal obtained by the digital-to-analog converter with an analog detection signal that is based on the drive signal as the frequency reference.

9. A physical quantity sensor device comprising:

a physical quantity sensor configured to vibrate from self-excitation by application of a drive signal to output a monitor signal responsive to the self-excited vibration, and also output a sensor signal according to a physical quantity given externally;

a drive circuit configured to control the drive signal based on the monitor signal from the physical quantity sensor; and

the physical quantity detection circuit of claim 1.