Circuit devices and physical quantity detection devices

Abstract

To provide a circuit device that can reduce the noise of physical quantity detection signals while suppressing an increase in circuit size. [Solution] A circuit device comprising: a drive circuit that drives a drive unit of a physical quantity detection element and generates a periodic signal based on a signal output from the drive unit; a detection circuit that generates a physical quantity detection signal corresponding to the physical quantity detected by the detection unit based on a signal output from the detection unit of the physical quantity detection element; and a bandpass filter circuit that receives the periodic signal and outputs a detection signal by digital processing, wherein the detection circuit includes an analog front end that amplifies the signal output from the detection unit, an A / D conversion circuit that converts the signal output from the analog front end into a digital signal, and a demodulation circuit that demodulates the physical quantity signal included in the digital signal output from the A / D conversion circuit based on the detection signal, and generates the physical quantity detection signal based on the demodulated physical quantity signal.

Description

Technical Field

[0001] The present invention relates to a circuit device and a physical quantity detection device.

Background Art

[0002] Currently, in various systems and electronic devices, devices capable of detecting various physical quantities, such as gyro sensors for detecting angular velocity and acceleration sensors for detecting acceleration, are widely used. For example, in Patent Document 1, an amplification circuit that amplifies a detection signal from a vibrator, a filter unit that performs filter processing on the amplified detection signal, and based on a sample hold signal obtained based on a drive signal, sample holds the detection signal after filter processing and performs A / D conversion on the sampled signal. The filter unit includes a band-pass filter having a frequency characteristic that removes frequency components of unnecessary signals and passes frequency components of desired signals. According to the detection device described in Patent Document 1, unnecessary signals can be removed by the band-pass filter at a stage before sample hold and A / D conversion, so that the S / N ratio can be improved. [[ID=​​​​​​​​​​​​​​​​​​​​In the detection device described in Patent Document 1, if the frequency of the drive signal is, for example, 50 kHz, the detection signal from the oscillator is modulated at 50 kHz, so the bandpass filter needs to ensure a passband with a center frequency of 50 kHz. On the other hand, in order to meet the demand for further noise reduction of the detection signal, the bandpass filter needs to ensure sufficient attenuation at 150 kHz to prevent noise from folding back into the signal band due to the third harmonic contained in the sample-and-hold signal. If a bandpass filter that satisfies these conditions is constructed using an analog circuit, the order of the filter needs to be increased, and furthermore, an adjustment circuit is required to compensate for the characteristic variations of the oscillator, which leads to the problem of increased circuit size. [Means for solving the problem]

[0005] One aspect of the circuit device according to the present invention is: A circuit device connected to a physical quantity detection element having a drive unit and a detection unit, A drive circuit that drives the drive unit and generates a periodic signal based on the signal output from the drive unit, A detection circuit that 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, A bandpass filter circuit receives the aforementioned periodic signal and outputs a detected signal through digital processing, Equipped with, The detection circuit is An analog front end that amplifies the signal output from the detection unit, A / D conversion circuit that converts the signal output from the analog front end into a digital signal, A demodulation circuit that demodulates the physical quantity signal included in the digital signal output from the A / D conversion circuit based on the detected signal, The system includes and generates the physical quantity detection signal based on the demodulated physical quantity signal.

[0006] Another aspect of the circuit device according to the present invention is: A circuit device connected to a physical quantity detection element having a drive unit and a detection unit, A drive circuit that drives the drive unit and generates a periodic signal based on the signal output from the drive unit, A detection circuit that 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, Equipped with, The detection circuit is An analog front end that amplifies the signal output from the detection unit, A / D conversion circuit that converts the signal output from the analog front end into a digital signal, A bandpass filter circuit to which the digital signal output from the A / D conversion circuit is input, A demodulation circuit that uses the aforementioned periodic signal as a detected signal and demodulates the physical quantity signal contained in the signal output from the bandpass filter circuit based on the detected signal, The system includes and generates the physical quantity detection signal based on the demodulated physical quantity signal.

[0007] One aspect of the physical quantity detection device according to the present invention is: One embodiment of the aforementioned circuit device, The aforementioned physical quantity detection element, It is equipped with. [Brief explanation of the drawing]

[0008] [Figure 1] Functional block diagram of the physical quantity detection device of the first embodiment. [Figure 2] Plan view of the vibrating element of the physical quantity detection element. [Figure 3] A diagram illustrating the operation of a physical quantity detection element. [Figure 4] A diagram illustrating the operation of a physical quantity detection element. [Figure 5] A diagram showing an example of a drive circuit configuration. [Figure 6] A diagram showing an example configuration of the analog front-end and demodulation circuit. [Figure 7]Functional block diagram of the physical quantity detection device according to the second embodiment. [Figure 8] Diagram showing a configuration example of an analog front end and a demodulation circuit. [Figure 9] Functional block diagram of the physical quantity detection device according to the third embodiment. [Figure 10] Functional block diagram of the physical quantity detection device of a modified example.

Embodiments for Carrying Out the Invention

[0009] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. Note that the embodiments described below do not unduly limit the content of the present invention described in the claims. Also, not all of the configurations described below are essential constituent elements of the present invention.

[0010] Hereinafter, a physical quantity detection device that detects an angular velocity as a physical quantity, that is, an angular velocity detection device will be described as an example.

[0011] 1. First Embodiment 1-1. Configuration of the Physical Quantity Detection Device FIG. 1 is a functional block diagram of the physical quantity detection device according to the first embodiment. As shown in FIG. 1, the physical quantity detection device 1 according to the first embodiment includes a physical quantity detection element 100 that detects a physical quantity, and a circuit device 200 connected to the physical quantity detection element 100. The circuit device 200 is realized by, for example, a one-chip integrated circuit. Further, the physical quantity detection element 100 and the circuit device 200 are housed in a package such as a ceramic package (not shown).

[0012] The circuit device 200 has DS terminals, DG terminals, S1 terminals, S2 terminals, SS terminals, SCK terminals, SI terminals, and SO terminals as external connection terminals. The DS terminals, DG terminals, S1 terminals, and S2 terminals are electrically connected to the physical quantity detection element 100. Also, the SS terminals, SCK terminals, SI terminals, and SO terminals are electrically connected to an MCU 5 which is an external device of the circuit device 200. MCU is an abbreviation for Micro Control Unit.

[0013] The physical quantity detection element 100 has a vibrating piece on which a drive electrode and a detection electrode are arranged. Generally, in order to reduce the impedance of the vibrating piece as much as possible and increase the oscillation efficiency, the vibrating piece is sealed in an airtight package. In this embodiment, the physical quantity detection element 100 has a so-called double T-shaped vibrating piece having two T-shaped drive vibrating arms.

[0014] Figure 2 is a plan view of the vibrating element of the physical quantity detection element 100. The physical quantity detection element 100 has a vibrating element made of quartz (SiO2). Quartz vibrating elements have the advantage of being able to improve the accuracy of angular velocity detection because the fluctuation of the resonant frequency with respect to temperature changes is extremely small. The physical quantity detection element 100 has, for example, a double T-shaped quartz vibrating element formed from a Z-cut quartz substrate. Note that the X, Y, and Z axes in Figure 2 represent the axes of the quartz.

[0015] As shown in Figure 2, the physical quantity detection element 100 includes a drive unit 100a, a detection unit 100b, and a plurality of connecting arms 105a, 105b that connect 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 also includes drive bases 104a, 104b connected to the detection base 107 by the plurality of connecting arms 105a, 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.

[0016] More specifically, the vibrating element of the physical quantity detection element 100 has two drive bases 104a and 104b from which drive vibrating arms 101a and 101b extend in the +Y axis direction and the -Y axis direction, respectively. Drive electrodes 112 and 113 are formed on the side and top surfaces of drive vibrating arm 101a, respectively, and drive electrodes 113 and 112 are formed on the side and top surfaces of drive vibrating arm 101b, respectively. The drive electrodes 112 and 113 are connected to the DG terminal and DS terminal of the circuit device 200 shown in Figure 1, respectively.

[0017] The drive bases 104a and 104b are connected to the rectangular detection base 107 via connecting arms 105a and 105b that extend in the -X axis direction and the +X axis direction, respectively.

[0018] The detection vibration arm 102 extends from the detection base 107 in the +Y axis direction and the -Y axis direction. Detection electrodes 114 and 115 are formed on the upper surface of the detection vibration arm 102, and a common electrode 116 is formed on the side surface of the detection vibration arm 102. The detection electrodes 114 and 115 are connected to terminals S1 and S2 of the circuit device 200 shown in Figure 1, respectively. The common electrode 116 is grounded.

[0019] When an AC voltage is applied as a drive signal between the drive electrodes 112 and 113 of the drive vibrating arms 101a and 101b, as shown in Figure 3, the drive vibrating arms 101a and 101b undergo bending vibrations, as indicated by arrow B, where the tips of the two drive vibrating arms 101a and 101b repeatedly move closer to and further apart from each other. The frequency of this bending vibration is approximately the same as the resonance frequency of the drive vibrating arms 101a and 101b.

[0020] In this state, when an angular velocity with the Z-axis as the axis of rotation is applied to the vibrating piece of the physical quantity detection element 100, the driving vibrating arms 101a and 101b receive a Coriolis force in a direction perpendicular to both the direction of the bending vibration indicated by arrow B and the Z-axis. As a result, as shown in Figure 4, the connecting arms 105a and 105b vibrate as indicated by arrow C. The detection vibrating arm 102 then bends in conjunction with the vibration of the connecting arms 105a and 105b as shown by arrow D. The frequency of this bending vibration matches the frequency of the bending vibration of the driving vibrating arms 101a and 101b. The bending vibration of the detection vibrating arm 102 and the bending vibration of the driving vibrating arms 101a and 101b are out of phase by 90° due to this Coriolis force.

[0021] Then, due to the piezoelectric effect, alternating current charges based on these bending vibrations are generated on the detection electrodes 114 and 115 of the detection vibration arm 102. Here, the alternating current charges generated based on the Coriolis force change according to the magnitude of the Coriolis force, in other words, the magnitude of the angular velocity applied to the physical quantity detection element 100.

[0022] Furthermore, the tips of the drive vibration arms 101a and 101b are formed with rectangular weights 103 that are wider than the drive vibration arms 101a and 101b. By forming weights 103 at the tips of the drive vibration arms 101a and 101b, the Coriolis force is increased and the desired resonance frequency can be obtained with relatively short vibration arms. Similarly, the tip of the detection vibration arm 102 is formed with a weight 106 that is wider than the detection vibration arm 102. By forming a weight 106 at the tip of the detection vibration arm 102, the alternating current charge generated at the detection electrodes 114 and 115 can be increased.

[0023] As described above, the physical quantity detection element 100 outputs an angular velocity signal, which is an alternating current charge based on the Coriolis force, via the detection electrodes 114 and 115, with the Z axis as the detection axis.

[0024] Returning to the description of Figure 1, the circuit device 200 comprises 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. Note that the circuit device 200 may be configured by omitting or changing some of these elements, or by adding other elements.

[0025] The drive circuit 10 drives the drive unit 100a of the physical quantity detection element 100 and generates a periodic signal SX based on the signal output from the drive unit 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, causing the physical quantity detection element 100 to vibrate due to the drive signal DRV. The drive circuit 10 also receives the oscillation current generated at the drive electrode 112 due to the excitation vibration of the physical quantity detection element 100 via the DG terminal and feedback-controls the amplitude level of the drive signal DRV so that the amplitude of this oscillation current remains constant. The drive circuit 10 also generates a periodic signal SX with the same phase as the drive signal DRV and outputs it to the bandpass filter circuit 30. Details of the drive circuit 10 will be described later.

[0026] The bandpass filter circuit 30 is a digital filter that receives a periodic signal SX as input and outputs a detected signal SDT through digital processing. Since the periodic signal SX is a square wave signal, it contains odd-order harmonics along with the fundamental wave. The bandpass filter circuit 30 uses the frequency of the fundamental wave of the periodic signal SX as its center frequency, allowing the fundamental wave to pass through while sufficiently attenuating the odd-order harmonics. For example, if the frequency of the fundamental wave is 50kHz, the frequency of the third harmonic is 150kHz, so the bandpass filter circuit 30 is a digital filter that includes 50kHz in its passband and has a high-frequency cutoff frequency lower than 150kHz.

[0027] 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 the angular velocity detection signal SDO, which is 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.

[0028] As shown in Figure 1, 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.

[0029] The analog front-end 21 amplifies the signal output from the detection unit 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, which is an analog signal.

[0030] 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 may also be a delta-sigma type A / D conversion circuit that outputs a 1-bit digital signal ADO. The noise shaping effect of the delta-sigma type A / D conversion circuit reduces the noise in the signal bandwidth contained in the digital signal ADO.

[0031] The demodulation circuit 23 demodulates the angular velocity signal AVO, which is a physical quantity signal included in the digital signal ADO output from the A / D conversion circuit 22, based on the detected 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 signal to be detected, and demodulates the angular velocity signal AVO by mixing the detected signal ADO with the detected signal SDT.

[0032] The correction circuit 24 performs various correction processes on the angular velocity signal AVO, such as low-pass filtering, offset correction, temperature correction, and sensitivity correction. The signal obtained by the correction circuit 24 is output from the detection circuit 20 to the interface circuit 50 as the angular velocity detection signal SDO, which is a physical quantity detection signal.

[0033] 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. Alternatively, the detection circuit 20 may output the angular velocity signal AVO itself as the angular velocity detection signal SDO to the MCU 5 via the interface circuit 50, and the MCU 5 may perform low-pass filtering and various correction processing on the angular velocity detection signal SDO.

[0034] The bandpass filter circuit 30, demodulation circuit 23, and correction circuit 24 are digital circuits and operate in synchronization 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 may be implemented by a DSP. DSP is an abbreviation for Digital Signal Processor.

[0035] The storage unit 60 has a non-volatile memory (not shown) in which various trimming data for the drive circuit 10 and the detection circuit 20 are stored. The non-volatile memory may be configured as, for example, a MONOS type memory or an EEPROM. MONOS is an abbreviation for Metal Oxide Nitride Oxide Silicon. EEPROM is an abbreviation for Electrically Erasable Programmable Read-Only Memory. Furthermore, the storage unit 60 may have a register (not shown) and may be configured so that when the circuit device 200 is powered on, that is, when the voltage at the VDD terminal rises from 0V to a desired voltage, the various trimming data stored in the non-volatile memory are transferred to and held in the register, and the various trimming data held in the register are supplied to the drive circuit 10 and the detection circuit 20.

[0036] The oscillator circuit 40 generates a master clock signal MCLK and supplies the master clock signal MCLK to the A / D conversion circuit 22, demodulation circuit 23, correction circuit 24, and bandpass filter circuit 30. The oscillator circuit 40 may generate the master clock signal MCLK using, for example, a ring oscillator or a CR oscillator circuit.

[0037] The interface circuit 50 processes the angular velocity detection signal SDO output from the detection circuit 20 to the MCU 5 in response to a request from the MCU 5, which is an external device of the circuit device 200.

[0038] Furthermore, the interface circuit 50 performs processes such as reading data stored in the non-volatile memory and registers of the storage unit 60 and outputting it to the MCU 5 in response to requests from the MCU 5, and writing data input from the MCU 5 to the non-volatile memory and registers of the storage unit 60.

[0039] The interface circuit 50 is, for example, an SPI bus interface circuit. The selection signal, clock signal, and data signal transmitted from the MCU 5 are input to the circuit device 200 via the SS, SCK, and SI terminals, respectively, and the data signal is output to the MCU 5 via the SO terminal of the circuit device 200. SPI is an abbreviation for Serial Peripheral Interface. Note that the interface circuit 50 can also be used with various other buses besides the SPI bus, for example, I 2 It may also be an interface circuit compatible with C-bus, etc. 2 C is an abbreviation for Inter-Integrated Circuit.

[0040] 1-2. Drive Circuit Configuration Figure 5 shows an example of the configuration of the drive circuit 10. As shown in Figure 5, the drive circuit 10 includes an I / V conversion circuit 11, a full-wave rectifier circuit 12, an auto-gain control circuit 13, a drive signal generation circuit 14, and a buffer circuit 15.

[0041] The oscillation 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 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.

[0042] The full-wave rectifier circuit 12 full-wave rectifies the AC voltage signal IVO output from the I / V conversion circuit 11 and outputs a DC signal.

[0043] The auto-gain control circuit 13 amplifies the output signal of the full-wave rectifier circuit 12 and outputs a signal of a predetermined voltage. The auto-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 the output signal remains constant at the predetermined voltage.

[0044] The drive signal generation circuit 14 outputs a drive signal DRV obtained by binarizing the AC voltage signal IVO. The high-level voltage of the drive signal DRV is the voltage of the output signal of the auto-gain control circuit 13 and remains constant at a predetermined voltage. The drive signal DRV is supplied to the drive electrode 113 of the physical quantity detection element 100 via the DS terminal. The physical quantity detection element 100 can continue to vibrate due to the supply of the drive signal DRV. Furthermore, by keeping the high-level voltage of the drive signal DRV constant, the drive vibration arms 101a and 101b of the physical quantity detection element 100 can obtain a constant vibration velocity. Therefore, the vibration velocity that generates the Coriolis force becomes constant, and the sensitivity can be made more stable.

[0045] The buffer circuit 15 receives the AC voltage signal IVO as input and outputs a periodic signal SX, which is a square wave signal in phase with the AC voltage signal IVO. The periodic signal SX is supplied to the bandpass filter circuit 30. A filter may also be provided between the output of the I / V conversion circuit 11 and the input of the buffer circuit 15.

[0046] 1-3. Configuration of the Analog Front-End and Demodulation Circuit Figure 6 shows an example configuration of the analog front-end 21 and demodulation circuit 23. As shown in Figure 6, the analog front-end 21 includes Q / V conversion circuits 211, 212 and a differential amplifier circuit 213.

[0047] The alternating current charge generated at the detection electrode 114 of the physical quantity detection element 100 is input to the Q / V conversion circuit 211 via terminal S1. The alternating current charge generated at the detection electrode 115 of the physical quantity detection element 100 is input to the Q / V conversion circuit 212 via terminal S2.

[0048] In this embodiment, as shown in Figure 2, when angular velocity is applied to the physical quantity detection element 100, the detection vibration arm 102 on which the detection electrode 114 is formed and the detection vibration arm 102 on which the detection electrode 115 is formed bend and vibrate in opposite directions to maintain balance. Therefore, the angular velocity signal contained in the AC charge generated at the detection electrode 114 and the angular velocity signal contained in the AC charge generated at the detection electrode 115 are in opposite phases. Here, the statement that the two angular velocity signals are in opposite phases includes not only the case where the phase difference between the two angular velocity signals is exactly 180°, but also the case where the phase difference between the two angular velocity signals has a slight difference from 180° due to manufacturing errors in the physical quantity detection element 100, errors in the delay time of the signal propagation path, etc.

[0049] The 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. The 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.

[0050] The differential amplifier circuit 213 receives a differential signal pair consisting of an AC voltage signal S1O output from the Q / V conversion circuit 211 and an AC voltage signal S2O output from the Q / V conversion circuit 212 as input, and 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 in phase with the drive signal DRV and is a signal modulated at the frequency of the drive signal DRV, for example, several tens of kHz.

[0051] 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 delta-sigma type A / D conversion circuit that operates in synchronization with the master clock signal MCLK and outputs a 1-bit digital signal ADO. For example, the frequency of the master clock signal MCLK is several tens of MHz, and due to the noise shaping effect of the delta-sigma type A / D conversion circuit, a digital signal ADO is obtained in which noise contained in a signal bandwidth of several tens of kHz is effectively reduced.

[0052] The demodulation circuit 23 includes a mixing circuit 231. The mixing circuit 231 uses the digital signal ADO output from the A / D conversion circuit 22 as the signal to be detected, and mixes the digital signal ADO, which is the signal to be detected, with the detection signal SDT output from the bandpass filter circuit 30. That is, the mixing circuit 231 outputs a digital signal obtained by multiplying the digital signal ADO and the detection signal SDT. For example, if the digital signal ADO is a 1-bit digital signal and the detection signal SDT is a 16-bit digital signal, the mixing circuit 231 outputs a 16-bit digital signal that is 0 when the value of the digital signal ADO is 0, and the digital value of the detection signal SDT when the value of the digital signal ADO is 1.

[0053] The angular velocity signal included in the digital signal ADO is in approximately the same phase as the periodic signal SX. Furthermore, since the phase of the detected signal SDT is approximately the same as the phase of the periodic signal SX, the angular velocity signal included in the digital signal ADO is in approximately the same phase as the detected signal SDT. Therefore, the angular velocity signal included in the digital signal ADO is demodulated by the mixing circuit 231, and the output signal of the mixing circuit 231 is output as the angular velocity signal AVO from the demodulation circuit 23 to the correction circuit 24.

[0054] As described above, the bandpass filter circuit 30 is a digital filter that receives a periodic signal SX as input and outputs a digital signal in which the harmonics contained in the periodic signal SX have been sufficiently attenuated. Therefore, as in this embodiment, by using the digital signal output from the bandpass filter circuit 30 as the detected signal SDT, the noise in the frequency band of harmonics folded back into the signal band by the mixing circuit 231 is reduced, so that the angular velocity signal AVO is demodulated with high accuracy. Furthermore, since the bandpass filter circuit 30 is composed of a digital circuit, it is possible to reduce the circuit area and power consumption compared to when it is composed of an analog circuit.

[0055] 1-4. Effects In the physical quantity detection device 1 of the first embodiment, the bandpass filter circuit 30 in the circuit device 200 can output a detected signal SDT in which harmonics included in the periodic signal SX are sufficiently attenuated. Therefore, when the demodulation circuit 23 demodulates the angular velocity signal AVO based on the detected signal SDT, high-frequency noise folded back into the signal band by harmonics included in the detected signal SDT is reduced. Furthermore, since the bandpass filter circuit 30 is composed of a digital circuit, it is possible to reduce the circuit area and power consumption compared to when it is composed of an analog circuit. Accordingly, the physical quantity detection device 1 of the first embodiment can achieve low noise of the physical quantity detection signal while suppressing an increase in the circuit size of the circuit device 200.

[0056] Furthermore, in the physical quantity detection device 1 of the first embodiment, the bandpass filtering and demodulation processing of the angular velocity signal AVO are performed by digital circuits in the circuit device 200. Compared to conventional technology in which the bandpass filtering and demodulation processing are performed by analog circuits, low-frequency noise such as 1 / f noise generated in the signal band of the angular velocity detection signal SDO is reduced. Therefore, according to the physical quantity detection device 1 of the first embodiment, it is possible to achieve low noise of the angular velocity detection signal SDO in the circuit device 200.

[0057] Furthermore, according to the physical quantity detection device 1 of the first embodiment, by making the A / D conversion circuit 22 a delta-sigma type A / D conversion circuit in the circuit device 200, the noise in the signal bandwidth included in the digital signal ADO is reduced due to the noise shaping effect of the delta-sigma type A / D conversion circuit. Moreover, by making the A / D conversion circuit 22 a delta-sigma type A / D conversion circuit, the digital signal ADO can be made into a 1-bit signal, so the mixing circuit 231 included in the demodulation circuit 23 can be realized with a simple configuration, and the size of the circuit device 200 can be reduced.

[0058] 2. Second Embodiment In the following description of the second embodiment, the same reference numerals are used for components similar to those in the first embodiment, and explanations that overlap with those in the first embodiment will be omitted or simplified. The main points to be described will be those that differ from the first embodiment.

[0059] Figure 7 is a functional block diagram of the physical quantity detection device 1 of the second embodiment. As shown in Figure 7, the physical quantity detection device 1 of the second embodiment comprises a physical quantity detection element 100 and a circuit device 200. The configuration of the physical quantity detection element 100 is the same as in the first embodiment, so its description is omitted.

[0060] The circuit device 200 comprises a drive circuit 10, a detection circuit 20, an oscillation circuit 40, an interface circuit 50, and a storage unit 60. The circuit device 200 may also be configured by omitting or modifying some of these elements, or by adding other elements.

[0061] Similar to the first embodiment, the drive circuit 10 drives the drive unit 100a of the physical quantity detection element 100 and generates a periodic signal SX based on the signal output from the drive unit 100a. In the second embodiment, the drive circuit 10 outputs the generated periodic signal SX to the demodulation circuit 23 of the detection circuit 20.

[0062] Similar to the first embodiment, 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. As shown in Figure 7, similar to the first embodiment, 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, and further includes a bandpass filter circuit 25.

[0063] The analog front-end 21 amplifies the signal output from the detection unit 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, which is an analog signal.

[0064] 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 may also be a delta-sigma type A / D conversion circuit that outputs a 1-bit digital signal ADO. The noise shaping effect of the delta-sigma type A / D conversion circuit reduces the noise in the signal bandwidth contained in the digital signal ADO.

[0065] The bandpass filter circuit 25 is a digital filter that receives the digital signal ADO output from the A / D conversion circuit 22 and outputs the digital signal BPO through digital processing. Since the signal output from the detection unit 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 the same frequency. Since the frequency of the periodic signal SX matches the frequency of the drive signal DRV, the bandpass filter circuit 25 has a passband with the frequency of the fundamental wave of the periodic signal SX as its center frequency, and sufficiently attenuates noise at odd multiples of that frequency. For example, if the frequency of the fundamental wave of the periodic signal SX is 50kHz, the bandpass filter circuit 25 is a digital filter that includes 50kHz in its passband and has a high-frequency cutoff frequency lower than 150kHz.

[0066] The demodulation circuit 23 uses the periodic signal SX output from the drive circuit 10 as the detection signal and demodulates the angular velocity signal AVO, which is a physical quantity signal included in the digital signal BPO output from the bandpass filter circuit 25, based on the detected periodic signal SX. In this embodiment, the demodulation circuit 23 uses the digital signal BPO output from the bandpass filter circuit 25 as the signal to be detected and demodulates the angular velocity signal AVO by mixing the detected digital signal BPO with the detected periodic signal SX.

[0067] The correction circuit 24 performs various correction processes on the angular velocity signal AVO, such as low-pass filtering, offset correction, temperature correction, and sensitivity correction. The signal obtained by the correction circuit 24 is output from the detection circuit 20 to the interface circuit 50 as the angular velocity detection signal SDO, which is a physical quantity detection signal.

[0068] 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. Alternatively, the detection circuit 20 may output the angular velocity signal AVO itself as the angular velocity detection signal SDO to the MCU 5 via the interface circuit 50, and the MCU 5 may perform low-pass filtering and various correction processing on the angular velocity detection signal SDO.

[0069] The configuration 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 will be omitted.

[0070] Figure 8 shows an example configuration of the analog front-end 21 and the demodulation circuit 23. As shown in Figure 8, the analog front-end 21 includes Q / V conversion circuits 211, 212 and a differential amplifier circuit 213, similar to the first embodiment.

[0071] The Q / V conversion circuit 211 receives the alternating current charge generated at the detection electrode 114 of the physical quantity detection element 100 via terminal S1, and converts this alternating current charge into an alternating current voltage signal S1O, which is then output. The Q / V conversion circuit 212 receives the alternating current charge generated at the detection electrode 115 of the physical quantity detection element 100 via terminal S2, and converts this alternating current charge into an alternating current voltage signal S2O, which is then output.

[0072] The differential amplifier circuit 213 receives a differential signal pair consisting of an AC voltage signal S1O output from the Q / V conversion circuit 211 and an AC voltage signal S2O output from the Q / V conversion circuit 212, and amplifies the difference between the AC voltage signal S1O and the AC voltage signal S2O to output an amplified signal SAO.

[0073] As mentioned 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.

[0074] As mentioned above, the bandpass filter circuit 25 receives the digital signal ADO output from the A / D conversion circuit 22 as input and outputs the digital signal BPO.

[0075] The demodulation circuit 23 includes a mixing circuit 231. The mixing circuit 231 uses the digital signal BPO output from the bandpass filter circuit 25 as the signal to be detected and mixes the digital signal BPO, which is the signal to be detected, with the periodic signal SX, which is the detected signal. That is, the mixing 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 mixing circuit 231 outputs a 16-bit digital signal that is 0 when the value of the periodic signal SX is 0, and the digital value of the digital signal BPO when the value of the periodic signal SX is 1.

[0076] The angular velocity signal contained in the digital signal BPO is in approximately the same phase as the periodic signal SX. Therefore, the angular velocity signal contained in the digital signal BPO is demodulated by the mixing circuit 231, and the output signal of the mixing circuit 231 is output as the angular velocity signal AVO from the demodulation circuit 23 to the correction circuit 24.

[0077] As described above, the bandpass filter circuit 25 is a digital filter that receives the digital signal ADO as input and outputs a digital signal BPO which has noise in the frequency band of odd multiples of the fundamental frequency of the periodic signal SX contained in the digital signal ADO reduced. Therefore, as in this embodiment, by using the digital signal BPO as the signal to be detected, the noise in the frequency band of odd-order harmonics of the periodic signal SX that is folded back into the signal band by the mixing circuit 231 is almost eliminated, so that the angular velocity signal AVO is demodulated with high accuracy.

[0078] The other components of the physical quantity detection device 1 in the second embodiment are the same as those in the first embodiment, so their description will be omitted.

[0079] 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 in which the high-frequency noise contained in the digital signal ADO output from the A / D conversion circuit 22 has been sufficiently attenuated. Therefore, when the demodulation circuit 23 demodulates the angular velocity signal AVO based on the detection signal SDT, the high-frequency noise that is folded back into the signal band by the harmonics contained in the detection signal SDT is reduced. Furthermore, since the bandpass filter circuit 25 is composed of a digital circuit, it is possible to reduce the circuit area and power consumption compared to when it is composed of an analog circuit. Accordingly, the physical quantity detection device 1 of the second embodiment can achieve low noise of the physical quantity detection signal while suppressing an increase in the circuit size of the circuit device 200. In addition, the physical quantity detection device 1 of the second embodiment can obtain the same effects as the physical quantity detection device 1 of the first embodiment.

[0080] 3. Third Embodiment In the following description of the third embodiment, the same reference numerals are used for components similar to those in the first embodiment, and explanations that overlap with those in the first embodiment will be omitted or simplified. The main points to be described will be those that differ from the first embodiment.

[0081] Figure 9 is a functional block diagram of the physical quantity detection device 1 of the third embodiment. As shown in Figure 9, the physical quantity detection device 1 of the third embodiment comprises a physical quantity detection element 100 and a circuit device 200. The configuration of the physical quantity detection element 100 is the same as in the first embodiment, so its description is omitted.

[0082] The circuit device 200, like the first embodiment, 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, and further includes a center frequency control circuit 70. Note that the circuit device 200 may have some of these elements omitted or modified, or other elements added. The configuration 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, and therefore their description is omitted.

[0083] The bandpass filter circuit 30 operates in synchronization with the master clock signal MCLK. Therefore, if the frequency of the master clock signal MCLK deviates from the target frequency, the center frequency of the bandpass filter circuit 30 will not match the frequency of the periodic signal SX, and some harmonics contained in the periodic signal SX may not be sufficiently reduced by the bandpass filter circuit 30. 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 detection signal SDT. Specifically, the center frequency control circuit 70 increases the center frequency of the bandpass filter circuit 30 when the phase of the detection signal SDT is slower than the phase of the periodic signal SX, and decreases the center frequency of the bandpass filter circuit 30 when the phase of the detection signal SDT is faster than the phase of the periodic signal SX. As a result, the center frequency of the bandpass filter circuit 30 is controlled to match the frequency of the periodic signal SX, so that harmonics contained in the periodic signal SX are sufficiently reduced, and a detection signal SDT close to a sine wave is obtained.

[0084] Therefore, by using the digital signal output from the bandpass filter circuit 30 as the detected signal SDT, the noise in the harmonic frequency band that is folded back into the signal band by the mixing circuit 231 is almost eliminated, so that the angular velocity signal AVO is demodulated with high accuracy.

[0085] The other components of the physical quantity detection device 1 in the third embodiment are the same as those in the first embodiment, so their description will be omitted.

[0086] 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 and the master clock signal MCLK for the bandpass filter circuit 30 to generate the detection signal SDT are asynchronous in the circuit device 200, 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 accuracy by the demodulation circuit 23 in the circuit device 200, so that the angular velocity can be detected with high accuracy.

[0087] 4. Variations The present invention is not limited to this embodiment, and various modifications can be implemented within the scope of the gist of the present invention.

[0088] 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, and 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, in the physical quantity detection device 1, a bandpass filter circuit 30 may be provided after the drive circuit 10, and a bandpass filter circuit 25 may be provided after the A / D conversion circuit 22. In this way, the angular velocity signal AVO is demodulated with higher accuracy by the demodulation circuit 23.

[0089] Furthermore, in each of the above embodiments, for example, the master clock signal MCLK is generated internally within the circuit device 200, but it may also be supplied from outside the circuit device 200. As an example, in the physical quantity detection device 1 shown in Figure 10, 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 an extremely small frequency deviation regardless 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 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 physical quantity detection device 1, the A / D conversion circuit 22, demodulation circuit 23, correction circuit 24, and bandpass filter circuit 30 operate with the master clock signal MCLK, which has an extremely small frequency deviation, so a highly accurate angular velocity detection signal SDO can be obtained.

[0090] Furthermore, in each of 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 include a physical quantity detection element that detects physical quantities such as acceleration, angular acceleration, velocity, and force.

[0091] Furthermore, in each of 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, and each of the multiple physical quantity detection elements may detect a physical quantity using one of two or more mutually orthogonal axes as the detection axis. Alternatively, for example, the physical quantity detection device 1 may include multiple physical quantity detection elements, and each of the multiple physical quantity detection elements may detect one of several types of physical quantities such as angular velocity, acceleration, angular acceleration, speed, and force. In other words, the physical quantity detection device 1 may be a composite sensor.

[0092] Furthermore, in the embodiments described above, examples were given in which the vibrating element of the physical quantity detection element 100 is a double T-shaped quartz vibrating element. However, the vibrating element of a physical quantity detection element that detects various physical quantities may be, for example, a tuning fork type or a comb-tooth type, or a sound-piece type with a triangular prism, square prism, cylindrical shape, etc. Also, instead of quartz (SiO2), piezoelectric materials such as piezoelectric single crystals of lithium tantalate (LiTaO3) or lithium niobate (LiNbO3) or piezoelectric ceramics of lead zirconate titanate (PZT) may be used as the material for the vibrating element of the physical quantity detection element, or silicon semiconductors may be used. In addition, the vibrating element of the physical quantity detection element may have a structure in which a piezoelectric thin film of zinc oxide (ZnO) or aluminum nitride (AlN) sandwiched between driving electrodes is arranged on a part of the surface of a silicon semiconductor. For example, the physical quantity detection element may be a MEMS element. MEMS is an abbreviation for Micro Electro Mechanical Systems.

[0093] Furthermore, although piezoelectric physical quantity detection elements were exemplified in the above embodiments, the physical quantity detection elements for detecting various physical quantities are not limited to piezoelectric elements, but may also be capacitive, electrodynamic, eddy current, optical, strain gauge, or other types of elements. Also, the detection method of the physical quantity detection element is not limited to vibration, but may be optical, rotary, or fluid type, for example.

[0094] The embodiments and variations described above are examples only and are not limited thereto. For example, each embodiment and each variation can be combined as appropriate.

[0095] The present invention includes configurations substantially identical to those described in the embodiments, for example, configurations with the same function, method, and results, or configurations with the same purpose and effect. Furthermore, the present invention includes configurations in which non-essential parts of the configurations described in the embodiments are replaced. Furthermore, the present invention includes configurations that produce the same effects or achieve the same purpose as those described in the embodiments. Finally, the present invention includes configurations that add known technology to the configurations described in the embodiments.

[0096] The following can be derived from the embodiments and modifications described above.

[0097] One embodiment of a circuit device is: A circuit device connected to a physical quantity detection element having a drive unit and a detection unit, A drive circuit that drives the drive unit and generates a periodic signal based on the signal output from the drive unit, A detection circuit that 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, A bandpass filter circuit receives the aforementioned periodic signal and outputs a detected signal through digital processing, Equipped with, The detection circuit is An analog front end that amplifies the signal output from the detection unit, A / D conversion circuit that converts the signal output from the analog front end into a digital signal, A demodulation circuit that demodulates the physical quantity signal included in the digital signal output from the A / D conversion circuit based on the detected signal, The system includes and generates the physical quantity detection signal based on the demodulated physical quantity signal.

[0098] In this circuit device, the bandpass filter circuit can output a detected signal with harmonics contained in the periodic signal sufficiently attenuated. Therefore, when the demodulation circuit demodulates the physical quantity signal based on the detected signal, high-frequency noise folded back into the signal band by the harmonics contained in the detected signal is reduced. Furthermore, since the bandpass filter circuit is composed of digital circuits, it is possible to reduce the circuit area and power consumption compared to when it is composed of analog circuits. Thus, this circuit device makes it possible to achieve low noise in the physical quantity detection signal while suppressing an increase in circuit size.

[0099] Furthermore, since this circuit device performs bandpass filtering and demodulation of physical quantity signals using digital circuits, it reduces low-frequency noise such as 1 / f noise generated in the signal band compared to conventional technologies that perform bandpass filtering and demodulation using analog circuits. Therefore, this circuit device makes it possible to achieve low noise in physical quantity detection signals.

[0100] In one embodiment of the circuit device, The demodulation circuit may include a mixing circuit that mixes the digital signal output from the A / D conversion circuit with the detected signal, using the detected signal as the detected signal.

[0101] Another aspect of the circuit device is, A circuit device connected to a physical quantity detection element having a drive unit and a detection unit, A drive circuit that drives the drive unit and generates a periodic signal based on the signal output from the drive unit, A detection circuit that 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, Equipped with, The detection circuit is An analog front end that amplifies the signal output from the detection unit, A / D conversion circuit that converts the signal output from the analog front end into a digital signal, A bandpass filter circuit to which the digital signal output from the A / D conversion circuit is input, A demodulation circuit that uses the aforementioned periodic signal as a detected signal and demodulates the physical quantity signal contained in the signal output from the bandpass filter circuit based on the detected signal, The system includes and generates the physical quantity detection signal based on the demodulated physical quantity signal.

[0102] In this circuit, the bandpass filter circuit can output a signal with sufficient attenuation of high-frequency noise contained 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 that is folded back into the signal band by harmonics contained in the detected signal is reduced. Furthermore, since the bandpass filter circuit is composed of digital circuits, it is possible to reduce the circuit area and power consumption compared to when it is composed of analog circuits. Thus, this circuit can achieve low noise in the physical quantity detection signal while suppressing an increase in circuit size.

[0103] Furthermore, since this circuit device performs bandpass filtering and demodulation of physical quantity signals using digital circuits, it reduces low-frequency noise such as 1 / f noise generated in the signal band compared to conventional technologies that perform bandpass filtering and demodulation using analog circuits. Therefore, this circuit device makes it possible to achieve low noise in physical quantity detection signals.

[0104] In one embodiment of the circuit device, The demodulation circuit may include a mixing circuit that mixes the signal output from the bandpass filter circuit with the detected signal, using the detected signal as the signal to be detected.

[0105] One embodiment of the aforementioned circuit device is: A center frequency control circuit may be provided that controls the center frequency of the bandpass filter circuit based on the phase difference between the periodic signal and the detection signal.

[0106] In this circuit, even if the periodic signal based on the signal output from the drive unit and the clock signal used by the bandpass filter circuit to generate the detection signal are asynchronous, a detection signal synchronized with the periodic signal can be obtained. Therefore, with this circuit, the physical quantity signal is demodulated accurately by the demodulation circuit, allowing for high-precision detection of the physical quantity.

[0107] In one embodiment of the circuit device, The A / D conversion circuit may be a delta-sigma type A / D conversion circuit.

[0108] This circuit reduces the noise in the signal bandwidth of the digital signal output from the A / D conversion circuit due to the noise shaping effect of the delta-sigma type A / D conversion circuit. Furthermore, this circuit allows the digital signal output from the A / D conversion circuit to be a 1-bit signal, enabling the demodulation circuit to be implemented with a simple configuration and thus reducing its size.

[0109] One embodiment of a physical quantity detection device is: One embodiment of the aforementioned circuit device, The aforementioned physical quantity detection element, It is equipped with.

[0110] In this physical quantity detection device, the bandpass filter circuit in the circuit device can output a detected signal with sufficient attenuation of harmonics contained in the periodic signal, or a signal with sufficient attenuation of high-frequency noise contained 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 folded back into the signal band by the harmonics contained in the detected signal is reduced. Furthermore, since the bandpass filter circuit is composed of a digital circuit, it is possible to reduce the circuit area and power consumption compared to when it is composed of an analog circuit. Accordingly, this physical quantity detection device makes it possible to reduce the noise of the physical quantity detection signal while suppressing an increase in the circuit size of the circuit device.

[0111] Furthermore, in this physical quantity detection 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 is reduced compared to conventional technologies that perform bandpass filtering and demodulation using analog circuits. Therefore, this physical quantity detection device makes it possible to achieve low noise in the physical quantity detection signal. [Explanation of Symbols]

[0112] 1...Physical quantity detection device, 5...MCU, 6...Temperature-compensated crystal oscillator, 10...Drive circuit, 11...I / V conversion circuit, 12...Full-wave rectifier circuit, 13...Automatic gain control circuit, 14...Drive signal generation circuit, 15...Buffer circuit, 20...Detection circuit, 21...Analog front end, 22...A / D conversion circuit, 23...Demodulation circuit, 24...Correction circuit, 25...Bandpass filter circuit, 30...Bandpass filter circuit, 40...Oscillator circuit, 50...Interface circuit, 60...Memory unit, 7 0...Center frequency control circuit, 100...Physical quantity detection element, 100a...Drive unit, 100b...Detection unit, 101a,101b...Drive vibration arm, 102...Detection vibration arm, 103...Weight unit, 104a,104b...Drive base, 105a,105b...Connecting arm, 106...Weight unit, 107...Detection base, 112,113...Drive electrode, 114,115...Detection electrode, 116...Common electrode, 200...Circuit device, 211...Q / V conversion circuit, 212...Q / V conversion circuit, 213...Differential amplifier circuit, 231...Mixing circuit

Claims

1. A circuit device connected to a physical quantity detection element having a drive unit and a detection unit, A drive circuit that drives the drive unit and generates a periodic signal based on the signal output from the drive unit, A detection circuit that 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, A bandpass filter circuit receives the aforementioned periodic signal and outputs a detected signal through digital processing, Equipped with, The detection circuit is An analog front end that amplifies the signal output from the detection unit, A / D conversion circuit that converts the signal output from the analog front end into a digital signal, A demodulation circuit that demodulates the physical quantity signal included in the digital signal output from the A / D conversion circuit based on the detection signal, A circuit device that includes and generates the physical quantity detection signal based on the demodulated physical quantity signal.

2. In claim 1, The demodulation circuit includes a mixing circuit that mixes the digital signal output from the A / D conversion circuit with the detected signal, using the detected signal as the detected signal.

3. A circuit device connected to a physical quantity detection element having a drive unit and a detection unit, A drive circuit that drives the drive unit and generates a periodic signal based on the signal output from the drive unit, A detection circuit that 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, Equipped with, The detection circuit is An analog front end that amplifies the signal output from the detection unit, A / D conversion circuit that converts the signal output from the analog front end into a digital signal, A bandpass filter circuit to which the digital signal output from the A / D conversion circuit is input, A demodulation circuit that uses the aforementioned periodic signal as a detected signal and demodulates the physical quantity signal contained in the signal output from the bandpass filter circuit based on the detected signal, A circuit device that includes and generates the physical quantity detection signal based on the demodulated physical quantity signal.

4. In claim 3, The demodulation circuit includes a mixing circuit that mixes the signal output from the bandpass filter circuit with the detected signal, using the detected signal as the detected signal.

5. In claim 1, A circuit device comprising a center frequency control circuit that controls the center frequency of the bandpass filter circuit based on the phase difference between the periodic signal and the detection signal.

6. In claim 1, The A / D conversion circuit is a delta-sigma type A / D conversion circuit, which is the circuit device.

7. A circuit device according to any one of claims 1 to 6, The aforementioned physical quantity detection element, A physical quantity detection device equipped with the following features.

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