Vibrator Device

A vibrator device includes: a vibrator; and a circuit device disposed apart from the vibrator, in which the circuit device includes a drive circuit configured to drive the vibrator, a temperature sensor configured to generate a temperature signal corresponding to a detected temperature, a temperature compensation circuit configured to compensate for temperature characteristics of a drive state of the vibrator based on the temperature signal, a heat source circuit configured to operate in a first state or in a second state in which current consumption is different from current consumption in the first state, and a transient response compensation circuit configured to compensate for, when the first state and the second state of the heat source circuit are switched, a difference between a transient response of a temperature detected by the temperature sensor and a transient response of a temperature of the vibrator.

The present application is based on, and claims priority from JP Application Serial Number 2023-009434, filed Jan. 25, 2023, the disclosure of which is hereby incorporated by reference herein in its entirety.

BACKGROUND

1. Technical Field

The present disclosure relates to a vibrator device.

2. Related Art

JP-A-2012-156977 discloses a temperature compensated crystal oscillator that includes a temperature sensor, a temperature compensation circuit, and a plurality of output buffers in an IC chip, in which as viewed from a quartz crystal connection terminal having a phase opposite to that of an output of an output buffer that can be subjected to on/off control, an output terminal of the output buffer is disposed at a position farther than an output terminal of an output buffer that is not subjected to on/off control. According to the temperature compensated crystal oscillator disclosed in JP-A-2012-156977, wraparound of an oscillation frequency component to an oscillation circuit side is reduced, and it is possible to reduce fluctuations in an oscillation frequency due to the on/off control over the output buffer.

JP-A-2012-156977 is an example of the related art.

However, in the temperature compensated crystal oscillator disclosed in JP-A-2012-156977, when the output buffer is switched on or off and a heat generation amount of the output buffer rapidly changes, the temperature sensor inside the IC rapidly detects a temperature change, whereas a temperature change in a vibrator that is separate from the IC chip is delayed, and thus an error may occur in a temperature compensation, and the oscillation frequency may fluctuate.

SUMMARY

An aspect of a vibrator device according to the present disclosure includes:a vibrator; anda circuit device disposed apart from the vibrator, in whichthe circuit device includesa drive circuit configured to drive the vibrator,a temperature sensor configured to generate a temperature signal corresponding to a detected temperature,a temperature compensation circuit configured to compensate for temperature characteristics of a drive state of the vibrator based on the temperature signal,a heat source circuit configured to operate in a first state or in a second state in which current consumption is different from current consumption in the first state, anda transient response compensation circuit configured to compensate for, when the first state and the second state of the heat source circuit are switched, a difference between a transient response of a temperature detected by the temperature sensor and a transient response of a temperature of the vibrator.

DESCRIPTION OF EMBODIMENTS

Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the drawings. The embodiments to be described below do not unduly limit contents of the present disclosure described in the claims. All configurations described below are not necessarily essential components of the present disclosure.

1. Functional Configuration of Vibrator Device

FIG.1is a diagram showing a functional configuration of a vibrator device according to the embodiment. As shown inFIG.1, a vibrator device1according to the embodiment includes a circuit device2and a vibrator3. The circuit device2and the vibrator3are housed in a package (not shown).

The circuit device2includes a temperature sensor100, a transient response compensation circuit110, a temperature compensation circuit120, a drive circuit130, a memory140, and a heat source circuit150. The circuit device2may have a configuration in which some of these elements are omitted or changed, or other elements are added.

The drive circuit130drives the vibrator3to vibrate the vibrator3.

The temperature sensor100detects a temperature and generates a temperature signal DT corresponding to the detected temperature. The temperature signal DT may be a digital signal.

The temperature compensation circuit120compensates for temperature characteristics of a drive state of the vibrator3based on the temperature signal DT generated by the temperature sensor100. Specifically, the memory140stores temperature compensation data TCD for compensating for the temperature characteristics of the drive state of the vibrator3, and the temperature compensation circuit120compensates for the temperature characteristics of the drive state of the vibrator3based on the temperature signal DT and the temperature compensation data TCD.

The heat source circuit150is a circuit that generates heat when the heat source circuit150operates, and operates in a first state or in a second state in which current consumption is different from that in the first state. A heat generation amount when the heat source circuit150operates in the first state is different from a heat generation amount when the heat source circuit150operates in the second state. For example, in a case in which current consumption when the heat source circuit150operates in the second state is larger than current consumption when the heat source circuit150operates in the first state, a heat generation amount when the heat source circuit150operates in the second state is larger than a heat generation amount when the heat source circuit150operates in the first state. Therefore, in this case, when the heat source circuit150is switched from the first state to the second state, the heat generation amount of the heat source circuit150increases. When the heat source circuit150switches from the second state to the first state, the heat generation amount of the heat source circuit150decreases. Conversely, in a case in which current consumption when the heat source circuit150operates in the second state is smaller than current consumption when the heat source circuit150operates in the first state, a heat generation amount when the heat source circuit150operates in the second state is smaller than the heat generation amount when the heat source circuit150operates in the first state. Therefore, in this case, when the heat source circuit150is switched from the first state to the second state, the heat generation amount of the heat source circuit150decreases. When the heat source circuit150switches from the second state to the first state, the heat generation amount of the heat source circuit150increases.

When the heat source circuit150switches between the first state and the second state, the transient response compensation circuit110compensates for a difference between a transient response of a temperature detected by the temperature sensor100and a transient response of a temperature of the vibrator3. For example, when the heat generation amount of the heat source circuit150increases before and after switching between the first state and the second state of the heat source circuit150, heat is propagated from the heat source circuit150to the temperature sensor100and a temperature of the temperature sensor100rises, and heat is propagated from the heat source circuit150, via a package, to the vibrator3and the temperature of the vibrator3rises. Conversely, when the heat generation amount of the heat source circuit150decreases before and after switching between the first state and the second state of the heat source circuit150, heat is propagated from the temperature sensor100to the heat source circuit150and the temperature of the temperature sensor100decreases, and heat is propagated from the vibrator3, via the package, to the heat source circuit150and the temperature of the vibrator3decreases. At this time, since the temperature sensor100and the heat source circuit150are in the circuit device2, heat rapidly propagates between the temperature sensor100and the heat source circuit150, whereas the circuit device2is disposed apart from the vibrator3. Therefore, heat propagates between the vibrator3and the heat source circuit150via the package, and heat propagation becomes slow. Therefore, when the heat source circuit150switches between the first state and the second state, the transient response of the temperature detected by the temperature sensor100is faster than the transient response of the temperature of the vibrator3. The transient response compensation circuit110compensates for this difference of the transient response.

For example, the temperature signal DT may be a digital signal, and the transient response compensation circuit110may include a digital filter that performs filter processing on the temperature signal DT. The digital filter may be a low-pass filter. When the temperature signal DT passes through the digital filter, a group delay occurs according to a cutoff frequency of the digital filter, and an input of the temperature signal DT to the temperature compensation circuit120is delayed. As a result, the difference between the transient response of the temperature detected by the temperature sensor100and the transient response of the temperature of the vibrator3is compensated for, and temperature compensation accuracy attained by the temperature compensation circuit120is improved.

The digital filter may operate at a cutoff frequency based on data stored in the memory140. That is, the cutoff frequency of the digital filter may be variable according to data stored in the memory140in advance.

When a temperature outside the package of the vibrator device1changes, a difference between a heat propagation time between the temperature sensor100and outside air and a heat propagation time between the vibrator3and the outside air is small. Therefore, when the transient response compensation circuit110is always operating, if an outside air temperature changes while the heat source circuit150remains unchanged in the first state or the second state, excessive temperature compensation is performed by the temperature compensation circuit120. Therefore, it is preferable that the transient response compensation circuit110stops operating after a predetermined period elapses after the heat source circuit150is switched between the first state and the second state. The predetermined period may be, for example, a period from when the heat source circuit150switches between the first state and the second state until the transient response of the temperature of the vibrator3converges.

2. Specific Example of Vibrator Device

Hereinafter, a temperature compensated oscillator will be described as a specific example of the vibrator device1shown inFIG.1.

2-1. First Embodiment

2-1-1. Structure of Vibrator Device

FIGS.2and3are diagrams showing an example of a structure of the vibrator device1according to a first embodiment.FIG.2is a perspective view of the vibrator device1.FIG.3is an example of a cross-sectional view taken along a line A-A inFIG.2.

As shown inFIGS.2and3, the vibrator device1includes the circuit device2, the vibrator3, a package4, a lid5, and a plurality of external terminals6.

In the embodiment, the vibrator3is a quartz crystal resonator using a quartz crystal as a substrate material, and is, for example, an AT cut quartz crystal resonator or a tuning fork type quartz crystal resonator. The vibrator3may be a SAW resonator or a MEMS vibrator. SAW is an abbreviation for surface acoustic wave. MEMS is an abbreviation for micro electro mechanical systems. As the substrate material for the vibrator3, in addition to the quartz crystal, a piezoelectric material such as a piezoelectric single crystal formed of lithium tantalate, lithium niobate, or the like, a piezoelectric ceramic formed of lead zirconate titanate or the like, or a silicon semiconductor material can be used. As an excitation unit for the vibrator3, one based on a piezoelectric effect may be used, or electrostatic drive based on Coulomb force may be used.

In the embodiment, the circuit device2is implemented by a one-chip integrated circuit. At least a part of the circuit device2may be implemented by a discrete part.

As shown inFIG.3, the vibrator3includes metal excitation electrodes3aand3bon a front surface and a back surface of the vibrator3, and oscillates at a desired frequency according to a shape and mass of the vibrator3including the excitation electrodes3aand3b.

As shown inFIG.3, the vibrator device1is an oscillator having a single seal structure, and the package4houses the circuit device2and the vibrator3in the same space. For example, the package4may be a ceramic package. Specifically, the package4is formed with a recess, and the recess is covered with the lid5to form a housing chamber7.

As shown inFIG.3, a plurality of terminals21are provided at a bottom surface20of the circuit device2. A plurality of external terminals are provided at a back surface of the package4that is a bottom surface of the vibrator device1. Interconnects (not shown) for electrically coupling the two terminals21of the circuit device2and the two excitation electrodes3aand3bof the vibrator3are provided inside the package4or at a front surface of the recess. The circuit device2is electrically coupled to the vibrator3by the interconnects. Interconnects (not shown) for electrically coupling other terminals21of the circuit device2and the plurality of external terminals6of the vibrator device1are provided inside the package4or at the front surface of the recess.

2-1-2. Configuration of Vibrator Device

FIG.4is a functional block diagram of the vibrator device1according to the first embodiment. InFIG.4, similar components as those inFIG.1are denoted by the same reference signs. As shown inFIG.4, the vibrator device1according to the first embodiment includes the circuit device2and the vibrator3. The vibrator device1includes, as the six external terminals6, a TV terminal, a TG terminal, a TO1terminal, a TO2terminal, a TE1terminal, and a TE2terminal. The circuit device2includes, as eight terminals21, a PV terminal, a PG terminal, a PO1terminal, a PO2terminal, a PE1terminal, a PE2terminal, a PXI terminal, and a PXO terminal. The PV terminal, the PG terminal, the PO1terminal, the PO2terminal, the PE1terminal, and the PE2terminal of the circuit device2are electrically coupled to the TV terminal, the TG terminal, the TO1terminal, the TO2terminal, the TE1terminal, and the TE2terminal of the vibrator device1, respectively. The PXI terminal of the circuit device2is electrically coupled to one end of the vibrator3. The PXO terminal of the circuit device2is electrically coupled to the other end of the vibrator3. The circuit device2operates by being supplied with a power supply voltage VDD supplied via the PV terminal from the TV terminal and a ground voltage GND supplied via the PG terminal from the TG terminal.

In the embodiment, the vibrator device1includes a temperature detection circuit101, an A/D conversion circuit102, a digital filter111, the temperature compensation circuit120, an oscillation circuit131, the memory140, an output circuit151, an interface circuit170, and a D/A conversion circuit180. The vibrator device1may have a configuration in which some of these elements are omitted or changed, or other elements are added.

The oscillation circuit131is electrically coupled to both the ends of the vibrator3via the PXI terminal and the PXO terminal, and generates an oscillation signal Vosc by oscillating the vibrator3. Specifically, the oscillation circuit131receives a signal output from the vibrator3via the PXO terminal, and supplies a signal obtained by amplifying the signal to the vibrator3via the PXI terminal. The oscillation circuit131includes a variable capacitance circuit132functioning as a load capacity, and the oscillation signal Vosc has a frequency corresponding to a capacity value of the variable capacitance circuit132. The oscillation circuit131corresponds to the drive circuit130shown inFIG.1.

The temperature detection circuit101detects a temperature and outputs a temperature signal VT that is an analog signal of a voltage corresponding to the detected temperature. For example, the temperature detection circuit101may be a circuit using temperature dependence of a forward voltage at a PN junction. The A/D conversion circuit102converts the temperature signal VT into the temperature signal DT. The temperature signal VT is an analog signal output from the temperature detection circuit101. The temperature signal DT is a digital signal. For example, the A/D conversion circuit102may be a successive approximation A/D conversion circuit. The temperature detection circuit101and the A/D conversion circuit102correspond to the temperature sensor100shown inFIG.1.

The digital filter111performs filter processing on the temperature signal DT output from the A/D conversion circuit102. The digital filter111may be a low-pass filter.

The temperature compensation circuit120compensates for, based on a temperature signal DTX output from the digital filter111, frequency-temperature characteristics of the oscillation signal Vosc as the temperature characteristics of the drive state of the vibrator3. Specifically, the temperature compensation data TCD for compensating for the frequency-temperature characteristics of the oscillation signal Vosc is stored in the memory140, and the temperature compensation circuit120generates, based on the temperature signal DTX and the temperature compensation data TCD, a temperature compensation signal DC that is a digital signal. For example, when the frequency-temperature characteristics of the vibrator3is a cubic curve, the temperature compensation circuit120corrects, based on the temperature compensation data TCD including a coefficient value for each order of the cubic curve that cancels out the frequency-temperature characteristics, a frequency of the oscillation signal Vosc such that the frequency approaches a constant value regardless of the temperature.

The digital filter111and the temperature compensation circuit120are implemented by, for example, a DSP160. The DSP is an abbreviation for digital signal processor.

The D/A conversion circuit180converts the temperature compensation signal DC into a temperature compensation voltage VC. The temperature compensation signal DC is a digital signal output from the temperature compensation circuit120. The temperature compensation voltage VC is an analog signal. The temperature compensation voltage VC is applied to the variable capacitance circuit132in the oscillation circuit131, and the variable capacitance circuit132has a capacity value corresponding to a magnitude of the temperature compensation voltage VC. An oscillation frequency of the oscillation circuit131changes according to the capacity value of the variable capacitance circuit132. The temperature compensation voltage VC output from the D/A conversion circuit180changes according to the temperature detected by the temperature detection circuit101. As a result, the oscillation frequency of the oscillation circuit131is controlled to approach a constant frequency regardless of the temperature.

The memory140includes a nonvolatile memory and a register (not shown) that store various types of information. The nonvolatile memory may be, for example, a MONOS 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. In a manufacturing process of the vibrator device1, various types of information for controlling each circuit, for example, data for setting a cutoff frequency and an order of the digital filter111, and temperature compensation data for controlling the temperature compensation circuit120are stored in the nonvolatile memory of the memory140. When supply of the power supply voltage VDD to a TVD terminal is started, various types of information stored in the nonvolatile memory of the memory140is transferred to the register, and various types of information stored in the register is appropriately supplied to each circuit.

When a control signal having a predetermined pattern is received from the TE2terminal within a predetermined period after the supply of the power supply voltage VDD to the TVD terminal is started, the interface circuit170sets an operation mode to an external communication mode after the predetermined period elapses. For example, the interface circuit170may set a period from start of oscillation of the vibrator3due to the supply of the power supply voltage VDD to detection of stable oscillation as the predetermined period, or may count the number of pulses of the oscillation signal Vosc and determine that the predetermined period elapses when a count value reaches a predetermined value. For example, the interface circuit170may measure the predetermined period based on an output signal of an RC time constant circuit, which starts an operation upon supply of the power supply voltage VDD.

In the external communication mode, the interface circuit170can perform data communication with an external device (not shown) coupled to the TE1terminal and the TE2terminal via the PE1terminal and the PE2terminal. According to a predetermined communication standard, the external device outputs a serial clock signal to the TE1terminal, outputs a serial data signal to the TE2terminal in synchronization with the serial clock signal, or acquires a signal output from the interface circuit170, via the PE2terminal, to the TE2terminal. In the external communication mode, the interface circuit170samples serial data signals as various commands for each edge of the serial clock signal according to, for example, a standard of an I2C bus. I2C is an abbreviation for inter-integrated circuit. The interface circuit170performs processing such as setting of an operation mode and writing and reading of data to and from the memory140based on the sampled command. In the embodiment, the interface circuit170communicates with an external device according to a communication standard of a two-wire bus such as the I2C bus, but may communicate with an external device according to a communication standard of a three-wire bus or a four-wire bus such as an SPI bus. SPI is an abbreviation for serial peripheral interface.

For example, when a write command to the memory140is sampled in the external communication mode, the interface circuit170writes data designated by the write command to an address of the memory140designated by the write command. When a read command from the memory140is sampled in the external communication mode, the interface circuit170reads data from an address of the memory140designated by the read command, converts the data into serial data, and outputs the serial data.FIG.5shows an example of a timing chart when writing and reading of data to and from the memory140are performed in the external communication mode after shifting to the external communication mode after the supply of the power supply voltage VDD to the TVD terminal is started.

For example, in the external communication mode, when a setting command for a normal operation mode is sampled, the interface circuit170shifts the operation mode from the external communication mode to the normal operation mode. In the normal operation mode, the interface circuit170supplies signals received from the TE1terminal and the TE2terminal via the PE1terminal and the PE2terminal to the output circuit151as a first enable control signal EN1and a second enable control signal EN2, respectively. Therefore, in the normal operation mode, outputs of a first output clock signal CK1from the TO1terminal and a second output clock signal CK2from the TO2terminal are controlled based on signals input to the TE1terminal and the TE2terminal.

When a signal having a predetermined pattern is not received from the TE2terminal within a predetermined period after the supply of the power supply voltage VDD is started, the interface circuit170directly sets the operation mode to the normal operation mode without setting the operation mode to the external communication mode after the predetermined period elapses.

The output circuit151outputs at least one output clock signal based on the oscillation signal Vosc output from the oscillation circuit131. For example, the output circuit151includes a first buffer circuit152and a second buffer circuit153. The first buffer circuit152outputs the first output clock signal CK1based on the oscillation signal Vosc. The second buffer circuit153outputs the second output clock signal CK2based on the oscillation signal Vosc. For example, the first buffer circuit152buffers the oscillation signal Vosc and outputs the first output clock signal CK1, and the second buffer circuit153buffers the oscillation signal Vosc and outputs the second output clock signal CK2. The first output clock signal CK1and the second output clock signal CK2may have the same frequency or different frequencies. The first output clock signal CK1and the second output clock signal CK2may have the same signal format or different signal formats. The first output clock signal CK1is output to an outside via the PO1terminal from the TO1terminal. The second output clock signal CK2is output to the outside via the PO2terminal from the TO2terminal. InFIG.4, the output circuit151outputs the two output clock signals CK1and CK2, and may output three or more output clock signals.

The output circuit151is a circuit that generates heat when the output circuit151operates, and operates in the first state or in the second state in which current consumption is different from that in the first state. That is, the output circuit151corresponds to the heat source circuit150shown inFIG.1. A heat generation amount when the output circuit151operates in the first state is different from a heat generation amount when the output circuit151operates in the second state. In the embodiment, at least one external control signal is received from the outside of the vibrator device1, and the first state and the second state of the output circuit151are switched based on the external control signal. For example, as at least one external control signal, the first enable control signal EN1and the second enable control signal EN2are received via the PE1terminal and the PE2terminal from the TE1terminal and the TE2terminal. In the output circuit151, when the first enable control signal EN1is active, the first buffer circuit152operates to output the first output clock signal CK1, and when the second enable control signal EN2is active, the second buffer circuit153operates to output the second output clock signal CK2.

In the embodiment, the first state of the output circuit151is a state in which the first output clock signal CK1is output, and the second state of the output circuit151is a state in which both the first output clock signal CK1and the second output clock signal CK2are output. That is, in the embodiment, in the first state of the output circuit151, the first buffer circuit152outputs the first output clock signal CK1, and in the second state of the output circuit151, the first buffer circuit152outputs the first output clock signal CK1, and the second buffer circuit153outputs the second output clock signal CK2.

Therefore, current consumption when the output circuit151operates in the second state is larger than current consumption when the output circuit151operates in the first state. Therefore, when the output circuit151switches from the first state to the second state, the heat generation amount of the output circuit151increases. Conversely, when the output circuit151switches from the second state to the first state, the heat generation amount of the output circuit151decreases.

When the heat generation amount of the output circuit151increases before and after switching between the first state and the second state of the output circuit151, heat is propagated from the output circuit151to the temperature detection circuit101and the temperature of the temperature detection circuit101rises, and heat is propagated from the output circuit151, via the package4, to the vibrator3and the temperature of the vibrator3rises. Conversely, when the heat generation amount of the output circuit151decreases before and after switching between the first state and the second state of the output circuit151, heat is propagated from the temperature detection circuit101to the output circuit151and the temperature of the temperature detection circuit101decreases, and heat is propagated from the vibrator3, via the package4, to the output circuit151and the temperature of the vibrator3decreases.

FIG.6shows a heat propagation path from the output circuit151to the temperature detection circuit101and a heat propagation path from the output circuit151to the vibrator3when the output circuit151is switched from the first state to the second state.FIG.7is a diagram showing a thermal network based on the propagation path inFIG.6. InFIGS.6and7, Qicis a heat flow rate generated by the output circuit151. Ric, Cic, and Ticare thermal resistance, a thermal capacity, and a temperature of the circuit device2, respectively. Rpkg, Cpkg, and Tpkgare thermal resistance, a thermal capacity, and a temperature of the package4, respectively. Rx, Cx, and Txare thermal resistance, a thermal capacity, and a temperature of the vibrator3, respectively. Tais a temperature of the outside air.

As shown inFIG.6, since the temperature sensor100and the output circuit151are in the circuit device2, heat is rapidly propagated between the output circuit151and the temperature detection circuit101in the temperature sensor100, whereas the circuit device2is disposed apart from the vibrator3, heat is propagated via the package4between the output circuit151and the vibrator3, and heat propagation becomes slow. Therefore, as shown inFIG.7, a time constant of heat propagation between the output circuit151and the temperature detection circuit101is larger than a time constant of heat propagation between the output circuit151and the vibrator3, and when the output circuit151is switched between the first state and the second state, a transient response of the temperature detected by the temperature detection circuit101is faster than a transient response of the temperature of the vibrator3.

When the temperature signal DT output from the A/D conversion circuit102passes through the digital filter111, a group delay occurs according to a cutoff frequency of the digital filter111, and an input of the temperature signal DT to the temperature compensation circuit120is delayed. As a result, due to a time constant of the digital filter111, a difference between the time constant of the heat propagation between the output circuit151and the temperature detection circuit101and the time constant of the heat propagation between the output circuit151and the vibrator3becomes small. Therefore, a difference between the transient response of the temperature detected by the temperature detection circuit101and the transient response of the temperature of the vibrator3is compensated for, and the temperature compensation accuracy attained by the temperature compensation circuit120is improved. That is, the digital filter111has a function of compensating for the difference between the transient response of the temperature detected by the temperature detection circuit101and the transient response of the temperature of the vibrator3when the first state and the second state of the output circuit151are switched, and corresponds to the transient response compensation circuit110shown inFIG.1.

The digital filter111may operate at an order or a cutoff frequency based on data stored in the memory140. That is, the order or the cutoff frequency of the digital filter111may be variable according to data stored in the memory140in advance. Accordingly, the time constant of the digital filter111can be finely adjusted, and compensation accuracy of a transient response by the digital filter111is improved. As a result, the temperature compensation accuracy attained by the temperature compensation circuit120is further improved.

When the temperature outside the package4of the vibrator device1changes, the difference between the heat propagation time between the temperature detection circuit101and the outside air and the heat propagation time between the vibrator3and the outside air is small. Therefore, when the digital filter111is always operating, and when the outside air temperature changes while the output circuit151is in the first state or the second state, excessive temperature compensation is performed by the temperature compensation circuit120. Therefore, after the first state and the second state of the output circuit151are switched, it is preferable to stop an operation of the digital filter111after a predetermined period elapses. The predetermined period may be, for example, a period from when the output circuit151switches between the first state and the second state until the transient response of the temperature of the vibrator3converges.

2-1-3. Operation and Effect

FIG.8is a diagram showing an example of changes over time in a transient response of a temperature indicated by the temperature signals DT and DTX, a transient response of a temperature of the vibrator3, and a frequency deviation of the first output clock signal CK1when the output circuit151is switched from the first state to the second state. InFIG.8, a change over time of the frequency deviation of the first output clock signal CK1in a vibrator device in a comparative example is also indicated by a one dot chain line. The vibrator device in the comparative example does not include the digital filter111inFIG.4, and other configurations are the same as those in the vibrator device1. In an example inFIG.8, when the first enable control signal EN1is active (high level), the second enable control signal EN2changes from inactive (low level) to active (high level) at a time point t1. Therefore, the output circuit151operates in the first state before the time point t1, and the output circuit151operates in the second state after the time point t1. A heat generation amount of the output circuit151increases before and after the time point t1, and the temperature detected by the temperature detection circuit101, that is, the temperature indicated by the temperature signal DT rises. Since the temperature of the vibrator3rises a little later thereafter, in the vibrator device according to the comparative example, the frequency deviation of the first output clock signal CK1increases due to excessive temperature compensation applied in a period from the time point t1to start of the temperature rise of the vibrator3, and becomes 109 ppb at a peak. On the other hand, in the vibrator device1according to the embodiment, a peak of a frequency deviation of the first output clock signal CK1is reduced to 18 ppb by applying appropriate temperature compensation based on the temperature signal DTX having a gentler slope than the temperature signal DT. In the example inFIG.8, when a predetermined period from the time point t1to a time point t2elapses, an operation of the digital filter111is stopped in order to speed up a response to a change in the outside air temperature.

Thus, in the vibrator device1according to the first embodiment, when the first state and the second state of the output circuit151are switched, and when current consumption of the output circuit151changes and a heat generation amount rapidly changes, due to the change in the heat generation amount, the temperature detection circuit101in the circuit device2as well as the output circuit151quickly detects the temperature change, but a temperature change of the vibrator3, which is separate from the circuit device2, is delayed. However, according to the vibrator device1in the first embodiment, a rapid change in the temperature signal DT generated by the temperature detection circuit101becomes gentle by the digital filter111. Therefore, the difference between the transient response of the temperature detected by the temperature detection circuit101and the transient response of the temperature of the vibrator3is compensated for, and even when the current consumption of the output circuit151rapidly changes, the temperature compensation circuit120can perform temperature compensation with high accuracy. Specifically, according to the vibrator device1in the first embodiment, even when the first state in which the first buffer circuit152outputs the first output clock signal CK1and the second state in which the first buffer circuit152and the second buffer circuit153output the first output clock signal CK1and the second output clock signal CK2, respectively, are switched by setting of the first enable control signal EN1and the second enable control signal EN2, which are the external control signals, and the heat generation amount of the output circuit151is changed, the first output clock signal CK1and the second output clock signal CK2that are appropriately temperature-compensated for can be output.

According to the vibrator device1in the first embodiment, the order and the cutoff frequency of the digital filter111can be changed by changing the data stored in the memory140, and the difference between the transient response of the temperature detected by the temperature detection circuit101and the transient response of the temperature of the vibrator3can be accurately compensated for, and as a result, accuracy of the temperature compensation is improved.

According to the vibrator device1in the first embodiment, when a transient situation after the switching between the first state and the second state of the output circuit151ends, the digital filter111stops the operation. Therefore, a possibility that the temperature compensation circuit120performs excessive temperature compensation against subsequent changes in outside air temperature is reduced.

2-2. Second Embodiment

Hereinafter, in a second embodiment, the same reference signs are given to similar configurations as those in the first embodiment, similar description as that in the first embodiment will be omitted or simplified, and contents different from those in the first embodiment will be mainly described.

A structure of the vibrator device1according to the second embodiment is similar as that inFIGS.2and3, and thus illustration and description thereof are omitted.FIG.9is a functional block diagram of the vibrator device1according to the second embodiment. As shown inFIG.9, the vibrator device1according to the second embodiment is different from the vibrator device1according to the first embodiment shown inFIG.4in that the circuit device2includes a PLL circuit190and the temperature compensation circuit120outputs a frequency division ratio setting signal DIV, which is a digital signal indicating a frequency division ratio of the PLL circuit190. The PLL is an abbreviation for phase locked loop. The oscillation circuit131may include the variable capacitance circuit132shown inFIG.4or may not include the variable capacitance circuit132.

The PLL circuit190receives the oscillation signal Vosc and outputs a clock signal CK. The PLL circuit190generates the clock signal CK by performing feedback control such that a phase of the oscillation signal Vosc coincides with a phase of a signal obtained by frequency-dividing the clock signal CK at a frequency division ratio designated by the frequency division ratio setting signal DIV output from the temperature compensation circuit120. The PLL circuit190may be an integer-type PLL circuit that frequency-divides the clock signal CK by an integer frequency division ratio or may be a fractional-N type PLL circuit that frequency-divides the clock signal CK by a fractional frequency division ratio.

The output circuit151outputs at least one output clock signal based on the clock signal CK output from the PLL circuit190. Specifically, the clock signal CK output from the PLL circuit190is input to the first buffer circuit152and the second buffer circuit153of the output circuit151. The first buffer circuit152buffers the clock signal CK and generates the first output clock signal CK1, and the second buffer circuit153buffers the clock signal CK and generates the second output clock signal CK2.

The temperature compensation circuit120compensates for, based on the temperature signal DTX output from the digital filter111, frequency-temperature characteristics of the clock signal CK based on the oscillation signal Vosc as the temperature characteristics of the drive state of the vibrator3. Specifically, the temperature compensation data TCD for compensating for the frequency-temperature characteristics of the clock signal CK is stored in the memory140, and the temperature compensation circuit120generates, based on the temperature signal DTX and the temperature compensation data TCD, the frequency division ratio setting signal DIV that is a digital signal.

FIG.10is a diagram showing a configuration example of the temperature compensation circuit120and the PLL circuit190. In the example inFIG.10, the PLL circuit190is a fractional-N type PLL circuit.

As shown inFIG.10, the temperature compensation circuit120includes an arithmetic circuit121and a delta-sigma modulation circuit122. The PLL circuit190includes a phase comparator191, a charge pump192, a low-pass filter193, a voltage-controlled oscillation circuit194, and a frequency division circuit195.

The arithmetic circuit121of the temperature compensation circuit120calculates, based on the temperature signal DTX output from the digital filter111and the temperature compensation data TCD stored in the memory140, a frequency division ratio of the frequency division circuit195necessary for temperature compensation of the oscillation signal Vosc. Frequency division ratio setting data VDIV is data indicating the frequency division ratio of the frequency division circuit195set at a reference temperature, for example, 25° C., and the arithmetic circuit121performs a calculation for obtaining, based on the frequency division ratio setting data VDIV, the fractional frequency division ratio at the temperature indicated by the temperature signal DTX.

The delta-sigma modulation circuit122performs delta-sigma modulation on the fractional frequency division ratio that is an arithmetic result of the arithmetic circuit121, and outputs the frequency division ratio setting signal DIV that sets the frequency division ratio of the frequency division circuit195. A time average value of the frequency division ratio setting signal DIV coincides with the fractional frequency division ratio that is the arithmetic result of the arithmetic circuit121.

The phase comparator191of the PLL circuit190compares the phase of the oscillation signal Vosc output from the oscillation circuit131with a phase of a clock signal FBCLK output from the frequency division circuit195, and outputs a comparison result as a pulse voltage.

The charge pump192converts the pulse voltage output from the phase comparator191into a current. The low-pass filter193smooths the current output from the charge pump192and converts the smoothed current into a voltage.

The voltage-controlled oscillation circuit194uses the output voltage of the low-pass filter193as a control voltage, and outputs the clock signal CK whose frequency changes according to the control voltage. The voltage-controlled oscillation circuit194can be implemented as various types of oscillation circuits such as an LC oscillation circuit implemented using an inductance element such as a coil and a capacitance element such as a capacitor and an oscillation circuit using a piezoelectric resonator such as a quartz crystal resonator.

The frequency division circuit195outputs, using a value of the frequency division ratio setting signal DIV output from the delta-sigma modulation circuit122of the temperature compensation circuit120as the frequency division ratio, the clock signal FBCLK obtained by frequency-dividing the clock signal CK output from the voltage-controlled oscillation circuit194.

The other configurations and functions of the vibrator device1in the second embodiment are similar as those in the first embodiment, and thus description thereof is omitted.

According to the vibrator device1in the second embodiment described above, similar effects as those of the vibrator device1in the first embodiment can be attained.

The present disclosure is not limited to the embodiment, and various modifications can be made within the scope of the gist of the present disclosure.

For example, the vibrator device1according to the above embodiments is not limited to the structure shown inFIGS.2and3. The vibrator device1may have, for example, a structure shown inFIG.11. InFIG.11, similar components as those inFIG.3are denoted by the same reference signs. The vibrator device1shown inFIG.11is an oscillator having an H-shaped structure, the package4is formed with two recesses on opposite surfaces thereof, the lid5covers one recess to form a housing chamber7a, and a sealing member8covers the other recess to form a housing chamber7b.The vibrator3is housed in the housing chamber7a,and the circuit device2is housed in the housing chamber7b.In the vibrator device1having the H-shaped structure shown inFIG.11, compared with the vibrator device having the single seal structure shown inFIG.3, heat is less likely to propagate between the circuit device2and the vibrator3via a space, and the difference between the transient response of the temperature detected by the temperature sensor100and the transient response of the temperature of the vibrator3is larger. However, since the vibrator device1having the H-shaped structure shown inFIG.11includes the transient response compensation circuit110, the difference between the transient response of the temperature detected by the temperature sensor100and the transient response of the temperature of the vibrator3is compensated for. Therefore, the temperature compensation can be performed with high accuracy.

In each of the above embodiments, the temperature compensated oscillator is taken as an example of the vibrator device1, but a type of the vibrator device1is not limited thereto. For example, the vibrator device1maybe various physical quantity sensors such as a gyro sensor. As an example, the vibrator device1that is a physical quantity sensor includes a sensor element that is the vibrator3and the circuit device2. The circuit device2includes the temperature sensor100, the transient response compensation circuit110that compensates for a difference between a transient response of a temperature detected by the temperature sensor100and a transient response of a temperature of the sensor element, the temperature compensation circuit120that compensates for temperature characteristics of a drive state of the sensor element, the drive circuit130that drives the sensor element, a detection circuit that detects a predetermined physical quantity based on an output signal of the sensor element, and a failure detection circuit that is the heat source circuit150. For example, the failure detection circuit is a circuit that detects a failure or the like of the sensor element. For example, among N times for which the detection circuit acquires the output signal of the sensor element, the failure detection circuit is in a first state in which failure detection is not performed N−1 times, and in a second state in which failure detection is performed once. Therefore, the failure detection circuit corresponds to the heat source circuit150. As another example, the vibrator device1that is a three-axis physical quantity sensor includes a three-axis sensor element that is the vibrator3and the circuit device2. The circuit device2includes the temperature sensor100, the transient response compensation circuit110that compensates for a difference between a transient response of a temperature detected by the temperature sensor100and a transient response of a temperature of the three-axis sensor element, the temperature compensation circuit120that compensates for temperature characteristics of a drive state of the three-axis sensor element, the drive circuit130that drives the sensor element, and the detection circuit that detects a predetermined physical quantity in three axes based on an output signal of the three-axis sensor element. For example, when the drive circuit130switches between drive of a part of the three-axis sensor element and drive of the entire three-axis sensor element, the detection circuit switches between a first state in which detection is performed on output signals of a part of the sensor element and a second state in which detection is performed on output signals of the entire sensor element. Therefore, the detection circuit corresponds to the heat source circuit150. According to the vibrator device1that is such a physical quantity sensor, detection accuracy of the physical quantity is improved by improving the temperature compensation accuracy.

The above embodiments and modification are examples, and the present disclosure is not limited thereto. For example, the embodiments and the modification may be combined as appropriate.

The present disclosure has substantially the same configurations as the configurations described in the embodiments, such as a configuration having the same function, method, and result or a configuration having the same object and effect. The present disclosure has a configuration in which a non-essential portion of the configuration described in the embodiments is replaced. The present disclosure has a configuration capable of achieving the same operation and effect or a configuration capable of achieving the same object as the configuration described in the embodiments. The present disclosure has a configuration obtained by adding a known technique to the configuration described in the embodiment.

The following contents are derived from the above embodiments and modification.

An aspect of a vibrator device including:a vibrator; anda circuit device disposed apart from the vibrator, in whichthe circuit device includesa drive circuit configured to drive the vibrator,a temperature sensor configured to generate a temperature signal corresponding to a detected temperature,a temperature compensation circuit configured to compensate for temperature characteristics of a drive state of the vibrator based on the temperature signal,a heat source circuit configured to operate in a first state or in a second state in which current consumption is different from current consumption in the first state, anda transient response compensation circuit configured to compensate for, when the first state and the second state of the heat source circuit are switched, a difference between a transient response of a temperature detected by the temperature sensor and a transient response of a temperature of the vibrator.

In the vibrator device, when the first state and the second state of the heat source circuit are switched, and when current consumption of the heat source circuit changes and a heat generation amount rapidly changes, due to this change in the heat generation amount, the temperature sensor in the circuit device as well as the heat source circuit quickly detects the temperature change, but a temperature change in the vibrator, which is separate from the circuit device, is delayed. However, according to the vibrator device, by compensating for the difference between the transient response of the temperature detected by the temperature sensor and the transient response of the temperature of the vibrator, the temperature compensation circuit can perform the temperature compensation with high accuracy even when the current consumption of the heat source circuit rapidly changes.

In an aspect of the vibrator device,the temperature signal may be a digital signal, andthe transient response compensation circuit may include a digital filter configured to perform filter processing on the temperature signal.

According to the vibrator device, the temperature signal generated by the temperature sensor is delayed by the digital filter. Therefore, the difference between the transient response of the temperature detected by the temperature sensor and the transient response of the temperature of the vibrator is compensated for.

In an aspect of the vibrator device,the digital filter may be a low-pass filter.

According to the vibrator device, a rapid change in the temperature signal generated by the temperature sensor becomes gentle by the low-pass filter, and thus the difference between the transient response of the temperature detected by the temperature sensor and the transient response of the temperature of the vibrator is compensated for.

In an aspect of the vibrator device,the digital filter may operate at a cutoff frequency based on data stored in a memory.

According to the vibrator device, the cutoff frequency of the digital filter can be changed by changing data stored in the memory, the difference between the transient response of the temperature detected by the temperature sensor and the transient response of the temperature of the vibrator can be accurately compensated for, and as a result, the accuracy of the temperature compensation is improved.

In an aspect of the vibrator device,the transient response compensation circuit may stop operating after a predetermined period elapses after the first state and the second state of the heat source circuit are switched.

According to the vibrator device, when a transient situation after the switching between the first state and the second state of the heat source circuit ends, the transient response compensation circuit stops an operation. Therefore, a possibility that the temperature compensation circuit performs excessive temperature compensation against subsequent changes in outside air temperature is reduced.

In an aspect of the vibrator device,the drive circuit may generate an oscillation signal by oscillating the vibrator,the temperature compensation circuit may compensate for frequency-temperature characteristics of the oscillation signal or a clock signal based on the oscillation signal, andthe heat source circuit may be an output circuit that outputs at least one output clock signal based on the oscillation signal or the clock signal.

According to the vibrator device, by compensating for the difference between the transient response of the temperature detected by the temperature sensor and the transient response of the temperature of the vibrator, even when the current consumption of the output circuit changes and the heat generation amount rapidly changes, an output clock signal that is appropriately temperature-compensated for can be output.

In an aspect of the vibrator device,at least one external control signal may be received, and the first state and the second state of the output circuit may be switched based on the external control signal.

According to the vibrator device, when the output circuit is switched between the first state and the second state by the external control signal and the heat generation amount is changed, the output clock signal that is appropriately temperature-compensated for can also be output.

In an aspect of the vibrator device,a first enable control signal and a second enable control signal may be received as the at least one external control signal, andthe output circuit mayoutput a first output clock signal when the first enable control signal is active, andoutput a second output clock signal when the second enable control signal is active.

According to the vibrator device, when the heat generation amount is changed by switching between the first state and the second state of the output circuit due to setting of the first enable control signal and the second enable control signal, the first output clock signal and the second output clock signal that are appropriately temperature-compensated for can also be output.

In an aspect of the vibrator device,the first state may be a state in which the first output clock signal is output, andthe second state may be a state in which both the first output clock signal and the second output clock signal are output.

According to the vibrator device, when the first state in which the first output clock signal is output and the second state in which both the first output clock signal and the second output clock signal are output are switched and the heat generation amount of the output circuit is changed, the first output clock signal and the second output clock signal that are appropriately temperature-compensated for can also be output.

In an aspect of the vibrator device,the output circuit may includea first buffer circuit configured to output the first output clock signal based on the oscillation signal, anda second buffer circuit configured to output the second output clock signal based on the oscillation signal,in the first state, the first buffer circuit may output the first output clock signal, andin the second state, the first buffer circuit may output the first output clock signal, and the second buffer circuit may output the second output clock signal.

According to the vibrator device, when the first state in which the first buffer circuit outputs the first output clock signal and the second state in which the first buffer circuit and the second buffer circuit output the first output clock signal and the second output clock signal, respectively, are switched and the heat generation amount of the output circuit is changed, the first output clock signal and the second output clock signal that are appropriately temperature-compensated for can also be output.