JP2008175805A - Vibration gyro sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a precise vibration gyro sensor not superposed with a direct current even when a noise of the frequency component same to that of an electric power source voltage exists. <P>SOLUTION: This vibration gyro sensor 2 including a vibrating element 10, drive electrodes 36A, 36B, detecting electrodes 38A, 38B, a monitor circuit 12, a drive circuit 14, an amplitude regulation circuit 16, amplifying circuits 18A, 18B, a differential amplification circuit 20, a synchronous detection circuit 22, a filter circuit 28 for outputting a filtered signal V12, and a ratiometric circuit 30 fluctuated proportionally to fluctuation of the electric power source voltage Vdd to output a sensitivity signal V13, corresponding to the filtered signal V12. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a vibration gyro sensor that detects angular velocity.

  In the car navigation device, when the vehicle position is specified by self-contained navigation, the traveling direction is detected based on the angular velocity information from the gyro sensor. Such a gyro sensor normally outputs an analog signal corresponding to the magnitude of the angular velocity. The analog signal is converted into a digital signal by an A / D converter, and this digital signal is taken into a navigation system and used for arithmetic processing. When an analog signal is converted into a digital signal, the voltage width per resolution or the reference voltage may fluctuate due to fluctuations in the power supply voltage of the A / D converter. For this reason, a gyro sensor having a ratiometric function that makes a detection signal dependent on a power supply voltage has been proposed so that an analog signal output from the gyro sensor also varies depending on the power supply voltage.

  For example, a vibration gyro sensor having a multiplying circuit that amplifies a detection signal in proportion to a power supply voltage makes the detection signal dependent on the power supply voltage instead of a ratiometric function realized by making the power supply voltage dependent on the drive signal. Thus, the dependency accuracy of the power supply voltage due to conversion errors in each of the electro-mechanical and mechanical-electrical conversion processes is prevented from decreasing (for example, refer to Patent Document 1 and Patent Document 2).

JP 2006-10408 A JP 2001-296140 A

However, the detection signal and the power supply voltage include noise having many frequency components. In the multiplication circuit of Patent Document 1, the detection signal is amplified and output in proportion to the divided voltage Ve by the detection signal input from the line and the divided voltage Ve depending on the power supply voltage. From the principle of the multiplication circuit, assuming that the two input signals are the same sinA, sinA × sinA is (1−cos2A) / 2. It is known to produce a signal of Therefore, when the same frequency component is input to the detection signal and the power supply noise, a DC error component is added to the detection signal, and the measurement accuracy is lowered.
Patent Document 2 discloses a configuration in which a filter circuit is provided before the absolute voltage-ratio conversion circuit. However, the absolute voltage-to-ratio conversion circuit disclosed in Patent Document 2 includes a difference voltage between an input signal from a filter and a reference voltage input from an absolute reference voltage circuit, an output voltage of a voltage dividing circuit, and an auxiliary voltage dividing circuit. It is driven by the difference voltage from the output voltage. That is, a differential amplifier circuit that outputs a differential voltage before the circuit that realizes the ratiometric function is required. Therefore, when power supply noise occurs in the circuit that outputs the differential voltage at the latter stage of the filter, the power supply noise of the same frequency component is input to the input signal to the circuit that realizes the ratiometric function and the power supply. The DC error component is added, resulting in a decrease in measurement accuracy.

  The present invention has been made paying attention to such conventional problems, and its purpose is to provide a highly accurate vibration gyro sensor that is not superimposed on direct current even if noise of the same frequency component is present in the power supply voltage. Is to provide.

  Application Example 1 A vibration gyro sensor according to this application example includes a vibration piece, a pair of drive electrodes for driving the vibration piece, and two or more detection electrodes for detecting a Coriolis force applied to the vibration piece. A monitor circuit that is connected to one electrode of the pair of drive electrodes and outputs a monitor signal; a drive circuit that amplifies the monitor signal and outputs it to the other electrode of the pair of drive electrodes; and the vibration A differential amplifier circuit that differentially amplifies two or more signals obtained from one detection electrode and outputs a differential amplified signal, and a synchronization that synchronously detects the differential amplified signal with the monitor signal and outputs a detection signal A detection circuit; a filter circuit that outputs a filter signal from which noise of the detection signal has been removed; and a ratio signal that receives the filter signal and outputs a sensitivity signal in which the filter signal is changed in proportion to a change in power supply voltage. Characterized in that it comprises a Rick circuit.

  According to this configuration, the filter circuit for removing the noise of the detection signal is inserted before the ratiometric circuit. As a result, the detection signal is attenuated by the filter circuit and then input to the ratiometric circuit. Therefore, even if noise of the same frequency component exists in the power supply voltage, a highly accurate vibration gyro sensor is not superimposed on the direct current. realizable.

  Application Example 2 In the vibration gyro sensor according to the application example described above, a power source input to a circuit preceding the filter circuit and a power source input to the ratiometric circuit may be common.

  Application Example 3 In the vibration gyro sensor, the filter circuit may be a passive low-pass filter.

  Application Example 4 In the vibration gyro sensor according to the application example described above, a first power supply circuit that supplies a first power supply to the filter circuit, and a second power supply that supplies a second power supply to the ratiometric circuit. A power supply circuit; a first reference voltage generation circuit that receives the first power supply; supplies a first reference voltage to a circuit preceding the ratiometric circuit; and the second power supply. And a second reference voltage generation circuit that supplies a second reference voltage to the ratiometric circuit.

  In this way, even if power supply noise generated in the filter circuit or power supply noise generated in the ratiometric circuit is generated, the frequency and phase of the noise are different, and thus superposition of power supply noise can be effectively suppressed. .

  Application Example 5 In the vibration gyro sensor according to the application example described above, the filter circuit may be an active low-pass filter driven by the first power source.

  Application Example 6 In the vibration gyro sensor according to the application example described above, the vibration piece may be a WT type vibration piece.

  Application Example 7 In the vibration gyro sensor according to the application example described above, the filter circuit may further include a filter having a filter order of 2 or more.

  Application Example 8 In the vibration gyro sensor according to the application example, the filter circuit may be provided immediately before the ratiometric circuit.

  Application Example 9 In the vibration gyro sensor according to the application example described above, the ratiometric circuit may be a multiplier.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.
(Configuration of vibration gyro sensor)
FIG. 1 is a block diagram showing a circuit configuration of the vibration gyro sensor of the present embodiment. First, the configuration of the vibration gyro sensor will be described with reference to FIG. As shown in FIG. 1, the vibration gyro sensor 2 includes a resonator element 10, a monitor circuit 12, a drive circuit 14, and an amplitude adjustment circuit 16. Further, the vibration gyro sensor 2 includes charge amplifier circuits 18A and 18B as amplifier circuits, a differential amplifier circuit 20, a synchronous detection circuit 22, a smoothing circuit 24, a variable amplifier circuit 26, a filter circuit 28, a ratio, A metric circuit 30 and a reference voltage generation circuit 32 are included.

Here, the configuration of the resonator element will be described with reference to FIG.
FIG. 2 is a plan view showing a resonator element constituting the vibration gyro sensor of the present embodiment.
As shown in FIG. 2, the vibration piece 10 detects a Coriolis force applied to the vibration piece 10 and a pair of drive vibration systems 36 </ b> A and 36 </ b> B including a base 34, a pair of drive electrodes for driving the vibration piece 10. And a pair of detection vibration systems 38A and 38B including two or more detection electrodes. The base 34 has a substantially square shape that is four-fold symmetric about the center of gravity GO of the vibrating piece (the center of gravity when the vibrating piece is not vibrating). The drive vibration systems 36A and 36B and the detection vibration systems 38A and 38B protrude from the sides of the peripheral edge 34a of the base 34, respectively.

  Each of the drive vibration systems 36A and 36B includes a pair of elongate support portions 40A and 40B protruding in the radial direction from the peripheral edge portion 34a of the base portion 34, and a pair of each extending in a direction orthogonal to the longitudinal direction of the support portions 40A and 40B. Drive vibration pieces 42A, 42B, 42C, 42D. In the present embodiment, wide hammer heads (weight portions) 44A, 44B, 44C, and 44D are provided at the tips of the drive vibration pieces, and through holes 46 are provided in the hammer heads 44A, 44B, 44C, and 44D. ing. Although not shown, drive electrodes are provided on the drive vibrating pieces 42A, 42B, 42C, and 42D, respectively.

Each of the detection vibration systems 38A and 38B includes an elongated detection vibration piece 48 extending in a radial direction from the peripheral edge 34a of the base portion 34. Wide hammer heads (weight portions) 50A and 50B are provided at the tips of the detection vibrating pieces 48, and through holes 52 are provided in the hammer heads 50A and 50B. Although not shown, the detection vibrating piece 48 extending from the base 34 to the hammer head 50A and the detection vibrating piece 48 extending from the base 34 to the hammer head 50B are provided with detection electrodes for detecting Coriolis force, respectively. Two or more detection electrodes may be provided.
In the present embodiment, the vibrating piece 10 is a WT type vibrating piece formed of a piezoelectric material such as quartz.

  Next, the operation of the resonator element 10 will be described. Using the drive electrodes, the drive vibration pieces 42A and 42B are excited in the same phase as indicated by arrow A, and the drive vibration pieces 42C and 42D are excited in the same phase as indicated by arrow A. The center of gravity of the drive vibration pieces 42A to 42D in the drive vibration is positioned on or near the center of gravity GO of the vibration piece.

  In this state, when the resonator element 10 is rotated in the ω direction within a predetermined plane (XY plane), Coriolis force acts on the resonator element 10 during the rotation. As a result, the support portions 40A and 40B are As described above, bending vibration is generated with the base 40a to the base 34 as the center. At this time, the phases of the bending vibrations of the support portions 40A and 40B are opposite to each other when viewed in the circumferential direction around the center of gravity GO. Correspondingly, as shown by the arrow C, each detection vibrating piece 48 is flexibly vibrated around the base to the base 34. When each detection vibrating piece 48 is bent and vibrated, a signal voltage is generated at the detection electrode, and the rotational angular velocity is calculated from this signal voltage.

  Preferably, each drive vibration system 36A, 36B is in a rotationally symmetric position about the center of gravity GO. This means that the plurality of drive vibration systems 36A and 36B in question are separated from each other by the same predetermined angle within a predetermined plane with the center of gravity GO as the center. Accordingly, when an operation of rotating one drive vibration system by a predetermined angle within a predetermined plane is performed, the drive vibration system is positioned at the other drive vibration system. For example, in FIG. 2, the drive vibration system 36A and the drive vibration system 36B are separated from each other by 180 °. Therefore, when an operation of rotating the drive vibration system 36A by 180 ° is performed, the drive vibration system 36A comes to the position of the drive vibration system 36B. The rotational symmetry is preferably 2-fold symmetry, 3-fold symmetry, and 4-fold symmetry.

  Next, as shown in FIG. 1, the monitor circuit 12 is connected to the drive electrode of the drive vibration system 36A of the resonator element 10, monitors the potential V1 of the drive vibration system 36A, and outputs a monitor signal V7. The drive circuit 14 is connected to the drive electrode of the drive vibration system 36B of the resonator element 10 and outputs the drive signal V2 from the monitor signal V7. The amplitude adjustment circuit 16 is connected in parallel with the drive circuit 14 and adjusts the amplitude of the drive signal V2 to be constant.

  The charge amplifier circuit 18A is connected to the detection electrode of the detection vibration system 38B of the resonator element 10, amplifies the signal V3, and outputs a detection signal V5. The charge amplifier circuit 18B is connected to the detection electrode of the detection vibration system 38A of the resonator element 10, amplifies the signal V4, and outputs a detection signal V6. The differential amplifier circuit 20 is connected to the charge amplifier circuits 18A and 18B, differentially amplifies the detection signals V5 and V6, and outputs a differential amplified signal V8.

  The synchronous detection circuit 22 is connected to the differential amplifier circuit 20 and the monitor circuit 12, synchronously detects the differential amplified signal V8 with the monitor signal V7, and outputs a detection signal V9.

  The smoothing circuit 24 is connected to the synchronous detection circuit 22, smoothes the detection signal V9, and outputs a smooth signal V10.

  The variable amplification circuit 26 is connected to the smoothing circuit 24, changes the angular velocity sensitivity of the smooth signal V10, and outputs the variable amplification signal V11.

  The filter circuit 28 is connected to the variable amplification circuit 26 and outputs a filter signal V12 from which noise of the variable amplification signal V11 has been removed. The filter circuit 28 is in front of the ratiometric circuit 30. The filter circuit 28 may be located immediately before the ratiometric circuit 30. In the present embodiment, the filter circuit 28 may include an SCF (switched capacitor filter) circuit. The frequency of the SCF circuit may be operated by inputting the monitor signal V7 from the resonator element 10. The filter circuit 28 may include a filter having a filter order of 2 or more.

  The ratiometric circuit 30 is connected to the filter circuit 28 and outputs a sensitivity signal V13 from the power supply voltage Vdd, the reference voltage Vref, and the filter signal V12. The ratiometric circuit 30 is after the filter circuit 28. The ratiometric circuit 30 may be immediately after the filter circuit 28. In the present embodiment, the ratiometric circuit 30 may be a multiplier. According to this configuration, the circuit design can be facilitated by using the multiplier as the ratiometric circuit. The ratiometric circuit 30 may be a Gilbert cell multiplier. According to this configuration, the circuit design can be facilitated by using the Gilbert cell multiplier as the ratiometric circuit. Further, the ratiometric circuit 30 may be a gain control amplifier. According to this configuration, the circuit design can be facilitated by using the gain control amplifier as the ratiometric circuit. Furthermore, the ratiometric circuit 30 may be a current control type amplifier. According to this configuration, the circuit design can be facilitated by using the current control type amplifier as the ratiometric circuit.

  The charge amplifier circuits 18A and 18B, the differential amplifier circuit 20, the synchronous detection circuit 22, the smoothing circuit 24, the variable amplifier circuit 26, the filter circuit 28, and the ratiometric circuit 30 operate at the reference voltage Vref output from the reference voltage generation circuit 32. To do.

(Output signal of vibration gyro sensor)
Here, the output signal of the vibration gyro sensor will be described with reference to FIG.

  FIG. 3 is a graph showing an output signal of the vibration gyro sensor according to the embodiment of the present invention. As shown in FIG. 3, the output signal of the vibration gyro sensor is roughly composed of three signals: a sensitivity signal, a stationary voltage, and an offset voltage.

  The sensitivity signal is generated by the charge amplifier circuits 18A and 18B, the differential amplifier circuit 20, the synchronous detection circuit 22, the smoothing circuit 24, the variable amplifier circuit 26, and the filter circuit 28, and the electric charge generated from the vibrating piece 10 by the Coriolis force. Output as. The voltage at rest is Vdd / 2 of the power supply voltage Vdd or a voltage desired by the user and is a voltage in a state where no angular velocity is applied, and is a reference voltage of the vibration gyro sensor 2. The offset voltage is an offset voltage generated from a leakage signal from the resonator element 10 or an amplifier of the vibration gyro sensor 2, and is a difference between the stationary voltage and the reference voltage.

(Sensitivity signal of ratiometric circuit)
Next, the sensitivity signal of the ratiometric circuit 30 will be described with reference to FIG. As shown in FIG. 1, the reference voltage generation circuit 32 includes resistors R1 and R2.

  The resistors R1 and R2 are connected in series between the power supply voltage Vdd and the ground potential, and the reference voltage Vref, which is the output voltage at the connection point of the resistors R1 and R2, is Vref = Vdd × R2 / (R1 + R2).

  The ratiometric circuit 30 receives the filter signal V12 that is the output voltage of the filter circuit 28 and the reference voltage Vref of the reference voltage generation circuit 32. The ratiometric circuit 30 outputs a sensitivity signal V13.

  The circuit operation reference voltage from the synchronous detection circuit 22 to the ratiometric circuit 30 depends on the power supply voltage Vdd, and the reference voltage (voltage at rest) of the angular velocity output voltage is proportional to the power supply voltage Vdd. The ratiometric circuit 30 uses the reference voltage Vref generated by the reference voltage generation circuit 32 as the amplitude (voltage corresponding to the angular velocity) of the filter signal V12 output from the filter circuit 28 which is the final stage of the signal processing circuit. Change). In this case, since the reference voltage Vref has a value proportional to the power supply voltage Vdd, the amplitude of the sensitivity signal V13 output from the ratiometric circuit 30 also depends on the power supply voltage Vdd. Thus, only the amplification factor of the ratiometric circuit 30 at the final stage of the signal processing circuit depends on the power supply voltage Vdd, and the sensitivity of the sensitivity signal V13 is purely power supply voltage dependent.

  According to the present embodiment, the filter circuit 28 for removing the noise of the variable amplification signal V11 is inserted before (immediately before) the ratiometric circuit 30. As a result, the filter signal V12 input to the ratiometric circuit 30 can be input after the noise is attenuated by the filter circuit 28. Therefore, even if noise of the same frequency component is present in the power supply voltage Vdd, the accuracy is not superimposed on the direct current. High vibration gyro sensor 2 can be realized.

(Comparative example)
As a comparative example of the present invention, consider a case where the connection order of the variable amplifier circuit 26 and the filter circuit 28 is switched. That is, the smoothed signal V10 output from the smoothing circuit 24 is input to the filter circuit 28, the filter signal V12 of the filter circuit 28 is input to the variable amplifier circuit 26, and the variable amplified signal V11 output from the variable amplifier circuit 26 is the ratio. Consider the case of input to the metric circuit 30. In this case, when power supply noise occurs, the variable amplification signal V11 in which noise having the same frequency component as the power supply noise is generated is input to the ratiometric circuit 30 without passing through the filter. In the ratiometric circuit 30, the noise of the variable amplification signal V11 and the power supply noise are superimposed, and a DC error component is added, resulting in a decrease in measurement accuracy.

  As another comparative example, consider a case where the connection order of the filter circuit 28 and the ratiometric circuit 30 is switched. That is, the variable amplified signal V11 output from the variable amplifier circuit 26 is input to the ratiometric circuit 30, the sensitivity signal V13 output from the ratiometric circuit 30 is input to the filter circuit 28, and the filter circuit 28 outputs to the subsequent stage. Consider the configuration to be. Also in this case, since the power supply noise of the variable amplification signal V11 is input to the ratiometric circuit 30 without passing through the filter, the noise of the variable amplification signal V11 and the power supply noise are superimposed in the ratiometric circuit 30. As a result, a DC error component is added to the sensitivity signal V13. Therefore, a filter circuit for removing superimposed noise is required to have high filter characteristics, and the circuit scale of the filter circuit increases. As described above, when the power supply noise is removed from the sensitivity signal V13 on which the power supply noise is superimposed, the circuit scale of the filter circuit 28 needs to be increased.

  On the other hand, in the present embodiment, the filter circuit 28 inserted between the power noise superimpositions generated when the power of the ratiometric circuit 30 and the circuit upstream of the filter circuit 28 (variable amplifier circuit 26) is shared. Effectively suppress. Therefore, the filter circuit 28 is not required to have high filter characteristics. Therefore, for example, a filter having a simple circuit configuration such as the passive low-pass filter circuit shown in FIG. 4A can be used as the filter circuit 28. In the passive low-pass filter circuit, a DC resistor R3 is disposed between the input node (IN) and the output node (OUT), and a capacitor C1 is disposed between the output node (OUT) and the ground. Further, since a passive low-pass filter circuit does not require a power supply circuit, power supply noise hardly occurs in the output filter signal V12. As a result, the superposition of power supply noise in the ratiometric circuit 30 to which the filter signal V12 is input is effectively suppressed.

(Second Embodiment)
Next, a second embodiment will be described with reference to FIG. Here, description of the configuration common to the first embodiment is omitted.
The vibration gyro sensor 2 includes a first reference voltage generation circuit 62, a second reference voltage generation circuit 63, a first power supply circuit 60, and a second power supply circuit 61.

  The first power supply circuit 60 receives the power supply voltage Vdd and outputs a DC supply voltage V14. The supply voltage V14 is supplied to each circuit from the monitor circuit 12, the charge amplifier circuits 18A and 18B to the filter circuit 28, and the first reference voltage generation circuit 62. The first reference voltage generation circuit 62 divides the supply voltage V14 by the resistors R6 and R7, and outputs the first reference voltage Vref1. The charge amplifier circuits 18A and 18B, the differential amplifier circuit 20, the synchronous detection circuit 22, the smoothing circuit 24, the variable amplifier circuit 26, and the filter circuit 28 use the reference voltage Vref1 output from the first reference voltage generation circuit 62 as a reference voltage. Operate.

  The second power supply circuit 61 receives the power supply voltage Vdd and outputs a DC supply voltage V15. The supply voltage V15 is supplied to the ratiometric circuit 30 and the second reference voltage generation circuit 63. The second reference voltage generation circuit 63 divides the supply voltage V15 by resistors R8 and R9 and outputs a second reference voltage Vref2. The ratiometric circuit 30 operates using the reference voltage Vref2 output from the second reference voltage generation circuit 63 as a reference voltage.

  Thus, by dividing the voltage V15 supplied to the ratiometric circuit 30 and the voltage V14 supplied to the preceding circuit, power noise generated in the filter circuit 28 and power generated in the ratiometric circuit 30 are obtained. Even if noise occurs, since the frequency and phase of the noise are different, the superposition of power supply noise can be effectively suppressed. That is, the power supply noise superimposed in the ratiometric circuit 30 can be suppressed.

Further, for example, an active low-pass filter (SCF (switched capacitor filter) circuit) as shown in FIG. In the active low-pass filter, a resistor R4 and an operational amplifier 64 are connected in series between an input node (IN) and an output node (OUT). A feedback resistor R5 and a feedback capacitor C2 are connected in parallel between the output node and the input node of the operational amplifier 64. The operational amplifier 64 is supplied with the supply voltage V14. Generally, the amplification factor (gain) is R5 / R4, and the cutoff frequency is 1 / (2π × C2 × R5).
Here, even if power supply noise occurs in the supply voltage V14, the noise component is different from the power supply noise component generated in the supply voltage V15 supplied to the subsequent ratiometric circuit 30, and therefore, noise superposition is suppressed. be able to.

  In addition, this invention is not limited to embodiment mentioned above, A various deformation | transformation is possible. For example, the present invention includes configurations that are substantially the same as the configurations described in the embodiments (for example, configurations that have the same functions, methods, and results, or configurations that have the same purposes and results). In addition, the invention includes a configuration in which a non-essential part of the configuration described in the embodiment is replaced. In addition, the present invention includes a configuration that exhibits the same operational effects as the configuration described in the embodiment or a configuration that can achieve the same object. In addition, the invention includes a configuration in which a known technique is added to the configuration described in the embodiment. Further, the present invention includes contents excluding any of the technical matters described in the implementation in a limited manner. Or this invention contains the content which excluded the well-known technique limitedly from embodiment mentioned above.

The block diagram which shows the circuit structure of the vibration gyro sensor in 1st Embodiment. FIG. 3 is a plan view showing a resonator element constituting the vibration gyro sensor in the first embodiment. The graph which shows the output signal of the vibration gyro sensor in 1st Embodiment. The figure which shows the filter circuit concerning 1st and 2nd embodiment. The block diagram which shows the circuit structure of the vibration gyro sensor in 2nd Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 2 ... Vibration gyro sensor, 10 ... Vibrating piece, 12 ... Monitor circuit, 14 ... Drive circuit, 16 ... Amplitude adjustment circuit, 18A, 18B ... Charge amplifier circuit (amplifier circuit), 20 ... Differential amplifier circuit, 22 ... Synchronous detection Circuit: 24: Smoothing circuit, 26: Variable amplification circuit, 28: Filter circuit, 30: Ratiometric circuit, 32: Reference voltage generation circuit, 34: Base part, 34a: Peripheral part, 36A, 36B: Drive vibration including drive electrodes System, 38A, 38B ... Detection vibration system including detection electrodes, 40A, 40B ... Supporting part, 40a ... Base, 42A, 42B, 42C, 42D ... Drive vibration piece, 44A, 44B, 44C, 44D ... Hammerhead, 46 ... Through hole 48... Detection vibrating piece 50A, 50B Hammer head 52. Through hole 60. First power circuit 61. Second power circuit 62. Reference voltage generating circuit, 63 ... second reference voltage generating circuit.

Claims (9)

A vibrating piece,
A pair of drive electrodes for driving the resonator element;
Two or more detection electrodes for detecting Coriolis force applied to the vibrating piece;
A monitor circuit connected to one electrode of the pair of drive electrodes and outputting a monitor signal;
A drive circuit for amplifying the monitor signal and outputting the amplified signal to the other electrode of the pair of drive electrodes;
A differential amplifier circuit that differentially amplifies two or more signals obtained from the detection electrodes of the vibration piece and outputs a differential amplified signal;
A synchronous detection circuit for synchronously detecting the differential amplification signal with the monitor signal and outputting a detection signal;
A filter circuit that outputs a filter signal from which noise of the detection signal is removed;
A vibration gyro sensor comprising: a ratiometric circuit that receives the filter signal and outputs a sensitivity signal in which the filter signal is changed in proportion to a change in power supply voltage. The vibration gyro sensor according to claim 1,
A vibration gyro sensor characterized in that a power source input to a circuit preceding the filter circuit and a power source input to the ratiometric circuit are common. The vibration gyro sensor according to claim 2,
The vibration gyro sensor, wherein the filter circuit is a passive low-pass filter. The vibration gyro sensor according to claim 1,
A first power supply circuit for supplying a first power supply to the filter circuit;
A second power supply circuit for supplying a second power supply to the ratiometric circuit;
A first reference voltage generation circuit that receives the first power supply and supplies a first reference voltage to a circuit preceding the ratiometric circuit;
A vibration gyro sensor comprising: a second reference voltage generation circuit that receives the second power supply and supplies a second reference voltage to the ratiometric circuit. The vibration gyro sensor according to claim 4,
The vibration gyro sensor, wherein the filter circuit is an active low-pass filter driven by the first power source. In the vibration gyro sensor according to any one of claims 1 to 5,
A vibration gyro sensor, wherein the vibration piece is a WT type vibration piece. The vibration gyro sensor according to any one of claims 1 to 6,
The vibration gyro sensor, wherein the filter circuit includes a filter having a filter order of 2 or more. In the vibration gyro sensor according to any one of claims 1 to 7,
The vibration gyro sensor according to claim 1, wherein the filter circuit is located immediately before the ratiometric circuit. The vibration gyro sensor according to any one of claims 1 to 8,
A vibration gyro sensor, wherein the ratiometric circuit is a multiplier.

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