Circuit devices and oscillators

Abstract

To provide circuit devices and other equipment that can achieve temperature compensation that appropriately reflects the effects of power supply voltage fluctuations and offset adjustments. [Solution] The circuit device 20, which operates when a power supply voltage VDD is supplied, includes an oscillation circuit 30 that causes the oscillator 10 to oscillate, a temperature sensor 50 that outputs a temperature detection voltage VTS, an offset adjustment circuit 60 that outputs an offset adjustment voltage VOF of the temperature detection voltage VTS, a correction voltage output circuit 70 that receives the power supply voltage VDD and the offset adjustment voltage VOF as inputs and outputs a correction voltage VCR that changes according to the power supply voltage VDD and the offset adjustment voltage VOF, a correction circuit 74 that receives the temperature detection voltage VTS and the correction voltage VCR as inputs and outputs a temperature detection voltage VTS2 corrected by the correction voltage VCR, and a temperature compensation circuit 40 that performs temperature compensation for the oscillation frequency of the oscillation circuit 30 based on the corrected temperature detection voltage VTS2.

Description

Technical Field

[0001] The present invention relates to a circuit device, an oscillator, and the like.

Background Art

[0002] In a circuit device that oscillates an oscillator such as a crystal oscillator, temperature compensation of the oscillation frequency is performed. For example, Patent Document 1 discloses an oscillator including a correction circuit that performs correction to change a temperature compensation voltage according to a change in power supply voltage. Patent Document 1 also discloses that a variable resistor is provided in a temperature sensor, and by changing the resistance value of the variable resistor, the offset of the temperature detection voltage is adjusted to perform temperature compensation such as a zero-order component of the frequency-temperature characteristic of the oscillator.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, no temperature compensation circuit method that appropriately reflects the influence of power supply voltage fluctuations and offset adjustment has been proposed.

Means for Solving the Problems

[0005] One aspect of the present disclosure relates to a circuit device that operates on a power supply voltage, and includes: an oscillation circuit that causes an oscillator to oscillate; a temperature sensor that outputs a temperature detection voltage; an offset adjustment circuit that outputs an offset adjustment voltage of the temperature detection voltage; a correction voltage output circuit that receives the power supply voltage and the offset adjustment voltage as inputs and outputs a correction voltage that changes according to the power supply voltage and the offset adjustment voltage; a correction circuit that receives the temperature detection voltage and the correction voltage as inputs and outputs the temperature detection voltage after correction by the correction voltage; and a temperature compensation circuit that performs temperature compensation for the oscillation frequency of the oscillation circuit based on the corrected temperature detection voltage.

[0006] Another aspect of this disclosure relates to an oscillator including the circuit device described above and the vibrator. [Brief explanation of the drawing]

[0007] [Figure 1] An example of the configuration of the circuit device and oscillator according to this embodiment. [Figure 2] Detailed configuration example of the circuit device and oscillator of this embodiment. [Figure 3] An example of frequency-temperature characteristics when the power supply voltage increases. [Figure 4] An example of frequency-temperature characteristics when the power supply voltage drops. [Figure 5] Example configuration of offset adjustment circuit, correction voltage output circuit, and correction circuit. [Figure 6] A detailed example of a correction voltage output circuit with variable resistance ratios, etc. [Figure 7] A diagram illustrating a method for generating a correction voltage according to the power supply voltage. [Figure 8] An example of the temperature characteristics of a temperature detection voltage. [Figure 9] An explanatory diagram of the correction method of this embodiment. [Figure 10] An example of a temperature compensation circuit configuration. [Figure 11] A first example configuration of a temperature sensor. [Figure 12] A second example configuration of a temperature sensor. [Figure 13]Configuration example of the temperature sensor of the comparative example. [Figure 14] Configuration example of the correction circuit of the comparative example. [Figure 15] Explanation diagram of the problem of the change in the slope characteristic of the temperature detection voltage in the comparative example. [Figure 16] Explanation diagram of the linearity of the offset adjustment voltage in the comparative example. [Figure 17] Explanation diagram of the linearity of the offset adjustment voltage in the present embodiment. [Figure 18] Explanation diagram of the change in the inflection point temperature due to offset adjustment. [Figure 19] First structural example of the oscillator. [Figure 20] Second structural example of the oscillator.

Mode for Carrying Out the Invention

[0008] Hereinafter, the present embodiment will be described. Note that the present embodiment described below does not unduly limit the content described in the claims. Also, not all of the configurations described in the present embodiment are essential constituent elements.

[0009] 1. Circuit device FIG. 1 shows a configuration example of the circuit device 20 of the present embodiment. The circuit device 20 of the present embodiment includes an oscillation circuit 30, a temperature compensation circuit 40, a temperature sensor 50, an offset adjustment circuit 60, a correction voltage output circuit 70, and a correction circuit 74. Further, the oscillator 4 of the present embodiment includes a vibrator 10 and the circuit device 20. The vibrator 10 is electrically connected to the circuit device 20. Note that the circuit device 20 and the oscillator 4 are not limited to the configuration of FIG. 1, and various modifications such as omitting some of these constituent elements, adding other constituent elements, or replacing some constituent elements with other constituent elements are possible.

[0010] The oscillator 10 is an element that generates mechanical vibrations in response to an electrical signal. The oscillator 10 can be realized by a vibrating element, such as a quartz crystal vibrator. For example, the oscillator 10 can be realized by a quartz crystal vibrator that vibrates with thickness shear, such as an AT cut or SC cut, a tuning fork type quartz crystal vibrator, or a double tuning fork type quartz crystal vibrator. For example, the oscillator 10 may be an oscillator built into a temperature-compensated crystal oscillator (TCXO) without a constant temperature chamber, or an oscillator built into a constant temperature chamber type quartz oscillator (OCXO) with a constant temperature chamber. The oscillator 10 of this embodiment can also be realized by various vibrating elements, such as vibrating elements other than thickness shear type, tuning fork type, or double tuning fork type, or piezoelectric vibrating elements made of materials other than quartz. For example, the oscillator 10 can be a SAW (Surface Acoustic Wave) resonator or a MEMS (Micro Electro Mechanical Systems) oscillator as a silicon oscillator formed using a silicon substrate.

[0011] The circuit device 20 is an integrated circuit (IC). For example, the circuit device 20 is an IC manufactured by a semiconductor process, and is a semiconductor chip in which circuit elements are formed on a semiconductor substrate. The circuit device 20 operates based on the power supply voltage VDD.

[0012] The oscillation circuit 30 is a circuit that oscillates the oscillator 10. For example, the oscillation circuit 30 generates an oscillation signal by oscillating the oscillator 10. The oscillation signal is an oscillation clock signal. For example, the oscillation circuit 30 can be realized by a driving circuit for oscillation that is electrically connected to one end and the other end of the oscillator 10 and passive elements such as capacitors and resistors. The driving circuit can be realized by, for example, a CMOS inverter circuit or a bipolar transistor. The driving circuit is the core circuit of the oscillation circuit 30, and the driving circuit oscillates the oscillator 10 by voltage-driving or current-driving the oscillator 10. As the oscillation circuit 30, various types of oscillation circuits such as an inverter type, a Pierce type, a Colpitts type, or a Hartley type can be used. Note that the connection in this embodiment is an electrical connection. An electrical connection is a connection in which an electrical signal can be transmitted, and it is a connection in which information can be transmitted by an electrical signal. The electrical connection may be a connection via a passive element or the like.

[0013] The temperature sensor 50 is a sensor that detects temperature. Specifically, the temperature sensor 50 outputs a temperature-dependent voltage that changes according to the temperature of the environment as a temperature detection voltage VTS. For example, the temperature sensor 50 generates a temperature detection voltage VTS, which is a temperature detection signal, using a circuit element having temperature dependence. Specifically, the temperature sensor 50 outputs a temperature detection voltage VTS whose voltage changes depending on temperature by using, for example, the temperature dependence of the forward voltage of a PN junction. It is also possible to use a modified embodiment in which a digital temperature sensor circuit is used as the temperature sensor 50. In this case, the temperature detection data may be D / A converted to generate the temperature detection voltage VTS.

[0014] The offset adjustment circuit 60 outputs an offset adjustment voltage VOF. The offset adjustment voltage VOF is, for example, a voltage used to adjust the offset of the temperature detection voltage VTS. This offset adjustment can also be called a zero-order offset adjustment. For example, the offset adjustment circuit 60 generates the offset adjustment voltage VOF based on zero-order correction data corresponding to the zero-order coefficient of the polynomial in the polynomial approximation of the temperature compensation characteristic. As a result, the temperature detection voltage VTS is offset by the amount of the offset indicated by the zero-order correction data, and the corrected temperature detection voltage VTS is input to the temperature compensation circuit 40. This makes it possible to adjust the offset fluctuations of the temperature detection voltage VTS caused by manufacturing variations, etc.

[0015] The correction voltage output circuit 70 outputs a correction voltage VCR. For example, the correction voltage output circuit 70 receives the power supply voltage VDD and the offset adjustment voltage VOF as inputs and outputs a correction voltage VCR that changes according to the power supply voltage VDD and the offset adjustment voltage VOF. For example, the correction voltage VCR is a voltage that changes only by the voltage corresponding to the change in the power supply voltage VDD and also by the voltage corresponding to the change in the offset adjustment voltage VOF. For example, the correction voltage VCR is a subtractive or additive voltage of the voltage obtained by multiplying the offset adjustment voltage VOF by a given coefficient and the voltage obtained by multiplying the power supply voltage VDD by a given coefficient. As an example, the correction voltage VCR decreases when the power supply voltage VDD increases and increases when the offset adjustment voltage VOF increases. In this way, the correction voltage output circuit 70 outputs a correction voltage VCR that reflects the voltage changes of both the power supply voltage VDD and the offset adjustment voltage VOF.

[0016] The correction circuit 74 outputs the corrected temperature detection voltage VTS2. For example, the correction circuit 74 receives the temperature detection voltage VTS and the correction voltage VCR as inputs and outputs the corrected temperature detection voltage VTS2 based on the correction voltage VCR. The corrected temperature detection voltage VTS2 is a voltage obtained by changing the temperature detection voltage VTS by, for example, the voltage corresponding to the correction voltage VCR. For example, the corrected temperature detection voltage VTS2 is a subtractive or additive voltage of the voltage obtained by multiplying the temperature detection voltage VTS by a given coefficient and the voltage obtained by multiplying the correction voltage VCR by a given coefficient. As an example, the corrected temperature detection voltage VTS2 increases when the temperature detection voltage VTS increases and decreases when the correction voltage VCR increases. In this way, the correction circuit 74 outputs a temperature detection voltage VTS2 in which the temperature detection voltage VTS is corrected by the correction voltage VCR, which is determined based on the power supply voltage VDD and the offset adjustment voltage VOF. As a result, a temperature detection voltage VTS2 is generated that reflects the changes in the power supply voltage VDD and the offset adjustment voltage VOF in relation to the temperature detection voltage VTS from the temperature sensor 50. Furthermore, it is also possible to implement a modified version in which the correction circuit 74 corrects the temperature detection voltage VTS from the temperature sensor 50 located outside the circuit device 20 and outputs the temperature detection voltage VTS2.

[0017] The temperature compensation circuit 40 performs temperature compensation for the oscillation frequency of the oscillation circuit 30. Temperature compensation is a process that suppresses and compensates for fluctuations in the oscillation frequency caused by temperature fluctuations, for example. That is, the temperature compensation circuit 40 performs temperature compensation for the oscillation frequency of the oscillation circuit 30 so that the oscillation frequency remains constant even when there are temperature fluctuations. In this embodiment, the temperature compensation circuit 40 performs temperature compensation for the oscillation frequency of the oscillation circuit 30 based on the corrected temperature detection voltage VTS2. For example, the temperature compensation circuit 40 outputs a temperature compensation voltage VCP that temperature-compensates the oscillation frequency based on the temperature detection voltage VTS2. In this way, the temperature compensation circuit 40 performs temperature compensation for the oscillation frequency of the oscillation circuit 30 based on the temperature detection voltage VTS2 obtained by correcting the temperature detection voltage VTS of the temperature sensor 50 with a correction voltage VCR obtained based on the power supply voltage VDD and the offset adjustment voltage VOF. It is also possible to implement a modified version in which the oscillation frequency is digitally adjusted in the variable capacitance circuit of the oscillation circuit 30 using temperature compensation data obtained by A / D conversion of the temperature compensation voltage VCP.

[0018] For example, when the power supply voltage VDD increases, the amount of heat generated by the circuit device 20, which operates under the power supply voltage VDD, increases, and the temperature detected by the temperature sensor 50 rises. However, since the circuit device 20 and the oscillator 10 are physically separated, the temperature detected by the circuit device 20 and the temperature of the oscillator 10 do not match, and for example, the temperature of the oscillator 10 may be lower. Therefore, if the temperature compensation circuit 40 outputs a temperature compensation voltage VCP based on the temperature detection voltage VTS of the temperature sensor 50 of the circuit device 20, and this temperature compensation voltage VCP is used to compensate for the oscillation frequency of the oscillator 10 by temperature, it becomes impossible to achieve accurate temperature compensation.

[0019] Furthermore, temperature compensation of the oscillation frequency requires zero-order offset adjustment. This zero-order offset adjustment can be achieved, for example, by adjusting the offset of the temperature detection voltage VTS. In this regard, the conventional technology described in Patent Document 1 above provided a variable resistor in the temperature sensor 50, and the offset adjustment of the temperature detection voltage VTS was performed within the temperature sensor 50 by adjusting the resistance value of this variable resistor. However, as will be detailed later, it was found that this conventional method has problems such as deterioration of the linearity of the offset adjustment and changes in the slope characteristics of the temperature detection voltage VTS with respect to temperature due to the offset adjustment.

[0020] Therefore, in this embodiment, the temperature sensor 50 does not have an offset adjustment function for the temperature detection voltage VTS, and an offset adjustment circuit 60 that outputs an offset adjustment voltage VOF is provided separately from the temperature sensor 50. Furthermore, a correction voltage output circuit 70 outputs a correction voltage VCR that changes according to the power supply voltage VDD and the offset adjustment voltage VOF, and a correction circuit 74 outputs a temperature detection voltage VTS2 obtained by correcting the temperature detection voltage VTS of the temperature sensor 50 with the correction voltage VCR. Then, the temperature compensation circuit 40 performs temperature compensation of the oscillation frequency of the oscillation circuit 30 based on the temperature detection voltage VTS2 corrected by the correction circuit 74. For example, temperature compensation of the oscillation frequency is performed by adjusting the capacitance of the variable capacitance circuit provided in the oscillation circuit 30 based on the temperature compensation voltage VCP from the temperature compensation circuit 40.

[0021] In this way, even if fluctuations in the power supply voltage VDD cause a large temperature difference between the temperature detected by the circuit device 20 and the temperature of the oscillator 10, resulting in errors in temperature compensation, a correction is performed to reduce this error, thereby improving the accuracy of the oscillation frequency and other aspects.

[0022] In this embodiment, an offset adjustment circuit 60 is provided separately from the temperature sensor 50 to generate an offset adjustment voltage VOF. The temperature detection voltage VTS of the temperature sensor 50 is corrected by the correction voltage VCR generated by the power supply voltage VDD and the offset adjustment voltage VOF, and temperature compensation is performed using the corrected temperature detection voltage VTS. Therefore, it is possible to suppress the problem of deterioration in the linearity of the offset adjustment that occurs when the temperature sensor 50 is given an offset adjustment function, and the problem that the slope characteristics of the temperature detection voltage VTS change due to the offset adjustment. In addition, since temperature compensation is performed by the temperature detection voltage VTS corrected by the correction voltage VCR based on the power supply voltage VDD and the offset adjustment voltage VOF, it becomes possible to perform correction in higher-order circuits of the temperature compensation circuit 40, and appropriate temperature compensation of the oscillation frequency can be achieved.

[0023] Figure 2 shows a detailed configuration example of the circuit device 20 and oscillator 4 of this embodiment. In Figure 2, the circuit device 20 includes an oscillation circuit 30, a temperature compensation circuit 40, a temperature sensor 50, an offset adjustment circuit 60, a corrected voltage output circuit 70, a correction circuit 74, as well as an output circuit 80, a power supply circuit 90, a control circuit 100, and a non-volatile memory 110. The oscillator 4 includes a vibrator 10 and the circuit device 20, with the vibrator 10 being electrically connected to the circuit device 20. For example, the vibrator 10 and the circuit device 20 are electrically connected using internal wiring, bonding wires, or metal bumps in the package housing the vibrator 10 and the circuit device 20. Note that the circuit device 20 and oscillator 4 are not limited to the configuration shown in Figure 2, and various modifications can be made, such as omitting some of these components, adding other components, or replacing some components with other components.

[0024] The circuit device 20 also includes pads PVDD, PGND, PX1, PX2, and PCK. The pads are terminals of the circuit device 20, which is a semiconductor chip. For example, in the pad area, a metal layer is exposed from the passivation film, which is an insulating layer, and this exposed metal layer constitutes the pads, which are terminals of the circuit device 20. Pads PVDD and PGND are the power supply pad and the ground pad, respectively. The power supply voltage VDD from an external power supply device is supplied to pad PVDD. Pad PGND is the pad to which the ground voltage GND is supplied. GND can also be called VSS, and the ground voltage is, for example, the earth potential. In this embodiment, ground will be written as GND as appropriate. For example, VDD corresponds to the high-potential side power supply, and GND corresponds to the low-potential side power supply. Pads PX1 and PX2 are pads for connecting the oscillator 10. Pad PCK is the pad for outputting the clock signal CK. Pads PVDD, PGND, and PCK are electrically connected to terminals TVDD, TGND, and TCK, which are external terminals for external connection of the oscillator 4, respectively. For example, each of these pads and terminals is electrically connected using internal wiring of the package, bonding wires, or metal bumps. Alternatively, terminals and pads to which an external control voltage is input may be provided so that an external system can control the oscillation frequency using this control voltage.

[0025] The oscillation circuit 30 is electrically connected to the vibrator 10 via pads PX1 and PX2. Pads PX1 and PX2 are pads for connecting to the vibrator. The drive circuit for oscillation of the oscillation circuit 30 is provided between pads PX1 and PX2. The oscillation circuit 30 includes a variable capacitance circuit 32. The variable capacitance circuit 32 is a circuit that changes the capacitance at least one of the two ends of the vibrator 10, and the oscillation frequency of the oscillation circuit 30 can be adjusted by adjusting the capacitance of the variable capacitance circuit 32. That is, by electrically connecting the variable capacitance circuit 32 to at least one of pads PX1 and PX2, the load capacitance of the oscillation circuit 30 can be variably adjusted. The variable capacitance circuit 32 can be realized by a variable capacitance element such as a varactor. For example, the variable capacitance circuit 32 is composed of at least one variable capacitance element.

[0026] The temperature compensation circuit 40 performs analog temperature compensation, for example, using polynomial approximation. For example, when the temperature compensation voltage VCP that compensates for the frequency-temperature characteristics of the oscillator 10 is approximated by a polynomial, the temperature compensation circuit 40 performs analog temperature compensation based on the coefficient information of the polynomial. Analog temperature compensation is temperature compensation realized by, for example, summing analog signals such as current signals and voltage signals. For example, when the temperature compensation voltage VCP is approximated by a higher-order polynomial, the zero-order coefficient, first-order coefficient, and higher-order coefficient of the polynomial are stored as zero-order correction data, first-order correction data, and higher-order correction data, respectively, in a storage unit realized by, for example, a non-volatile memory 110. The higher-order coefficient is, for example, a coefficient of a higher order than the first order, and the higher-order correction data is correction data corresponding to the higher-order coefficient. For example, when the temperature compensation voltage VCP is approximated by a cubic polynomial, the zeroth, first, second, and third coefficients of the polynomial are stored in the memory as zeroth correction data, first, second, and third correction data. The temperature compensation circuit 40 then performs temperature compensation based on the zeroth to third correction data. In this case, the second correction data and temperature compensation based on the second correction data may be omitted. Also, for example, when the temperature compensation voltage VCP is approximated by a quintic polynomial, the zeroth, first, second, third, fourth, and fifth coefficients of the polynomial are stored in the memory as zeroth correction data, first, second, third, fourth, and fifth correction data. The temperature compensation circuit 40 then performs temperature compensation based on the zeroth to fifth correction data. In this case, the second or fourth correction data and temperature compensation based on the second or fourth correction data may be omitted. Furthermore, the degree of the polynomial approximation is arbitrary; for example, a polynomial approximation of a degree greater than 5th degree may be used.

[0027] The control circuit 100 is a circuit that performs various control processing. For example, it can be implemented by a logic circuit. For example, the control circuit 100 controls the entire circuit device 20 or controls the operation sequence of the circuit device 20. The control circuit 100 also performs various processing for controlling the oscillation circuit 30, controls the temperature compensation circuit 40, temperature sensor 50, offset adjustment circuit 60, correction voltage output circuit 70, correction circuit 74, output circuit 80, or power supply circuit 90, or controls the reading and writing of information to the non-volatile memory 110. The control circuit 100 can be implemented by an ASIC (Application Specific Integrated Circuit) circuit with automatic placement and routing, such as a gate array. The control circuit 100 also includes a register 102. For example, the register 102 can be implemented by a memory circuit such as a flip-flop circuit. This register 102 stores various information necessary for temperature compensation processing and correction processing. For example, based on this information read from the non-volatile memory 110 and loaded into the register 102, the control circuit 100 performs various control processing.

[0028] The non-volatile memory 110 is a memory that retains information even without a power supply. For example, the non-volatile memory 110 is a memory that can retain information even without a power supply and can also rewrite information. The non-volatile memory 110 stores various information necessary for the operation of the circuit device 20. The non-volatile memory 110 can be implemented as an EEPROM (Electrically Erasable Programmable Read-Only Memory) realized by FAMOS memory (Floating gate Avalanche injection MOS memory) or MONOS memory (Metal-Oxide-Nitride-Oxide-Silicon memory). The non-volatile memory 110 stores correction data such as primary correction data and higher-order correction data used for temperature compensation of the temperature compensation circuit 40.

[0029] The output circuit 80 outputs a clock signal CK based on the oscillation signal of the oscillator circuit 30. For example, the output circuit 80 buffers the oscillation signal, which is the oscillation clock signal from the oscillator circuit 30, and outputs it as a clock signal CK to the pad PCK. This clock signal CK is then output externally via the clock output terminal TCK of the oscillator 4. For example, the output circuit 80 outputs the clock signal CK in single-ended CMOS signal format. Alternatively, the output circuit 80 may output the clock signal CK in a signal format other than CMOS. Furthermore, a clock signal generation circuit, such as a PLL circuit, may be provided after the oscillator circuit 30 to generate a clock signal CK with a frequency multiplied by the frequency of the oscillation signal, and the output circuit 80 may buffer and output the clock signal CK generated by this clock signal generation circuit.

[0030] The power supply circuit 90 receives the power supply voltage VDD from pad PVDD and the ground voltage GND from pad PGND, and supplies various power supply voltages for the internal circuits of the circuit device 20. For example, the power supply circuit 90 supplies a regulated power supply voltage, which is a regulated power supply voltage obtained by regulating the power supply voltage VDD, to each circuit of the circuit device 20, such as the oscillator circuit 30.

[0031] The oscillation circuit 30 includes a variable capacitance circuit 32 whose capacitance change characteristic with respect to the capacitance control voltage is, for example, a positive characteristic. A positive capacitance change characteristic means that the capacitance increases as the capacitance control voltage increases. The capacitance change characteristic of the variable capacitance circuit 32 may also be a negative characteristic. The temperature compensation circuit 40 supplies a temperature compensation voltage VCP to the variable capacitance circuit 32 as the capacitance control voltage. Since the variable capacitance circuit 32 is a variable capacitance circuit with a positive characteristic, when the temperature compensation voltage VCP from the temperature compensation circuit 40 increases, the capacitance of the variable capacitance circuit 32 increases, and when the temperature compensation voltage VCP decreases, the capacitance of the variable capacitance circuit 32 decreases. By providing the oscillation circuit 30 with a variable capacitance circuit 32 with a positive characteristic to which the temperature compensation voltage VCP from the temperature compensation circuit 40 is supplied as the capacitance control voltage, for example, when the temperature rises, the capacitance of the variable capacitance circuit 32 increases, and the oscillation frequency of the oscillation circuit 30 decreases. This allows for temperature compensation to be achieved, for example, when the oscillation frequency of the oscillator 10 increases in a high-temperature region, by increasing the capacitance of the variable capacitance circuit 32, thereby offsetting the increase in oscillation frequency. Furthermore, by providing a variable capacitance circuit 32 with positive characteristics in the oscillation circuit 30, it becomes possible to use, for example, a Class A amplifier circuit as the output amplifier of the temperature compensation voltage VCP of the temperature compensation circuit 40, thereby enabling miniaturization of the circuit. Alternatively, the oscillation circuit 30 may be provided with a variable capacitance circuit whose capacitance is controlled by an externally input frequency control voltage, allowing the oscillation frequency to be variably controlled by this frequency control voltage.

[0032] 2. Offset adjustment circuit, correction voltage output circuit, correction circuit In recent years, as oscillators 4 have become smaller, their heat capacity has decreased, resulting in a greater temperature rise in oscillators 4 even when the same amount of heat is generated in the circuit device 20. This increases the temperature difference between the circuit device 20, which is the heat source, and the ambient temperature, and also increases the temperature difference between the circuit device 20 and the oscillator 10. When the temperature difference between the circuit device 20 and the oscillator 10 becomes large in this way, the difference between the characteristics of the temperature compensation voltage VCP, which is generated based on the temperature detection voltage VTS of the temperature sensor 50 built into the circuit device 20, and the frequency-temperature characteristics determined by the temperature of the oscillator 10 becomes large, increasing the error in temperature compensation.

[0033] For example, the frequency-temperature characteristics of oscillator 4 have individual variations due to manufacturing variations and mounting effects of the IC circuit device 20 and the resonator 10. Therefore, adjustments are made before shipment and through the adjustment function of the circuit device 20 to generate an optimal temperature compensation voltage VCP that absorbs these errors. However, measures against the surrounding environment that occurs after the product is shipped have been insufficient. For example, the circuit device 20 operates on an external power supply voltage VDD, but the fluctuation of the power supply voltage VDD is specified in the product specifications, for example, 3.3V ± 10%. When the power supply voltage VDD fluctuates, the amount of heat generated by the circuit device 20, which operates based on the power supply voltage VDD, also fluctuates, and when the power supply voltage VDD rises, the amount of heat generated by the circuit device 20 also increases. In this case, as the package of oscillator 4 on which the circuit device 20 is mounted is miniaturized, the temperature rise of oscillator 4 due to the heat generated by the circuit device 20 also increases. As a result, as described above, the temperature difference between the circuit device 20 and the resonator 10 increases, and the error in temperature compensation increases.

[0034] For example, Figure 3 shows an example of frequency-temperature characteristics when the power supply voltage VDD increases. In Figure 3, the horizontal axis is temperature T, and the vertical axis is the oscillation frequency, which is frequency f. In reality, the vertical axis is the frequency deviation from the nominal frequency, but in the following explanation, the frequency deviation will be described as frequency f. A1 in Figure 3 shows the frequency-temperature characteristics of the oscillator 10 when the power supply voltage VDD is a typical voltage such as 3.3V. For example, adjustments are made during the pre-shipment adjustment process of the product so that the temperature characteristics due to the temperature compensation voltage VCP of the circuit device 20 match those of the frequency-temperature characteristics of the oscillator 10. Specifically, in the circuit device 20 in Figure 2, temperature compensation is performed using a variable capacitance circuit 32 with a positive characteristic. Therefore, when the temperature compensation voltage VCP increases, the capacitance of the variable capacitance circuit 32 increases and the oscillation frequency decreases, and when the temperature compensation voltage VCP decreases, the capacitance of the variable capacitance circuit 32 decreases and the oscillation frequency increases. Therefore, by setting the frequency-temperature characteristics of the temperature compensation voltage VCP to the characteristics shown in Figure 3A1, it becomes possible to cancel out the frequency-temperature characteristics of the oscillator 10, thereby achieving temperature compensation that keeps the oscillation frequency constant.

[0035] Figure 3A2 shows the frequency-temperature characteristics of the oscillator 10 when VDD increases by +5%, and A3 shows the frequency-temperature characteristics of the oscillator 10 when VDD increases by +10%. For example, the temperature of the oscillator 10 rises due to the heat generated by the circuit device 20 when VDD increases, but by adjusting the temperature compensation voltage VCP to have the frequency-temperature characteristics shown in A2 and A3, proper temperature compensation that keeps the oscillation frequency constant can be achieved. Specifically, as mentioned above, in Figure 2, temperature compensation is performed using a variable capacitance circuit 32 with a positive characteristic, so when the power supply voltage VDD fluctuates, temperature compensation that keeps the oscillation frequency constant can be achieved by making the frequency-temperature characteristics of the temperature compensation voltage VCP have the characteristics shown in A2 and A3.

[0036] However, the circuit device 20 generates a temperature compensation voltage VCP based on the temperature detected by the built-in temperature sensor 50 to perform temperature compensation for the oscillation frequency. As mentioned above, there is a temperature difference between the circuit device 20 and the oscillator 10, and as shown in Figure 3, when the power supply voltage VDD increases and the amount of heat generated by the circuit device 20 increases, the temperature difference between the temperature detected by the temperature sensor 50 of the circuit device 20 and the temperature of the oscillator 10 increases. As a result, the circuit device 20 performs temperature compensation using the temperature compensation voltage VCP of the frequency-temperature characteristics shown in A4 and A5 of Figure 3, and a discrepancy occurs between this and the frequency-temperature characteristics A2 and A3 which are based on the actual temperature of the oscillator 10. As a result, an error occurs in the oscillation frequency after temperature compensation, and it becomes impossible to keep the oscillation frequency within the specified frequency accuracy.

[0037] On the other hand, Figure 4 shows an example of frequency-temperature characteristics when the power supply voltage VDD decreases. B1 in Figure 4 is the frequency-temperature characteristics of the oscillator 10 when the power supply voltage VDD is a typical voltage such as 3.3V. B2 in Figure 4 is the frequency-temperature characteristics of the oscillator 10 when VDD decreases by -5%, and B3 is the frequency-temperature characteristics of the oscillator 10 when VDD decreases by -10%. In this way, even when the power supply voltage VDD decreases, the temperature difference between the temperature detected by the temperature sensor 50 of the circuit device 20 and the temperature of the oscillator 10 causes the circuit device 20 to perform temperature compensation using the temperature compensation voltage VCP of the frequency-temperature characteristics as shown in B4 and B5 of Figure 4, resulting in a discrepancy between the frequency-temperature characteristics B2 and B3, which are based on the actual temperature of the oscillator 10, and the temperature difference between the temperature detected by the temperature sensor 50 of the circuit device 20 and the temperature of the oscillator 10.

[0038] Furthermore, temperature compensation requires zero-order offset adjustment, and while the aforementioned Patent Document 1 performed zero-order offset adjustment in the temperature sensor, it was found that this resulted in problems such as deterioration of the linearity of the offset adjustment and changes in the slope characteristics of the temperature detection voltage.

[0039] In this embodiment, the offset adjustment circuit 60 generates an offset adjustment voltage VOF, the correction voltage output circuit 70 generates a correction voltage VCR based on the offset adjustment voltage VOF and the power supply voltage VDD, the correction circuit 74 corrects the temperature detection voltage VTS based on the correction voltage VCR, and the temperature compensation circuit 40 performs temperature compensation using the corrected temperature detection voltage VTS2. This makes it possible to achieve temperature compensation that appropriately reflects the effects of fluctuations in the power supply voltage VDD and the offset adjustment. Figure 5 shows an example of the configuration of the offset adjustment circuit 60, the correction voltage output circuit 70, and the correction circuit 74. Note that the configuration of the offset adjustment circuit 60, the correction voltage output circuit 70, and the correction circuit 74 is not limited to the configuration in Figure 5, and various modifications can be implemented.

[0040] In Figure 5, an R-2R ladder type D / A conversion circuit is used as the offset adjustment circuit 60. For example, the offset adjustment circuit 60 is a circuit that D / A converts offset adjustment data to an offset adjustment voltage VOF using the R-2R ladder method. That is, the R-2R ladder method realizes the 0th order offset adjustment function. The offset adjustment data corresponds to, for example, the 0th order correction data for temperature compensation. In the R-2R ladder method, switches SW1 to SWm are provided for switching between VREG and GND, corresponding to the number of bits of the offset adjustment data. Then, by switching each switch SW1 to SWm to the VREG side or the GND side based on each bit of the offset adjustment data, the resistance value is switched to generate the offset adjustment voltage VOF. Specifically, the offset adjustment circuit 60 includes resistors RA1 and RA2 provided in series between the VREG power supply node and the GND node, switches SW1 to SWm, a resistor with resistance value 2R provided between nodes N1 to Nm and switches SW1 to SWm, and a resistor with resistance value R provided between nodes N1 to Nm. Then, based on the m-bit offset adjustment data, switches SW1 to SWm are switched to either the VREG side or the GND side, and the voltage obtained by D / A conversion of the offset adjustment data is generated at node N1 as the offset adjustment voltage VOF.

[0041] Thus, the R-2R ladder type offset adjustment circuit 60 improves the linearity of the offset adjustment compared to a configuration where the temperature sensor has an offset adjustment function. It also prevents the problem of the slope characteristics of the temperature detection voltage changing due to the offset adjustment.

[0042] Furthermore, as a variation of the offset adjustment circuit 60, it is also possible to use a series resistance type D / A conversion circuit having multiple resistors arranged in series between the power supply node and the GND node, and multiple switches arranged between the multiple resistor connection nodes and the output node of the offset adjustment voltage VOF. However, a configuration using a series resistance type D / A conversion circuit has the problem of a large layout area. In contrast, the offset adjustment circuit 60 using the R-2R ladder method shown in Figure 5 has the advantage of reducing the layout area of ​​the resistors compared to using the series resistance method, and reducing the circuit layout area by, for example, about 40%. Note that the offset adjustment circuit 60 is not limited to a configuration using the R-2R ladder method, and various modifications can be implemented, such as a D / A conversion circuit configuration using a series resistance method or a capacitance distribution method.

[0043] In Figure 5, the correction voltage output circuit 70 includes an operational amplifier OPB to which a power supply compensation voltage VB, which changes according to the power supply voltage VDD, is input to the first input terminal, an offset adjustment voltage VOF is input to the second input terminal, and a correction voltage VCR is output from the output terminal. The first input terminal is, for example, the inverting input terminal of the operational amplifier OPB, and the second input terminal is, for example, the non-inverting input terminal of the operational amplifier OPB. The operational amplifier OPB is the first operational amplifier. The power supply compensation voltage VB is a voltage used to perform compensation according to the power supply voltage VDD, and is a voltage that changes in accordance with changes in the power supply voltage VDD. For example, the power supply compensation voltage VB increases when the power supply voltage VDD increases and decreases when the power supply voltage VDD decreases.

[0044] In this way, the operational amplifier OPB of the correction voltage output circuit 70 receives a power supply compensation voltage VB corresponding to the power supply voltage VDD as input to the first input terminal, and an offset adjustment voltage VOF as input to the second input terminal. As a result, it can output a correction voltage VCR from its output terminal that reflects the power supply voltage VDD and the offset adjustment voltage VOF. For example, the correction voltage output circuit 70 can output a correction voltage VCR that is obtained by subtracting or adding a voltage obtained by multiplying the offset adjustment voltage VOF by a given coefficient and a voltage obtained by multiplying the power supply voltage VDD by a given coefficient. This allows the temperature detection voltage VTS from the temperature sensor 50 to be corrected by the correction voltage VCR that reflects the power supply voltage VDD and the offset adjustment voltage VOF, and the corrected temperature detection voltage VTS2 can be output to the temperature compensation circuit 40.

[0045] Specifically, the compensation voltage output circuit 70 includes resistors RB1 and RB2 connected in series between the input node NVD of the power supply voltage VDD and the output terminal node NB3 of the operational amplifier OPB. Resistor RB1 is the first resistor, and resistor RB2 is also the first resistor. The power supply compensation voltage VB from the connection node NB1 of resistors RB1 and RB2 is supplied to the first input terminal of the operational amplifier OPB. For example, the power supply compensation voltage VB is input to the connection node NB1 of the inverting input terminal, which is the first input terminal of the operational amplifier OPB. Also, the offset adjustment voltage VOF is input to node NB2 of the non-inverting input terminal, which is the second input terminal of the operational amplifier OPB. In this way, the resistor division voltage by resistors RB1 and RB2 can be input to the first input terminal of the operational amplifier OPB as the power supply compensation voltage VB. As a result, the first input terminal of the operational amplifier OPB, to which the offset adjustment voltage VOF is input as the second input terminal, receives a power supply compensation voltage VB that changes according to the power supply voltage VDD. Therefore, the correction voltage output circuit 70 can output a correction voltage VCR that reflects the power supply voltage VDD and the offset adjustment voltage VOF.

[0046] For example, if the resistance values ​​of resistors RB1 and RB2 are R1 and R2, the correction voltage VCR is expressed as shown in equation (1) below.

[0047]

number

[0048] Thus, the operational amplifier OPB acts as an inverting amplifier that receives the offset adjustment voltage VOF and the power supply voltage VDD as inputs. It outputs a correction voltage VCR, which is the result of subtracting, for example, the voltage obtained by multiplying the offset adjustment voltage VOF by a coefficient (1 + R2 / R1) from the voltage obtained by multiplying the power supply voltage VDD by a coefficient (R2 / R1). Therefore, the correction voltage VCR, which reflects the power supply voltage VDD and the offset adjustment voltage VOF, is output from the correction voltage output circuit 70.

[0049] In Figure 5, the correction circuit 74 includes an operational amplifier OPC to which a compensation voltage VC, which changes according to the correction voltage VCR, is input to the first input terminal, and a temperature detection voltage VTS from the temperature sensor 50 is input to the second input terminal, and which outputs the corrected temperature detection voltage VTS2 from its output terminal. The first input terminal is, for example, the inverting input terminal of the operational amplifier OPC, and the second input terminal is, for example, the non-inverting input terminal of the operational amplifier OPC. The operational amplifier OPC is the second operational amplifier. The compensation voltage VC is a voltage used to perform temperature compensation according to the correction voltage VCR, and is a voltage that changes in accordance with changes in the correction voltage VCR. For example, the compensation voltage VC increases when the correction voltage VCR increases and decreases when the correction voltage VCR decreases.

[0050] In this way, the operational amplifier OPC of the correction circuit 74 receives a compensation voltage VC corresponding to the correction voltage VCR at the first input terminal, and the temperature detection voltage VTS from the temperature sensor 50 at the second input terminal. As a result, it can output a temperature detection voltage VTS2 from the output terminal, which is the temperature detection voltage VTS with the correction voltage VCR reflected in it. For example, the correction circuit 74 can output a voltage obtained by subtracting or adding the voltage obtained by multiplying the temperature detection voltage VTS by a given coefficient and the voltage obtained by multiplying the correction voltage VCR by a given coefficient as the corrected temperature detection voltage VTS2. This allows the temperature detection voltage VTS from the temperature sensor 50 to be corrected by the correction voltage VCR, which reflects the power supply voltage VDD and the offset adjustment voltage VOF, and the corrected temperature detection voltage VTS2 to be output to the temperature compensation circuit 40.

[0051] Specifically, the correction circuit 74 includes resistors RC1 and RC2 connected in series between the input node NVC of the correction voltage VCR and the output terminal node NC3 of the operational amplifier OPC. Resistor RC1 is the first resistor, and resistor RC2 is also the first resistor. The compensation voltage VC from the connection node NC1 of resistors RC1 and RC2 is supplied to the first input terminal of the operational amplifier OPC. For example, the compensation voltage VC is input to the connection node NC1 of the inverting input terminal, which is the first input terminal of the operational amplifier OPC. Also, the temperature detection voltage VTS is input to node NC2 of the non-inverting input terminal, which is the second input terminal of the operational amplifier OPC. In this way, the resistance division voltage by resistors RC1 and RC2 can be input to the first input terminal of the operational amplifier OPC as the compensation voltage VC. As a result, the first input terminal of the operational amplifier OPC, to which the temperature detection voltage VTS is input as the second input terminal, receives a compensation voltage VC that changes according to the correction voltage VCR. Therefore, the correction circuit 74 can output a corrected temperature detection voltage VTS2, which is obtained by correcting the temperature detection voltage VTS from the temperature sensor 50 with a correction voltage VCR that changes according to the power supply voltage VDD and the offset adjustment voltage VOF.

[0052] For example, if the resistance values ​​of resistors RC1 and RC2 are R3 and R4, the temperature detection voltage VTS after correction by the correction circuit 74 is expressed as shown in equation (2) below.

[0053]

number

[0054] Thus, the operational amplifier OPC acts as an inverting amplifier that receives the temperature detection voltage VTS and the correction voltage VCR as inputs. As shown in equation (2) above, it outputs a corrected temperature detection voltage VTS2, which is the result of subtracting, for example, the voltage obtained by multiplying the temperature detection voltage VTS by a coefficient (1 + R4 / R3) from the voltage obtained by multiplying the correction voltage VCR by a coefficient (R4 / R3). The correction voltage VCR is a voltage that changes according to the power supply voltage VDD and the offset adjustment voltage VOF, as shown in equation (1) above. Therefore, as shown in equation (3) above, the temperature detection voltage VTS2 obtained by correcting the temperature detection voltage VTS from the temperature sensor 50 based on the power supply voltage VDD and the offset adjustment voltage VOF is output from the correction circuit 74.

[0055] Next, the correction using the correction voltage VCR will be explained in detail. In this embodiment, the resistance ratio Rr=(R2 / R1) of resistors RB1 and RB2 of the correction voltage output circuit 70 is variable, or at least one of the resistance values ​​R1 of resistor RB1 and resistor RB2 is variable. In this way, it becomes possible to variably control how the power supply voltage VDD and the offset adjustment voltage VOF are reflected in the correction voltage VCR by the resistance ratio Rr or resistance values ​​of resistors RB1 and RB2.

[0056] Figure 6 shows a detailed configuration example of the correction voltage output circuit 70. In Figure 6, multiple resistors are connected in series between the input node NVD of the power supply voltage VDD and the output terminal node NB3 of the operational amplifier OPB. The nodes of the connection taps of these multiple resistors are connected to the first input terminal (inverting input terminal) of the operational amplifier OPB as connection node NB1. For example, multiple switches are provided between the multiple connection taps and the first input terminal of the operational amplifier OPB. When any of these switches are turned on based on adjustment data, the connection tap connected to the turned-on switch is connected to the first input terminal of the operational amplifier OPB. Resistor RB1 corresponds to the resistance between the connection tap and the input node NVD of the power supply voltage VDD, and resistor RB2 corresponds to the resistance between the connection tap and the output terminal node NB3. In this way, the resistance ratio Rr=(R2 / R1) of resistors RB1 and RB2 is variably controlled based on the adjustment data of the correction voltage output circuit 70. As a result, as shown in equation (1) above, VCR = (1 + R2 / R1)VOF - (R2 / R1)VDD, it becomes possible to variably control how each of the power supply voltage VDD and the offset adjustment voltage VOF is reflected in the correction voltage VCR.

[0057] Figure 7 is an explanatory diagram illustrating an example of setting the correction voltage VCR. In Figure 7, the horizontal axis represents the power supply voltage VDD, and the vertical axis represents the correction voltage VCR. C1 is the characteristic of the temperature detection voltage VTS2 when the resistance ratio Rr=(R2 / R1), adjusted by n=4 bits of adjustment data, is smallest, and C2 is the characteristic of the temperature detection voltage VTS2 when the resistance ratio Rr=(R2 / R1) is largest. Note that based on the adjustment data, only the resistance value R1 of resistor RB1 may be controlled, only the resistance value R2 of resistor RB2 may be controlled, or both resistance values ​​R1 and R2 may be controlled. In this case, C1 in Figure 7 represents the characteristic of the temperature detection voltage VTS2 when the resistance value R2 is smallest, and C2 represents the characteristic of the temperature detection voltage VTS2 when the resistance value R2 is largest. The adjustment data for the correction voltage output circuit 70 is, for example, n bits (where n is an integer of 2 or more), and is stored in, for example, the non-volatile memory 110 in Figure 2.

[0058] As shown in Figure 7, the correction voltage output circuit 70 outputs a correction voltage VCR that monotonically decreases in response to an increase in the power supply voltage VDD, and whose voltage change in response to fluctuations in the power supply voltage VDD is variable. In this way, the correction voltage VCR, which monotonically decreases as the power supply voltage VDD increases and whose voltage change in response to fluctuations in the power supply voltage VDD is variable, is used to correct the temperature detection voltage VTS of the temperature sensor 50, thereby performing temperature compensation. This prevents the occurrence of oscillation frequency errors due to excessive temperature compensation by the temperature compensation voltage VCP. Note that the correction voltage VCR may also be a voltage that monotonically increases in response to an increase in the power supply voltage VDD. For example, when a variable capacitor circuit with negative characteristics is used as the variable capacitor circuit for temperature compensation, the correction voltage VCR can be made to monotonically increase in response to an increase in the power supply voltage VDD.

[0059] The correction circuit 74 then corrects the temperature detection voltage VTS of the temperature sensor 50 using such a correction voltage VCR and outputs the corrected temperature detection voltage VTS2. For example, from equations (1) and (2) above, the corrected temperature detection voltage VTS can be expressed as shown in equation (3) below, where VTS is the temperature detection voltage, VOF is the offset adjustment voltage, and VDD is the power supply voltage.

[0060]

number

[0061] Therefore, as shown in equation (3) above, the corrected temperature detection voltage VTS2 changes in accordance with fluctuations in the power supply voltage VDD, enabling temperature compensation that reflects fluctuations in the power supply voltage VDD.

[0062] Figure 8 shows an example of the temperature characteristics of a temperature detection voltage. As shown in Figure 8, the temperature detection voltage has, for example, a negative temperature characteristic with respect to temperature T. E1 in Figure 8 is the temperature characteristic of the temperature detection voltage VTS2 when the power supply voltage VDD is a typical voltage, E2 is the temperature characteristic when VDD increases, and E3 is the temperature characteristic when VDD decreases.

[0063] For example, suppose the temperature at the temperature sensor 50 is T=t1 when the power supply voltage VDD rises. In this case, the correction circuit 74 outputs a voltage VTS2=V1 as the corrected temperature detection voltage. As shown in Figure 8, this voltage VTS2=V1 corresponds to the temperature detection voltage at temperature T=t2 when the power supply voltage VDD is at the typical voltage. In other words, when the power supply voltage VDD rises, the correction circuit 74 outputs a temperature detection voltage VTS2 that corresponds to a temperature T=t2 which is lower than the temperature T=t1 at the temperature sensor 50.

[0064] Furthermore, let's assume that when the power supply voltage VDD drops, the temperature at the temperature sensor 50 is T=t3. In this case, the correction circuit 74 outputs a temperature detection voltage VTS2=V1 as the corrected temperature detection voltage, corresponding to the temperature T=t2 when the power supply voltage VDD is the typical voltage. That is, when the power supply voltage VDD drops, the correction circuit 74 outputs a temperature detection voltage VTS2 corresponding to a temperature T=t2 that is higher than the temperature T=t3 at the temperature sensor 50.

[0065] As mentioned above, when the power supply voltage VDD increases, the temperature rise of the circuit device 20 becomes greater than the temperature rise of the oscillator 10, and the temperature at the location of the temperature sensor 50 of the circuit device 20 becomes higher than the temperature at the oscillator 10.

[0066] As shown in Figure 8, the correction circuit 74 outputs a temperature detection voltage VTS2 corresponding to a temperature T=t2 that is lower than temperature T=t1 when the power supply voltage VDD rises. This ensures that the temperature detection voltage VTS2 corresponding to the temperature at the oscillator 10, which is lower than the temperature at the circuit device 20, is input to the temperature compensation circuit 40, preventing excessive temperature compensation as shown in Figures 3A4 and A5. Furthermore, the correction circuit 74 outputs a temperature detection voltage VTS2 corresponding to a temperature T=t2 that is higher than temperature T=t3 when the power supply voltage VDD drops. This also prevents excessive temperature compensation as shown in Figures 3A4 and A5.

[0067] Furthermore, in equation (3) above, the coefficient of the power supply voltage VDD is set to cf(Rr)=(R4 / R3)(R2 / R1)=(R4 / R3)Rr. This coefficient cf(Rr) increases as the resistance ratio Rr=R2 / R1 in the correction voltage output circuit 70 in Figure 6 increases. For example, the smaller the oscillator 4 is and the smaller its thermal capacity, the greater the temperature change due to fluctuations in the power supply voltage VDD. Therefore, as shown in C2 in Figure 8, the resistance ratio Rr=R2 / R1 is increased to increase the coefficient cf(Rr). In this way, the correction circuit 74 allows adjustment of the coefficient cf(Rr) of the power supply voltage VDD by setting the resistance ratio Rr and the resistance values ​​R1 and R2. Accordingly, by setting the resistance ratio Rr and the resistance values ​​R1 and R2 according to the thermal capacity of the oscillator 4, it becomes possible to achieve appropriate temperature compensation according to the thermal capacity of the oscillator 4. For example, as described above, the adjustment data for the resistance ratio Rr and the resistance values ​​R1 and R2 can be stored in the non-volatile memory 110. Therefore, by writing appropriate adjustment data for the oscillator 4 and circuit device 20 according to the product to the non-volatile memory 110, it becomes possible to achieve appropriate temperature compensation according to the product's thermal capacity.

[0068] Figure 9 is an explanatory diagram of the correction method of this embodiment. In Figure 9, D1 is the frequency-temperature characteristic of the oscillator 10 before the power supply voltage VDD increases, and D2 is the frequency-temperature characteristic of the oscillator 10 after the power supply voltage VDD increases. D1 and D2 show the case where temperature compensation is properly performed based on the temperature TX of the oscillator 10. On the other hand, D3 is the frequency-temperature characteristic of the temperature compensation voltage VCP when the temperature is excessively compensated by the temperature TJ detected by the temperature sensor 50 of the circuit device 20 after the power supply voltage VDD increases. As described above, when a variable capacitance circuit 32 with a positive voltage-capacitance characteristic is used, when the temperature compensation voltage VCP increases, the capacitance increases and the oscillation frequency decreases, and when the temperature compensation voltage VCP decreases, the capacitance decreases and the oscillation frequency increases. Therefore, the frequency-temperature characteristic of the oscillator 10 is compensated by the temperature compensation voltage VCP with a frequency-temperature characteristic like D3.

[0069] As shown in Figure 9, when the power supply voltage VDD increases, excessive temperature compensation is performed based on the temperature TJ detected by the temperature sensor 50, as shown in D4, and temperature compensation is also performed based on the temperature compensation voltage VCP shown in D3. As a result, an error in the oscillation frequency occurs due to the error in temperature compensation. Therefore, the correction circuit 74 of this embodiment performs the correction shown in D5 to prevent excessive temperature compensation as shown in D4. In this way, it is possible to suppress the occurrence of an error in the oscillation frequency caused by excessive temperature compensation.

[0070] In other words, a temperature difference TJ-TX is generated between the temperature TJ detected by the temperature sensor 50 of the circuit device 20 and the temperature TX of the oscillator. As shown in A4 and A5 of Figure 3 and B4 and B5 of Figure 4, this temperature difference TJ-TX increases as the fluctuation of the power supply voltage VDD increases. Therefore, the correction circuit 74 of this embodiment changes the temperature detection voltage VTS2 by a voltage change amount corresponding to the temperature difference TJ-TX when the temperature difference TJ-TX between the temperature TJ detected by the temperature sensor 50 and the temperature TX of the oscillator 10 changes due to fluctuations in the power supply voltage VDD. For example, the correction circuit 74 performs a correction by changing the temperature detection voltage VTS2 by a voltage change amount that increases as the temperature difference TJ-TX increases. This correction is realized by changing the correction voltage VCR from the correction voltage output circuit 70. For example, in Figure 3, the temperature difference TJ-TX between the temperature TJ detected by the temperature sensor 50 and the temperature TX of the oscillator 10 is larger in case A5, where VDD is +10%, compared to case A4, where VDD is +5%. Therefore, in case A5, when the power supply voltage VDD fluctuates significantly and the temperature difference TJ-TX becomes large, the correction circuit 74 performs a correction by changing the temperature detection voltage VTS2 with a larger voltage change compared to case A4. Even when the power supply voltage VDD decreases as shown in Figure 4, the correction circuit 74 performs a correction by changing the temperature detection voltage VTS2 with a voltage change that increases as the temperature difference TJ-TX increases. In this way, even when the temperature difference TJ-TX between the temperature detected temperature TJ of the temperature sensor 50 and the temperature TX of the oscillator 10 changes due to fluctuations in the power supply voltage VDD, the error in temperature compensation caused by the temperature difference TJ-TX can be reduced, and the accuracy of the oscillation frequency can be improved.

[0071] As shown in Figure 9, the frequency-temperature characteristics shown in D3, which have been excessively temperature-compensated, are corrected to return to the appropriate frequency-temperature characteristics shown in D2, as shown in D5. In other words, the frequency-temperature characteristics are shifted along the horizontal axis, which is the axis of temperature T, in the opposite direction to the direction in which the excessive temperature compensation was applied. By doing so, it becomes possible to correct errors caused by excessive temperature compensation, thereby improving the accuracy of the oscillation frequency, etc.

[0072] 3.Temperature compensation circuit Figure 10 shows an example of the configuration of the temperature compensation circuit 40. Note that the temperature compensation circuit 40 is not limited to the configuration shown in Figure 10; various modifications are possible, such as omitting some of these components, adding other components, or replacing some components with other components.

[0073] The temperature compensation circuit 40 is a circuit that outputs a temperature compensation voltage VCP by polynomial approximation with temperature as the variable. This temperature compensation circuit 40 includes a current generation circuit 42 and a current-voltage conversion circuit 46. The current generation circuit 42 generates a function current based on the temperature detection result of the temperature sensor 50. For example, the temperature detection voltage VTS, which is the temperature detection result of the temperature sensor 50, is corrected by the correction circuit 74, and the current generation circuit 42 generates a function current to temperature compensate the frequency-temperature characteristics of the oscillator 10 based on the corrected temperature detection voltage VTS2 from the correction circuit 74. The current-voltage conversion circuit 46 then converts the function current from the current generation circuit 42 into a voltage and outputs the temperature compensation voltage VCP. Specifically, the current-voltage conversion circuit 46 outputs the temperature compensation voltage VCP using the operational amplifier OPD1.

[0074] The current generation circuit 42 includes a first-order correction circuit 43 and a higher-order correction circuit 44. The first-order correction circuit 43 outputs a first-order current that approximates a first-order function based on the temperature detection voltage VTS2. For example, the first-order correction circuit 43 outputs a first-order function current based on first-order correction data corresponding to the first-order coefficients of the polynomial in the polynomial approximation. The higher-order correction circuit 44 outputs a higher-order current that approximates a higher-order function to the current-voltage conversion circuit 46 based on the temperature detection voltage VTS2. For example, the higher-order correction circuit 44 outputs a higher-order current based on higher-order correction data corresponding to the higher-order coefficients of the polynomial in the polynomial approximation. As an example, the higher-order correction circuit 44 outputs a third-order current that approximates a third-order function. In this case, the higher-order correction circuit 44 includes a differential circuit that performs differential operation based on the temperature detection voltage VTS2, and a differential circuit that outputs a third-order current by performing differential operation based on the output voltage of the differential circuit and the temperature detection voltage VTS2. The higher-order correction circuit 44 may further include a correction circuit that performs correction of the fourth order or higher. For example, the higher-order correction circuit 44 may further include a fourth-order correction circuit that outputs a fourth-order current approximating a fourth-order function, and a fifth-order correction circuit that outputs a fifth-order current approximating a fifth-order function.

[0075] The first-order correction circuit 43 includes the operational amplifier OPD2 and resistors RD1 and RD2. The first-order correction circuit 43 may also include a resistor RD3 with a variable resistance value. The operational amplifier OPD2 receives the reference voltage VRC as input to its non-inverting input terminal. Resistor RD1 is placed between the input node ND1 of the temperature detection voltage VTS2 and the inverting input terminal node ND2 of the operational amplifier OPD2. Resistor RD2 is placed between the inverting input terminal node ND2 of the operational amplifier OPD2 and the output terminal node ND3 of the operational amplifier OPD2. Resistor RD3 is placed between the output terminal node ND3 of the operational amplifier OPD2 and the output node ND4 of the current generation circuit 42.

[0076] The current-voltage conversion circuit 46 adds the primary current and higher-order currents, and outputs a temperature compensation voltage VCP by converting the added current into a current-voltage. This generates a temperature compensation voltage VCP that approximates a polynomial function. Specifically, the current-voltage conversion circuit 46 includes an operational amplifier OPD1 and a feedback circuit element. The operational amplifier OPD1 has a reference voltage VRC input to its non-inverting input terminal, and the output node ND4 of the current generation circuit 42 is connected to its inverting input terminal. The feedback circuit element is a circuit element provided between the output terminal of the operational amplifier OPD1 and the inverting input terminal of the operational amplifier OPD1. In Figure 10, a resistor RD and a capacitor CD are provided in parallel between the output terminal and the inverting input terminal of the operational amplifier OPD1 as a feedback circuit element.

[0077] As shown above, the temperature compensation circuit 40 in Figure 10 has a primary correction circuit 43 and a higher-order correction circuit 44 to which the corrected temperature detection voltage VTS2 is input, a current generation circuit 42 that generates a function current using the primary correction circuit 43 and the higher-order correction circuit 44, and a current-voltage conversion circuit 46 that converts the function current into a voltage and outputs a temperature compensation voltage VCP. With this configuration of the temperature compensation circuit 40, the function current generated by the current generation circuit 42 based on the corrected temperature detection voltage VTS2 can be converted into a voltage by the current-voltage conversion circuit 46 and output as a temperature compensation voltage VCP.

[0078] 4. Temperature sensor Next, an example configuration of the temperature sensor 50 will be described. Figure 11 shows a first example configuration of the temperature sensor 50. The temperature sensor 50 includes a constant current source IS1, a bipolar transistor BPE1, and a resistor RE1. The constant current source IS1, resistor RE1, and bipolar transistor BPE1 are connected in series between the VDD node and the GND node. Specifically, the connection node between the constant current source IS1 and one end of resistor RE1 is connected to the base of bipolar transistor BPE1, and the other end of resistor RE1 is connected to the collector of bipolar transistor BPE1. The emitter of bipolar transistor BPE1 is also connected to the GND node.

[0079] In Figure 11, if IE is the current flowing from the constant current source IS1, R1 is the resistance value of resistor RE1, and VBE1 is the base-emitter voltage of bipolar transistor BPE1, then the temperature detection voltage VTS is expressed by equation (4) below.

[0080] VTS=VBE1-IE×R1 ···(4)

[0081] Since the base-emitter voltage VBE1 of the bipolar transistor BPE1 has a negative temperature characteristic, the temperature sensing voltage VTS will also have a negative temperature characteristic.

[0082] Figure 12 shows a second configuration example of the temperature sensor 50. The temperature sensor 50 in Figure 12 includes constant current sources IS1 and IS2, bipolar transistors BPE1 and BPE2, and resistors RE1 and RE3.

[0083] The connection configuration of the constant current source IS1, bipolar transistor BPE1, and resistor RE1 is the same as in the first configuration example in Figure 11. The constant current source IS2, resistor RE3, and bipolar transistor BPE2 are connected in series between the VDD node and the collector node of bipolar transistor BPE1. Specifically, the connection node between the constant current source IS2 and one end of resistor RE3 is connected to the base of bipolar transistor BPE2, and the other end of resistor RE3 is connected to the collector of bipolar transistor BPE2. The emitter of bipolar transistor BPE2 is also connected to the collector of bipolar transistor BPE1.

[0084] In Figure 12, the collector voltage of bipolar transistors BPE1 and BPE2 is denoted as VGA, the current flowing through constant current sources IS1 and IS2 is denoted as IE, and the resistance values ​​of resistors RE1 and RE3 are denoted as R1 and R3, respectively. The base-emitter voltages of bipolar transistors BPE1 and BPE2 are denoted as VBE1 and VBE2. Then, the voltages of VGA and VTS are expressed as shown in equations (5) and (6) below. Note that the offset voltage of the operational amplifier OPE is assumed to be zero here.

[0085] VGA=VBE1-IE×R1 ···(5)

[0086] VTS = VBE2-IE×R3 + VGA =VBE1+VBE2-IE×(R1+R3) ···(6)

[0087] In the second configuration example shown in Figure 12, two bipolar transistors BPE1 and BPE2 are provided, so the two base-emitter voltages VBE1 and VBE2 are added together. As a result, compared to the first configuration example shown in Figure 11, the slope of the temperature detection voltage VTS with respect to temperature can be increased, making it possible to generate a temperature detection voltage VTS that is highly sensitive to temperature.

[0088] Figure 13 shows the configuration of a temperature sensor 58 that is a comparative example of this embodiment. The temperature sensor 58 in Figure 13 has the configuration disclosed in Patent Document 1. In the comparative example in Figure 13, a buffer circuit 59 is further provided, which includes variable resistance resistors RE2 and RE4, an operational amplifier OPE, and resistors RE5 and RE6, compared to the configuration in Figure 12. By changing the resistance values ​​of resistors RE2 and RE4, it is possible to adjust the zero-order offset of the temperature detection voltage VTS. As a result, the temperature detection voltage VTS includes an offset component, enabling zero-order offset adjustment by the temperature sensor 58. In addition, in Figure 13, by providing the buffer circuit 59, it is possible to output the temperature detection voltage VTS with the operational amplifier OPE, which has high driving capability.

[0089] Figure 14 shows the configuration of a comparative example correction circuit 52. The correction circuit 52 in Figure 14 is the configuration disclosed in Patent Document 1. In Figure 14, the correction circuit 52 includes an offset generation circuit 54 and an adder circuit 55. The offset generation circuit 54 includes an operational amplifier OPF1 and resistors RF1, RF2, RF3, RF4, and receives the power supply voltage VDD and the temperature detection voltage VTS as inputs to generate an offset voltage VDDOF for VDD compensation. This offset voltage VDDOF is a voltage that changes in conjunction with the power supply voltage VDD and is an offset voltage to compensate for changes in the power supply voltage VDD. The adder circuit 55 includes an operational amplifier OPF2 and resistors RF5, RF6, RF7, RF8, and adds the temperature detection voltage VTS from the temperature sensor 50 and the offset voltage VDDOF for VDD compensation to output a temperature detection voltage VTSVDD.

[0090] In the comparative example shown in Figure 13, the temperature sensor 58 adjusts the offset of the temperature detection voltage VTS based on zero-order correction data corresponding to the zero-order coefficient of the polynomial in the polynomial approximation of the temperature compensation characteristics. For example, in the temperature sensor 58, zero-order offset adjustment is made possible by adjusting the resistance values ​​of resistors RE2 and RE4.

[0091] However, in the comparative example temperature sensor 58 shown in Figure 13, there is a problem in that the linearity of the offset adjustment deteriorates because the zero-order offset adjustment is performed at multiple locations. For example, the linearity of the offset adjustment deteriorates because the offset adjustment of the temperature detection voltage VTS is performed at multiple locations, such as by adjusting the resistance value of resistor RE2 and resistor RE4. For example, in order to ensure that the offset adjustment can be performed appropriately even when the manufacturing process fluctuates, the adjustment range by resistor RE2 and the adjustment range by resistor RE4 are set to overlap, but the linearity deteriorates at the points corresponding to this overlapping adjustment range. In addition, in the comparative example in Figure 13, there is also the problem that the slope characteristic of the temperature detection voltage VTS with respect to temperature changes due to the offset adjustment.

[0092] For example, Figure 15 shows the temperature characteristics of the temperature detection voltage VTS when the zero-order offset adjustment voltage is changed in the temperature sensor 58 of the comparative example in Figure 13. As shown in Figure 15, in the temperature sensor 58 of the comparative example, the slope of the temperature detection voltage VTS with respect to temperature T changes depending on the magnitude of the offset adjustment voltage. For example, in Figure 15, when the offset adjustment voltage is large, the slope of the temperature detection voltage VTS is large, and when the offset adjustment voltage is small, the slope is small. When the slope of the temperature detection voltage VTS changes in this way depending on the offset adjustment voltage, it becomes difficult to achieve proper temperature compensation.

[0093] Figure 16 illustrates the linearity of the offset adjustment voltage of the temperature sensor 58 in the comparative example. In the comparative example, the offset adjustment voltage is adjusted by register settings for the offset adjustment data, but as shown in Figure 16, the linearity of the offset adjustment deteriorates, for example, in areas corresponding to the overlapping range of the adjustment. When the linearity of the offset adjustment deteriorates in this way, it becomes difficult to achieve proper temperature compensation.

[0094] In contrast, Figure 17 illustrates the linearity of the offset adjustment voltage in this embodiment. As shown in Figure 17, this embodiment makes it possible to significantly improve the linearity of the offset adjustment voltage compared to the comparative example in Figure 16.

[0095] In the comparative example, as shown in Figures 13 and 14, the temperature sensor 58 is equipped with an operational amplifier OPE, which is a buffer amplifier for the temperature detection voltage VTS, and the correction circuit 52 is equipped with an operational amplifier OPF1, which is a generation amplifier for the offset voltage VDDOF for VDD compensation, and an operational amplifier OPF2, which is an additive amplifier. Therefore, a total of three amplifiers are required, which leads to problems such as an increase in circuit area and an increase in current consumption.

[0096] In contrast, in this embodiment shown in Figure 5, only two operational amplifiers, OPB and OPC, which act as inverting amplifiers, are required. This reduces the number of amplifiers compared to the comparative examples in Figures 13 and 14, resulting in the advantages of reduced circuit area and lower current consumption. For example, in Figure 5, the temperature detection voltage VTS from the temperature sensor 50 is input to the gate of the differential transistor, which is the non-inverting input terminal of the operational amplifier OPC of the correction circuit 74. Therefore, the operational amplifier OPE of the buffer circuit 59 shown in Figure 13 is unnecessary. Furthermore, the operational amplifier OPB of the correction voltage output circuit 70, to which the power supply voltage VDD is input, also serves as a buffer amplifier for the offset adjustment circuit 60. As a result, in Figure 5, it is possible to reduce the number of amplifiers compared to the comparative examples in Figures 13 and 14, thereby reducing the circuit area and lowering current consumption.

[0097] Furthermore, in this embodiment, as shown in Figure 10, the temperature detection voltage VTS2 after correction by the correction circuit 74 is input to the higher-order correction circuit 44 of the temperature compensation circuit 40. This makes it possible to correct the temperature compensation, including the higher-order correction of the higher-order correction circuit 44.

[0098] For example, when zero-order offset adjustment is performed, the inflection point temperature in higher-order correction changes in addition to the zero-order offset. For example, if the ambient temperature is t, the temperature detected by the temperature sensor 50 is t0, the change in inflection point temperature is Δt0, the change in the zero-order offset adjustment voltage is ΔV0, and the coefficients are a and b, then the temperature compensation voltage VCP is expressed as shown in equation (7) below.

[0099]

number

[0100] In equation (7) above, the coefficient a term corresponds to a third-order higher-order correction. As shown in Figure 18, the inflection point temperature of the higher-order correction also changes in accordance with the change in the offset adjustment voltage. Therefore, by inputting the temperature detection voltage VTS2, which has been corrected according to the temperature difference between the circuit device 20 and the oscillator 10, into the higher-order correction circuit 44 of the temperature compensation circuit 40, it becomes possible to achieve appropriate temperature compensation that also responds to changes in the inflection point temperature.

[0101] 5. Oscillator Figure 19 shows a first structural example of the oscillator 4 of this embodiment. The oscillator 4 has a resonator 10, a circuit device 20, and a package 15 that houses the resonator 10 and the circuit device 20. The package 15 is made of, for example, ceramic, and has a housing space inside, in which the resonator 10 and the circuit device 20 are housed. The housing space is hermetically sealed and preferably in a reduced-pressure state, close to a vacuum. The package 15 can suitably protect the resonator 10 and the circuit device 20 from shock, dust, heat, moisture, etc.

[0102] Package 15 has a base 16 and a lid 17. Specifically, package 15 consists of a base 16 that supports the resonator 10 and the circuit device 20, and a lid 17 that is joined to the upper surface of the base 16 to form a housing space between it and the base 16. The resonator 10 is supported by terminal electrodes on a stepped portion provided on the inside of the base 16. The circuit device 20 is located on the inner bottom surface of the base 16. Specifically, the circuit device 20 is positioned so that its active surface faces the inner bottom surface of the base 16. The active surface is the surface on which the circuit elements of the circuit device 20 are formed. Bumps BMP are formed on the terminals of the circuit device 20. The circuit device 20 is supported on the inner bottom surface of the base 16 via conductive bumps BMP. The conductive bumps BMP are, for example, metal bumps, and the resonator 10 and the circuit device 20 are electrically connected via these bumps BMP, the internal wiring of package 15, and terminal electrodes. The circuit device 20 is also electrically connected to the external terminals 18 and 19 of the oscillator 4 via the bump BMP and the internal wiring of the package 15. The external terminals 18 and 19 are formed on the outer bottom surface of the package 15. The external terminals 18 and 19 are connected to an external device via external wiring. The external wiring is, for example, wiring formed on the circuit board on which the external device is mounted. This allows the output of a clock signal and the like to the external device.

[0103] In Figure 19, the circuit device 20 is flip-mounted so that its active surface faces downwards, but this embodiment is not limited to this mounting. For example, the circuit device 20 may be mounted so that its active surface faces upwards. That is, the circuit device 20 may be mounted so that its active surface faces the oscillator 10.

[0104] Figure 20 shows a second structural example of the oscillator 4. The oscillator 4 has a resonator 10, a circuit device 20, and a package 15 that houses the resonator 10 and the circuit device 20. The package 15 has a base 16 and a lid 17. The base 16 has a first substrate 6 which is an intermediate substrate, a second substrate 7 which is a roughly rectangular frame shape and is laminated on the upper side of the first substrate 6, and a third substrate 8 which is a roughly rectangular frame shape and is laminated on the bottom side of the first substrate 6. The lid 17 is bonded to the upper surface of the second substrate 7, and the resonator 10 is housed in a housing space S1 formed by the first substrate 6, the second substrate 7 and the lid 17. For example, the resonator 10 is hermetically sealed in the housing space S1, and preferably in a reduced-pressure state that is close to a vacuum. This allows the resonator 10 to be suitably protected from shock, dust, heat, moisture, etc. The circuit device 20, which is a semiconductor chip, is housed in a housing space S2 formed by the first substrate and the third substrate 8. Furthermore, external terminals 18 and 19, which are electrode terminals for external connection of the oscillator 4, are formed on the bottom surface of the third substrate 8.

[0105] In the housing space S1, the vibrator 10 is connected to a first electrode terminal and a second electrode terminal (not shown) formed on the upper surface of the first substrate 6 by conductive connectors CDC1 and CDC2. The conductive connectors CDC1 and CDC2 may be realized by conductive bumps such as metal bumps, or by conductive adhesive. Specifically, for example, a first electrode pad (not shown) formed at one end of a tuning fork-type vibrator 10 is connected to a first electrode terminal formed on the upper surface of the first substrate 6 via the conductive connector CDC1. The first electrode terminal is then electrically connected to pad PX1 of the circuit device 20. A second electrode pad (not shown) formed at the other end of the tuning fork-type vibrator 10 is connected to a second electrode terminal formed on the upper surface of the first substrate 6 via the conductive connector CDC2. The second electrode terminal is then electrically connected to pad PX2 of the circuit device 20. This allows one end and the other end of the vibrator 10 to be electrically connected to pads PX1 and PX2 of the circuit device 20 via the conductive connectors CDC1 and CDC2. Furthermore, conductive bump BMPs are formed on multiple pads of the semiconductor chip circuit device 20, and these conductive bump BMPs are connected to multiple electrode terminals formed on the bottom surface of the first substrate 6. The electrode terminals connected to the pads of the circuit device 20 are then electrically connected to the external terminals 18 and 19 of the oscillator 4 via internal wiring, etc.

[0106] The oscillator 4 may also be a wafer-level package (WLP) oscillator. In this case, the oscillator 4 includes a semiconductor substrate, a base having through-electrodes penetrating between the first and second surfaces of the semiconductor substrate, a resonator 10 fixed to the first surface of the semiconductor substrate via a conductive bonding member such as a metal bump, and external terminals provided on the second surface side of the semiconductor substrate via an insulating layer such as a redistribution wiring layer. An integrated circuit forming the circuit device 20 is then formed on the first or second surface of the semiconductor substrate. In this case, the multiple bases and multiple lids are joined by attaching a first semiconductor wafer, on which multiple bases with the resonator 10 and integrated circuit are formed, to a second semiconductor wafer, on which multiple lids are formed, and then the oscillator 4 is diced using a dicing saw or the like. In this way, a wafer-level package oscillator 4 can be realized, enabling high-throughput and low-cost manufacturing of the oscillator 4.

[0107] As described above, the circuit device of this embodiment is a circuit device that operates when a power supply voltage is supplied, and includes an oscillation circuit that causes an oscillator to oscillate, a temperature sensor that outputs a temperature detection voltage, and an offset adjustment circuit that outputs an offset adjustment voltage of the temperature detection voltage. The circuit device also includes a correction voltage output circuit that receives the power supply voltage and the offset adjustment voltage as input and outputs a correction voltage that changes according to the power supply voltage and the offset adjustment voltage, a correction circuit that receives the temperature detection voltage and the correction voltage as input and outputs a temperature detection voltage corrected by the correction voltage, and a temperature compensation circuit that performs temperature compensation of the oscillation frequency of the oscillation circuit based on the corrected temperature detection voltage.

[0108] According to this embodiment, an offset adjustment voltage is generated by an offset adjustment circuit, and the temperature detection voltage of the temperature sensor is corrected by the correction voltage generated by the power supply voltage and the offset adjustment voltage, and temperature compensation is performed using the corrected temperature detection voltage. Therefore, problems such as deterioration of the linearity of the offset adjustment that occur when the temperature sensor is equipped with an offset adjustment function can be suppressed. This makes it possible to provide a circuit device that can realize temperature compensation that appropriately reflects the effects of power supply voltage fluctuations and offset adjustment.

[0109] In this embodiment, the correction voltage output circuit may also include an operational amplifier that receives a power supply compensation voltage that changes according to the power supply voltage at the first input terminal, an offset adjustment voltage at the second input terminal, and outputs a correction voltage from its output terminal.

[0110] In this way, a correction voltage that reflects the power supply voltage and the offset adjustment voltage can be output from the output terminal of the operational amplifier.

[0111] In this embodiment, the compensation voltage output circuit may also include a first resistor and a second resistor connected in series between the power supply voltage input node and the output terminal node, and the power supply compensation voltage from the connection node of the first resistor and the second resistor may be supplied to the first input terminal of the operational amplifier.

[0112] In this way, the voltage divided by the first and second resistors can be input to the first input terminal of the operational amplifier as a power supply compensation voltage.

[0113] In this embodiment, the resistance ratio of the first resistor and the second resistor may be variable, or at least one of the resistance values ​​of the first resistor and the second resistor may be variable.

[0114] In this way, it becomes possible to variably control how the power supply voltage and the offset adjustment voltage are reflected in the correction voltage by adjusting the resistance ratio and resistance values ​​of the first and second resistors.

[0115] In this embodiment, the offset adjustment circuit may also be a circuit that performs D / A conversion of the offset adjustment data to an offset adjustment voltage using an R-2R ladder method.

[0116] Thus, the offset adjustment circuit of the R-2R ladder type D / A conversion circuit can improve the linearity of the offset adjustment compared to a configuration in which the temperature sensor has an offset adjustment function.

[0117] In this embodiment, the correction circuit may also include an operational amplifier that receives a compensation voltage that changes according to the correction voltage at a first input terminal, a temperature detection voltage at a second input terminal, and outputs the corrected temperature detection voltage from its output terminal.

[0118] In this way, the corrected temperature detection voltage, which reflects the correction voltage applied to the temperature detection voltage of the temperature sensor, can be output from the output terminal of the operational amplifier.

[0119] In this embodiment, the correction circuit may also include a first resistor and a second resistor connected in series between the input node of the correction voltage and the output terminal node, and the compensation voltage from the connection node of the first resistor and the second resistor may be supplied to the first input terminal of the operational amplifier.

[0120] In this way, the resistance division voltage between the first and second resistors can be input as a compensation voltage to the first input terminal of the operational amplifier. As a result, the first input terminal of the operational amplifier, to which the temperature detection voltage is input at the second input terminal, will receive a compensation voltage that changes according to the correction voltage.

[0121] In this embodiment, the correction circuit may also change the corrected temperature detection voltage by a voltage change amount corresponding to the temperature difference when the temperature difference between the temperature detected by the temperature sensor and the temperature of the oscillator changes due to fluctuations in the power supply voltage.

[0122] In this way, even if the temperature difference between the temperature sensor's detected temperature and the oscillator's temperature changes due to fluctuations in the power supply voltage, a correction is made by changing the temperature detection voltage by an amount of voltage change corresponding to the temperature difference, thereby reducing temperature compensation errors caused by temperature differences.

[0123] In this embodiment, the correction voltage output circuit may output a correction voltage that monotonically decreases or increases in response to an increase in the power supply voltage, and whose voltage change in response to fluctuations in the power supply voltage is variable.

[0124] In this way, a correction voltage that monotonically decreases or increases as the power supply voltage rises, and whose voltage change in response to fluctuations in the power supply voltage is variable, is used to correct the temperature detection of the temperature sensor, thereby performing temperature compensation.

[0125] Furthermore, the oscillator of this embodiment includes the circuit device described above and a vibrator.

[0126] Although this embodiment has been described in detail above, it will be readily apparent to those skilled in the art that many modifications are possible without substantially departing from the novelty and effects of this disclosure. Therefore, all such modifications are included within the scope of this disclosure. For example, any term that appears at least once in the specification or drawings together with a broader or synonymous term may be replaced with that different term anywhere in the specification or drawings. Furthermore, all combinations of this embodiment and its modifications are also included within the scope of this disclosure. In addition, the configuration and operation of the circuit device, oscillator, etc., are not limited to those described in this embodiment, and various modifications are possible. [Explanation of Symbols]

[0127] 4…Oscillator, 6…First board, 7…Second board, 8…Third board, 10…Resonator, 15…Package, 16…Base, 17…Lid, 18, 19…External terminals, 20…Circuit device, 30…Oscillator circuit, 32…Variable capacitance circuit, 40…Temperature compensation circuit, 42…Current generation circuit, 43…First-order correction circuit, 44…Higher-order correction circuit, 46…Current-voltage conversion circuit, 50…Temperature sensor, 52…Correction circuit, 54…Offset generation circuit, 55…Adder circuit, 58…Temperature sensor, 59…Buffer circuit, 60…Offset adjustment circuit, 70…Correction voltage output circuit Path, 74...Correction circuit, 80...Output circuit, 90...Power supply circuit, 100...Control circuit, 102...Resistor, 110...Non-volatile memory, BPE1, BPE2...Bipolar transistor, OPB, OPC, OPD1, OPD2, OPE, OPF1, OPF2...Operational amplifier, RA1, RA2, RB1, RB2...Resistor, RC1...Resistor, RC2...Resistor, VB...Power supply compensation voltage, VC...Compensation voltage, VCP...Temperature compensation voltage, VCR...Correction voltage, VDD...Power supply voltage, VOF...Offset adjustment voltage, VTS, VTS2...Temperature detection voltage

Claims

1. A circuit device that operates when power supply voltage is supplied, An oscillator circuit that causes the oscillator to oscillate, A temperature sensor that outputs a temperature detection voltage, An offset adjustment circuit that outputs an offset adjustment voltage for the temperature detection voltage, A correction voltage output circuit receives the power supply voltage and the offset adjustment voltage as inputs and outputs a correction voltage that changes according to the power supply voltage and the offset adjustment voltage, A correction circuit that receives the temperature detection voltage and the correction voltage as inputs and outputs the temperature detection voltage after correction by the correction voltage, A temperature compensation circuit that performs temperature compensation for the oscillation frequency of the oscillation circuit based on the corrected temperature detection voltage, A circuit device characterized by including the following.

2. In the circuit device described in claim 1, The correction voltage output circuit is, A circuit device characterized by including an operational amplifier to which a power supply compensation voltage that changes according to the power supply voltage is input to a first input terminal, the offset adjustment voltage is input to a second input terminal, and the correction voltage is output from an output terminal.

3. In the circuit device described in claim 2, The correction voltage output circuit is, It includes a first resistor and a second resistor provided in series between the input node of the power supply voltage and the output terminal node, A circuit device characterized in that the power supply compensation voltage from the connection node of the first resistor and the second resistor is supplied to the first input terminal of the operational amplifier.

4. In the circuit device described in claim 3, A circuit device characterized in that the resistance ratio of the first resistor and the second resistor is variable, or at least one of the resistance values ​​of the first resistor and the resistance value of the second resistor is variable.

5. In the circuit device described in claim 1, The offset adjustment circuit is, A circuit device characterized by being a circuit that performs D / A conversion of offset adjustment data to the offset adjustment voltage using an R-2R ladder method.

6. In the circuit device described in claim 1, The correction circuit described above is A circuit device characterized by including an operational amplifier that receives a compensation voltage that changes according to the correction voltage at a first input terminal, the temperature detection voltage at a second input terminal, and outputs the corrected temperature detection voltage at an output terminal.

7. In the circuit device described in claim 6, The correction circuit described above is The system includes a first resistor and a second resistor provided in series between the input node of the correction voltage and the output terminal node, A circuit device characterized in that the compensation voltage from the connection node of the first resistor and the second resistor is supplied to the first input terminal of the operational amplifier.

8. In the circuit device according to claim 1, The correction circuit described above is A circuit device characterized in that, when the temperature difference between the temperature detected by the temperature sensor and the temperature of the oscillator changes due to fluctuations in the power supply voltage, the corrected temperature detection voltage is changed by a voltage change amount corresponding to the temperature difference.

9. In the circuit device according to claim 1, The correction voltage output circuit is, A circuit device characterized by outputting a correction voltage that monotonically decreases or increases in response to an increase in the power supply voltage, and whose voltage change amount in response to fluctuations in the power supply voltage is variable.

10. A circuit device according to any one of claims 1 to 9, The oscillator and, An oscillator characterized by including [a certain component].

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