JP6092643B2 - Temperature compensated crystal oscillator - Google Patents

Description

  The present invention relates to a temperature-compensated crystal oscillator that performs temperature compensation, in particular, canceling the frequency drift characteristic of the temperature compensation voltage, compensating the frequency drift characteristic of the crystal, and compensating the frequency drift characteristic of the oscillation circuit, The present invention relates to a temperature compensated crystal oscillator that suppresses swell characteristics of frequency drift characteristics.

[Conventional technology]
A conventional temperature compensated crystal oscillator (TCXO) is obtained by adding a temperature compensation circuit to a voltage controlled oscillator to reduce frequency fluctuation due to a change in ambient temperature.

  In the conventional temperature-compensated crystal oscillator, the frequency may drift (fluctuate or fluctuate) immediately after the power is supplied, and the frequency drift characteristic changes due to the heat generated when the power is turned on.

A conventional method for compensating the frequency drift characteristic has been proposed, and the amount of compensation has been constant (see Patent Document 1).
The frequency drift characteristic in the temperature compensated crystal oscillator is a characteristic in which the frequency drift characteristic has undulations.

[Frequency drift characteristics: Fig. 21]
The frequency drift characteristic will be described with reference to FIG. FIG. 21 is a diagram showing frequency drift characteristics at a high temperature (+ 85 ° C.). The frequency (Freq.) On the vertical axis is represented by Linear, and the time (Time (s)) on the horizontal axis is represented by Log.
Although frequency drift occurs after the power is turned on, a portion surrounded by a thick broken line portion in FIG. 21 indicates a wavy portion.

[Change in heat generation of crystal and IC after power-on: Fig. 22]
A change in heat generation of the crystal and the IC after power-on will be described with reference to FIG. FIG. 22 is a diagram illustrating changes in heat generation of the crystal and the IC after the power is turned on. The temperature on the vertical axis is displayed in Linear, and the temperature on the horizontal axis (Temp.) Is displayed in Linear.
As shown in FIG. 22, the change in the heat generation of the IC is a broken line, the change in the crystal temperature is a solid line, and the change in the crystal temperature occurs later than the change in the heat generation of the IC.

[Frequency characteristics of each element: FIG. 23]
Next, each element that causes the swell of the frequency drift characteristic shown in FIG. 21 will be described with reference to FIG. FIG. 23 is a diagram showing the frequency characteristics of each element that causes swell at high or low temperatures. The frequency (Freq.) On the vertical axis is represented by Linear, and the time (Time (s)) on the horizontal axis is represented by Linear.
Each element that causes undulation includes a temperature compensated frequency drift characteristic, a crystal frequency drift characteristic, and an oscillation circuit frequency drift characteristic.
Since the time constant and size of each element are different, the frequency drift characteristic of the conventional oscillator is swelled.

[Temperature sensor voltage VT: FIG. 24]
Here, the temperature sensor voltage VT with respect to the temperature will be described with reference to FIG. FIG. 24 is a diagram illustrating the temperature sensor voltage. The vertical axis represents voltage [V] as Linear, and the horizontal axis represents temperature (temp. [° C.]) as Linear.
As shown in FIG. 24, in the temperature sensor used for temperature compensation, the temperature sensor voltage VT is high when the temperature is low, and the temperature sensor voltage VT is low when the temperature is high.

[Related technologies]
As related prior art, Japanese Patent Laid-Open No. 10-224148, “Piezoelectric Oscillator” (Toyo Tsushinki Co., Ltd.) [Patent Document 1], Japanese Patent Laid-Open No. 07-254818, “Voltage Controlled Oscillator” (Toshiba Co., Ltd.) [Patent Document 2], Japanese Patent Application Laid-Open No. 2003-258551, “Temperature Compensation Circuit of Oscillation Circuit and its Temperature Compensation Method” (Seiko Epson Corporation) [Patent Document 3], Japanese Patent Application Laid-Open No. 2008-271355 “ “Temperature Compensated Crystal Oscillator” (Nippon Denpa Kogyo Co., Ltd.) [Patent Document 4], Japanese Patent No. 4745102 “Reference Current Control Circuit, Crystal Oscillator Control IC with Temperature Compensation Function, Crystal Oscillator, TCXO Module, and Mobile Phone” (Panasonic Corporation Company) [Patent Document 5], International Publication No. 2004/025824, “Approximate nth Order Function Generator and Temperature Compensated Water” There is an oscillation circuit "(Asahi Kasei Microsystems Inc.) [Patent Document 6].

Patent Document 1 discloses an anode terminal of a variable-capacitance diode in a voltage-controlled piezoelectric oscillator composed of an amplifying unit including a transistor, a resistor and a capacitor, a piezoelectric vibrator, a variable-capacitance diode, and a control voltage unit including a resistor and a capacitor. It has been shown that the frequency starting characteristic of the piezoelectric oscillation circuit can be shortened by making the voltage of 1 variable with time.
Patent Document 2 discloses that in a voltage controlled oscillator, temperature drift compensation is performed for a linearity best point of control characteristics of a control voltage by a temperature drift compensation circuit.

In Patent Document 3, in an oscillation circuit, a correction interval determination circuit obtains a temperature change based on a temperature detected from a temperature sensor, and determines a correction interval for correcting the oscillation frequency of the oscillation circuit according to the temperature change. It is shown.
In Patent Document 4, in a temperature compensated crystal oscillator, a compensation error of a temperature compensation voltage based on a temperature difference between a detection temperature due to heat generation at the time of activation of an IC chip and an operating temperature of a crystal piece is measured in advance, and the compensation error is calculated. It is shown that a start-up correction voltage to be corrected is applied to the voltage variable capacitance element.

  In Patent Document 5, in the reference current control circuit, the cancel circuit outputs a voltage V2 (t) in the opposite direction to the fluctuation of the voltage V1 (t) and is added to V1 (t) by the addition circuit, and there is no fluctuation. The voltage V3 (t) is input to the base of the input transistor of the voltage-current conversion circuit, and it is shown that the switch between the cancellation circuit and the addition circuit is turned off after a certain time by the time constant circuit. .

  Further, it is known that the temperature characteristic of the oscillation frequency of the crystal (crystal frequency temperature characteristic) is expressed by a function of the third order or higher of the temperature, and Patent Document 6 discloses a crystal using a function in a crystal oscillation circuit. Compensating for frequency temperature characteristics is described.

The temperature compensation crystal oscillation circuit in Patent Document 6 will be described with reference to FIG. FIG. 25 is a configuration block diagram of a conventional temperature compensated crystal oscillation circuit.
As shown in FIG. 25, the conventional temperature-compensated crystal oscillation circuit includes a temperature detection circuit 210, an approximate quintic function generator 200, and a VCXO (Voltage Controlled Crystal Oscillator) 230.

The temperature detection circuit 210 outputs an analog output that changes in a linear function with respect to a temperature change.
The VCXO 230 includes a crystal resonator and outputs a frequency corresponding to the control voltage.
The approximate quintic function generator 200 generates an approximate quintic function for the voltage corresponding to the temperature from the temperature detection circuit 210 and outputs it to the VCXO 230 as a temperature compensation voltage.

The approximate fifth order function generator 200 includes a first order component generator 201, a third order component generator 203, a fourth order component generator 204, a fifth order component generator 205, and a zeroth order component generator 206. And a circuit 207.
The n-order component generation units (n = 0, 1, 3, 4, 5) 201 to 206 output n-order components of the output voltage of the temperature detection circuit 210, respectively.

The adder circuit 207 adds the outputs from the n-order component generators 201 to 206 and outputs the result to the VCXO 230 as a temperature compensation voltage.
Thus, in the temperature compensated crystal oscillation circuit of FIG. 25, the crystal frequency temperature characteristic in the VCXO 230 is compensated by the approximate quintic function of the temperature and output.
Since the temperature compensation voltage does not include a secondary component, the conventional approximate quintic function generator 200 is not provided with a secondary component generator that generates a secondary component.

JP-A-10-224148 Japanese Patent Application Laid-Open No. 07-254818 JP 2003-258551 A JP 2008-271355 A Japanese Patent No. 4745102 International Publication No. 2004/025824

  However, the conventional temperature compensated crystal oscillator does not consider the swell characteristic of the frequency drift characteristic, and does not cancel the frequency drift characteristic due to the temperature compensation to suppress the swell characteristic of the frequency drift characteristic. There is a problem that the frequency drift characteristic of the vibrator and the frequency drift characteristic of the oscillation circuit are not compensated to suppress the swell characteristic of the frequency drift characteristic.

  The present invention has been made in view of the above circumstances, and can cancel the frequency drift characteristic due to temperature compensation, and further compensate the frequency drift characteristic of the crystal resonator and the oscillation circuit to suppress the swell characteristic of the frequency drift characteristic. An object is to provide a temperature-compensated crystal oscillator.

  The present invention for solving the problems of the conventional example includes a crystal resonator, an amplifier connected in parallel to the crystal resonator, a voltage variable capacitance element connected to an input side and an output side of the amplifier, a temperature A temperature-compensated crystal oscillator having a temperature compensation circuit that outputs a control voltage for compensation, and a temperature sensor that detects the ambient temperature of the crystal resonator and outputs a voltage corresponding to the detected temperature, and a temperature sensor A temperature compensation cancellation circuit that outputs a voltage for canceling the temperature compensation frequency drift characteristic when temperature compensation is performed by the temperature compensation circuit based on the detected temperature, and a voltage for compensating the frequency drift characteristic of the crystal unit Is output from a temperature compensation sensor, a crystal compensation circuit that outputs a voltage, an oscillation circuit characteristic compensation circuit that outputs a voltage for compensating the frequency drift characteristic of an oscillation circuit including an amplifier, and a temperature sensor. A first addition circuit that adds the voltage, the voltage output from the temperature compensation cancel circuit, and the voltage output from the crystal compensation circuit to output to the temperature compensation circuit, the voltage output from the temperature compensation circuit, and the oscillation circuit And a second adder circuit that adds the voltages output from the characteristic compensation circuit and outputs the added voltage to the voltage variable capacitance element.

  In the temperature compensated crystal oscillator according to the present invention, a frequency control circuit (AFC circuit) that outputs a control voltage for making the output frequency variable is provided, and the second adder circuit outputs the voltage output from the temperature compensation circuit. And the voltage output from the oscillation circuit characteristic compensation circuit and the voltage output from the frequency control circuit are added together and output to the voltage variable capacitance element.

  According to the present invention, in the temperature compensated crystal oscillator, the temperature compensation cancel circuit includes an amplifier in which a constant current source circuit and a capacitor are connected in series, and amplifies a voltage between the constant current source circuit and the capacitor. The diode anode is connected to the stage, the cathode of the diode is grounded, and the temperature compensation frequency drift characteristic compensation control voltage that is a temperature compensation frequency cancellation characteristic that cancels the temperature compensation frequency drift characteristic in the temperature compensation circuit is output to the first adder circuit It is characterized by doing.

  According to the present invention, in the above temperature compensated crystal oscillator, the crystal compensation circuit includes an amplifier in which a constant current source circuit and a capacitor are connected in series, and a voltage between the constant current source circuit and the capacitor is amplified. The diode anode is connected to the diode, the diode cathode is grounded, and a crystal frequency drift characteristic compensation control voltage which is a crystal frequency compensation characteristic for compensating for the crystal frequency drift characteristic in the crystal resonator is output to the first adder circuit. Features.

  According to the present invention, in the temperature compensated crystal oscillator, the oscillation circuit characteristic compensation circuit includes an amplifier in which a constant current source circuit and a capacitor are connected in series, and a voltage between the constant current source circuit and the capacitor is amplified. The anode of the diode is connected to the input stage, the cathode of the diode is grounded, and the oscillation circuit frequency drift characteristic compensation control voltage which becomes the oscillation circuit frequency compensation characteristic for compensating the oscillation circuit frequency drift characteristic in the oscillation circuit is supplied to the second adder circuit. It is characterized by outputting.

  Further, the present invention for solving the problems of the conventional example includes a crystal resonator, an amplifier connected in parallel to the crystal resonator, a voltage variable capacitance element connected to the input side and the output side of the amplifier, A temperature-compensated crystal oscillator having a temperature compensation circuit that outputs a control voltage for temperature compensation, and a parallel circuit composed of a parallel-connected resistor and a capacitor is connected to the anode side of the voltage variable capacitance element, The other end is grounded, the temperature compensation circuit detects the ambient temperature of the crystal unit, and outputs a voltage corresponding to the detected temperature. The temperature detected by the temperature sensor is the frequency temperature of the crystal unit. From an n-order function generator that generates a third-order or higher-order n-order function that approximates the compensation characteristics of the characteristics, a (n−1) -order function generator that generates a differential function of the n-order function, and an n-order function generator Reference voltage specific to the output of A first adder circuit that generates the control voltage and inputs it to a point between the anode of the voltage variable capacitance element and the parallel circuit; and (n−1) a reference voltage as an output from the linear function generator. Is added to generate a voltage for compensating the frequency drift characteristic of the crystal resonator based on the second addition circuit that outputs the addition voltage, and when the addition voltage is larger than the reference voltage, When the voltage is output to a point between the anode of the voltage variable capacitance element and the parallel circuit, and the addition voltage is smaller than the reference voltage, the crystal compensation circuit that outputs to the cathode side of the voltage variable capacitance element and the temperature based on the addition voltage Generates a voltage to cancel the temperature compensated frequency drift characteristics when temperature compensation is performed by the compensation circuit. If the added voltage is greater than the reference voltage, it is output to the cathode side of the voltage variable capacitance element, and the added voltage is the reference voltage. If the voltage is smaller than the pressure, a voltage for compensating the frequency drift characteristic of the oscillation circuit including the temperature compensation cancellation circuit and the amplifier that outputs to the point between the anode of the voltage variable capacitance element and the parallel circuit is generated, and the voltage And an oscillation circuit characteristic compensation circuit that outputs to a point between the anode of the variable capacitance element and the parallel circuit.

  According to the present invention, in the above temperature compensated crystal oscillator, the n-order function generation unit generates a power of the temperature detected by the temperature sensor for each order except the second order, and function generation for each order. A plurality of multipliers provided by being connected to the circuit and outputting the output from the function generation circuit by multiplying a set coefficient, and the (n−1) -order function generation unit includes a plurality of function generation circuits. Are connected to a function generation circuit of (n−1) th order or less, and a function generation circuit of each order of (n−1) th order or less, and set to an output from the function generation circuit. And a plurality of multipliers for multiplying and outputting the obtained coefficients.

  The present invention is characterized in that the temperature compensated crystal oscillator includes a quintic function generator and a quartic function generator when n = 5.

  In the temperature compensated crystal oscillator according to the present invention, the crystal compensation circuit determines the magnitude of the addition voltage with respect to the reference voltage and outputs a determination result, and adjusts the gain of the absolute value of the difference between the reference voltage and the addition voltage. Based on the gain adjustment voltage, the absolute value circuit that outputs the voltage, the crystal time constant generation circuit that generates the crystal frequency drift characteristics compensation control voltage that compensates the frequency drift characteristics of the crystal oscillator, and the crystal frequency drift characteristics compensation control voltage Based on the determination result of the variable gain amplifier and the comparator, the gain of the variable gain amplifier is adjusted to the anode side of the voltage variable capacitance element when the addition voltage is large, and the voltage when the addition voltage is small. And a switch circuit for switching to the cathode side of the variable capacitance element.

In the temperature compensated crystal oscillator according to the present invention, the temperature compensation cancel circuit determines a magnitude of the addition voltage with respect to the reference voltage and outputs a determination result, and gains an absolute value of a difference between the reference voltage and the addition voltage. An absolute value circuit that outputs as an adjustment voltage, an IC time constant generation circuit that generates a temperature compensation cancellation voltage that cancels the temperature compensation frequency drift characteristic in the temperature compensation circuit, and the temperature compensation cancellation voltage are adjusted based on the gain adjustment voltage Based on the determination result of the variable gain amplifier that amplifies with the gain and the comparator, the output of the variable gain amplifier is on the anode side of the voltage variable capacitance element when the addition voltage is small, and the cathode of the variable capacitance element when the addition voltage is large And a switch circuit for switching to the side.

  According to the present invention, in the above temperature compensated crystal oscillator, the oscillation circuit characteristic compensation circuit includes an amplifier in which a constant current source circuit and a capacitor are connected in series, and amplifies a voltage between the constant current source circuit and the capacitor. The anode of the diode is connected to the input stage, the cathode of the diode is grounded, and the oscillation circuit frequency drift characteristic compensation control voltage that compensates for the oscillation circuit frequency drift characteristic in the oscillation circuit is applied to the anode of the voltage variable capacitance element. It outputs to the side.

  According to the present invention, the temperature sensor detects the ambient temperature of the crystal resonator, outputs a voltage corresponding to the detected temperature, and the temperature compensation cancel circuit is based on the temperature detected by the temperature sensor. The voltage for canceling the temperature compensated frequency drift characteristic when the temperature compensation is performed at is output, the crystal compensation circuit outputs the voltage for compensating the frequency drift characteristic of the crystal oscillator, and the oscillation circuit characteristic compensation circuit is A voltage for compensating the frequency drift characteristics of the oscillation circuit including the amplifier, the first adder circuit outputs the voltage output from the temperature sensor, the voltage output from the temperature compensation cancel circuit, and the crystal compensation circuit The second output circuit adds the voltage output from the temperature compensation circuit and the voltage output from the oscillation circuit characteristic compensation circuit. Since the temperature compensated crystal oscillator outputs the voltage to the voltage variable capacitance element, the swell characteristic of the frequency drift characteristic based on the temperature compensated frequency drift characteristic, the crystal frequency drift characteristic, and the oscillation circuit frequency drift characteristic can be suppressed. .

  Further, according to the present invention, a crystal resonator, an amplifier connected in parallel to the crystal resonator, a voltage variable capacitance element connected to the input side and the output side of the amplifier, and a control voltage for performing temperature compensation are output. A temperature compensation type crystal oscillator having a temperature compensation circuit, wherein the parallel side consisting of a parallel connected resistor and capacitor is connected to the anode side of the voltage variable capacitance element, and the other end is grounded, and the temperature compensation circuit Detects the ambient temperature of the crystal unit and outputs a voltage corresponding to the detected temperature, and the third order that approximates the compensation characteristic of the frequency temperature characteristic of the crystal unit for the temperature detected by the temperature sensor. A specific reference voltage is added to the output from the n-order function generation unit that generates the n-order function, the (n-1) -order function generation unit that generates a differential function of the n-order function, and the n-order function generation unit. To generate the control voltage A first adder circuit that inputs a point between the anode of the voltage variable capacitance element and the parallel circuit, and a reference voltage added to the output from the (n−1) degree function generator to output the added voltage. 2 and a voltage for compensating the frequency drift characteristics of the crystal resonator based on the added voltage. When the added voltage is larger than the reference voltage, the voltage variable capacitance element anode and the parallel circuit If the added voltage is lower than the reference voltage, the crystal compensation circuit that outputs to the cathode of the voltage variable capacitance element and the temperature compensation when temperature compensation is performed by the temperature compensation circuit based on the added voltage Generates a voltage to cancel the frequency drift characteristics. If the added voltage is larger than the reference voltage, it is output to the cathode side of the voltage variable capacitance element. If the added voltage is smaller than the reference voltage, the voltage is variable. A temperature compensation cancel circuit that outputs to a point between the anode of the quantity element and the parallel circuit, a voltage for compensating the frequency drift characteristics of the oscillation circuit including the amplifier, and an anode and parallel circuit of the voltage variable capacitance element, Since the temperature compensated crystal oscillator is provided with an oscillation circuit characteristic compensation circuit that outputs to a point between the two, each of the temperature compensated crystal oscillators using a differential function of the nth order function in addition to the highly accurate temperature compensation using the nth order function. The frequency drift characteristics can be compensated with high accuracy, the undulation characteristics of the frequency drift characteristics can be suppressed, and a good frequency starting characteristic can be realized.

1 is a configuration diagram of a temperature compensated crystal oscillator according to an embodiment of the present invention. FIG. It is a circuit diagram of a temperature compensation cancellation circuit. It is a circuit diagram of a crystal compensation circuit and an oscillation circuit characteristic compensation circuit. It is a figure which shows the output voltage VIC of a temperature compensation cancellation circuit. It is a figure which shows the output voltage VX of a crystal compensation circuit. It is a figure which shows the output voltage Vo of an oscillation circuit characteristic compensation circuit. It is a figure which shows a temperature compensation circuit output voltage. It is a figure which shows a frequency variable characteristic. It is a figure which shows the cancellation characteristic of a temperature compensation frequency drift characteristic. It is a figure which shows the compensation characteristic of a crystal frequency drift characteristic. It is a figure which shows the compensation characteristic of an oscillation circuit frequency drift characteristic. It is a figure which shows an oscillator frequency drift characteristic. It is a block diagram of another temperature compensation type | mold crystal oscillator. (A) is explanatory drawing which shows the temperature characteristic of the temperature compensation control voltage Va from the addition circuit A112, and the addition voltage Vb from the addition circuit B113, (b) expanded and showed the vertical axis | shaft about the addition voltage Vb. Is. It is explanatory drawing which shows the frequency variable characteristic of VCXO. FIG. 6 is a block diagram showing the configuration of a crystal frequency drift compensation circuit 115. It is explanatory drawing which shows the characteristic of the addition voltage Vb and the gain adjustment voltage Vg. It is explanatory drawing which shows the characteristic of the crystal frequency drift characteristic compensation control voltage Vx 'output from the time constant circuit 121. FIG. FIG. 6 is a block diagram showing the configuration of an IC frequency drift cancel circuit 116. It is explanatory drawing which shows the frequency drift characteristic of another temperature compensation type | mold crystal oscillator. It is a figure which shows the frequency drift characteristic in high temperature (+85 degreeC). It is a figure which shows the change of the heat_generation | fever of a crystal | crystallization and IC after power activation. It is a figure which shows the frequency characteristic of each element which becomes a generation | occurrence | production of a wave | undulation. It is a figure which shows a temperature sensor voltage. It is a configuration block diagram of a conventional temperature compensated crystal oscillation circuit.

Embodiments of the present invention will be described with reference to the drawings.
[Outline of the embodiment]
In the temperature compensated crystal oscillator according to the embodiment of the present invention, the temperature compensation frequency drift characteristic is canceled by the temperature compensation cancel circuit, the crystal frequency drift characteristic is compensated by the crystal compensation circuit, and the oscillation circuit frequency is compensated by the oscillation circuit characteristic compensation circuit. In order to compensate the drift characteristic, the swell characteristic of the frequency drift characteristic based on the temperature compensated frequency drift characteristic, the crystal frequency drift characteristic, and the oscillation circuit frequency drift characteristic can be suppressed.

  In particular, in the temperature compensated crystal oscillator according to the embodiment of the present invention, a temperature compensation cancel circuit, a crystal compensation circuit, and an oscillation circuit characteristic compensation circuit are provided in addition to the temperature compensation circuit, and three different time constants and sizes are provided. The frequency fluctuation due to the elements is individually adjusted to suppress the undulation of the frequency drift characteristic over a wide temperature range and realize a good frequency starting characteristic that converges quickly.

[Temperature compensated crystal oscillator: Fig. 1]
A temperature compensated crystal oscillator according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a configuration diagram of a temperature compensated crystal oscillator according to an embodiment of the present invention.
As shown in FIG. 1, a temperature compensated crystal oscillator (TCXO: this oscillator) according to an embodiment of the present invention includes a temperature compensation circuit 1, an AFC (Auto Frequency Control) circuit 2, and a temperature sensor. 3, adder circuit 4, crystal resonator 5, inverter IC (Integrated Circuit) 6, voltage variable capacitance elements 7 a and 7 b, buffer (Buff 1) 8, output terminal (OUTPUT 1) 9, and temperature compensation cancellation The circuit 11, the crystal compensation circuit 12, the addition circuit 13, and the oscillation circuit characteristic compensation circuit 14 are basically included.

[Each oscillator part]
Each part of the oscillator will be specifically described.
The temperature compensation circuit 1 inputs the control voltage (addition voltage Va) added by the addition circuit 13 and outputs a temperature compensation control voltage (temperature compensation control voltage Vc) to the addition circuit 4 in accordance with the addition voltage Va. .

The AFC circuit 2 outputs a control voltage (oscillation frequency control voltage Vafc) for changing the frequency output from the output terminal 9 to the adder 4.
The temperature sensor 3 detects the temperature around the crystal unit 5 and outputs temperature information as a voltage to the adder circuit 13 according to the detected temperature.

The temperature compensation cancel circuit 11 outputs a control voltage (temperature compensation frequency drift characteristic compensation control voltage VIC) for compensating (cancelling) the temperature compensation frequency drift characteristic due to the fluctuation at the start of the temperature sensor voltage to the adder circuit 13.
Since the compensation voltage in the temperature compensation circuit 1 is mainly generated by the temperature sensor voltage VT of the temperature sensor 3, the frequency drift characteristic of the temperature compensation voltage can be canceled by canceling the fluctuation of the temperature sensor voltage at the time of startup.

  The crystal compensation circuit 12 outputs a control voltage (crystal frequency drift characteristic compensation control voltage VX) for compensating the crystal frequency drift characteristic by the crystal oscillator 5 to the adder circuit 13.

  The adder circuit 13 receives the temperature compensation control voltage VT from the temperature sensor 3, the temperature compensation frequency drift characteristic compensation control voltage VIC from the temperature compensation cancel circuit 11, and the crystal frequency drift characteristic compensation control voltage VX from the crystal compensation circuit 12. An added voltage Va (= VT + VIC + VX) obtained by adding them is output to the temperature compensation circuit 1.

The oscillation circuit characteristic compensation circuit 14 outputs a compensation voltage (oscillation circuit frequency drift characteristic compensation voltage Vo) for compensating the frequency drift characteristic in the oscillation circuit portion to the adder circuit 4.
The frequency drift characteristic of the oscillation circuit is presumed to be mainly caused by the temperature characteristic of the semiconductor PN junction, has a linear function temperature characteristic, and the frequency fluctuation direction is the same and the magnitude is equal in a wide temperature range.

The adder circuit 4 receives the temperature compensation control voltage Vc from the temperature compensation circuit 1, the oscillation frequency control voltage Vafc from the AFC circuit 2, and the oscillation circuit frequency drift characteristic compensation voltage Vo from the oscillation circuit characteristic compensation circuit 14. By adding them, an added output voltage VOUT (= Vc + Vafc + Vo) is outputted to a point between the capacitor C1 and the varicap diode D1, and to a point between the capacitor C2 and the varicap diode D2.
The addition in the adder 4 may be performed by weighting each input voltage.

The crystal unit 5 oscillates at a resonance frequency determined by the load capacitance viewed from both ends of the crystal unit.
An inverter IC (Integrated Circuit) 6 amplifies the oscillation frequency of the crystal unit 5, inverts the phase, and outputs it to the buffer 8.

The varicap diodes D1 and D2, which are voltage variable capacitance elements, change the capacitance according to the applied voltage, and change the load capacitance of the crystal resonator 5 to adjust the oscillation frequency.
Specifically, the anode side of the varicap diode D1 is grounded, one end of the capacitor C1 is connected to the cathode side, and the other end is connected to one end of the crystal resonator 5 and the input side of the inverter IC6.
The anode side of the varicap diode D2 is grounded, one end of the capacitor C2 is connected to the cathode side, and the other end is connected to the other end of the crystal resonator 5 and the output side of the inverter IC6.

  Then, the control voltage (VOUT) from the adder circuit 4 is applied to the cathode side of the varicap diodes D1 and D2.

The buffer (Buff) 8 is a signal amplifier that amplifies the oscillation frequency from the inverter IC 6 and outputs it to the output terminal 9.
An output terminal (OUTPUT) 9 is a terminal for outputting an oscillation signal of the present oscillator.

[Temperature compensation cancel circuit 11: FIG. 2]
Next, the temperature compensation cancel circuit 11 will be described with reference to FIG. FIG. 2 is a circuit diagram of the temperature compensation cancel circuit.
As shown in FIG. 2, the temperature compensation cancel circuit 11 includes a constant current source circuit 24 and a capacitor 22 connected in series, the other end of the capacitor 22 is grounded, and a point between the constant current source circuit 24 and the capacitor 22. Is input to the input terminal of the amplifier (AMP) 23, the anode of the diode 25 is connected to the input terminal, and the cathode of the diode 25 is grounded.
By setting the current of the constant current source circuit 24 to a minute current, a large time constant can be adjusted.

  In the temperature compensation cancel circuit 11 of FIG. 2, the time constant is adjusted by adjusting the current flowing through the constant current source circuit 24 and the capacitance of the capacitor 22, and the gain of the AMP 23 is adjusted. Thus, the voltage level is adjusted.

[Crystal Compensation Circuit 12 / Oscillation Circuit Characteristics Compensation Circuit 14: FIG. 3]
Next, the crystal compensation circuit 12 and the oscillation circuit characteristic compensation circuit 14 will be described with reference to FIG. FIG. 3 is a circuit diagram of the crystal compensation circuit and the oscillation circuit characteristic compensation circuit.
As shown in FIG. 3, in the crystal compensation circuit 12 and the oscillation circuit characteristic compensation circuit 14, a constant current source circuit 34 and a capacitor 32 are connected in series, the other end of the capacitor 32 is grounded, and the constant current source circuit 34 and the capacitor 32 are connected. The voltage at a point between 32 and 32 is input to the input terminal of the amplifier (AMP) 33, the anode of the diode 35 is connected to the input terminal, and the cathode of the diode 35 is grounded.

In the crystal compensation circuit 12 and the oscillation circuit characteristic compensation circuit 14, the AMP 33 is different from the AMP 23 of the temperature compensation cancel circuit 11 and outputs an inverted signal.
A large time constant can be adjusted by making the current of the constant current source circuit 34 a very small current.
Further, in the compensation circuit of FIG. 3, the time constant can be adjusted by adjusting the current flowing through the constant current source circuit 34 and the capacitance of the capacitor 32, and the gain of the AMP 33 can be adjusted. Thus, the voltage level is adjusted.

[Output voltage of temperature compensation cancel circuit: Fig. 4]
Next, the output voltage VIC of the temperature compensation cancel circuit 11 will be described with reference to FIG. FIG. 4 is a diagram showing the output voltage VIC when the temperature compensation cancel circuit is activated. The vertical axis indicates voltage [V] by Linear, and the horizontal axis indicates elapsed time (Time) by Linear.

As shown in FIG. 4, the solid line is the output voltage VT from the temperature sensor 3, and the broken line is the temperature compensation cancel voltage VIC output from the temperature compensation cancel circuit 11 for canceling the voltage VT.
The temperature compensation cancel voltage VIC for canceling the voltage VT is adjusted so as to be output from the temperature compensation cancel circuit 11.

[Output voltage of crystal compensation circuit: Fig. 5]
Next, the output voltage VX of the crystal compensation circuit 12 will be described with reference to FIG. FIG. 5 is a diagram showing the output voltage VX of the crystal compensation circuit. The vertical axis indicates temperature [° C.] and voltage [V] by Linear, and the horizontal axis indicates elapsed time (Time) by Linear.
As shown in FIG. 5, the solid line indicates the crystal temperature, and the broken line indicates the crystal compensation voltage VX output from the crystal compensation circuit 12.

  The crystal compensation voltage VX is a voltage for compensating the crystal frequency drift characteristic, and is a voltage that has the same downward curve as the output voltage of the temperature sensor at the time of startup. Therefore, the crystal compensation voltage VX is adjusted so as to be output from the crystal compensation circuit 12.

[Output voltage of oscillation circuit characteristic compensation circuit: Fig. 6]
Next, the output voltage Vo of the oscillation circuit characteristic compensation circuit 14 will be described with reference to FIG. FIG. 6 is a diagram showing the output voltage Vo of the oscillation circuit characteristic compensation circuit. The vertical axis indicates voltage [V] by Linear, and the horizontal axis indicates elapsed time (Time) by Linear.
As shown in FIG. 6, the solid line is the output voltage VT from the temperature sensor 3, and the broken line is the oscillation circuit characteristic compensation voltage Vo output from the oscillation circuit characteristic compensation circuit 14.

  The oscillation circuit characteristic compensation voltage Vo is a voltage for compensating the characteristic of the oscillation circuit (IC), and is a voltage having the same downward curve as the output voltage of the temperature sensor at the time of startup. Accordingly, the oscillation circuit characteristic compensation voltage Vo is adjusted so as to be output from the oscillation circuit characteristic compensation circuit 14.

[Temperature compensation circuit output voltage: Fig. 7]
Next, the output voltage Vc of the temperature compensation circuit 1 will be described with reference to FIG. FIG. 7 is a diagram illustrating the temperature compensation circuit output voltage. The vertical axis indicates voltage [V] by Linear, and the horizontal axis indicates temperature (Temp) [° C.] by Linear.
As shown in FIG. 7, the temperature compensation voltage Vc output from the temperature compensation circuit 1 is an n-order approximation function obtained by approximating the temperature characteristics with a third-order or higher-order n-order function in order to compensate the crystal oscillator temperature characteristics. It becomes a point-symmetric characteristic curve at the inflection point.

[Variable frequency characteristics: Fig. 8]
The frequency characteristics of the adder circuit 4 with respect to the output voltage VOUT will be described with reference to FIG. FIG. 8 is a diagram showing frequency variable characteristics. The vertical axis indicates the frequency (Freq.) With Linear, and the horizontal axis indicates the voltage [V] with Linear.
As shown in FIG. 8, the frequency characteristic of the adder circuit 4 with respect to the output voltage VOUT increases linearly in proportion to the voltage.

[Cancellation of temperature compensated frequency drift characteristics: Fig. 9]
Next, the cancel characteristic of the temperature compensated frequency drift characteristic will be described with reference to FIG. FIG. 9 is a diagram illustrating the cancel characteristic of the temperature compensated frequency drift characteristic. The vertical axis indicates the frequency (Freq) by Linear, and the horizontal axis indicates the elapsed time (Time) by Linear.
As shown in FIG. 9, the solid line is the temperature compensated frequency drift characteristic (temperature compensated frequency characteristic), and the broken line is the cancel characteristic (temperature compensated frequency cancel characteristic) of the temperature compensated frequency drift characteristic for canceling the temperature compensated frequency characteristic.

The temperature compensation frequency characteristic is constant with the frequency gradually decreasing with time.
Accordingly, the temperature compensation cancel circuit 11 is set to output a temperature compensation frequency drift characteristic compensation control voltage VIC that has a temperature compensation frequency cancellation characteristic that cancels the temperature compensation frequency characteristic.

[Quartz crystal frequency drift compensation: Fig. 10]
Next, the compensation characteristic of the crystal frequency drift characteristic will be described with reference to FIG. FIG. 10 is a diagram illustrating compensation characteristics of crystal frequency drift characteristics. The vertical axis indicates the frequency (Freq) by Linear, and the horizontal axis indicates the elapsed time (Time) by Linear.
As shown in FIG. 10, the solid line is the crystal frequency drift characteristic (crystal frequency characteristic), and the broken line is the crystal frequency drift characteristic compensation characteristic (crystal frequency compensation characteristic) for compensating the crystal frequency characteristic.

The crystal frequency characteristic is constant with the frequency gradually increasing with time.
Accordingly, the crystal compensation circuit 12 is set so as to output the crystal frequency drift characteristic compensation control voltage VX having the crystal frequency compensation characteristic for compensating the crystal frequency characteristic.

[Compensation of oscillation circuit frequency drift characteristics: FIG. 11]
Next, compensation characteristics of the oscillation circuit frequency drift characteristic will be described with reference to FIG. FIG. 11 is a diagram illustrating compensation characteristics of the oscillation circuit frequency drift characteristics. The vertical axis indicates the frequency (Freq) by Linear, and the horizontal axis indicates the elapsed time (Time) by Linear.
As shown in FIG. 11, the solid line is the oscillation circuit frequency drift characteristic (oscillation circuit frequency characteristic), and the broken line is the compensation characteristic (oscillation circuit frequency compensation characteristic) of the oscillation circuit frequency drift characteristic that compensates the oscillation circuit frequency characteristic.

In the oscillation circuit frequency characteristics, the frequency gradually increases slightly with time, and is constant at time T1.
Therefore, the oscillation circuit characteristic compensation circuit 14 is set so as to output the oscillation circuit frequency characteristic compensation control voltage Vo which becomes an oscillation circuit frequency compensation characteristic that compensates for the oscillation circuit frequency characteristic.

[Oscillator frequency drift characteristics: Fig. 12]
Next, the frequency drift characteristics of the entire oscillator according to the present embodiment will be described with reference to FIG. FIG. 12 is a diagram showing oscillator frequency drift characteristics. The vertical axis indicates the frequency (Freq) as Linear, and the horizontal axis indicates the elapsed time (Time) as Log.
As shown in FIG. 12, the solid line is the frequency drift characteristic (oscillator frequency drift characteristic) of the entire oscillator according to the present embodiment.

In the oscillator frequency drift characteristic, the frequency rapidly decreases at the beginning of time, but the frequency thereafter is constant and changes stably.
This is a result of the temperature compensation frequency drift characteristic being canceled by the temperature compensation cancel circuit 11, the crystal frequency drift characteristic being compensated by the crystal compensation circuit 12, and the oscillation circuit frequency drift characteristic being compensated by the oscillation circuit characteristic compensation circuit. .

[Effects of the present embodiment]
According to this oscillator, the temperature compensation frequency drift characteristic is canceled by the temperature compensation cancel circuit 11, the crystal frequency drift characteristic is compensated by the crystal compensation circuit 12, and the oscillation circuit frequency drift characteristic is compensated by the oscillation circuit characteristic compensation circuit 14. Therefore, the swell characteristic of the frequency drift characteristic based on the temperature compensated frequency drift characteristic, the crystal frequency drift characteristic, and the oscillation circuit frequency drift characteristic can be suppressed, and an excellent frequency starting characteristic can be realized.

[Temperature compensated crystal oscillator according to another implementation]
Next, a temperature compensated crystal oscillator according to another embodiment of the present invention will be described.
[Outline of another embodiment]
A temperature-compensated crystal oscillator according to another embodiment (another temperature-compensated crystal oscillator) includes an n (n ≧ 3) order function generation circuit as a temperature compensation circuit that compensates the frequency temperature characteristics of a crystal resonator, and n A (n-1) order function generation circuit that generates a (n-1) order function that differentiates the order function, and a crystal that compensates the frequency drift characteristics of the oscillator output accompanying a temperature change based on the (n-1) order function. A frequency drift compensation circuit, an IC frequency drift cancellation circuit, and an oscillation circuit frequency drift compensation circuit are provided. The temperature compensation characteristic is approximated by an n-order function, and the temperature compensation control voltage based on the temperature compensation characteristic is used for highly accurate temperature compensation. Each frequency drift characteristic can be compensated with high accuracy using a voltage based on a differential function of the compensation characteristic, and a good frequency starting characteristic can be realized.

[Configuration of Another Temperature Compensated Crystal Oscillator: FIG. 13]
The configuration of another temperature compensated crystal oscillator will be described with reference to FIG. FIG. 13 is a configuration diagram of another temperature-compensated crystal oscillator.
As shown in FIG. 13, another temperature compensation type crystal oscillator includes a VCXO and a temperature compensation control circuit unit.

The VCXO is substantially the same as the configuration of FIG. 1, and as the same portion as FIG. 1, an AFC circuit 2, a crystal resonator 5, an inverter IC (Integrated Circuit) 6, voltage variable capacitance elements 7a and 7b, A buffer (Buff) 8 and an output terminal (OUTPUT) 9 are provided, and resistors 118a and 118b and capacitors 119a and 119b are provided as characteristic features of another temperature compensated crystal oscillator.
One end of the resistor 118a and the capacitor 119a connected in parallel is connected to the anode side of the diode 7a, and the other end is grounded.
Similarly, one end of the resistor 118b and the capacitor 119b connected in parallel is connected to the anode side of the diode 7b, and the other end is grounded.

Further, the temperature compensation control circuit section includes a temperature sensor (Tsensor) 3 similar to that in FIG. 1, 0th to 5th order n-order function generation circuits 100 to 105, which are characteristic parts of another temperature compensated crystal oscillator, Multiplier circuits 110a to 110f ', adder circuit A (112), adder circuit B (113), reference voltage (Vco) generator 114, memory 111, crystal frequency drift compensation circuit 115, IC frequency drift cancel A circuit 116 and a time constant generation circuit 117 are provided.
Of the above-described components, the portions denoted by the same reference numerals as those in FIG.
The n-order function generation circuits 100 to 105 are function generation circuits that generate n-order components, respectively, as in Patent Document 6.

A characteristic part of another temperature compensated crystal oscillator will be specifically described.
In another temperature-compensated crystal oscillator, similarly to Patent Document 6, compensation of the frequency temperature characteristic of the crystal resonator is performed with a compensation voltage based on a compensation characteristic function represented by a quintic function of temperature, and another temperature As a characteristic of the compensation type crystal oscillator, the crystal frequency drift compensation circuit 115, the IC frequency drift cancellation circuit 116, and the time constant generation circuit 117 each compensate for the frequency drift characteristic by a voltage based on a quartic function obtained by differentiating the quintic function. The control voltage is generated.
In addition, it is good also as a structure approximated not only by a 5th-order but by a 3rd-order or more n-order function.

[Compensation of frequency temperature characteristics using a function: FIG. 13]
First, in the temperature compensation control circuit unit, a configuration part for compensating the frequency temperature characteristic of the crystal resonator in the same manner as the conventional temperature compensation crystal oscillator shown in FIG. 25 will be described with reference to FIG.
In general, the crystal frequency temperature characteristic (F (T)) is approximated by a third-order or higher-order n-order function, and the temperature point T0 (about 30 ° C.) serving as the inflection point of each function is used as a reference. Expressed as a function.

For example, when approximated by a quintic function, the crystal frequency temperature characteristic F (T) is
F (T) = X ₅ (T−T0) ⁵ + X ₄ (T−T0) ⁴ + X ₃ (T−T0) ³ + X ₁ (T−T0) + X0 (Formula 1)
It is expressed.

And if the compensation voltage for compensating this crystal frequency temperature characteristic F (T) is V _A (T),
V _A (T) = A ₅ (T−T0) ⁵ + A ₄ (T−T0) ⁴ + A ₃ (T−T0) ³ + A ₁ (T−T0) + A ₀ (Formula 2)
Is approximated by

In another temperature-compensated crystal oscillator, as shown in FIG. 13, a zero-order function generator circuit 100 and a linear function are used as a configuration for generating a compensation voltage that compensates the crystal frequency temperature characteristic using a quintic function of temperature. Generating circuit 101, cubic function generating circuit 103, quartic function generating circuit 104, quintic function generating circuit 105, and amplifiers (multipliers) 110a, 110b, 110c connected to function generating circuits 105-100. , 110e, 110f.
The component corresponds to the n-order function generation unit recited in the claims.

  Then, the fifth order function (compensation characteristic function) of Equation 2 for compensating the frequency temperature characteristic of the crystal resonator by the function generation circuits 100 to 105 of each order and the amplifiers 110a to 110f connected to the function generation circuits 100 to 105. ) Of each order of () and is output to the adder circuit A112.

  Specifically, the quintic function generation circuit 105 calculates and outputs the fifth power of the temperature sensor output (Vt) as in the conventional temperature compensated crystal oscillator of FIG. The temperature sensor output (Vt) is a voltage value corresponding to (T−T0) in (Expression 2), and Expression 2 can also be expressed as a quintic function of Vt.

Similarly, the quartic function generation circuit 104 calculates and outputs the fourth power of the temperature sensor output (Vt).
The cubic function generation circuit 103 calculates the cube of the temperature sensor output (Vt), the quadratic function generation circuit 103 calculates and outputs the square, the linear function generation circuit 102 outputs the square, The zero-order function generation circuit 100 outputs 0th power.

The amplifiers 110a, 110b, 110c, 110e, and 110f are set with gains G ₅ , G ₄ , G ₃ , G ₁ , and G ₀ , respectively, and the order of the compensation voltage output from each function generation circuit The component is weighted by the corresponding gain and output.
The gain values of the amplifiers 110a to 110f are adjusted and set in the memory 111 so that each order component has an appropriate value.
As a result, the terms of the respective orders of the compensation function shown in Expression 2 are generated.

For example, the adjustment of the fifth-order component will be described.
The fifth-order function generation circuit 105 calculates the fifth power of the temperature sensor output (Vt) and outputs a fifth-order component voltage V _R5 .
Then, the amplifier 110a multiplies the output V _R5 of the _quintic function generation circuit 105 by the gain G ₅ and outputs a weighted quintic component V ₅ = V _R5 G ₅ .

Here, the value of the gain G ₅ is set so that the output V ₅ from the amplifier 110a matches the fifth-order component shown in Equation 2.
Similarly, the output V ₄ = V _R4 G ₄ from the amplifier 110b matches the quaternary component of Equation 2, the output V ₃ = V _R3 G ₃ from the amplifier 110c matches the third order component, and the amplifier 110e The value of each gain is adjusted so that the output V ₃ = V _R3 G ₃ matches the first-order component and the output V ₀ = V _R0 G _{0 of the} amplifier 110f matches the zero-order component.

  The reference voltage generation unit 114 outputs a reference voltage (Vco). Vco is a reference value of the compensation voltage input to the varicap diodes 7a and 7b.

The adder circuit A112 adds the outputs of the amplifiers 110a, 110b, 110c, 110e, and 110f and the output Vco of the reference voltage generation unit 114, and outputs a temperature-compensated control voltage (temperature compensation control voltage) Va.
That is, Va = V _A (T) + Vco.
The temperature compensation control voltage Va is a control voltage for compensating the frequency temperature characteristic of the crystal resonator, and is applied to the anode side of the varicap diodes 7a and 7b.
As a result, another temperature-compensated crystal oscillator can accurately perform temperature compensation using a quintic function.

[Compensation of frequency drift characteristics using differential functions]
Further, if the heat generation temperature ΔT of the oscillator is considered to be minute, the magnitude of the swell of the frequency drift characteristic shown in FIG. 21 can be expressed by an (n−1) th order function that is a derivative of the nth order approximation function. When n = 5, the size of the swell can be expressed by a quartic function obtained by differentiating a quintic approximation function.

Therefore, as another feature of the temperature-compensated crystal oscillator, a quaternary function generation unit that generates a quartic function that is a differential function of the compensation characteristic of the crystal frequency temperature characteristic is provided. The quartic function generator corresponds to the (n-1) order function generator described in the claims.
(N-1) The linear function generation unit includes a zero-order function generation circuit 100, a quadratic function generation circuit 102, a cubic function generation circuit 103, a quartic function generation circuit 104, and function generation circuits 104 to 100. And amplifiers 110b ', 110c', 110d ', and 110f' connected to each other.

  That is, in another temperature-compensated crystal oscillator, a circuit for generating each order component is common in an n-order function generation unit similar to the conventional one and a (n−1) -order function generation unit that generates a differential function thereof. The increase in circuit scale is suppressed.

  In particular, another temperature-compensated crystal oscillator includes a quadratic function generation circuit 102 and a weighting amplifier 110d 'in order to generate a quadratic function that is a main component of a function obtained by differentiating the compensation voltage. However, this is different from the conventional temperature compensated crystal oscillator.

Specifically, the differential function V _A ′ (T) of the compensation voltage V _A (T) represented by the quintic function of Equation 2 is a quartic function,
V _A ′ (T) = 5A ₅ (T−T0) ⁴ + 4A ₄ (T−T0) ³ + 3A ₃ (T−T0) ² + A ₁ (Formula 3)
It is expressed.
Here, since the secondary component is not included in Formula 2, the primary component is not included in Formula 3 that is a derivative thereof. That is, the (n−1) order function generation unit does not include a linear function generation circuit and an amplifier connected thereto.

When the coefficient of Equation 3 is simplified and rewritten as V _B (T),
V _B (T) = B ₄ (T−T0) ⁴ + B ₃ (T−T0) ³ + B ₂ (T−T0) ² + B ₀ (Formula 4)
It becomes.

Equations 3 and 4 are equivalent, and the relationship between the coefficients is
B ₄ = 5A ₅
B ₃ = 4A ₄
B ₂ = 3A ₃
B ₀ = A ₁
It has become.

The gains G _4f , G _3f , G _2f , and G _0f are set in the amplifiers 110b ′, 110c ′, 110d ′, and 110f ′, respectively, and the order components of the differential voltages output from the function generation circuits. Are weighted by the corresponding gain and output.
The gain values of the amplifiers 110b ′ to 110f ′ are adjusted and set in the memory 111 so that each order component has an appropriate value.
As a result, a term of each order of the differential function shown in Expression 4 is generated.

The adder circuit B113 adds the outputs of the amplifiers 110b 'to 110f' and the output Vco of the reference voltage generator 114, and outputs an added voltage Vb.
That is, Vb = V _B (T) + Vco.
The added voltage Vb is a control voltage that compensates for frequency drift characteristics.

Another temperature-compensated crystal oscillator includes a circuit that compensates for the frequency drift characteristic of the oscillator using the value of the differential function of an n-order function (here, a quintic function).
The crystal frequency drift compensation circuit 115 generates a control voltage that compensates for the crystal frequency drift characteristics of the crystal resonator 5 and adjusts it using a differential function to obtain an adjusted control voltage (adjusted crystal compensation control voltage). Output V _A1 or V _A2 .
The adjusted crystal compensation control voltage V _A2 is applied to the cathode side of the varicap diodes 7a and 7b, and V _A1 is applied between the resistor 118 and the capacitor 119 connected in parallel with the anode side.
A specific configuration and operation of the crystal frequency drift compensation circuit 115 will be described later. The crystal frequency drift compensation circuit 115 corresponds to the crystal compensation circuit recited in the claims.

The IC frequency drift cancellation circuit 116 generates a control voltage that compensates for temperature compensation frequency drift characteristics due to fluctuations at the start of the temperature sensor voltage, adjusts it using a differential function, and adjusts the adjusted control voltage (after adjustment) Temperature compensation cancel control voltage) V _B1 or V _B2 is output.
The adjusted temperature compensation cancel control voltage V _B2 is applied between the anode side of the varicap diodes 7a and 7b and the resistor 118 and the capacitor 119 connected in parallel, and V _B1 is applied to the cathode side.
The specific configuration and operation of the IC frequency drift cancellation circuit 116 will be described later. The IC frequency drift cancel circuit 116 corresponds to the temperature compensation cancel circuit described in the claims.

The time constant generation circuit 117 outputs a control voltage (oscillation circuit frequency drift compensation voltage) V _C1 that compensates the oscillation circuit frequency drift characteristic.
The time constant generation circuit 117 corresponds to the oscillation circuit characteristic compensation circuit recited in the claims, and the oscillation circuit frequency drift compensation voltage V _C1 corresponds to the oscillation circuit frequency drift characteristic compensation control voltage recited in the claims.

  The memory 111 stores various parameters set from the outside. In addition to the coefficients of the multipliers 110a to 110f and the coefficients of the multipliers 110b 'to 110f', a crystal frequency drift compensation circuit 115, which will be described later, and an IC frequency drift cancellation. Parameters for adjusting the output voltage from the circuit 116 and the time constant generation circuit 117 are stored. These parameters will be described later.

[Adder circuit output voltage: FIG. 14]
Next, the output Va from the adder circuit A112 and the output Vb from the adder circuit B113 will be described with reference to FIG. FIG. 14A is an explanatory diagram showing temperature characteristics of the temperature compensation control voltage Va from the addition circuit A112 and the addition voltage Vb from the addition circuit B113. FIG. 14B is an enlarged view of the vertical axis of the addition voltage Vb. It is shown.
As shown in FIGS. 14 (a) and 14 (b), the temperature characteristic of the temperature compensation control voltage Va from the adder circuit A112 is an n-order curve that is a maximum at the temperature TL and a minimum at the temperature TH, and is added from the adder circuit B113. The voltage Vb has a characteristic obtained by differentiating Va.

Vco is a reference voltage of the compensation voltage applied to the varicap diodes 7a and 7b, and is a voltage at a temperature point that is the center of point symmetry of the curve Va in FIG.
Further, as shown in FIG. 14B, the addition voltage Vb has a differential value of 0 (zero) at the temperature (TL, TH) at which the n-order curve of the temperature compensation control voltage Va is maximum and minimum, and Vco and Intersect.

[Variable frequency characteristics of VCXO: FIG. 15]
Next, the variable frequency characteristics of VCXO in another crystal oven-equipped crystal oscillator will be described with reference to FIG. FIG. 15 is an explanatory diagram showing frequency variable characteristics of VCXO. The horizontal axis indicates the voltage (Vd) applied between both terminals of the varicap diode, and the vertical axis indicates the frequency shift (ΔF / F) (denoted as Frequency in the figure).
As shown in FIG. 15, when the voltage applied to the varicap diode is the reference voltage Vco, the output frequency of the VCXO is zero from the desired frequency.

[Configuration of crystal frequency drift compensation circuit: FIG. 16]
Next, the configuration of the crystal frequency drift compensation circuit 115 will be described with reference to FIG. FIG. 16 is a configuration block diagram of the crystal frequency drift compensation circuit 115.
As shown in FIG. 16, the crystal frequency drift compensation circuit 115 includes a time constant generation circuit (crystal time constant generation circuit, crystal frequency compensation circuit) 121, an absolute value circuit 122, a comparator 123, a variable gain amplifier 124, And a switch circuit 125.

Each component will be described.
In the time constant generation circuit 121, the constant current source circuit and the capacitor are connected in series, the other end of the capacitor is grounded, and the constant current source circuit and the capacitor are connected in the same manner as the crystal compensation circuit 12 shown in FIG. In this configuration, an output is obtained from this point, and a control voltage (crystal frequency drift characteristic compensation control voltage) Vx ′ for compensating the crystal frequency drift characteristic by the crystal unit 5 is output.

  The absolute value circuit 122 receives the reference voltage Vco from the reference voltage generation circuit 114 and the addition voltage Vb from the addition circuit B113, calculates the absolute value of the difference between them, and adjusts the gain of the variable gain amplifier 124. Outputs gain adjustment voltage Vg.

The variable gain amplifier 124 amplifies the crystal frequency drift characteristic compensation control voltage Vx ′ from the time constant generation circuit 121 with the gain G adjusted by the gain adjustment voltage Vg, and outputs the adjusted control voltage. The adjusted crystal frequency drift characteristic compensation control voltage is defined as an adjusted crystal compensation control voltage V _A.

Here, the gain G of the variable gain amplifier 124 is determined by G = Gx · Vg (1). Gx is an initial setting value of the variable gain amplifier 124 and is set from the memory 111.
When the magnitude of Vx ′ is Vm, the output Vx ′ of the time constant circuit 121 is
Vx ′ = Vm (1−e ^{(−t / τ)} ) τ is a time constant.
The magnitude Vm of Vx ′ is adjusted by the gain G, and the adjusted crystal compensation control voltage V _A is output.
V _A = Vm · G (1-e ^{(−t / τ)} ) (2)
Substituting equation (1) into equation (2),
V _A = Vm · Gx · Vg (1−e ^{(−t / τ)} ) is obtained.
That is, V _A is adjusted based on the initial set value Gx from the memory 111 and the gain adjustment voltage Vg from the absolute value circuit 122.

The comparator 123 compares the reference voltage Vco and the added voltage Vb, and outputs the determination result to the switch circuit 125.
The switch circuit 125 switches the output to SW (1) or SW (2) based on the determination result from the comparator 123, and outputs either the adjusted crystal compensation control voltage V _A1 or V _A2 . V _A1 is output from SW (1), and V _A2 is output from SW (2).

As will be described later, when the addition voltage Vb is larger than the reference voltage Vco, the switch switching condition is switched to SW (1) to output the adjusted crystal compensation control voltage V _A1 , and the addition voltage Vb is the reference voltage. In the case of Vco or less, switching to SW (2) is performed, and the adjusted crystal compensation control voltage V _A2 is output.

  The magnitude relationship between the added voltage Vb and the reference voltage Vco is determined by the temperature as shown in FIG. 17, and the value of the temperature (Temp) is compared with the temperatures TL and TH shown in FIG. When> TM, the switch circuit 125 is switched to SW1, and when TL ≦ Temp ≦ TH, the switch circuit 125 is switched to SW2.

In another temperature compensated crystal oscillator, the current of the constant current source circuit in the time constant generation circuit 121, the capacitance of the capacitor, and the initial value of the gain of the variable gain amplifier 124 are stored in the memory 111 as parameters. The part operates based on the set parameters.
The time constant (τ) is adjusted by adjusting the current of the constant current source circuit and the capacitance of the capacitor, and the voltage level is adjusted by adjusting the gain of the variable gain amplifier 124.

[Additional voltage Vb and gain adjustment voltage Vg: FIG. 17]
Next, the gain adjustment voltage Vg in the crystal frequency drift compensation circuit 115 will be described with reference to FIG. FIG. 17 is an explanatory diagram showing characteristics of the addition voltage Vb and the gain adjustment voltage Vg. In FIG. 17, the horizontal axis represents temperature (° C.) and the vertical axis represents voltage (V).
As shown in FIG. 17, the addition voltage Vb intersects with the reference voltage Vco at the temperature TL and the temperature TH as shown in FIG.

The gain adjustment voltage Vg output from the absolute value circuit 122 of FIG. 16 is the absolute value of the difference between the addition voltage Vb and the reference voltage Vco, and has a characteristic indicated by a thick line.
That is, Vg has a characteristic in which the addition voltage Vb is inverted with respect to the reference voltage Vco in the range where the temperature is not less than TL and not more than TH.
In order to show the characteristics in an easy-to-understand manner, Vg is described as being overlapped with Vb and Vco here. However, in Vg, the position of Vco on the vertical axis is 0 (zero).

[Output of Time Constant Generation Circuit: FIG. 18]
Next, the output of the time constant generation circuit 121 of the crystal frequency drift compensation circuit 115 shown in FIG. 16 will be described with reference to FIG. FIG. 18 is an explanatory diagram showing the characteristics of the crystal frequency drift characteristic compensation control voltage Vx ′ output from the time constant circuit 121. In FIG. 18, the horizontal axis represents time (s) and the vertical axis represents voltage (V).
As shown in FIG. 18, the crystal frequency drift characteristic compensation control voltage Vx ′ increases after startup, and becomes a substantially constant value after a certain period of time. This is a characteristic obtained by inverting the crystal compensation circuit output voltage Vx shown in FIG.
In another temperature compensated crystal oscillator, the output from the time constant circuit 121 is output without being inverted.

[Configuration of IC Frequency Drift Cancellation Circuit 116: FIG. 19]
The configuration of the IC frequency drift cancel circuit 116 will be described with reference to FIG. FIG. 19 is a block diagram showing the configuration of the IC frequency drift cancel circuit 116.
As shown in FIG. 19, the IC frequency drift cancellation circuit 116 has substantially the same configuration as the crystal frequency drift compensation circuit 115 shown in FIG. 16, and includes an IC time constant generation circuit 131, an absolute value circuit 132, and a comparator 133. And a variable gain amplifier 134 and a switch circuit 135.
However, the IC frequency drift cancel circuit 116 has parameters different from those of the crystal frequency drift compensation circuit 115 set in the memory 111, and operates based on the set constant.

The absolute value circuit 132 and the comparator 133 are the same as those in the crystal frequency drift compensation circuit 115 described above.
The IC time constant generation circuit 131 outputs a temperature compensation cancel voltage V _IC that cancels the frequency drift characteristic of the temperature compensation circuit IC.

The variable gain amplifier 134 amplifies and adjusts the temperature compensation cancellation voltage VIC by the gain G, and outputs the adjusted temperature compensation cancellation voltage V _B. The initial value of the gain is a GIC set from the memory 111 and is adjusted by the gain adjustment voltage Vg from the absolute value circuit 132 as in the case of the crystal frequency drift compensation circuit 115.

The switch circuit 135 switches the output to SW (1) or SW (2) based on the determination result from the comparator 133, and outputs either the adjusted temperature compensation cancel voltage V _B1 or V _B2 . V _B1 is output from SW (1), and V _B2 is output from SW (2).

The switch circuit 135 switches to SW (1) when the added voltage Vb is larger than the reference voltage Vco (when Vb−Vco> 0), and switches when the added voltage Vb is equal to or lower than the reference voltage Vco (Vb−Vco ≦ 0). Switch to SW (2).
In terms of temperature conditions, when the temperature (Temp) value is Temp <TL or Temp> TH, the switch circuit 125 is switched to SW1, and the adjusted temperature compensation cancel voltage V _B1 is output, and TL ≦ Temp When ≦ TH, the switch is made to SW2, and the adjusted temperature compensation cancel voltage V _B2 is output.

[Configuration of Time Constant Generation Circuit 117]
The time constant generation circuit 117 has the same configuration and operation as the temperature compensation cancellation circuit shown in FIG. 2, and outputs an oscillation circuit frequency drift compensation voltage V _C1 that compensates for the frequency drift characteristics of the oscillation circuit.
The current of the constant current source circuit of the time constant generation circuit 117, the capacitance of the capacitor, and the gain of AMP are stored in the memory 111.

[Input of each control voltage to varicap diode: Fig. 13]
Next, the input to the varicap diode of the temperature compensation control voltage input to the VCXO and the three types of control voltages for compensating the frequency drift characteristics will be described with reference to FIG.
As shown in FIG. 13, the temperature compensation control voltage Va for compensating the frequency temperature characteristic of the oscillator is input to the anode side of the varicap diodes 7a and 7b.

Further, as shown in FIGS. 9 and 10, since the crystal frequency drift characteristic and the temperature compensated frequency drift characteristic are opposite to each other, the adjusted crystal compensation control voltage V _A for compensating them is provided. And the characteristics of the adjusted temperature compensated frequency drift cancel voltage V _B are also opposite.

Therefore, the input directions of V _A and V _{B to} the varicap diodes 7a and 7b are opposite.
That is, when the temperature (Temp) value is Temp <TL or Temp> TH, both the switch circuits 125 and 135 are switched to SW (1), and the crystal frequency drift compensation circuit 115 controls the adjusted crystal compensation control. The voltage V _A1 is output and applied to the anode side of the varicap diodes 7a and 7b, and the adjusted temperature compensation cancel voltage V _B1 is output from the IC frequency drift cancel circuit 116 to the cathode side of the varicap diodes 7a and 7b. Applied.

When TL ≦ Temp ≦ TH, both the switch circuits 125 and 135 are switched to SW (2), and the adjusted crystal compensation control voltage V _A2 is output from the crystal frequency drift compensation circuit 115, and the varicap diode is output. 7a and 7b is applied to the cathode side, and the IC frequency drift cancel circuit 116 outputs the adjusted temperature compensation cancel voltage V _B2 and applies it to the anode side of the varicap diodes 7a and 7b.

In another temperature-compensated crystal oscillator, the adjusted crystal compensation control voltage V _A and the adjusted temperature-compensated frequency drift cancel depending on the situation according to the magnitude of the reference voltage Vco and the added voltage Vb obtained using a differential function. The voltage V _B is applied to either the cathode side or the anode side of the varicap diodes 7a and 7b.
Thereby, in another temperature compensation type crystal oscillator, in addition to the temperature compensation using the n-order function, the frequency drift characteristic is compensated using the differential function of the n-order function.

Since the oscillation circuit frequency drift characteristic is a one-way characteristic regardless of the temperature, the oscillation circuit frequency drift compensation voltage V _C1 that is the output of the time constant generation circuit 117 is always input to the anode side regardless of the temperature.

[Frequency drift characteristics of another temperature compensated crystal oscillator: FIG. 20]
The frequency drift characteristics of another temperature compensated crystal oscillator will be described with reference to FIG. FIG. 20 is an explanatory diagram showing frequency drift characteristics of another temperature compensated crystal oscillator.
FIG. 20 shows frequency drift characteristics of Vout in a wide temperature range from low temperature to high temperature.
As shown in FIG. 20, in another temperature compensated crystal oscillator, as compared with the conventional temperature compensated crystal oscillator of FIG. 21, there is almost no swell immediately after power-on, and the frequency drift characteristic is greatly improved. You can see that

[Effect of another embodiment]
According to the temperature-compensated crystal oscillator according to another embodiment of the present invention, the fifth-order function generating circuits 100 to 105 and the amplifiers 110a to 110f and 110a ′ are used as the temperature compensation circuits for compensating the frequency temperature characteristics of the crystal resonator. ˜110f ′, a quintic function generating circuit for generating a quintic function and a quaternary function generating circuit for generating a quartic function which is a derivative of the quaternary function generating circuit are provided. The crystal frequency drift compensation circuit 115, the IC frequency drift cancellation circuit 116, and the time constant generation circuit 117 compensate for the temperature characteristics, respectively, and use the addition voltage Vb based on the quaternary function, respectively. , Temperature compensation frequency drift characteristics, oscillation circuit frequency drift characteristics are compensated by outputting a control voltage to compensate each frequency drift characteristics In addition to high-precision temperature compensation, each frequency drift characteristic can be compensated with high accuracy, suppressing frequency fluctuations (swells) at startup, improving frequency drift characteristics, and providing good frequency startup characteristics. There is an effect that can be realized.

  The present invention is suitable for a temperature-compensated crystal oscillator that can cancel the frequency drift characteristic due to temperature compensation and further suppresses the swell characteristic of the frequency drift characteristic by compensating even the frequency drift characteristic of the crystal resonator and the oscillation circuit.

  DESCRIPTION OF SYMBOLS 1 ... Temperature compensation circuit, 2 ... AFC circuit, 3 ... Temperature sensor, 4 ... Adder circuit, 5 ... Crystal oscillator, 6 ... Inverter IC, 8 ... Buffer, DESCRIPTION OF SYMBOLS 9 ... Output terminal, 11 ... Temperature compensation cancellation circuit, 12 ... Crystal compensation circuit, 13 ... Adder circuit, 14 ... Oscillation circuit characteristic compensation circuit, 21, 31 ... Resistance, 22 , 32 ... Capacitor, 23, 33 ... Amplifier (AMP), 24, 34 ... Constant current source circuit, 25, 35 ... Diode, 100-105 ... Function generation circuit, 110a-110f '... Amplifier (multiplier), 111 ... Memory, 112 ... Adder circuit A, 113 ... Adder circuit B, 114 ... Reference voltage generator, 115 ... Crystal frequency drift compensation circuit 116 ... IC frequency drift cancellation circuit, 117 ... Time constant generation circuit, 118 ... Resistance, 119 ... Capacitor, 121, 131 ... time constant generation circuit, 122, 132 ... absolute value circuit, 123, 133 ... comparator, 124, 134 ... variable gain amplifier, 125, 135 ... switch circuit, 200. ..Approximate quintic function generator, 210 ... temperature detection circuit, 230 ... VCXO, 201 ... primary component generator, 203 ... third component generator, 204 ... quaternary component Generator, 205 ... fifth-order component generator, 206 ... zero-order component generator, 207 ... adder circuit

Claims (11)

A crystal resonator, an amplifier connected in parallel to the crystal resonator, a voltage variable capacitance element connected to an input side and an output side of the amplifier, and a temperature compensation circuit that outputs a control voltage for performing temperature compensation A temperature compensated crystal oscillator,
A temperature sensor that detects the ambient temperature of the crystal unit and outputs a voltage corresponding to the detected temperature;
A temperature compensation cancellation circuit that outputs a voltage for canceling a temperature compensation frequency drift characteristic when temperature compensation is performed by the temperature compensation circuit based on the temperature detected by the temperature sensor;
A crystal compensation circuit that outputs a voltage for compensating the frequency drift characteristics of the crystal resonator;
An oscillation circuit characteristic compensation circuit that outputs a voltage for compensating a frequency drift characteristic of an oscillation circuit including the amplifier; and
A first addition circuit that adds the voltage output from the temperature sensor, the voltage output from the temperature compensation cancellation circuit, and the voltage output from the crystal compensation circuit to output to the temperature compensation circuit;
A temperature-compensated crystal having a second adder circuit that adds the voltage output from the temperature compensation circuit and the voltage output from the oscillation circuit characteristic compensation circuit and outputs the sum to the voltage variable capacitance element Oscillator. A frequency control circuit that outputs a control voltage for making the output frequency variable is provided,
The second adder circuit adds the voltage output from the temperature compensation circuit, the voltage output from the oscillation circuit characteristic compensation circuit, and the voltage output from the frequency control circuit, and outputs the result to the voltage variable capacitance element. The temperature-compensated crystal oscillator according to claim 1.   The temperature compensation cancel circuit includes a constant current source circuit and a capacitor connected in series, and includes an amplifier that amplifies a voltage between the constant current source circuit and the capacitor, and an anode of a diode is connected to an input stage of the amplifier, The temperature compensation frequency drift characteristic compensation control voltage which becomes a temperature compensation frequency cancellation characteristic which cancels the temperature compensation frequency drift characteristic in the temperature compensation circuit is output to the first addition circuit. The temperature-compensated crystal oscillator according to 1 or 2.   The crystal compensation circuit includes a constant current source circuit and a capacitor connected in series, and includes an amplifier that amplifies a voltage between the constant current source circuit and the capacitor, and an anode of a diode is connected to an input stage of the amplifier, 3. The crystal frequency drift characteristic compensation control voltage, which becomes a crystal frequency compensation characteristic for compensating for the crystal frequency drift characteristic in the crystal resonator, is output to the first adder circuit. The temperature compensated crystal oscillator described.   The oscillation circuit characteristic compensation circuit includes a constant current source circuit and a capacitor connected in series, and includes an amplifier that amplifies a voltage between the constant current source circuit and the capacitor, and an anode of a diode is connected to an input stage of the amplifier. The cathode of the diode is grounded, and an oscillation circuit frequency drift characteristic compensation control voltage which is an oscillation circuit frequency compensation characteristic for compensating for an oscillation circuit frequency drift characteristic in the oscillation circuit is output to the second adder circuit. Item 3. A temperature compensated crystal oscillator according to item 1 or 2. A crystal resonator, an amplifier connected in parallel to the crystal resonator, a voltage variable capacitance element connected to an input side and an output side of the amplifier, and a temperature compensation circuit that outputs a control voltage for performing temperature compensation A temperature compensated crystal oscillator,
The voltage variable capacitance element is connected to the anode side of a parallel circuit consisting of a resistor and a capacitor connected in parallel, and the other end is grounded,
The temperature compensation circuit is
A temperature sensor that detects the ambient temperature of the crystal unit and outputs a voltage corresponding to the detected temperature;
An n-order function generation unit that generates a third-order or higher-order n-order function that approximates the compensation characteristic of the frequency temperature characteristic of the crystal resonator for the temperature detected by the temperature sensor;
An (n-1) order function generator that generates a differential function of the n order function;
A first addition circuit that generates a control voltage by adding a specific reference voltage to an output from the n-order function generation unit and inputs the control voltage to a point between the anode of the voltage variable capacitance element and the parallel circuit When,
A second adder circuit that adds the reference voltage to the output from the (n-1) order function generator and outputs an added voltage;
A voltage for compensating the frequency drift characteristic of the crystal resonator is generated based on the added voltage, and when the added voltage is larger than the reference voltage, an anode of the voltage variable capacitance element and the parallel circuit When the sum voltage is smaller than the reference voltage, a crystal compensation circuit that outputs to the cathode side of the voltage variable capacitor,
A voltage for canceling a temperature compensated frequency drift characteristic when temperature compensation is performed by the temperature compensation circuit based on the added voltage is generated, and when the added voltage is larger than the reference voltage, the voltage variable capacitance element A temperature compensation cancellation circuit that outputs to a point between the anode of the voltage variable capacitance element and the parallel circuit when the added voltage is smaller than the reference voltage.
And an oscillation circuit characteristic compensation circuit that generates a voltage for compensating the frequency drift characteristic of the oscillation circuit including the amplifier and outputs the voltage to a point between the anode of the voltage variable capacitance element and the parallel circuit. A temperature-compensated crystal oscillator. The n-th order function generation unit is provided in connection with a plurality of function generation circuits that generate powers of the temperature sensor output for each order excluding the second order, and the function generation circuit of each order, and outputs from the function generation circuit And a plurality of multipliers that multiply and output the set coefficient,
The (n-1) order function generation unit includes a function generation circuit of (n-1) th order or less excluding the first order among the plurality of function generation circuits, and a function of each order of the (n-1) th order or less. 7. A temperature-compensated crystal according to claim 6, further comprising a plurality of multipliers that are provided in connection with a generation circuit and multiply the output from the function generation circuit by a set coefficient. Oscillator.   8. The temperature-compensated crystal oscillator according to claim 6, further comprising a quintic function generator and a quartic function generator when n = 5. The crystal compensation circuit determines the magnitude of the addition voltage relative to the reference voltage and outputs a determination result;
An absolute value circuit that outputs an absolute value of a difference between the reference voltage and the addition voltage as a gain adjustment voltage;
A crystal time constant generation circuit for generating a crystal frequency drift characteristic compensation control voltage for compensating the frequency drift characteristic of the crystal unit;
A variable gain amplifier that amplifies the crystal frequency drift characteristic compensation control voltage with a gain adjusted based on the gain adjustment voltage;
Based on the determination result of the comparator, the output of the variable gain amplifier is switched to the anode side of the voltage variable capacitance element when the addition voltage is large, and to the cathode side of the voltage variable capacitance element when the addition voltage is small. 9. The temperature compensated crystal oscillator according to claim 6, further comprising a switch circuit. The temperature compensation cancellation circuit determines the magnitude of the addition voltage with respect to the reference voltage and outputs a determination result;
An absolute value circuit that outputs an absolute value of a difference between the reference voltage and the addition voltage as a gain adjustment voltage;
An IC time constant generation circuit for generating a temperature compensation cancellation voltage that cancels the temperature compensation frequency drift characteristic in the temperature compensation circuit;
A variable gain amplifier that amplifies the temperature compensation cancellation voltage with a gain adjusted based on the gain adjustment voltage;
A switch that switches the output of the variable gain amplifier to the anode side of the voltage variable capacitance element when the addition voltage is small and to the cathode side of the variable capacitance element when the addition voltage is large based on the determination result of the comparator A temperature-compensated crystal oscillator according to claim 6, further comprising a circuit.   The oscillation circuit characteristic compensation circuit includes a constant current source circuit and a capacitor connected in series, and includes an amplifier that amplifies a voltage between the constant current source circuit and the capacitor, and an anode of a diode is connected to an input stage of the amplifier. The cathode of the diode is grounded, and an oscillation circuit frequency drift characteristic compensation control voltage, which becomes an oscillation circuit frequency compensation characteristic for compensating for the oscillation circuit frequency drift characteristic in the oscillation circuit, is output to the anode side of the voltage variable capacitance element. The temperature-compensated crystal oscillator according to any one of claims 6 to 10.

Images