Oscillation circuit and temperature compensation method for oscillation circuit

Abstract

To provide an oscillation circuit with high frequency stability.SOLUTION: The oscillator circuit 100 that compensates for the frequency variation caused by the temperature change of the resonator 10 and the integrated circuit 40 includes the first temperature measuring unit 30 that measures the internal temperature of the oscillator circuit 100. The oscillator includes a current generator 41 that generates a heater current, a first heater 20 that heats the resonator 10 based on the heater current, a second heater 42 that heats the integrated circuit 40 based on the heater current, a second temperature detector 43 that detects the temperature of the integrated circuit 40, a first compensation voltage generator 44 that generates a first compensation voltage for compensating for a first frequency variation caused by a temperature change of the integrated circuit 40 based on the temperature of the integrated circuit 40, a second compensation voltage generator 45 that generates a second compensation voltage for compensating for a second frequency variation caused by a temperature change of the resonator based on the internal temperature, and an oscillator 46 that generates an oscillation signal based on the first compensation voltage and the second compensation voltage.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to an oscillator circuit and a method for temperature compensation of an oscillator circuit. [Background technology]

[0002] It is known that the resonant frequency of a quartz crystal unit fluctuates due to temperature changes. For example, Patent Document 1 discloses an oven-controlled crystal oscillator (OCXO) that uses a temperature-compensated crystal oscillator (TCXO) to compensate for fluctuations in the resonant frequency in region P where the ambient temperature is high (70°C to 100°C) and the heater is turned off (see FIG. 14). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-243629 Summary of the Invention [Problem to be solved by the invention]

[0004] However, while conventional oscillator circuits were able to compensate for the fluctuations in the resonant frequency in the region where the ambient temperature was high and the heater was turned off, they did not sufficiently compensate for the fluctuations in the oscillation frequency caused by the temperature change of the crystal unit in the region where the ambient temperature was low and the heater was turned on, or the fluctuations in the oscillation frequency caused by the temperature change of the integrated circuit that generates a temperature difference with the crystal unit, resulting in a problem of low frequency stability of the oscillator circuit.

[0005] In view of the above circumstances, an object of the present disclosure is to provide an oscillator circuit with high frequency stability. [Means for solving the problem]

[0006] An oscillator circuit according to one embodiment is an oscillator circuit that compensates for frequency fluctuations caused by temperature changes in a resonator and an integrated circuit, and is characterized by comprising: a first temperature detection unit that detects the internal temperature of the oscillator circuit; a current generation unit that generates a heater current so that the internal temperature matches a target temperature; a first heater that heats the resonator based on the heater current; a second heater that heats the integrated circuit based on the heater current; a second temperature detection unit that detects the temperature of the integrated circuit; a first compensation voltage generation circuit that generates a first compensation voltage based on the temperature of the integrated circuit to compensate for first frequency fluctuations caused by temperature changes in the integrated circuit; a second compensation voltage generation circuit that generates a second compensation voltage based on the internal temperature to compensate for second frequency fluctuations caused by temperature changes in the resonator; and an oscillator that generates an oscillation signal based on the first compensation voltage and the second compensation voltage.

[0007] a first compensation voltage generation circuit that generates a first compensation voltage based on the temperature of the integrated circuit to compensate for a first frequency variation due to temperature variation of the integrated circuit; a second compensation voltage generation circuit that generates a second compensation voltage based on the internal temperature to compensate for a second frequency variation due to temperature variation of the resonator; and an oscillator that generates an oscillation signal based on the first compensation voltage and the second compensation voltage, wherein the current generation circuit generates a heater current so that the internal temperature matches a target temperature, in a heater-on region when the ambient temperature is constant. the resistance value of the variable resistor in the second heater being set to a first resistance value and the temperature of the integrated circuit being detected; the resistance value of the variable resistor in the second heater being set to a second resistance value smaller than the first resistance value and the temperature of the integrated circuit being detected; the first compensation voltage generation circuit generating the first compensation voltage to compensate for the first frequency variation based on the temperature of the integrated circuit when the resistance value is the first resistance value and the temperature of the integrated circuit when the resistance value is the second resistance value; the second compensation voltage generation circuit generating the second compensation voltage to compensate for the second frequency variation based on the change in the second frequency variation relative to the internal temperature in a heater-off region when the ambient temperature is changing; and the current generation unit generating the target temperature to compensate for the second frequency variation relative to the ambient temperature in a heater-on region when the ambient temperature is changing. [Effects of the Invention]

[0008] According to the present disclosure, it is possible to provide an oscillator circuit with high frequency stability. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 2 is a diagram illustrating an example of the configuration of an oscillation circuit according to the first embodiment. [Figure 2] 5A and 5B are diagrams illustrating an example of the relationship between temperature and frequency fluctuations caused by temperature changes in a resonator and the relationship between temperature and frequency fluctuations caused by temperature changes in an integrated circuit according to the first embodiment. [Figure 3A] FIG. 4 is a diagram showing an example of the relationship between an environmental temperature and a target temperature according to the first embodiment. [Figure 3B] FIG. 4 is a diagram illustrating an example of the relationship between the environmental temperature and the total frequency fluctuation in the oscillation circuit according to the first embodiment. [Figure 4A] FIG. 2 is a diagram illustrating an example of the configuration of a temperature control circuit in the oscillation circuit according to the first embodiment. [Figure 4B] FIG. 3 is a diagram illustrating an example of a thermal resistance model according to the first embodiment. [Figure 5A] FIG. 2 is a diagram illustrating an example of the configuration of an oscillation circuit according to the first embodiment. [Figure 5B] FIG. 2 is a diagram illustrating an example of the configuration of an oscillation circuit according to the first embodiment. [Figure 6] 4 is a diagram showing an example of the relationship between the internal temperature of the oscillation circuit according to the first embodiment and the frequency fluctuation caused by the temperature change of the resonator. FIG. [Figure 7] 4 is a flowchart illustrating an example of a temperature compensation method for the oscillation circuit according to the first embodiment. [Figure 8A] 10A and 10B are diagrams illustrating an example of the relationship between the environmental temperature and the temperature of the resonator and the relationship between the environmental temperature and the internal temperature of the oscillation circuit according to the second embodiment. [Figure 8B] 10A and 10B are diagrams illustrating an example of the relationship between the temperature of a resonator and frequency fluctuations caused by temperature changes of the resonator, and the relationship between the internal temperature of an oscillation circuit and a temperature compensation component according to the second embodiment. [Figure 9A] FIG. 10 is a diagram illustrating an example of a thermal resistance model according to the second embodiment. [Figure 9B] FIG. 11 is a diagram illustrating an example of the relationship between environmental temperature and electric power according to the second embodiment. [Figure 10A] 10A and 10B are diagrams illustrating an example of the relationship between the environmental temperature and the temperature of the resonator and the relationship between the environmental temperature and the internal temperature of the oscillation circuit according to the second embodiment. [Figure 10B] 10A and 10B are diagrams illustrating an example of the relationship between the temperature of a resonator and frequency fluctuations caused by temperature changes of the resonator, and the relationship between the internal temperature of an oscillation circuit and a temperature compensation component according to the second embodiment. [Figure 11] FIG. 11 is a diagram illustrating an example of temperature compensation in the case where no discontinuity occurs according to the third embodiment. [Figure 12] FIG. 11 is a diagram showing an example of temperature compensation when a discontinuity occurs according to the third embodiment. [Figure 13A] 11A and 11B are diagrams illustrating an example of the relationship between the environmental temperature and the temperature of the resonator and the relationship between the environmental temperature and the internal temperature of the oscillation circuit according to the third embodiment. [Figure 13B] 10A and 10B are diagrams illustrating an example of the relationship between the environmental temperature and the temperature of the resonator and the relationship between the environmental temperature and the internal temperature of the oscillation circuit according to the fourth embodiment. [Figure 14] FIG. 1 is a diagram illustrating an example of the relationship between temperature and frequency stability of a conventional crystal resonator. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In principle, the same components are designated by the same reference numerals, and duplicated descriptions will be omitted.

[0011] In this specification, "zero" includes not only substantially zero, but also a range of values ​​close to substantially zero.

[0012] In addition, in this specification, "ambient temperature" means the ambient temperature surrounding the oscillation circuit. "Target temperature" means the temperature targeted when controlling the internal temperature of the oscillation circuit by heating using a heater. "Boundary temperature" means the boundary temperature between the heater-on region and the heater-off region. "Heater-on region" means the region where the heater is on and where the ambient temperature is below the boundary temperature. "Heater-off region" means the region where the heater is off and where the ambient temperature is higher than the boundary temperature. However, these terms are merely defined for convenience and should not be interpreted in a limiting manner.

[0013] First Embodiment

[0014] [Oscillation circuit] An example of the configuration of an oscillator circuit 100 according to the first embodiment will be described with reference to FIGS.

[0015] The oscillator circuit 100 is a circuit that compensates for frequency fluctuations caused by temperature changes in the resonator 10 and the integrated circuit 40. In this specification, the frequency fluctuations caused by temperature changes in the resonator 10 are referred to as ΔF xtl The frequency fluctuation caused by the temperature change of the integrated circuit 40 is expressed in [ppm]. IC The total frequency fluctuation in the oscillator circuit 100 is expressed as ΔF total The temperature compensation component is expressed in [ppm]. C Expressed in [ppm].

[0016] Frequency fluctuation ΔF due to temperature change of the resonator 10 xtl For example, when the resonator 10 is a quartz crystal resonator, [ppm] is expressed by a cubic function such as the following equation (see FIG. 2).

[0017]

number

[0018] Frequency variation ΔF due to temperature change of integrated circuit 40 IC [ppm] can be approximated by the following linear function (see Figure 2):

[0019]

number

[0020] The total frequency fluctuation ΔF in the oscillator circuit 100 after temperature compensation total [ppm] is expressed by the following formula:

[0021]

number

[0022] The oscillation circuit 100 includes a resonator 10, a first heater 20, a first temperature detection unit 30, and an integrated circuit 40. The oscillation circuit 100 is connected to a control unit 200 provided outside the oscillation circuit 100 via an input / output terminal DATA and an input terminal CLK.

[0023] The integrated circuit 40 includes a current generating unit 41, a second heater 42, a second temperature detecting unit 43, a first temperature-compensated voltage generating circuit 44, a second temperature-compensated voltage generating circuit 45, an oscillator 46, an interface unit 47, a memory unit 50, and an interface unit 60. The integrated circuit 40 may also include a test path for monitoring the temperature detecting unit. The integrated circuit 40 is connected to the first heater 20 via a terminal RH and to the first temperature detecting unit 30 via a terminal THM.

[0024] The resonator 10 may be, for example, an SC-cut crystal resonator, an AT-cut crystal resonator, a MEMS (Micro Electro Mechanical Systems) resonator, or a ceramic resonator. The resonator 10 is connected to an oscillator 46 via a connection terminal X1 and a connection terminal X2.

[0025] The first heater 20 heats the resonator 10 based on a heater current supplied from the current generating unit 41. The first heater 20 is preferably provided close to the resonator 10. One end of the first heater 20 is connected to the ground, and the other end is connected to the second heater 42 and the current generating unit 41 via a terminal RH. The first heater 20 is, for example, a resistor R x The heater resistance may be

[0026] The first temperature detector 30 detects the internal temperature T thm The first temperature detection unit 30 is preferably provided in the vicinity of the resonator 10. One end of the first temperature detection unit 30 is connected to the ground, and the other end is connected to the interface unit 47 via the terminal THM. The first temperature detection unit 30 may be, for example, a thermistor whose resistance value changes according to temperature, a platinum resistance element, or a thermocouple whose potential changes according to temperature.

[0027] The interface unit 47 is provided between the first temperature detection unit 30 and the current generation unit 41 and between the first temperature detection unit 30 and the second temperature compensation voltage generation circuit 45. For example, the interface unit 47 converts the resistance value input from the first temperature detection unit 30 via the terminal THM into a voltage signal, and outputs the internal temperature T thm and outputs the data (for example, a voltage signal) S1 indicating the temperature compensation voltage to the current generating section 41 and the second temperature compensation voltage generating circuit 45.

[0028] The current generating unit 41 includes a target temperature generating circuit 411, a differential amplifier 412, and a heater driver 413. The current generating unit 41 receives the internal temperature T thm Based on the data S1 indicating the internal temperature T thm and target temperature T gt The current generating unit 41 generates a heater current (for example, about several hundred mA) so that the target temperature T gt is preferably set to a temperature about 15°C higher than the ambient temperature Ta. For example, when the ambient temperature Ta is about 105°C, the target temperature T gt is set at around 120°C.

[0029] The target temperature generating circuit 411 calculates the target temperature T based on the voltage Vh at the terminal RH, which indicates the ambient temperature Ta. gt The target temperature generating circuit 411 generates the target temperature T gt and outputs data (e.g., a voltage signal) S2 indicating the target temperature to the differential amplifier 412. The target temperature generating circuit 411 may be, for example, an approximate Nth-order function generating circuit, an approximate hyperbolic function generating circuit, an approximate sigmoid function generating circuit, or the like. For details of the approximate Nth-order function generating circuit, refer to Japanese Patent No. 4,070,139. ​​For details of the approximate hyperbolic function generating circuit and the approximate sigmoid function generating circuit, refer to U.S. Patent No. 1,079,0831.

[0030] For example, in the heater-on region, when the environmental temperature Ta is changing, the target temperature generating circuit 411 calculates the total frequency fluctuation ΔF in the oscillation circuit 100 with respect to the environmental temperature Ta. total (=ΔF xtl +ΔF IC -ΔF c ) is zero, the target temperature T gt (=Internal temperature T thm )

[0031] The total frequency variation ΔF in the oscillator circuit 100 as shown in FIG. total The target temperature T gt When calibrated, the ambient temperature Ta and the target temperature T gt The data showing the relationship between the total frequency fluctuation ΔF in the oscillation circuit 100 as shown in FIG. total The target temperature T gt When the ambient temperature Ta is calibrated, the total frequency fluctuation ΔF in the oscillator circuit 100 total The data indicating the relationship is stored in the storage unit 50.

[0032] Target temperature T gt By properly calibrating the temperature T of the resonator 10 in the heater-on region, the temperature T xtl and the internal temperature T of the oscillator circuit 100 thm While both of these are changing, the total frequency fluctuation ΔF in the oscillator circuit 100 total can be set to zero.

[0033] Here, with reference to FIGS. 4A and 4B, the reason why the voltage Vh at the terminal RH represents the ambient temperature Ta will be briefly described.

[0034] The internal power P [W] of the oscillation circuit 100 is the product of the power supply voltage Vdd [V] and the sum Ih [A] of the heater current supplied from the current generating unit 41 to the first heater 20 and the heater current supplied from the current generating unit 41 to the second heater 42. Therefore, referring to the thermal resistance model, the following equation holds:

[0035]

number

[0036] θa is the thermal resistance [° C. / W] from the first temperature detection unit 30 to the ambient temperature Ta.

[0037] Here, the sum Ih of the heater current supplied from the current generating unit 41 to the first heater 20 and the heater current supplied from the current generating unit 41 to the second heater 42 is calculated by multiplying the resistance R of the first heater 20 by x , the variable resistance R of the second heater 42 IC Using the voltage Vh at terminal RH, this can be expressed as follows:

[0038]

number

[0039] Eliminating Ih from equations (4) and (5) and solving for Vh gives the following equation:

[0040]

number

[0041] From equation (6), it can be seen that the voltage Vh at the terminal RH is a linear expression of the ambient temperature Ta. In other words, the target temperature generating circuit 411 calculates the target temperature T gt The target temperature generating circuit 411 generates the target temperature T based on the environmental temperature Ta. gt It can be seen that this is equivalent to generating

[0042] The target temperature generating circuit 411 calculates the primary target temperature T gt Not only does it generate the Nth (N≧1)th target temperature T gt may be generated.

[0043] The differential amplifier 412 detects the internal temperature T thm and the target temperature T input from the target temperature generating circuit 411. gt The differential amplifier 412 amplifies the difference between the data S2 indicating the difference and generates an amplified signal (for example, a voltage signal) S3. The differential amplifier 412 outputs the amplified signal S3 to the heater driver 413.

[0044] The heater driver 413 generates a heater current based on the amplified signal S3 input from the differential amplifier 412, and supplies the heater current to the first heater 20 and the second heater .

[0045] For example, when the heater driver 413 turns on the first heater 20 and the second heater 42, it supplies heater current to the first heater 20 and the second heater 42. In this case, the first heater 20 and the second heater 42 generate heat.

[0046] For example, when turning off the first heater 20 and the second heater 42, the heater driver 413 does not supply heater current to the first heater 20 and the second heater 42. In this case, the first heater 20 and the second heater 42 do not generate heat. The means for turning off the heaters may be, for example, a means for setting the output current of the heater driver 413 to zero, or a means for adding a switch to the current path of the first heater 20 and the second heater 42 and turning off the switch.

[0047] The second heater 42 heats the integrated circuit 40 based on the heater current supplied from the current generating unit 41. The second heater 42 is preferably built into or provided in the vicinity of the integrated circuit 40. One end of the second heater 42 is connected to the ground, and the other end is connected to the current generating unit 41 via a terminal RH. The second heater 42 is, for example, a variable resistor R whose resistance value is variable. IC The heater resistance may be

[0048] Variable resistor R IC The resistance value of the variable resistor R is not particularly limited, and may be set to any value by the control unit 200. IC The resistance value of the variable resistor R IC As the resistance value of the resistor 10 changes, the power distribution ratio between the resonator 10 and the integrated circuit 40 also changes.

[0049] For example, as shown in FIG. 5A, when the ambient temperature Ta is constant, the variable resistor R IC When the resistance value of the second heater 42 is set to a large value (for example, about 20Ω), the proportion of the heater current supplied from the current generating unit 41 to the second heater 42 becomes smaller than the proportion of the heater current supplied from the current generating unit 41 to the first heater 20. Also, the proportion (for example, 30%) at which the second heater 42 heats the integrated circuit 40 becomes smaller than the proportion (for example, 70%) at which the first heater 20 heats the resonator 10. In this case, the oscillation circuit 100 is heated by the internal temperature T thm and the temperature T of the resonator 10 xtl the target temperature T gt , while the temperature T IC Temperature control can be performed to lower the temperature.

[0050] For example, as shown in FIG. 5B, when the ambient temperature Ta is constant, the variable resistor R ICWhen the resistance value of the second heater 42 is set to a small value (for example, about 3.7 Ω), the proportion of the heater current supplied from the current generating unit 41 to the first heater 20 becomes larger than the proportion of the heater current supplied from the current generating unit 41 to the first heater 20. Also, the proportion (for example, 70%) at which the second heater 42 heats the integrated circuit 40 becomes larger than the proportion (for example, 30%) at which the first heater 20 heats the resonator 10. In this case, the oscillation circuit 100 heats the internal temperature T thm and the temperature T of the resonator 10 xtl the target temperature T gt , while the temperature T IC Temperature control can be performed to increase the temperature.

[0051] That is, in the oscillation circuit 100, the variable resistor R IC By appropriately changing the resistance value of the resistor 10, the temperature T xtl The temperature T IC As a result, the oscillation circuit 100 can significantly change the total frequency fluctuation ΔF total (=ΔF xtl +ΔF IC ), the frequency fluctuation ΔF due to the temperature change of the integrated circuit 40 IC It is possible to generate a temperature compensation component that independently compensates only for the temperature.

[0052] The second temperature detector 43 detects the temperature T IC The second temperature detector 43 is preferably built into or provided in the vicinity of the integrated circuit 40. The second temperature detector 43 detects the temperature T IC and outputs the data (for example, a voltage signal) S4 indicating the temperature to the first temperature compensation voltage generation circuit 44. The second temperature detection unit 43 may be, for example, a known temperature sensor.

[0053] The first temperature compensation voltage generating circuit 44 detects the temperature T ICBased on the data S4 indicating the frequency variation ΔF due to the temperature change of the integrated circuit 40, IC The first temperature compensation voltage generating circuit 44 outputs the first compensation voltage V1 to the oscillator 46.

[0054] For example, in the heater-on region, when the ambient temperature Ta is constant, the first temperature compensation voltage generating circuit 44 controls the variable resistor R IC When the resistance value of the oscillator 46 is set to a large value, the data indicating the actually measured frequency F1 of the oscillation signal in the oscillator 46, the internal temperature T of the oscillation circuit 100 detected by the first temperature detection unit 30, thm1 data S1 indicating the temperature T of the integrated circuit 40 detected by the second temperature detection unit 43; IC1 The frequency F1 of the oscillation signal in the oscillator 46 is calculated based on the temperature T IC1 The first-order temperature coefficient α for the temperature T of the resonator 10 xtl1 Using the linear temperature coefficient β for

[0055]

number

[0056] For example, in the heater-on region, when the ambient temperature Ta is constant, the first temperature compensation voltage generating circuit 44 controls the variable resistor R IC When the resistance value of the oscillator 46 is set to a small value, the data indicating the actually measured frequency F2 of the oscillation signal in the oscillator 46, the internal temperature T thm2 data S1 indicating the temperature T of the integrated circuit 40 detected by the second temperature detection unit 43; IC2 The frequency F2 of the oscillation signal in the oscillator 46 is calculated based on the temperature T IC2 The first-order temperature coefficient α for the temperature T of the resonator 10 xtl2 Using the linear temperature coefficient β for

[0057]

number

[0058] Variable resistance R in the second heater 42 IC When the resistance value of the oscillator circuit 100 is changed to a larger value or a smaller value, the internal temperature T thm Since the change in temperature of the resonator 10 is small, the frequency change ΔF xtl can be approximated as being of first order. Therefore, the temperature T IC The linear temperature coefficient α for is expressed as follows by solving the simultaneous equations of equations (7) and (8):

[0059]

number

[0060] The first temperature compensation voltage generating circuit 44 calculates the temperature T IC The first-order temperature coefficient α for the integrated circuit 40 is calculated, and the frequency fluctuation ΔF IC Compensation (ΔF IC =0), a first compensation voltage V1 is generated to compensate for the frequency fluctuation ΔF caused by the temperature change of the integrated circuit 40. IC is optimally adjusted.

[0061] In addition, the variable resistor R IC The number of ways to switch the resistance value is not limited to two, but may be N (N≧2) ways. In the case of N ways, the first temperature compensation voltage generating circuit 44 IC Nth-order temperature coefficient α N is calculated, and the frequency variation ΔF due to the temperature change of the integrated circuit 40 is calculated. IC Therefore, a first compensation voltage V1 may be generated to compensate for the above.

[0062] The second temperature compensation voltage generating circuit 45 receives the internal temperature T thmBased on the data S1 showing the frequency fluctuation ΔF due to the temperature change of the resonator 10, xtl The second temperature compensation voltage generating circuit 45 outputs the second compensation voltage V2 to the oscillator 46.

[0063] For example, in the heater-off region, when the ambient temperature Ta is changing, the second temperature compensation voltage generation circuit 45 uses data indicating the frequency F of the oscillation signal in the oscillator 46 that is actually measured before temperature compensation, and the internal temperature T of the oscillation circuit 100 detected by the first temperature detection unit 30. thm Data S1 indicating the internal temperature T of the oscillation circuit 100 thm and the frequency fluctuation ΔF due to the temperature change of the resonator 10 xtl Then, the second temperature compensation voltage generating circuit 45 obtains data showing the relationship between the temperature compensation component ΔF C The internal temperature T thm and the frequency fluctuation ΔF due to the temperature change of the resonator 10 xtl The data indicating the relationship is stored in the storage unit 50.

[0064]

number

[0065] The second temperature compensation voltage generating circuit 45 calculates the frequency fluctuation ΔF due to the temperature change of the resonator 10 based on the equation (10). xtl Compensation (ΔF xtl =0), a second compensation voltage V2 is generated to compensate for the frequency fluctuation ΔF caused by the temperature change of the resonator 10. xtl is optimally adjusted.

[0066] The oscillator 46 generates an oscillation signal for oscillating the resonator 10 based on the first compensation voltage V1 input from the first temperature compensation voltage generation circuit 44 or the second compensation voltage V2 input from the second temperature compensation voltage generation circuit 45. The oscillator 46 is an oscillator that changes its oscillation frequency depending on the voltage supplied thereto, and may be, for example, a voltage controlled crystal oscillator (VCXO). By the oscillator 46 generating an oscillation signal based on the first compensation voltage V1 input from the first temperature compensation voltage generation circuit 44 or the second compensation voltage V2 input from the second temperature compensation voltage generation circuit 45, the oscillation circuit 100 can output an oscillation signal having a highly accurate oscillation frequency in which frequency fluctuations due to temperature changes of the resonator 10 and the integrated circuit 40 are compensated for.

[0067] The storage unit 50 may be, for example, a non-volatile memory or a one-time memory. IC The storage unit 50 may store, for example, the resistance value of the terminal RH and the voltage Vh of the terminal RH. gt The data showing the relationship between the ambient temperature Ta and the total frequency fluctuation ΔF in the oscillator circuit 100 total The storage unit 50 may store data indicating the relationship between the internal temperature T thm and the frequency fluctuation ΔF due to the temperature change of the resonator 10 xtl The storage unit 50 may store data indicating the relationship between the above and other data. In addition to the above data, the storage unit 50 may store any data used in the operation of the oscillator circuit 100. These data are input to the storage unit 50 from the control unit 200 via the interface unit 60. It is preferable that the various data stored in the storage unit 50 be used appropriately.

[0068] The interface unit 60 is provided between the storage unit 50 and the control unit 200, and provides a communication interface. The interface unit 60 may be, for example, a serial interface such as an I2C interface or an SPI interface.

[0069] The control unit 200 sets various data. For example, the control unit 200 sets a variable resistor R IC For example, the control unit 200 sets the output gain of the target temperature generation circuit and the output gains of the two temperature compensation voltage generation circuits. The control unit 200 outputs various data to the storage unit 50 via the interface unit 60. The control unit 200 also outputs the voltage Vh at the terminal RH and the internal temperature T of the oscillation circuit 100 via a temperature sensor monitor test path. thm , the temperature T of the integrated circuit 40 IC , target temperature T gt The above can be monitored via the control unit 200.

[0070] The oscillation circuit 100 according to the first embodiment performs appropriate temperature control by using the current generating unit 41, the first heater 20, the second heater 42, the first temperature detecting unit 30, etc., and by using two temperature compensation voltage generating circuits, the frequency fluctuation ΔF caused by the temperature change of the resonator 10 is reduced. xtl and frequency fluctuation ΔF due to temperature change of the integrated circuit 40 IC This generates a temperature compensation component to compensate for the temperature T xtl , the temperature T of the integrated circuit 40 IC , and the internal temperature T thm Even in the heater-on region where the frequencies do not match, the frequency fluctuations caused by temperature changes in the resonator 10 and the integrated circuit 40 can be sufficiently compensated for, so that the oscillator circuit 100 with high frequency stability can be realized.

[0071] [Operation of the oscillator circuit] An example of a temperature compensation method in the oscillation circuit 100 according to the first embodiment will be described with reference to FIG.

[0072] <ΔF in the heater-on region IC Compensation> In the heater-on region, the ambient temperature Ta remains constant.

[0073] In step S101, the first heater 20 and the second heater 42 are turned on. The current generating unit 41 generates the internal temperature T thm and target temperature T gt The heater current is generated so that

[0074] In step S102, the second heater 42 is connected to the variable resistor R IC The resistance value of the first temperature compensation voltage generating circuit 44 is set to a large value. IC1 The data indicating the temperature is acquired from the second temperature detection unit 43.

[0075] In step S103, the second heater 42 is connected to the variable resistor R IC The resistance value of the first temperature compensation voltage generating circuit 44 is set to a small value. IC2 The data indicating the temperature is acquired from the second temperature detection unit 43.

[0076] In step S104, the first temperature compensation voltage generating circuit 44 receives data indicating the frequency F1 of the oscillation signal in the oscillator 46, the internal temperature T thm1 , data showing the temperature T of the integrated circuit 40 IC1 data indicating the frequency F2 of the oscillation signal in the oscillator 46; data indicating the internal temperature T thm2 , data showing the temperature T of the integrated circuit 40 IC2 Based on the data showing the frequency variation ΔF due to the temperature change of the integrated circuit 40, IC A first compensation voltage V1 is generated so that

[0077] By performing the above-described processes from step S101 to step S104, the frequency fluctuation ΔF due to the temperature fluctuation of the integrated circuit 40 is IC can be compensated for.

[0078] <ΔF in the heater-off region xtl Compensation> In the heater-off region, the ambient temperature Ta is in a state of change.

[0079] In step S105, the first heater 20 and the second heater 42 are turned off. thm The second temperature compensation voltage generating circuit 45 acquires data indicating the internal temperature T thm (= temperature T xtl ) and the frequency fluctuation ΔF due to the temperature change of the resonator 10 xtl The data indicating the relationship between the above is acquired from the storage unit 50.

[0080] In step S106, the second temperature compensation voltage generating circuit 45 receives data indicating the frequency F of the oscillation signal in the oscillator 46, the internal temperature T thm Data showing the internal temperature T of the oscillator circuit 100 thm Frequency variation ΔF due to temperature change of the resonator 10 xtl Based on the change in xtl A second compensation voltage V2 is generated so that

[0081] By performing the processes from step S105 to step S106 described above, the frequency fluctuation ΔF caused by the temperature change of the resonator 10 is xtl can be compensated for.

[0082] <ΔF in the heater-on region total Compensation> In the heater-on region, the ambient temperature Ta is in a state of change.

[0083] In step S107, the first heater 20 and the second heater 42 are turned on. The target temperature generating circuit 411 calculates the total frequency fluctuation ΔF in the oscillation circuit 100. total The target temperature T gt When calibrated, the ambient temperature Ta and the target temperature T gt Relationship with (Ta-T gt The data indicating the characteristics is acquired from the storage unit 50.

[0084] In step S108, the oscillation circuit 100 calculates Ta-T based on the voltage Vh at the terminal RH, which indicates the ambient temperature Ta. gt Using the characteristics, the target temperature T gt Generate.

[0085] By going through the processes from step S107 to step S108 described above, a temperature gradient is generated starting from the heater, and T xtl ≠T thm Even if the total frequency fluctuation in the oscillator circuit 100 is total (=ΔF xtl +ΔF IC -ΔF c ) can be compensated.

[0086] By applying the temperature compensation method to the oscillator circuit 100 according to the first embodiment, it is possible to realize an oscillator circuit 100 with high frequency stability.

[0087] Second Embodiment An example of a temperature compensation method in the oscillation circuit 100 according to the second embodiment will be described with reference to FIGS. 8A to 10B.

[0088] The temperature compensation method in the oscillator circuit 100 according to the second embodiment differs from the temperature compensation method in the oscillator circuit 100 according to the first embodiment in that the temperature compensation method in the oscillator circuit 100 according to the second embodiment compensates for the frequency fluctuation ΔF caused by the temperature change of the resonator 10 at an arbitrary ambient temperature. xtl fully compensated (ΔF xtl =ΔF C ) The other methods are the same as the temperature compensation method in the oscillation circuit 100 according to the first embodiment, so a duplicated description will be omitted.

[0089] At any ambient temperature, the frequency fluctuation ΔF due to the temperature change of the resonator 10 is xtl The necessary condition for complete compensation is that the boundary temperature Tz and the minimum temperature Tp are equal (Tz=Tp). This will be explained. The minimum temperature Tp is the temperature T xtland the frequency fluctuation ΔF due to the temperature change of the resonator 10 xtl In the graph showing the relationship between the frequency fluctuation ΔF due to the temperature change of the resonator 10 xtl The temperature T of the resonator when is the minimum xtl means.

[0090] The solution for perfect compensation is not necessarily Tp=Tz, but Tp≠Tz, and ΔF xtl =ΔF C As shown in Figure 8A and Figure 8B, in all of (a) → (b) → (c) → (d), (a)' → (b)' → (c)' → (d), ΔF xtl =ΔF C Solve the equation so that the following holds true.

[0091] The temperature T of the resonator 10 xtl The temperature T of the resonator is controlled in a narrow range around the minimum temperature Tp by the temperature control in the oscillation circuit 100. xtl and the frequency fluctuation ΔF due to the temperature change of the resonator 10 xtl The graph showing the relationship between the frequency fluctuation ΔF and the resonator 10 is approximated by an even function (for example, a quadratic function). xtl can be expressed as follows:

[0092]

number

[0093] In the heater-off region, the temperature gradient around the heater becomes zero, and T xtl =T thm In this state, ΔF xtl =ΔF C The temperature compensation component is optimally adjusted so that

[0094] ΔF on the left side of equation (11) xtl ΔF C and T on the right side of equation (11) xtl T thm When replaced with the temperature compensation component ΔF C can be expressed by the following equation:

[0095]

number

[0096]

number

[0097]

number

[0098]

number

[0099] In the heater-on area, at any ambient temperature Ta, ΔF xtl =ΔF C In order to satisfy the above, the internal temperature T thm is T thm <Tz<T xtl This is because the first heater 20 is closer to the resonator 10 than the first temperature detection unit 30, and in the heater-on region, T xtl >T thm This is because the following equation is obtained by dividing the right-hand side of equation (11) by A2, which is obtained by assuming that the right-hand side of equation (14) is equal to the right-hand side of equation (11).

[0100]

number

[0101] Here, the internal temperature T thm , the temperature T of the resonator 10 xtl , and the environmental temperature Ta are related by a thermal resistance model as shown in FIGS. 9A and 9B.

[0102] From the thermal resistance model, (T thm -Ta):(T xtl -T thm ) = θa:α × θa holds, so T xtl By solving for , we obtain the following equation:

[0103]

number

[0104] Substituting equation (17) into equation (16), T xtl Eliminating this, we obtain the following equation:

[0105]

number

[0106] T thm By rearranging, the following equation is obtained:

[0107]

number

[0108] Equation (19) expresses the internal temperature T thm This is a quadratic equation for , and when solved, we obtain the following equation.

[0109]

number

[0110] One of the two solutions is when ± is replaced with + in equation (20), and T thm =Ta. However, this is because the internal temperature T thmThis indicates that the temperature Ta is equal to the ambient temperature, meaning that the amount of heat generated by the heater is zero. This contradicts the fact that the heater is on, and is not an actual solution. The other solution is the desired solution, and the following equation is obtained.

[0111]

number

[0112] Substituting equation (21) into equation (17), we obtain the following equation.

[0113]

number

[0114] From equations (21) and (22), the internal temperature T thm and the temperature T of the resonator 10 xtl The average value of and can be expressed by the following formula.

[0115]

number

[0116] As shown in FIG. 10A, the internal temperature T thm The gradient of the temperature T xtl The absolute value of the gradient of the temperature difference Vt with respect to the ambient temperature Ta is equal to that of the gradient of the temperature difference Vt with respect to the ambient temperature Ta, but the polarity is opposite.

[0117] Therefore, as shown in FIG. 10B, at any ambient temperature, the frequency fluctuation ΔF xtl fully compensated (ΔF xtl =ΔF C ) the boundary temperature Tz and the minimum temperature Tp must match (Tz=Tp). In the state where the boundary temperature Tz and the minimum temperature Tp match, the oscillation circuit 100 is in a state where the internal temperature T thm The temperature can be controlled in the primary stage.

[0118] According to the temperature compensation method in the oscillator circuit 100 of the second embodiment, the frequency fluctuation ΔF caused by the temperature change of the resonator 10 at any ambient temperature is xtl This makes it possible to realize an oscillator circuit 100 with extremely high frequency stability.

[0119] <Third embodiment> An example of a temperature compensation method in the oscillation circuit 100 according to the third embodiment will be described with reference to FIGS.

[0120] The temperature compensation method in the oscillation circuit 100 according to the third embodiment differs from the temperature compensation method in the oscillation circuit 100 according to the second embodiment in that the boundary temperature Tz and the minimum temperature Tp do not coincide in the temperature compensation method in the oscillation circuit 100 according to the third embodiment. Note that other methods are the same as the temperature compensation method in the oscillation circuit 100 according to the second embodiment, so redundant explanations will be omitted.

[0121] When the boundary temperature Tz and the minimum temperature Tp do not coincide, the frequency fluctuation ΔF due to the temperature change of the resonator 10 xtl A method for compensating for this will be described.

[0122] As shown in FIG. 11, in the heater-off region ((a)→(b)), the oscillation circuit 100 reduces the frequency fluctuation ΔF due to the temperature change of the resonator 10. xtl Temperature compensation component ΔF to compensate for C Generate.

[0123] As shown in FIG. 11, in the heater-on region ((b)→(c)), the internal temperature T thm and the frequency fluctuation ΔF due to the temperature change of the resonator 10 xtl The graph showing the relationship between the internal temperature T thm is a smooth function (for example, a cubic function) at point (b) where the boundary temperature Tz is reached. thm Then, the oscillation circuit 100 controls the temperature of the temperature compensation component ΔF based on the function.C Generate.

[0124] As shown in FIG. 12, the internal temperature T thm and slope dΔF c / dT thm On the graph showing the relationship between the internal temperature T thm The gradient dΔF at which the boundary temperature Tz c / dT thm If a discontinuity occurs in the temperature compensation circuit 100, a large residual error component may occur after temperature compensation, or the frequency stability may deteriorate due to temperature changes. However, according to the temperature compensation method for the oscillation circuit 100 of the third embodiment, as shown in FIG. thm and slope dΔF c / dT thm On the graph showing the relationship between the internal temperature T thm The gradient dΔF at which the boundary temperature Tz c / dT thm Since no discontinuity occurs in the

[0125] In the third embodiment, the case where the minimum temperature Tp is higher than the boundary temperature Tz has been described as an example, but it goes without saying that a similar temperature compensation method can be applied even when the minimum temperature Tp is equal to or lower than the boundary temperature Tz.

[0126] According to the temperature compensation method for the oscillation circuit 100 of the third embodiment, the total frequency fluctuation ΔF in the oscillation circuit 100 can be reduced without the boundary temperature Tz and the minimum temperature Tp being equal to each other. total (=ΔF xtl -ΔF c ) can be set to zero. This increases the tolerance to individual variations in the minimum temperature Tp, thereby improving mass productivity.

[0127] <Fourth embodiment> An example of a temperature compensation method in the oscillation circuit 100 according to the fourth embodiment will be described with reference to FIGS. 13A and 13B.

[0128] The temperature compensation method in the oscillation circuit 100 according to the fourth embodiment differs from the temperature compensation method in the oscillation circuit 100 according to the third embodiment in that the boundary temperature Tz coincides with the maximum environmental temperature Ta_MAX in the temperature compensation method in the oscillation circuit 100 according to the fourth embodiment. Note that other methods are the same as the temperature compensation method in the oscillation circuit 100 according to the third embodiment, and therefore redundant explanations will be omitted.

[0129] As shown in FIG. 13A, in the temperature compensation method for the oscillation circuit 100 according to the third embodiment, the boundary temperature Tz is set to be lower than the maximum value Ta_MAX of the environmental temperature.

[0130] On the other hand, as shown in FIG. 13B, in the temperature compensation method for the oscillation circuit 100 according to the fourth embodiment, the boundary temperature Tz is set to coincide with the maximum value Ta_MAX of the environmental temperature.

[0131] According to the temperature compensation method in the oscillation circuit 100 of the fourth embodiment, the boundary temperature Tz coincides with the maximum value Ta_MAX of the environmental temperature, so that the oscillation circuit 100 operates only in the heater-on region at the environmental temperature where normal operation is performed. thm Since fine adjustment of the temperature can be avoided, an oscillation circuit 100 that allows for simple temperature compensation can be realized.

[0132] Fifth Embodiment In the fifth embodiment, the frequency fluctuation ΔF caused by the temperature change of the resonator 10 xtl , the temperature T of the resonator 10 at an arbitrary ambient temperature Ta is calculated by using xtl The estimation method for estimating the above will be explained.

[0133] First, the frequency fluctuation ΔF caused by the temperature change of the integrated circuit 40 IC Regarding the compensation, the oscillation circuit 100 performs the same temperature compensation as in the first embodiment.

[0134] Next, the oscillator circuit 100 detects a frequency fluctuation ΔF due to a temperature change of the resonator 10 in a state where the heater is off and the ambient temperature Ta is changing. xtl At the same time, the oscillator circuit 100 measures the temperature T IC and the internal temperature T of the oscillator circuit 100 thm Measure (T IC =T xtl =T thm ), the temperature T of the resonator 10 xtl and the frequency fluctuation ΔF due to the temperature change of the resonator 10 xtl Based on the relationship between these two functions, an approximate function is calculated using an N-th order function.

[0135] Next, in the heater-on state, the oscillation circuit 100 calculates the frequency fluctuation ΔF due to the temperature change of the resonator 10 at the minimum environmental temperature Ta_min. xtl and calculate the temperature T of the resonator 10 based on the calculated approximation function. xtl At the same time, the oscillation circuit 100 calculates the internal temperature T thm is measured, and the thermal resistance ratio α is calculated using the following equation derived from the thermal resistance model (see FIG. 9A).

[0136]

number

[0137] The minimum value Ta_min of the environmental temperature is used because the internal temperature T thm and the ambient temperature Ta, and the temperature T xtl and the environmental temperature Ta, the difference between them is the largest, and therefore the thermal resistance ratio α can be calculated with high accuracy.

[0138] The oscillation circuit 100 uses the thermal resistance ratio α calculated based on the formula (24) to calculate the temperature T xtl Furthermore, the oscillation circuit 100 can calculate the temperature T xtl and the frequency fluctuation ΔF due to the temperature change of the resonator 10 xtlBy using an approximation function calculated based on the relationship between xtl It is also possible to calculate

[0139] According to the estimation method of the fifth embodiment, the temperature T xtl By applying the estimation method according to the fifth embodiment to the temperature compensation method in the oscillation circuit 100 according to each of the above-described embodiments, the oscillation circuit 100 can estimate the internal temperature T thm The temperature control can be easily performed.

[0140] <Modification> In each of the above-described embodiments, the integrated circuit 40 has been described as including a current generating unit 41, a second heater 42, a second temperature detecting unit 43, a first temperature compensation voltage generating circuit 44, a second temperature compensation voltage generating circuit 45, an oscillator 46, an interface unit 47, a memory unit 50, and an interface unit 60 as an example, but the integrated circuit 40 is not limited to this configuration.

[0141] For example, the integrated circuit 40 may be configured to include a current generating unit 41, a second heater 42, a second temperature detecting unit 43, a first temperature compensated voltage generating circuit 44, an oscillator 46, and an interface unit 47. When the integrated circuit 40 has this configuration, the oscillation circuit 100 can reduce a frequency fluctuation ΔF caused by a temperature change of the integrated circuit 40. IC It is possible to perform temperature compensation so that

[0142] Although the above-described embodiments have been described as typical examples, it will be apparent to those skilled in the art that many modifications and substitutions can be made within the spirit and scope of the present invention. Therefore, the present invention should not be construed as being limited by the above-described embodiments, and various modifications and alterations are possible without departing from the scope of the claims. For example, multiple building blocks shown in the configuration diagrams of the embodiments can be combined into one, or a single building block can be divided. Furthermore, multiple steps shown in the flowcharts of the embodiments can be combined into one, or a single step can be divided. [Explanation of symbols]

[0143] 10 resonator 20 First heater 30 First temperature detection unit 40 Integrated Circuits 41 Current generation section 42 Second heater 43 Second temperature detection unit 44 First temperature compensation voltage generating circuit 45 Second temperature compensation voltage generating circuit 46 Oscillator 47 Interface section 50 Storage section 60 Interface section 100 Oscillator Circuit 411 Target temperature generation circuit 412 Differential Amplifier 413 Heater Driver

Claims

1. An oscillator circuit that compensates for frequency fluctuations caused by temperature changes of a resonator and an integrated circuit, comprising: a first temperature detection unit that detects an internal temperature of the oscillation circuit; a current generating unit that generates a heater current so that the internal temperature coincides with a target temperature; a first heater that heats the resonator based on the heater current; a second heater that heats the integrated circuit based on the heater current; a second temperature detection unit that detects the temperature of the integrated circuit; a first compensation voltage generating circuit that generates a first compensation voltage based on a temperature of the integrated circuit to compensate for a first frequency fluctuation caused by a temperature change of the integrated circuit; a second compensation voltage generating circuit that generates a second compensation voltage based on the internal temperature to compensate for a second frequency fluctuation caused by a temperature change of the resonator; an oscillator that generates an oscillation signal based on the first compensation voltage and the second compensation voltage; An oscillator circuit comprising:

2. the second heater is a variable resistor whose resistance value changes; 2. The oscillator circuit according to claim 1.

3. The current generating unit a target temperature generating circuit configured to generate the target temperature in a heater-on region while the environmental temperature is changing, so as to compensate for the second frequency fluctuation with respect to the environmental temperature; 3. The oscillator circuit according to claim 1.

4. the boundary temperature coincides with a minimum temperature, which is a temperature of the resonator at which the second frequency variation is minimal, in a graph showing the relationship between the temperature of the resonator and the second frequency variation; The second compensation voltage generating circuit generating the second compensation voltage such that the second frequency variation is zero; 4. The oscillator circuit according to claim 1.

5. the boundary temperature does not coincide with a minimum temperature, which is a temperature of the resonator at which the second frequency variation is minimal, in a graph showing the relationship between the temperature of the resonator and the second frequency variation; The second compensation voltage generating circuit generating the second compensation voltage such that the second frequency variation is zero; 4. The oscillator circuit according to claim 1.

6. The boundary temperature corresponds to the maximum value of the environmental temperature.

6. The oscillator circuit according to claim 4 or 5.

7. An oscillator circuit that compensates for frequency fluctuations caused by temperature changes of a resonator and an integrated circuit, comprising: a first temperature detection unit that detects an internal temperature of the oscillation circuit; a current generating unit that generates a heater current so that the internal temperature coincides with a target temperature; a first heater that heats the resonator based on the heater current; a second heater, which is a variable resistor whose resistance value changes and which heats the integrated circuit based on the heater current; a second temperature detection unit that detects the temperature of the integrated circuit; a compensation voltage generating circuit that generates a compensation voltage based on the temperature of the integrated circuit to compensate for frequency fluctuations caused by temperature changes of the integrated circuit; an oscillator that generates an oscillation signal based on the compensation voltage; An oscillator circuit comprising:

8. A temperature control circuit provided in an oscillator circuit that compensates for frequency fluctuations caused by temperature changes of a resonator and an integrated circuit, a first temperature detection unit that detects an internal temperature of the oscillation circuit; a current generating unit that generates a heater current so that the internal temperature coincides with a target temperature, and that generates the target temperature in a heater-on region while the environmental temperature is changing, to compensate for a frequency fluctuation caused by a temperature change of the resonator relative to the environmental temperature; a first heater that heats the resonator based on the heater current; a second heater that heats the integrated circuit based on the heater current; A temperature control circuit comprising:

9. Compensating for frequency variations due to temperature changes in the resonator and integrated circuit; a first temperature detection unit that detects an internal temperature of the oscillation circuit; a current generating unit that generates a heater current so that the internal temperature coincides with a target temperature; a first heater that heats the resonator based on the heater current; a second heater that heats the integrated circuit based on the heater current; a second temperature detection unit that detects the temperature of the integrated circuit; a first compensation voltage generating circuit that generates a first compensation voltage based on a temperature of the integrated circuit to compensate for a first frequency fluctuation caused by a temperature change of the integrated circuit; a second compensation voltage generating circuit that generates a second compensation voltage based on the internal temperature to compensate for a second frequency fluctuation caused by a temperature change of the resonator; an oscillator that generates an oscillation signal based on the first compensation voltage and the second compensation voltage; A method for temperature compensation of an oscillator circuit, comprising: In a heater-on region, the current generating unit generates the heater current so that the internal temperature coincides with the target temperature while the environmental temperature is constant; a resistance value of a variable resistor in the second heater is set to a first resistance value, and a temperature of the integrated circuit is detected; a resistance value of a variable resistor in the second heater is set to a second resistance value smaller than the first resistance value, and a temperature of the integrated circuit is detected; a first compensation voltage generating circuit generating the first compensation voltage for compensating for the first frequency variation based on a temperature of the integrated circuit when the resistance value is the first resistance value and a temperature of the integrated circuit when the resistance value is the second resistance value; generating, by the second compensation voltage generating circuit, the second compensation voltage for compensating for the second frequency fluctuation based on a change in the second frequency fluctuation relative to the internal temperature in a state in which the environmental temperature is changing in a heater-off region; In the heater-on region, while the environmental temperature is changing, the current generating unit generates the target temperature so as to compensate for the second frequency fluctuation with respect to the environmental temperature; A temperature compensation method comprising:

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