Circuit device and physical quantity detection device

Abstract

The invention relates to a circuit device and a physical quantity detection device. A circuit device is provided with: a drive circuit that drives a drive unit of a physical quantity detection element and generates a periodic signal on the basis of a signal output from the drive unit; a detection circuit that, on the basis of a signal output from the detection unit of the physical quantity detection element, generates a physical quantity detection signal corresponding to the physical quantity detected by the detection unit; and a band-pass filter circuit to which the periodic signal is input, the band-pass filter circuit outputting a detection signal by digital processing, the detection circuit including: an analog front end that amplifies the signal output from the detection unit; an A / D conversion circuit that converts a signal output from the analog front end into a digital signal; and a demodulation circuit that demodulates a physical quantity signal included in the digital signal output from the A / D conversion circuit on the basis of the detection signal, and the detection circuit generates a physical quantity detection signal on the basis of the demodulated physical quantity signal.

Description

Technical Field

[0001] This invention relates to circuit devices and physical quantity detection devices. Background Technology

[0002] Currently, various systems and electronic devices widely utilize devices capable of detecting various physical quantities, such as gyroscopes for detecting angular velocity and accelerometers for detecting acceleration. For example, Patent Document 1 describes a detection device comprising: an amplification circuit for amplifying a detection signal from an oscillator; a filtering unit for filtering the amplified detection signal; and an A / D conversion unit for sampling and holding the filtered detection signal based on a sample-and-hold signal obtained from a drive signal, and performing A / D conversion on the sample-and-hold signal. The filtering unit includes a bandpass filter having frequency characteristics that remove frequency components of unwanted signals and allow frequency components of the desired signal to pass through. According to the detection device described in Patent Document 1, unwanted signals can be removed by the bandpass filter before the sample-and-hold and A / D conversion stages, thus improving the signal-to-noise ratio (S / N ratio).

[0003] Patent Document 1: Japanese Patent Application Publication No. 2008-224230

[0004] However, in the detection device described in Patent Document 1, when the frequency of the drive signal is set to, for example, 50 kHz, the detection signal from the oscillator is modulated at 50 kHz, so the bandpass filter needs to ensure a pass-through region with a center frequency of 50 kHz. On the other hand, in order to meet the requirement of further low noise of the detection signal, the bandpass filter needs to ensure sufficient attenuation at 150 kHz so that noise does not fold back into the signal band due to the third harmonic included in the sample-and-hold signal.

[0005] However, when constructing a bandpass filter that meets this condition using analog circuits, the number of filters needs to be increased. In addition, an adjustment circuit is needed to correct the characteristic deviation of the oscillator, so there is a technical problem of increasing the circuit size. Summary of the Invention

[0006] One embodiment of the circuit device involved in this invention is as follows:

[0007] A circuit device is connected to a physical quantity detection element having a driving section and a detection section, the circuit device comprising:

[0008] A driving circuit drives the driving unit and generates a periodic signal based on the signal output from the driving unit;

[0009] The detection circuit generates a physical quantity detection signal corresponding to the physical quantity detected by the detection unit, based on the signal output from the detection unit; and

[0010] A bandpass filter circuit is provided, to which the periodic signal is input, and which outputs a detector signal after digital processing.

[0011] The detection circuit includes:

[0012] The analog front end amplifies the signal output from the detection unit;

[0013] An A / D conversion circuit converts the signal output from the analog front end into a digital signal; and

[0014] The demodulation circuit, based on the detected signal, demodulates the physical quantity signals included in the digital signal output from the A / D conversion circuit.

[0015] The detection circuit generates the physical quantity detection signal based on the demodulated physical quantity signal.

[0016] Another embodiment of the circuit device involved in this invention is,

[0017] A circuit device is connected to a physical quantity detection element having a driving section and a detection section, the circuit device comprising:

[0018] A driving circuit drives the driving unit and generates a periodic signal based on the signal output from the driving unit; and

[0019] The detection circuit generates a physical quantity detection signal corresponding to the physical quantity detected by the detection unit, based on the signal output from the detection unit.

[0020] The detection circuit includes:

[0021] The analog front end amplifies the signal output from the detection unit;

[0022] The A / D conversion circuit converts the signal output from the analog front end into a digital signal;

[0023] A bandpass filter circuit, wherein the digital signal output from the A / D conversion circuit is input to the bandpass filter circuit; and

[0024] The demodulation circuit uses the periodic signal as a detection signal and, based on the detection signal, demodulates the physical quantity signals included in the signal output from the bandpass filter circuit.

[0025] The detection circuit generates the physical quantity detection signal based on the demodulated physical quantity signal.

[0026] One aspect of the physical quantity detection device according to the present invention comprises:

[0027] One mode of the circuit device; and

[0028] The physical quantity detection element. Attached Figure Description

[0029] Figure 1 This is a functional block diagram of the physical quantity detection device of the first embodiment.

[0030] Figure 2 This is a top view of the vibrating plate of the physical quantity detection element.

[0031] Figure 3 It is a diagram used to illustrate the operation of a physical quantity detection element.

[0032] Figure 4 It is a diagram used to illustrate the operation of a physical quantity detection element.

[0033] Figure 5 This is a diagram showing an example of the structure of a drive circuit.

[0034] Figure 6 This is a diagram illustrating an example of the structure of an analog front-end and demodulation circuit.

[0035] Figure 7 This is a functional block diagram of the physical quantity detection device according to the second embodiment.

[0036] Figure 8 This is a diagram illustrating an example of the structure of an analog front-end and demodulation circuit.

[0037] Figure 9 This is a functional block diagram of the physical quantity detection device in the third embodiment.

[0038] Figure 10 This is a functional block diagram of the physical quantity detection device in the modified example. Detailed Implementation

[0039] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that the embodiments described below do not unduly limit the scope of the invention as defined in the claims. Furthermore, the structures described below are not necessarily all essential components of the present invention.

[0040] The following explanation will take an angular velocity detection device as an example, which is a physical quantity detection device that detects angular velocity as a physical quantity.

[0041] 1. First Implementation Method

[0042] 1-1. Structure of a physical quantity detection device

[0043] Figure 1 This is a functional block diagram of the physical quantity detection device according to the first embodiment. For example...Figure 1 As shown, the physical quantity detection device 1 of the first embodiment includes: a physical quantity detection element 100 for detecting physical quantities; and a circuit device 200 connected to the physical quantity detection element 100. The circuit device 200 is implemented, for example, by a single-chip integrated circuit. In addition, the physical quantity detection element 100 and the circuit device 200 are housed in a package such as a ceramic package (not shown).

[0044] The circuit device 200 has DS, DG, S1, S2, SS, SCK, SI, and SO terminals as external connection terminals. The DS, DG, S1, and S2 terminals are electrically connected to the physical quantity detection element 100. Additionally, the SS, SCK, SI, and SO terminals are electrically connected to the external device MCU5 of the circuit device 200. MCU is short for Micro Control Unit.

[0045] The physical quantity sensing element 100 has a vibrating plate configured with a drive electrode and a detection electrode. Generally, in order to minimize the impedance of the vibrating plate and improve the oscillation efficiency, the vibrating plate is sealed in a hermetically sealed package. In this embodiment, the physical quantity sensing element 100 has a so-called double-T type vibrating plate, which has two T-shaped drive vibrating arms.

[0046] Figure 2 This is a top view of the vibrating plate of the physical quantity detection element 100. The physical quantity detection element 100 has a vibrating plate made of crystal (SiO2). Crystal vibrating plates have the advantage of improving the detection accuracy of angular velocity because their resonant frequency changes very little with temperature variations. The physical quantity detection element 100, for example, has a double-T-shaped crystal vibrating plate formed by a Z-cut crystal substrate. It should be noted that... Figure 2 The X, Y, and Z axes in the diagram represent the axes of the crystal.

[0047] like Figure 2 As shown, the physical quantity detection element 100 includes: a drive unit 100a; a detection unit 100b; and a plurality of connecting arms 105a and 105b connecting the detection unit 100b and the drive unit 100a. The detection unit 100b includes: a detection base 107; and a plurality of detection vibration arms 102 extending from the detection base 107. The drive unit 100a includes: drive bases 104a and 104b, respectively connected to the detection base 107 via the plurality of connecting arms 105a and 105b; a plurality of drive vibration arms 101a extending from the drive base 104a; and a plurality of drive vibration arms 101b extending from the drive base 104b.

[0048] More specifically, the driving vibrating arms 101a and 101b of the vibrating plate of the physical quantity detection element 100 extend from the two driving bases 104a and 104b along the +Y axis and -Y axis directions, respectively. Driving electrodes 112 and 113 are formed on the side and upper surfaces of the driving vibrating arm 101a, respectively, and driving electrodes 113 and 112 are formed on the side and upper surfaces of the driving vibrating arm 101b, respectively. The driving electrodes 112 and 113 are respectively connected to… Figure 1 The DG and DS terminals of the circuit device 200 shown are connected.

[0049] The driving bases 104a and 104b are connected to the rectangular detection base 107 via connecting arms 105a and 105b extending along the -X-axis and +X-axis directions, respectively.

[0050] The detection vibrating arm 102 extends from the detection base 107 along the +Y axis and -Y axis directions. Detection electrodes 114 and 115 are formed on the upper surface of the detection vibrating arm 102, and a common electrode 116 is formed on the side surface of the detection vibrating arm 102. The detection electrodes 114 and 115 are respectively connected to... Figure 1 The S1 and S2 terminals of the circuit device 200 shown are connected. In addition, the common electrode 116 is grounded.

[0051] When an AC voltage is applied as a driving signal between the driving electrodes 112 and 113 of the driving vibrating arms 101a and 101b, such as Figure 3 As shown, due to the inverse piezoelectric effect, the driving vibration arms 101a and 101b undergo repeated bending vibrations, as indicated by arrow B, with their front ends repeatedly approaching and separating from each other. The frequency of this bending vibration is approximately the same as the resonant frequency of the driving vibration arms 101a and 101b.

[0052] In this state, when an angular velocity with the Z-axis as the rotation axis is applied to the vibrating plate of the physical quantity detection element 100, the driving vibrating arms 101a and 101b obtain a Coriolis force in both the direction of bending vibration (arrow B) and the Z-axis. The result is as follows: Figure 4 As shown, connecting arms 105a and 105b vibrate as indicated by arrow C. Additionally, the detection vibrating arm 102, in conjunction with the vibrations of connecting arms 105a and 105b, undergoes bending vibration as indicated by arrow D. The frequency of this bending vibration is consistent with the frequency of the bending vibrations of the driving vibrating arms 101a and 101b. Accompanying this Coriolis force, the bending vibrations of the detection vibrating arm 102 and the bending vibrations of the driving vibrating arms 101a and 101b are phase-shifted by 90°.

[0053] Furthermore, through the piezoelectric effect, alternating current charges based on these bending vibrations are generated in the detection electrodes 114 and 115 of the detection arm 102. Here, the alternating current charges generated based on the Coriolis force vary according to the magnitude of the Coriolis force, in other words, according to the magnitude of the angular velocity applied to the physical quantity detection element 100.

[0054] It should be noted that a rectangular counterweight 103, wider than the driving vibration arms 101a and 101b, is formed at the front end of each driving vibration arm 101a and 101b. By forming the counterweight 103 at the front end of the driving vibration arms 101a and 101b, the Coriolis force can be increased, and the desired resonant frequency can be obtained with a relatively short vibration arm. Similarly, a counterweight 106, wider than the detection vibration arm 102, is formed at the front end of the detection vibration arm 102. By forming the counterweight 106 at the front end of the detection vibration arm 102, the alternating current charge generated in the detection electrodes 114 and 115 can be increased.

[0055] As described above, the physical quantity detection element 100 uses the Z-axis as the detection axis and outputs an alternating charge, i.e., an angular velocity signal based on the Coriolis force, via the detection electrodes 114 and 115.

[0056] return Figure 1 As described above, the circuit device 200 includes a drive circuit 10, a detection circuit 20, a bandpass filter circuit 30, an oscillation circuit 40, an interface circuit 50, and a storage unit 60. It should be noted that the circuit device 200 may also have a structure that omits or modifies some of these elements, or adds other elements.

[0057] The drive circuit 10 drives the drive section 100a of the physical quantity detection element 100 and generates a periodic signal SX based on the signal output from the drive section 100a. Specifically, the drive circuit 10 applies a drive signal DRV to the drive electrode 113 of the physical quantity detection element 100 via the DS terminal, and the physical quantity detection element 100 is excited to vibrate by the drive signal DRV. In addition, the drive circuit 10 receives an oscillating current generated in the drive electrode 112 by the excitation vibration of the physical quantity detection element 100 via the DG terminal, and the drive circuit 10 performs feedback control on the amplitude level of the drive signal DRV to keep the amplitude of the oscillating current constant. Furthermore, the drive circuit 10 generates a periodic signal SX with the same phase as the drive signal DRV and outputs it to the bandpass filter circuit 30. Details about the drive circuit 10 will be described below.

[0058] The bandpass filter circuit 30 is a digital filter that takes a periodic signal SX as input and outputs a detector signal SDT through digital processing. Since the periodic signal SX is a rectangular wave signal, it includes odd-order harmonics along with the fundamental frequency. The bandpass filter circuit 30 allows the fundamental frequency of the periodic signal SX to pass through, while sufficiently attenuating the odd-order harmonics. For example, if the fundamental frequency is 50kHz, the frequency of the third harmonic is 150kHz, so the bandpass filter circuit 30 is a digital filter that includes 50kHz in the pass region and has a cutoff frequency lower than 150kHz on the high-frequency side.

[0059] The detection circuit 20 generates an angular velocity detection signal SDO corresponding to the angular velocity detected by the detection unit 100b based on the signal output from the detection unit 100b of the physical quantity detection element 100. Specifically, the detection circuit 20 generates an angular velocity detection signal SDO as a digital signal based on the signals output from the detection electrodes 114 and 115 of the physical quantity detection element 100, and outputs the generated angular velocity detection signal SDO to the interface circuit 50.

[0060] like Figure 1 As shown, the detection circuit 20 includes an analog front-end 21, an A / D conversion circuit 22, a demodulation circuit 23, and a correction circuit 24.

[0061] The analog front end 21 amplifies the signal output from the detection section 100b of the physical quantity detection element 100. Specifically, the analog front end 21 differentially amplifies the two signals output from the detection electrodes 114 and 115 of the physical quantity detection element 100 and outputs an amplified signal SAO as an analog signal.

[0062] The A / D conversion circuit 22 converts the amplified signal SAO output from the analog front-end 21 into a digital signal ADO. The A / D conversion circuit 22 can also be a Δ-Σ type A / D conversion circuit that outputs a 1-bit digital signal ADO. Through the noise shaping effect of the Δ-Σ type A / D conversion circuit, the noise in the signal frequency band included in the digital signal ADO can be reduced.

[0063] The demodulation circuit 23 demodulates the physical quantity signal, namely the angular velocity signal AVO, included in the digital signal ADO output from the A / D conversion circuit 22, based on the detector signal SDT output from the bandpass filter circuit 30. In this embodiment, the demodulation circuit 23 uses the digital signal ADO output from the A / D conversion circuit 22 as the detected signal, and mixes the digital signal ADO and the detector signal SDT to demodulate the angular velocity signal AVO.

[0064] The calibration circuit 24 performs various calibration processes on the angular velocity signal AVO, including low-pass filtering, offset correction, temperature correction, and sensitivity correction. The signal obtained through the processing of the calibration circuit 24 is used as the physical quantity detection signal, namely the angular velocity detection signal SDO, and is output from the detection circuit 20 to the interface circuit 50.

[0065] Thus, the detection circuit 20 generates an angular velocity detection signal SDO based on the angular velocity signal AVO, which has been demodulated by the demodulation circuit 23. It should be noted that, alternatively, the detection circuit 20 can output the angular velocity signal AVO itself as the angular velocity detection signal SDO via the interface circuit 50 to the MCU5, where the MCU5 performs low-pass filtering and various correction processes on the angular velocity detection signal SDO.

[0066] The bandpass filter circuit 30, demodulation circuit 23, and correction circuit 24 are digital circuits that operate synchronously with the master clock signal MCLK. At least some of the functions of the bandpass filter circuit 30, demodulation circuit 23, and correction circuit 24 can also be implemented using a DSP (Digital Signal Processor).

[0067] The storage unit 60 has a non-volatile memory (not shown) that stores various fine-tuning data for the drive circuit 10 and the detection circuit 20. The non-volatile memory can be configured as, for example, a MONOS-type memory or an EEPROM. MONOS is short for Metal Oxide Nitride Oxide Silicon. EEPROM is short for Electrically Erasable Programmable Read-Only Memory. Furthermore, the storage unit 60 can also be configured to have a register (not shown) in which, when the power supply to the circuit device 200 is turned on, i.e., when the voltage at the VDD terminal rises from 0V to a desired voltage, various fine-tuning data stored in the non-volatile memory are transferred to and held in the register, and the fine-tuning data held in the register is supplied to the drive circuit 10 and the detection circuit 20.

[0068] The oscillation circuit 40 generates the master clock signal MCLK and supplies it to the A / D conversion circuit 22, the demodulation circuit 23, the correction circuit 24, and the bandpass filter circuit 30. The oscillation circuit 40 can also generate the master clock signal MCLK, for example, through a ring oscillator or a CR oscillation circuit.

[0069] The interface circuit 50 processes the angular velocity detection signal SDO output from the detection circuit 20 to the MCU5 according to the request from the MCU5, which is an external device of the circuit device 200.

[0070] In addition, the interface circuit 50 performs the following processes according to the request from the MCU5: reading data stored in the non-volatile memory and registers of the storage unit 60 and outputting it to the MCU5; and writing data input from the MCU5 into the non-volatile memory and registers of the storage unit 60.

[0071] Interface circuit 50, for example, is an interface circuit for the SPI bus. The select signal, clock signal, and data signal sent from MCU5 are input via the SS terminal, SCK terminal, and SI terminal of circuit device 200, respectively, and the data signal is output to MCU5 via the SO terminal of circuit device 200. SPI is short for Serial Peripheral Interface. It should be noted that interface circuit 50 can also interface with various buses other than the SPI bus, such as I... 2 C-bus and corresponding interface circuits. 2 C is short for Inter-Integrated Circuit.

[0072] 1-2. Structure of the driving circuit

[0073] Figure 5 This is a diagram illustrating an example of the structure of the drive circuit 10. (For example...) Figure 5 As shown, the drive circuit 10 includes an I / V conversion circuit 11, a full-wave rectifier circuit 12, an automatic gain control circuit 13, a drive signal generation circuit 14, and a buffer circuit 15.

[0074] The oscillating current generated in the drive electrode 112 by the excitation vibration of the physical quantity detection element 100 is input to the I / V conversion circuit 11 via the DG terminal, and is converted into an AC voltage signal IVO by the I / V conversion circuit 11. The AC voltage signal IVO output from the I / V conversion circuit 11 is input to the full-wave rectifier circuit 12, the drive signal generation circuit 14, and the buffer circuit 15.

[0075] The full-wave rectifier circuit 12 performs full-wave rectification on the AC voltage signal IVO output from the I / V conversion circuit 11, and outputs a DC-converted signal.

[0076] The automatic gain control circuit 13 amplifies the output signal of the full-wave rectifier circuit 12 and outputs a signal with a specified voltage. The automatic gain control circuit 13 controls the amplification gain according to the magnitude of the output signal of the full-wave rectifier circuit 12, so that its output signal is constant under the specified voltage.

[0077] The drive signal generation circuit 14 outputs a drive signal DRV that binarizes the AC voltage signal IVO. The high-level voltage of the drive signal DRV is the voltage of the output signal of the automatic gain control circuit 13, and remains constant under a specified voltage. The drive signal DRV is supplied to the drive electrode 113 of the physical quantity detection element 100 via the DS terminal. By being supplied with the drive signal DRV, the physical quantity detection element 100 can continue to be excited to vibrate. Furthermore, by maintaining the high-level voltage of the drive signal DRV at a constant level, the drive vibration arms 101a and 101b of the physical quantity detection element 100 can obtain a certain vibration velocity. Therefore, the constant vibration velocity, which forms the basis for generating the Coriolis force, allows for more stable sensitivity.

[0078] The buffer circuit 15 receives an AC voltage signal IVO as input and outputs a rectangular wave signal, i.e., a periodic signal SX, that is in phase with the AC voltage signal IVO. The periodic signal SX is supplied to the bandpass filter circuit 30. It should be noted that a filter can also be set between the output of the I / V conversion circuit 11 and the input of the buffer circuit 15.

[0079] 1-3. Structure of Analog Front-End and Demodulation Circuit

[0080] Figure 6 This is a diagram illustrating an example of the structure of the analog front-end 21 and the demodulation circuit 23. (See diagram for example.) Figure 6 As shown, the analog front end 21 includes Q / V conversion circuits 211 and 212 and a differential amplifier circuit 213.

[0081] The alternating current charge generated in the detection electrode 114 of the physical quantity detection element 100 is input to the Q / V conversion circuit 211 via the S1 terminal. In addition, the alternating current charge generated in the detection electrode 115 of the physical quantity detection element 100 is input to the Q / V conversion circuit 212 via the S2 terminal.

[0082] In this embodiment, such as Figure 2 As shown, when an angular velocity is applied to the physical quantity detection element 100, the detection vibrating arm 102 with the detection electrode 114 and the detection vibrating arm 102 with the detection electrode 115 bend and vibrate in opposite directions to achieve balance. Therefore, the angular velocity signal included in the AC charge generated in the detection electrode 114 and the angular velocity signal included in the AC charge generated in the detection electrode 115 are out of phase. Here, the two angular velocity signals being out of phase means not only that the phase difference between the two angular velocity signals is exactly 180°, but also that the phase difference between the two angular velocity signals has a slight difference relative to 180° due to manufacturing errors of the physical quantity detection element 100, errors in the delay time of the signal propagation path, etc.

[0083] Q / V conversion circuit 211 converts the AC charge input from the detection electrode 114 of the physical quantity detection element 100 into an AC voltage signal S1O and outputs it. In addition, Q / V conversion circuit 212 converts the AC charge input from the detection electrode 115 of the physical quantity detection element 100 into an AC voltage signal S2O and outputs it.

[0084] The differential amplifier circuit 213 receives a differential signal pair consisting of the AC voltage signal S1O output from the Q / V conversion circuit 211 and the AC voltage signal S2O output from the Q / V conversion circuit 212. It amplifies the difference between the AC voltage signals S1O and S2O to output an amplified signal SAO. The angular velocity signal included in the amplified signal SAO is approximately in phase with the drive signal DRV, and is modulated at the frequency of the drive signal DRV, for example, tens of kHz.

[0085] The amplified signal SAO is input to the A / D conversion circuit 22. As described above, the A / D conversion circuit 22 converts the amplified signal SAO output from the analog front-end 21 into a digital signal ADO and outputs it to the demodulation circuit 23. For example, the A / D conversion circuit 22 is a Δ-Σ type A / D conversion circuit that operates synchronously with the master clock signal MCLK, outputting a 1-bit digital signal ADO. For example, if the frequency of the master clock signal MCLK is tens of MHz, the noise shaping effect of the Δ-Σ type A / D conversion circuit can effectively reduce the noise included in the signal band of tens of kHz, resulting in a digital signal ADO with significantly reduced noise.

[0086] The demodulation circuit 23 includes a mixer circuit 231. The mixer circuit 231 uses the digital signal ADO output from the A / D conversion circuit 22 as the detected signal and mixes it with the detected signal SDT output from the bandpass filter circuit 30. That is, the mixer circuit 231 outputs a digital signal obtained by multiplying the digital signal ADO and the detected signal SDT. For example, if the digital signal ADO is a 1-bit digital signal and the detected signal SDT is a 16-bit digital signal, the mixer circuit 231 outputs 0 when the value of the digital signal ADO is 0, and the digital value of the detected signal SDT (i.e., a 16-bit digital signal) when the value of the digital signal ADO is 1.

[0087] The angular velocity signal included in the digital signal ADO is approximately in phase with the periodic signal SX. Furthermore, the phase of the detector signal SDT is approximately in phase with the phase of the periodic signal SX. Therefore, the angular velocity signal included in the digital signal ADO is approximately in phase with the detector signal SDT. Consequently, the angular velocity signal included in the digital signal ADO is demodulated by the mixer circuit 231, and the output signal of the mixer circuit 231 is output as the angular velocity signal AVO from the demodulation circuit 23 to the correction circuit 24.

[0088] As described above, the bandpass filter circuit 30 is a digital filter that takes a periodic signal SX as input and outputs a digital signal that sufficiently attenuates the harmonics included in the periodic signal SX. Therefore, as in this embodiment, by using the digital signal output from the bandpass filter circuit 30 as the detector signal SDT, noise in the harmonic band reflected back to the signal band by the mixer circuit 231 can be reduced, so the angular velocity signal AVO is demodulated with high precision. Furthermore, since the bandpass filter circuit 30 is constructed of digital circuitry, it can reduce circuit area and power consumption compared to the case where it is constructed of analog circuitry.

[0089] 1-4. Effects

[0090] In the physical quantity detection device 1 of the first embodiment, the bandpass filter circuit 30 in the circuit device 200 can output a detector signal SDT that sufficiently attenuates the harmonics included in the periodic signal SX. Therefore, when the demodulation circuit 23 demodulates the angular velocity signal AVO based on the detector signal SDT, the high-frequency noise reflected back to the signal band due to the harmonics included in the detector signal SDT is reduced. Furthermore, since the bandpass filter circuit 30 is composed of digital circuitry, it can reduce circuit area and power consumption compared to the case where it is composed of analog circuitry. Therefore, according to the physical quantity detection device 1 of the first embodiment, the noise reduction of the physical quantity detection signal can be achieved while suppressing the increase in the circuit size of the circuit device 200.

[0091] Furthermore, in the physical quantity detection device 1 of the first embodiment, the bandpass filter processing and demodulation processing of the angular velocity signal SDO are performed using digital circuitry in the circuit device 200. Therefore, compared with the prior art that uses analog circuitry for bandpass filter processing and demodulation processing, low-frequency noise such as 1 / f noise generated in the signal band of the angular velocity detection signal SDO can be reduced. Thus, according to the physical quantity detection device 1 of the first embodiment, the angular velocity detection signal SDO can be reduced in noise in the circuit device 200.

[0092] Furthermore, according to the physical quantity detection device 1 of the first embodiment, in the circuit device 200, by setting the A / D conversion circuit 22 as a Δ-Σ type A / D conversion circuit, the noise shaping effect of the Δ-Σ type A / D conversion circuit can be utilized to reduce the noise in the signal band included in the digital signal ADO. Moreover, by setting the A / D conversion circuit 22 as a Δ-Σ type A / D conversion circuit, the digital signal ADO can be set as a 1-bit signal, so the mixer circuit 231 included in the demodulation circuit 23 can be implemented with a simple structure, and the size of the circuit device 200 can be reduced.

[0093] 2. Second Implementation Method

[0094] Hereinafter, with respect to the second embodiment, the same reference numerals will be used to mark the same constituent elements as in the first embodiment, and descriptions that are repeated in the first embodiment will be omitted or simplified. The description will mainly focus on the contents that are different from the first embodiment.

[0095] Figure 7 This is a functional block diagram of the physical quantity detection device 1 according to the second embodiment. For example... Figure 7 As shown, the physical quantity detection device 1 of the second embodiment includes a physical quantity detection element 100 and a circuit device 200. The structure of the physical quantity detection element 100 is the same as that of the first embodiment, so its description is omitted.

[0096] The circuit device 200 includes a drive circuit 10, a detection circuit 20, an oscillation circuit 40, an interface circuit 50, and a storage unit 60. It should be noted that the circuit device 200 may also be a structure that omits or modifies some of these elements, or adds other elements.

[0097] The driving circuit 10 is the same as in the first embodiment, driving the driving section 100a of the physical quantity detection element 100 and generating a periodic signal SX based on the signal output from the driving section 100a. In the second embodiment, the driving circuit 10 outputs the generated periodic signal SX to the demodulation circuit 23 of the detection circuit 20.

[0098] The detection circuit 20 is the same as in the first embodiment, generating an angular velocity detection signal SDO corresponding to the angular velocity detected by the detection unit 100b based on the signal output from the detection unit 100b of the physical quantity detection element 100. For example... Figure 7 As shown, the detection circuit 20 is the same as in the first embodiment, including an analog front-end 21, an A / D conversion circuit 22, a demodulation circuit 23, and a correction circuit 24, and also includes a bandpass filter circuit 25.

[0099] The analog front end 21 amplifies the signal output from the detection section 100b of the physical quantity detection element 100. Specifically, the analog front end 21 differentially amplifies the two signals output from the detection electrodes 114 and 115 of the physical quantity detection element 100 and outputs an analog signal, namely the amplified signal SAO.

[0100] The A / D conversion circuit 22 converts the amplified signal SAO output from the analog front-end 21 into a digital signal ADO. The A / D conversion circuit 22 can also be a Δ-Σ type A / D conversion circuit that outputs a 1-bit digital signal ADO. Through the noise shaping effect of the Δ-Σ type A / D conversion circuit, the noise in the signal frequency band included in the digital signal ADO can be reduced.

[0101] The bandpass filter circuit 25 is a digital filter that takes the digital signal ADO output from the A / D conversion circuit 22 as input and outputs the digital signal BPO through digital processing. Since the signal output from the detection section 100b of the physical quantity detection element 100 is modulated at the frequency of the drive signal DRV, the digital signal ADO is also modulated at that frequency. Because the frequency of the periodic signal SX is the same as the frequency of the drive signal DRV, the bandpass filter circuit 25 has a pass-through region centered on the fundamental frequency of the periodic signal SX, and sufficiently attenuates noise at odd multiples of its frequencies. For example, if the fundamental frequency of the periodic signal SX is 50kHz, then the bandpass filter circuit 25 is a digital filter that includes 50kHz in the pass-through region and has a cutoff frequency on the high-frequency side lower than 150kHz.

[0102] The demodulation circuit 23 uses the periodic signal SX output from the drive circuit 10 as the detection signal, and demodulates the physical quantity signal, namely the angular velocity signal AVO, included in the digital signal BPO output from the bandpass filter circuit 25 based on the periodic signal SX used as the detection signal. In this embodiment, the demodulation circuit 23 uses the digital signal BPO output from the bandpass filter circuit 25 as the detected signal, and mixes the digital signal BPO used as the detected signal and the periodic signal SX used as the detection signal, thereby demodulating the angular velocity signal AVO.

[0103] The calibration circuit 24 performs various calibration processes on the angular velocity signal AVO, including low-pass filtering, offset correction, temperature correction, and sensitivity correction. The signal obtained through the processing of the calibration circuit 24 is used as the physical quantity detection signal, namely the angular velocity detection signal SDO, and is output from the detection circuit 20 to the interface circuit 50.

[0104] Thus, the detection circuit 20 generates an angular velocity detection signal SDO based on the angular velocity signal AVO demodulated by the demodulation circuit 23. It should be noted that the detection circuit 20 can also output the angular velocity signal AVO itself as the angular velocity detection signal SDO through the interface circuit 50 to the MCU5, and the MCU5 performs low-pass filtering and various correction processing on the angular velocity detection signal SDO.

[0105] The structure and processing of the oscillation circuit 40, interface circuit 50, and storage unit 60 are the same as in the first embodiment, so their description is omitted.

[0106] Figure 8 This is a diagram illustrating an example of the structure of the analog front-end 21 and the demodulation circuit 23. (See diagram for example.) Figure 8 As shown, similar to the first embodiment, the analog front end 21 includes Q / V conversion circuits 211 and 212 and a differential amplifier circuit 213.

[0107] The alternating current charge generated in the detection electrode 114 of the physical quantity detection element 100 is input to the Q / V conversion circuit 211 via the S1 terminal, and the Q / V conversion circuit 211 converts the alternating current charge into an alternating current voltage signal S1O and outputs it. Additionally, the alternating current charge generated in the detection electrode 115 of the physical quantity detection element 100 is input to the Q / V conversion circuit 212 via the S2 terminal, and the Q / V conversion circuit 212 converts the alternating current charge into an alternating current voltage signal S2O and outputs it.

[0108] The differential amplifier circuit 213 is input with a differential signal pair consisting of the AC voltage signal S1O output from the Q / V conversion circuit 211 and the AC voltage signal S2O output from the Q / V conversion circuit 212, and the differential amplifier circuit 213 amplifies the difference between the AC voltage signal S1O and the AC voltage signal S2O to output an amplified signal SAO.

[0109] As described above, the A / D conversion circuit 22 converts the amplified signal SAO output from the analog front end 21 into a digital signal ADO, and outputs it to the bandpass filter circuit 25.

[0110] As described above, the bandpass filter circuit 25 is input with the digital signal ADO output from the A / D conversion circuit 22 and outputs the digital signal BPO.

[0111] The demodulation circuit 23 includes a mixer circuit 231. The mixer circuit 231 uses the digital signal BPO output from the bandpass filter circuit 25 as the detected signal and mixes the detected digital signal BPO with the periodic signal SX. That is, the mixer circuit 231 outputs a digital signal obtained by multiplying the digital signal BPO and the periodic signal SX. For example, if the digital signal BPO is a 16-bit digital signal and the periodic signal SX is a 1-bit digital signal, the mixer circuit 231 outputs a 16-bit digital signal that becomes 0 when the value of the periodic signal SX is 0, and becomes the digital value of the digital signal BPO when the value of the periodic signal SX is 1.

[0112] The angular velocity signal included in the digital signal BPO is approximately in phase with the periodic signal SX. Therefore, the angular velocity signal included in the digital signal BPO is demodulated by the mixer circuit 231, and the output signal of the mixer circuit 231 is output from the demodulation circuit 23 to the correction circuit 24 as the angular velocity signal AVO.

[0113] As described above, the bandpass filter circuit 25 is a digital filter that takes the input digital signal ADO as input and outputs the digital signal BPO. The digital signal BPO reduces noise at frequencies that are odd multiples of the fundamental frequency of the periodic signal SX included in the digital signal ADO. Therefore, as in this embodiment, by using the digital signal BPO as the detected signal, the noise in the frequency band of the odd-order harmonics of the periodic signal SX, which is folded back to the signal band by the mixer circuit 231, is almost eliminated, so the angular velocity signal AVO is demodulated with high precision.

[0114] The physical quantity detection device 1 of the second embodiment has the same other structure as the first embodiment, so its description is omitted.

[0115] In the physical quantity detection device 1 of the second embodiment described above, the bandpass filter circuit 25 in the circuit device 200 can output a signal that sufficiently attenuates the high-frequency noise included in the digital signal ADO output from the A / D conversion circuit 22. Therefore, when the demodulation circuit 23 demodulates the angular velocity signal AVO based on the detector signal SDT, the high-frequency noise reflected back to the signal frequency band due to harmonics included in the detector signal SDT can be reduced. Furthermore, since the bandpass filter circuit 25 is composed of digital circuitry, the circuit area and power consumption can be reduced compared to the case where it is composed of analog circuitry. Therefore, according to the physical quantity detection device 1 of the second embodiment, the noise reduction of the physical quantity detection signal can be achieved while suppressing the increase in the circuit size of the circuit device 200. In addition, the physical quantity detection device 1 of the second embodiment can achieve the same effect as the physical quantity detection device 1 of the first embodiment.

[0116] 3. Third Implementation Method

[0117] Hereinafter, regarding the third embodiment, the same reference numerals will be used to mark the same constituent elements as in the first embodiment, and descriptions that are repeated in the first embodiment will be omitted or simplified. The description will mainly focus on the contents that are different from the first embodiment.

[0118] Figure 9 This is a functional block diagram of the physical quantity detection device 1 according to the third embodiment. For example... Figure 9 As shown, the physical quantity detection device 1 of the third embodiment includes a physical quantity detection element 100 and a circuit device 200. The structure of the physical quantity detection element 100 is the same as that of the first embodiment, so its description is omitted.

[0119] The circuit device 200 is the same as in the first embodiment, including a drive circuit 10, a detection circuit 20, a bandpass filter circuit 30, an oscillation circuit 40, an interface circuit 50, and a storage unit 60, as well as a center frequency control circuit 70. It should be noted that the circuit device 200 may also have a structure that omits or modifies some of these elements, or adds other elements. The structure and processing of the drive circuit 10, detection circuit 20, oscillation circuit 40, interface circuit 50, and storage unit 60 are the same as in the first embodiment, therefore their description is omitted.

[0120] The bandpass filter circuit 30 operates synchronously with the master clock signal MCLK. Therefore, when the frequency of the master clock signal MCLK deviates from the target frequency, the center frequency of the bandpass filter circuit 30 is inconsistent with the frequency of the periodic signal SX, potentially preventing the bandpass filter circuit 30 from adequately reducing some of the harmonics included in the periodic signal SX. Therefore, in this embodiment, the center frequency control circuit 70 controls the center frequency of the bandpass filter circuit 30 based on the phase difference between the periodic signal SX and the detector signal SDT. Specifically, the center frequency control circuit 70 increases the center frequency of the bandpass filter circuit 30 when the phase of the detector signal SDT lags behind the phase of the periodic signal SX, and decreases the center frequency of the bandpass filter circuit 30 when the phase of the detector signal SDT leads the phase of the periodic signal SX. As a result, since the center frequency of the bandpass filter circuit 30 is controlled to be consistent with the frequency of the periodic signal SX, the harmonics included in the periodic signal SX are adequately reduced, resulting in a detector signal SDT that is close to a sine wave.

[0121] Therefore, by using the digital signal output from the bandpass filter circuit 30 as the detector signal SDT, the noise in the harmonic band of the signal frequency band folded back to the signal frequency band by the mixer circuit 231 is almost eliminated, so the angular velocity signal AVO is demodulated with high precision.

[0122] The physical quantity detection device 1 of the third embodiment has the same other structure as the first embodiment, so its description is omitted.

[0123] In the physical quantity detection device 1 of the third embodiment described above, even if the periodic signal SX based on the signal output from the drive unit 100a of the physical quantity detection element 100 is not synchronized with the master clock signal MCLK used by the bandpass filter circuit 30 to generate the detection signal SDT, a detection signal SDT synchronized with the periodic signal SX can be obtained. Therefore, according to the physical quantity detection device 1 of the third embodiment, the angular velocity signal AVO is demodulated with high precision by the demodulation circuit 23 in the circuit device 200, so the angular velocity can be detected with high precision.

[0124] 4. Variations

[0125] This invention is not limited to this embodiment, and various modifications can be made within the scope of the spirit of this invention.

[0126] For example, in the physical quantity detection device 1 of the first or third embodiment described above, a bandpass filter circuit 30 is provided after the drive circuit 10; in the physical quantity detection device 1 of the second embodiment described above, a bandpass filter circuit 25 is provided after the A / D conversion circuit 22. However, it is also possible that the physical quantity detection device 1 has both a bandpass filter circuit 30 and a bandpass filter circuit 25 after the A / D conversion circuit 22. In this way, the angular velocity signal AVO is demodulated with higher precision by the demodulation circuit 23.

[0127] Additionally, for example, in the embodiments described above, the master clock signal MCLK is generated internally in the circuit device 200, but it can also be supplied from outside the circuit device 200. As an example, in... Figure 10 In the physical quantity detection device 1 shown, the circuit device 200 has an EXCK terminal for inputting a clock signal as an external connection terminal, and a temperature-compensated crystal oscillator 6 is connected to the EXCK terminal. The temperature-compensated crystal oscillator 6 outputs a clock signal with extremely small frequency deviation independent of temperature. The clock signal output from the temperature-compensated crystal oscillator 6 is input to the circuit device 200 via the EXCK terminal and is supplied as the master clock signal MCLK to the A / D conversion circuit 22, demodulation circuit 23, correction circuit 24, and bandpass filter circuit 30. According to this modified example of the physical quantity detection device 1, since the A / D conversion circuit 22, demodulation circuit 23, correction circuit 24, and bandpass filter circuit 30 operate with the master clock signal MCLK with extremely small frequency deviation, a high-precision angular velocity detection signal SDO can be obtained.

[0128] Furthermore, in the above embodiments, the physical quantity detection device 1 includes a physical quantity detection element 100 that detects angular velocity as a physical quantity, but it may also include a physical quantity detection element that detects physical quantities other than angular velocity. For example, the physical quantity detection device 1 may also include a physical quantity detection element that detects physical quantities such as acceleration, angular acceleration, velocity, and force.

[0129] Furthermore, in the above embodiments, the physical quantity detection device 1 includes one physical quantity detection element, but it may also include multiple physical quantity detection elements. For example, the physical quantity detection device 1 may include multiple physical quantity detection elements, each of which uses any one of two or more mutually orthogonal axes as its detection axis to detect a physical quantity. Alternatively, for example, the physical quantity detection device 1 may include multiple physical quantity detection elements, each of which detects any one of multiple types of physical quantities such as angular velocity, acceleration, angular acceleration, velocity, and force. That is, the physical quantity detection device 1 may also be a composite sensor.

[0130] Furthermore, in the embodiments described above, the example given is a double-T type crystal oscillator for the physical quantity detection element 100. However, the oscillator of the physical quantity detection element for detecting various physical quantities can be, for example, a tuning fork type or a comb type, or a prism, square prism, cylindrical, or other similar shaped oscillator. Additionally, the material of the oscillator for the physical quantity detection element can be piezoelectric materials such as lithium tantalate (LiTaO3), lithium niobate (LiNbO3), or piezoelectric ceramics such as lead zirconate titanate (PZT), instead of crystal (SiO2). Silicon semiconductors can also be used. Furthermore, the oscillator of the physical quantity detection element can also be a structure in which a piezoelectric thin film of zinc oxide (ZnO), aluminum nitride (AlN), etc., held by a driving electrode is disposed on a portion of the surface of a silicon semiconductor. For example, the physical quantity detection element can also be a MEMS element. MEMS is an abbreviation for Micro Electro Mechanical Systems.

[0131] Furthermore, while piezoelectric physical quantity sensing elements have been exemplified in the above embodiments, physical quantity sensing elements for detecting various physical quantities are not limited to piezoelectric elements; they can also be electrostatic capacitive, kinetic, eddy current, optical, strain gauge, or other types of elements. Additionally, the detection method of the physical quantity sensing element is not limited to vibration-based methods; for example, it can also be optical, rotational, or fluid-based methods.

[0132] The above-described embodiments and modifications are examples only and are not limited thereto. For example, the various embodiments and modifications can also be appropriately combined.

[0133] This invention includes structures that are substantially the same as those described in the embodiments, such as structures with the same function, method, and result, or structures with the same purpose and effect. Additionally, this invention includes structures that replace non-essential parts of the structures described in the embodiments. Furthermore, this invention includes structures that achieve the same effect as those described in the embodiments or that can achieve the same purpose. Additionally, this invention includes structures incorporating known techniques into the structures described in the embodiments.

[0134] The following can be derived from the above implementation methods and variations.

[0135] One way to configure the circuit is as follows:

[0136] A circuit device is connected to a physical quantity detection element having a driving section and a detection section, the circuit device comprising:

[0137] A driving circuit drives the driving unit and generates a periodic signal based on the signal output from the driving unit;

[0138] The detection circuit generates a physical quantity detection signal corresponding to the physical quantity detected by the detection unit, based on the signal output from the detection unit; and

[0139] A bandpass filter circuit is provided, to which the periodic signal is input, and which outputs a detector signal after digital processing.

[0140] The detection circuit includes:

[0141] The analog front end amplifies the signal output from the detection unit;

[0142] An A / D conversion circuit converts the signal output from the analog front end into a digital signal; and

[0143] The demodulation circuit, based on the detected signal, demodulates the physical quantity signals included in the digital signal output from the A / D conversion circuit.

[0144] The detection circuit generates the physical quantity detection signal based on the demodulated physical quantity signal.

[0145] In this circuit arrangement, since the bandpass filter circuit can output a detected signal that sufficiently attenuates the harmonics included in the periodic signal, the high-frequency noise reflected back to the signal band due to the harmonics included in the detected signal can be reduced when the demodulation circuit demodulates the physical quantity signal based on the detected signal. Furthermore, since the bandpass filter circuit is constructed from digital circuitry, it reduces circuit area and power consumption compared to cases constructed from analog circuitry. Therefore, according to this circuit arrangement, low-noise physical quantity detection signals can be achieved while suppressing the increase in circuit size.

[0146] Furthermore, in this circuit device, since bandpass filtering and demodulation of the physical quantity signal are performed using digital circuits, low-frequency noise such as 1 / f noise generated in the signal band can be reduced compared to existing techniques that use analog circuits for bandpass filtering and demodulation. Therefore, according to this circuit device, low-noise processing of the physical quantity detection signal can be achieved.

[0147] Alternatively, in one embodiment of the circuit arrangement,

[0148] The demodulation circuit includes a mixer circuit, which uses the digital signal output from the A / D conversion circuit as the detected signal and mixes the detected signal and the detected signal.

[0149] Another way to make a circuit device is,

[0150] A circuit device is connected to a physical quantity detection element having a driving section and a detection section, the circuit device comprising:

[0151] A driving circuit drives the driving unit and generates a periodic signal based on the signal output from the driving unit; and

[0152] The detection circuit generates a physical quantity detection signal corresponding to the physical quantity detected by the detection unit, based on the signal output from the detection unit.

[0153] The detection circuit includes:

[0154] The analog front end amplifies the signal output from the detection unit;

[0155] The A / D conversion circuit converts the signal output from the analog front end into a digital signal;

[0156] A bandpass filter circuit, wherein the digital signal output from the A / D conversion circuit is input to the bandpass filter circuit; and

[0157] The demodulation circuit uses the periodic signal as a detection signal and, based on the detection signal, demodulates the physical quantity signals included in the signal output from the bandpass filter circuit.

[0158] The detection circuit generates the physical quantity detection signal based on the demodulated physical quantity signal.

[0159] In this circuit arrangement, because the bandpass filter circuit can output a signal that sufficiently attenuates the high-frequency noise included in the digital signal output from the A / D conversion circuit, the high-frequency noise reflected back to the signal band due to harmonics included in the detected signal can be reduced when the demodulation circuit demodulates the physical quantity signal based on the detected signal. Furthermore, since the bandpass filter circuit is constructed from digital circuitry, it reduces circuit area and power consumption compared to cases constructed from analog circuitry. Therefore, according to this circuit arrangement, low-noise reduction of the physical quantity detection signal can be achieved while suppressing the increase in circuit size.

[0160] Furthermore, in this circuit device, since bandpass filtering and demodulation of the physical quantity signal are performed using digital circuits, low-frequency noise such as 1 / f noise generated in the signal band can be reduced compared to existing techniques that use analog circuits for bandpass filtering and demodulation. Therefore, according to this circuit device, low-noise processing of the physical quantity detection signal can be achieved.

[0161] Alternatively, in one embodiment of the circuit arrangement,

[0162] The demodulation circuit includes a mixer circuit, which uses the signal output from the bandpass filter circuit as the detected signal and mixes the detected signal and the detected signal.

[0163] Alternatively, one embodiment of the circuit device is as follows:

[0164] The circuit device includes a center frequency control circuit, which controls the center frequency of the bandpass filter circuit based on the phase difference between the periodic signal and the detected signal.

[0165] In this circuit arrangement, even if the periodic signal based on the signal output from the drive unit is out of sync with the clock signal used by the bandpass filter circuit to generate the detection signal, a detection signal synchronized with the periodic signal can still be obtained. Therefore, according to this circuit arrangement, the physical quantity signal is demodulated with high precision by the demodulation circuit, thus enabling high-precision detection of the physical quantity.

[0166] Alternatively, in one embodiment of the circuit arrangement,

[0167] The A / D conversion circuit is a Δ-Σ type A / D conversion circuit.

[0168] According to this circuit arrangement, the noise shaping effect of the Δ-Σ type A / D conversion circuit can reduce the noise in the signal band included in the digital signal output from the A / D conversion circuit. Furthermore, since this circuit arrangement can make the digital signal output from the A / D conversion circuit a 1-bit signal, the demodulation circuit can be implemented with a simple structure, achieving a smaller size.

[0169] One type of physical quantity detection device is one that includes:

[0170] One mode of the circuit device; and

[0171] The physical quantity detection element.

[0172] In this physical quantity detection device, the bandpass filter circuit in the circuitry can output a detected signal that sufficiently attenuates the harmonics included in the periodic signal, or a signal that sufficiently attenuates the high-frequency noise included in the digital signal output from the A / D conversion circuit. Therefore, when the demodulation circuit demodulates the physical quantity signal based on the detected signal, the high-frequency noise reflected back to the signal band can be reduced by removing the harmonics included in the detected signal. Furthermore, since the bandpass filter circuit is composed of digital circuitry, it can reduce circuit area and power consumption compared to the case where it is composed of analog circuitry. Therefore, according to this physical quantity detection device, it is possible to achieve low noise in the physical quantity detection signal while suppressing the increase in the circuit size of the circuitry.

[0173] Furthermore, in this physical quantity detection device, digital circuitry is used for bandpass filtering and demodulation of the physical quantity signal. Therefore, compared to existing technologies that use analog circuitry for bandpass filtering and demodulation, low-frequency noise such as 1 / f noise generated in the signal band can be reduced. Thus, this physical quantity detection device can achieve low-noise processing of the physical quantity detection signal.

Claims

1. A circuit device, characterized in that, The circuit device is connected to a physical quantity detection element including a driving unit and a detection unit, and the circuit device includes: A driving circuit drives the driving unit and generates a periodic signal based on the signal output from the driving unit; The detection circuit generates a physical quantity detection signal corresponding to the physical quantity detected by the detection unit, based on the signal output from the detection unit; and A bandpass filter circuit is provided, to which the periodic signal is input, and which outputs a detector signal after digital processing. The detection circuit includes: The analog front end amplifies the signal output from the detection unit; An A / D conversion circuit converts the signal output from the analog front end into a digital signal; and The demodulation circuit, based on the detected signal, demodulates the physical quantity signals included in the digital signal output from the A / D conversion circuit. The detection circuit generates the physical quantity detection signal based on the demodulated physical quantity signal.

2. The circuit device according to claim 1, characterized in that, The demodulation circuit includes a mixer circuit, which uses the digital signal output from the A / D conversion circuit as the detected signal and mixes the detected signal and the detected signal.

3. A circuit device, characterized in that, The circuit device is connected to a physical quantity detection element having a driving section and a detection section, and the circuit device includes: A driving circuit drives the driving unit and generates a periodic signal based on the signal output from the driving unit; and The detection circuit generates a physical quantity detection signal corresponding to the physical quantity detected by the detection unit, based on the signal output from the detection unit. The detection circuit includes: The analog front end amplifies the signal output from the detection unit; The A / D conversion circuit converts the signal output from the analog front end into a digital signal; A bandpass filter circuit, wherein the digital signal output from the A / D conversion circuit is input to the bandpass filter circuit; and The demodulation circuit uses the periodic signal as a detection signal and, based on the detection signal, demodulates the physical quantity signals included in the signal output from the bandpass filter circuit. The detection circuit generates the physical quantity detection signal based on the demodulated physical quantity signal.

4. The circuit device according to claim 3, characterized in that, The demodulation circuit includes a mixer circuit, which uses the signal output from the bandpass filter circuit as the detected signal and mixes the detected signal and the detected signal.

5. The circuit device according to claim 1, characterized in that, The circuit device includes a center frequency control circuit, which controls the center frequency of the bandpass filter circuit based on the phase difference between the periodic signal and the detected signal.

6. The circuit device according to claim 1, characterized in that, The A / D conversion circuit is a Δ-Σ type A / D conversion circuit.

7. A physical quantity detection device, characterized in that, include: The circuit device according to any one of claims 1 to 6; as well as The physical quantity detection element.

Images