JP2007300518A - Temperature-compensated piezoelectric oscillating circuit and temperature compensation method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a temperature-compensated piezoelectric oscillating circuit and a temperature compensation method, with which temperature compensation characteristics can be stabilized, even at a low-temperature region and a high-temperature region. <P>SOLUTION: The temperature-compensated piezoelectric oscillating circuit is provided with a piezoelectric vibrator, with a piezoelectric element excited at a predetermined frequency, an amplifier 142 for oscillation for exciting the piezoelectric element by supplying current and a frequency temperature compensating circuit for compensating the variations in the oscillation frequency due to temperature variations. In the temperature-compensation method thereof, temperature-compensation waveform corresponding to the temperature variation output from the frequency/temperature compensating circuit and equivalent waveform, consisting of one or more trapezoidal shapes regarded as being substantially equivalent are generated, and the temperature compensating waveform is compensated by impressing an inverted equivalent waveform by inverting the equivalent waveform to the output terminal of the frequency temperature compensation circuit. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a piezoelectric oscillator using a piezoelectric resonator such as a crystal resonator, and more particularly to a temperature-compensated piezoelectric oscillation circuit and a temperature compensation method capable of temperature compensation of an oscillation frequency of an AT-cut crystal resonator with a simple circuit configuration. .

  The area of use of land mobile communication devices represented by mobile phones is steadily expanding. At the same time, the competition for technological development is intensifying due to the proliferation of mobile phones. Crystal oscillators used in mobile phones are also required to be smaller, lower cost, and higher performance. In particular, a system that requires coexistence with a GPS system not only has excellent temperature characteristics, but also strongly requires low noise.

  FIG. 9 shows temperature characteristics depending on a difference in cutting angle of a crystal resonator (At-Cut) used in a mobile phone. As shown in FIG. 9, the temperature characteristics of the vibrator show characteristics close to a cubic function. However, this is not sufficient in terms of characteristics, and temperature compensation is performed so as to obtain a higher frequency stability than this characteristic.

  In order to solve such a problem, in the temperature compensated piezoelectric oscillation circuit 100 of Patent Document 1, as shown in FIG. 10, the capacitance varies depending on the crystal oscillation circuit 140 including the crystal resonator 141 and the potential difference between both ends. A variable capacitance diode VCa, high resistances Rak and Raa for isolating each circuit, a capacitor C1, a temperature sensor unit 120 for detecting the ambient temperature, and a temperature compensation voltage based on the voltage of the temperature sensor unit 120. And a compensation voltage generation circuit 130.

  FIG. 4C shows a graph G1 showing the temperature characteristics of the crystal resonator and the compensation applied to the crystal resonator by applying the temperature compensation voltage generated by the compensation voltage generation circuit 130 to both ends of the variable capacitance diode VCa. It is the graph G2 which shows a temperature characteristic, and the graph G3 which shows a temperature compensation result. In the section from the temperature t4 to the temperature t8 in FIG. 4C, the temperature compensation result is gentle and relatively stable as shown in the graph G3.

Japanese Patent Laid-Open No. 2005-6028

  However, in the section from the temperature t1 to t4, which is the low temperature region in FIG. 4C, and the section from the temperature t8 to t11, which is the high temperature region, the temperature characteristic becomes a cubic curve as shown in the graph G3. There is a problem that it cannot be stabilized.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a temperature compensation type piezoelectric oscillation circuit and a temperature compensation method capable of stabilizing temperature compensation characteristics even in a low temperature region and a high temperature region. To do.

  In order to solve the above problems, in the temperature compensation method for a temperature-compensated piezoelectric oscillation circuit according to the present invention, in order to compensate for the temperature characteristics of the oscillation frequency in an oscillation signal whose oscillation frequency can change with temperature, The gist of the invention is to include a step of adding a compensation characteristic including one or more inverted trapezoids obtained by inverting one or more trapezoids that can be regarded as substantially equivalent to the temperature characteristic.

  In order to solve the above-described problem, in the temperature compensation method for a temperature-compensated piezoelectric oscillation circuit according to the present invention, a piezoelectric vibrator having a piezoelectric element excited at a predetermined frequency, and an electric current is passed through the piezoelectric element for excitation. A temperature compensation method for a temperature compensated piezoelectric oscillation circuit comprising an oscillation amplifier and a frequency temperature compensation circuit that compensates for a change in oscillation frequency due to a temperature change, corresponding to a temperature change output from the frequency temperature compensation circuit. Generating an equivalent waveform having one or more trapezoidal shapes that can be regarded as substantially equivalent to the temperature compensation waveform, and applying an inverted equivalent waveform obtained by inverting the equivalent waveform to an output terminal of the frequency temperature compensation circuit; The gist is to compensate the temperature compensation waveform.

  Further, in the temperature compensated piezoelectric oscillation circuit of the present invention, a piezoelectric vibrator having a piezoelectric element excited at a predetermined frequency, an oscillation amplifier for exciting the piezoelectric element by passing a current, and an oscillation frequency due to temperature change A temperature-compensated piezoelectric oscillation circuit comprising a frequency-temperature compensation circuit that compensates for a change in the temperature-compensated piezoelectric oscillation circuit, and the temperature-compensated piezoelectric oscillation circuit substantially includes a temperature-compensated waveform corresponding to a temperature change output from the frequency-temperature compensated circuit. A secondary compensation voltage generation circuit for generating an inverted equivalent waveform obtained by inverting an equivalent waveform composed of one or more trapezoidal shapes that can be regarded as equivalent to each other, and applying the inverted equivalent waveform to an output terminal of the frequency temperature compensation circuit Thus, the temperature compensation waveform is compensated.

  According to this configuration, in the temperature compensation waveform as a result of compensation by the frequency temperature compensation circuit, by applying an inversion equivalent waveform to compensate for the temperature region waveform that could not be stabilized, temperature characteristics in all temperature regions Can provide a stable temperature compensated piezoelectric oscillation circuit.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, embodiments of the invention will be described with reference to the drawings.
(First embodiment)

<Configuration of temperature compensated piezoelectric oscillation circuit>
First, the configuration of the temperature compensated piezoelectric oscillation circuit according to the first embodiment will be described with reference to FIG. FIG. 1 is a circuit diagram illustrating a configuration of a temperature compensated piezoelectric oscillation circuit according to the first embodiment of the present invention. As shown in FIG. 1, the temperature compensated piezoelectric oscillation circuit 1 is configured by adding a secondary compensation voltage generator 200 to the conventional temperature compensated piezoelectric oscillation circuit 100.

  The conventional temperature compensated piezoelectric oscillation circuit 100 may have any configuration. In the first embodiment, the constant voltage circuit 110, the temperature sensor unit 120, the primary compensation voltage generation circuit 130, and the crystal oscillation circuit 140 are used. , Is composed of.

  The constant voltage circuit 110 receives the external voltage VCC and generates a stable internal voltage Vref. The temperature sensor unit 120 outputs a voltage Vt1 corresponding to the external temperature. The primary compensation voltage generation circuit 130 receives the voltage Vt1, inputs the compensation voltage VCak via the high resistance Rak to the cathode side of the variable capacitance element VCa, and compensates the compensation voltage VCak via the high resistance Raa to the anode side of the variable capacitance element VCa. VCaa is output.

  The cathode side of the variable capacitance element VCa is connected to the crystal resonator 141 of the crystal oscillation circuit 140, and the anode side of the variable capacitance element VCa is connected to the external control terminal VCONT via the capacitor C1. The cathode side of the variable capacitance element VCb is connected to the external control terminal VCONT, and the anode side of the variable capacitance element VCb is connected to the ground potential GND through the capacitor C2.

  The secondary compensation voltage generator 200 receives the voltage Vt1, receives the compensation voltage VCbk via the high resistance Rbk on the cathode side of the variable capacitance element VCb, and the compensation voltage via the high resistance Rba on the anode side of the variable capacitance element VCb. Each VCba is output.

<Configuration of temperature sensor>
Next, the configuration of the temperature sensor unit will be described with reference to FIG. FIG. 2 is a circuit diagram showing a configuration of the temperature sensor unit. As shown in FIG. 2, the temperature sensor unit 120 includes an operational amplifier OP1, a diode D11, resistors R11, R12, R13, R14, and a variable resistor R15. Between the internal voltage Vref and the ground potential GND, a resistor R11, a diode D11, and a resistor R12 are connected in series, and resistors R13 and R14 are connected in series. The + terminal (non-inverting input terminal) of the operational amplifier OP1 is connected to the anode of the diode D11, and the − terminal (inverting input terminal) is connected to the connection point between the resistors R13 and R14. The variable resistor R15 is connected between the negative terminal and the output terminal of the operational amplifier OP1.

  The temperature sensor unit 120 outputs a voltage Vt1 corresponding to the external temperature from the output terminal of the operational amplifier OP1. As shown in FIG. 4A, the voltage Vt1 linearly decreases from the internal voltage Vref to the ground potential GND (0 V) from the low temperature side (t1 or lower) to the high temperature side (t11 or higher) of the external temperature.

<Configuration of primary compensation voltage generation circuit>
Next, the configuration of the primary compensation voltage generation circuit will be described with reference to FIG. FIG. 3 is a circuit diagram showing a configuration of the primary compensation voltage generation circuit. As shown in FIG. 3, the primary compensation voltage generation circuit 130 includes a reference voltage generation circuit 131, operational amplifiers OPaa, OPab, OPac, resistors Raa1, Raa2, Raa3, Raa4, Rab1, Rab2, Rab3, Rac1, Rac2 , Rac3, R15 and capacitors Ca1, Ca2.

  The reference voltage generating circuit 131 is configured by connecting resistors Ra1, Ra2, Ra3, Ra4 in series between the internal voltage Vref and the ground potential GND. The voltage Vab1 is output from the connection point between the resistors Ra1 and Ra2, the voltage Vaa1 is output from the connection point between the resistors Ra2 and Ra3, and the voltage Vac1 is output from the connection point between the resistors Ra3 and Ra4.

  In the operational amplifier OPaa, the voltage Vaa1 is input to the + terminal, the voltage Vt1 is input to the − terminal via the resistor Raa1, the resistor Raa2 is connected between the output terminal and the − terminal, and one end of the resistor Raa3 is connected to the output terminal. Has been.

  In the operational amplifier OPab, the voltage Vab1 is input to the + terminal, the voltage Vt1 is input to the − terminal via the resistor Rab1, the resistor Rab2 is connected between the output terminal and the − terminal, and one end of the resistor Rab3 is connected to the output terminal. Has been.

  In the operational amplifier OPac, the voltage Vac1 is input to the + terminal, the voltage Vt1 is input to the − terminal via the resistor Rac1, the resistor Rac2 is connected between the output terminal and the − terminal, and one end of the resistor Rac3 is connected to the output terminal. Has been.

  The other end of the resistor Raa3 is connected to one end of a resistor Raa4 whose other end is connected to the internal voltage Vref and one end of a capacitor Ca1 whose other end is connected to the ground potential GND, and outputs an output signal VCak.

  The other end of the resistor Rab3 and the other end of the resistor Rac3 are connected to each other, one end of the resistor R15 having the other end connected to the ground potential GND, and one end of the capacitor Ca2 having the other end connected to the ground potential GND, respectively. The output signal VCaa is output.

  The primary compensation voltage generation circuit 130 compensates the temperature characteristic shown in the graph G1 of FIG. 4C by using the compensation voltage VCak at the cathode terminal of the variable capacitor VCa in FIG. 1 and the compensation voltage VCaa in FIG. The voltage is applied to the anode terminal of the variable capacitance element VCa. The temperature characteristic of the graph G1 is compensated by the capacitance change shown in the graph G2 of FIG. 4C obtained as a result, and the primary temperature compensation result shown in the graph G3 of FIG. 4C is obtained.

  FIG. 4A is a graph showing the change in the output voltage Vt1 from the temperature sensor unit 120 and the potentials of Vaa2, Vab2, and Vac2 in FIG. 3 corresponding to the temperature change. 4B shows the output voltage Vt1 from the temperature sensor unit 120 corresponding to the temperature change, changes in the potentials of VCak, Vab2, and VCaa in FIG. 3, and between the cathode and anode of the variable capacitance element VCa in FIG. It is a graph which shows the change of the electric potential of electric potential (DELTA) Va. With the change in the potential ΔVa in FIG. 4B, the change in capacitance shown in the graph G2 in FIG. 4C is obtained.

<Configuration of secondary compensation voltage generator>
Next, the configuration of the secondary compensation voltage generator will be described with reference to FIG. FIG. 5 is a circuit diagram illustrating the configuration of the secondary compensation voltage generator. As shown in FIG. 5, the secondary compensation voltage generation unit 200 includes secondary compensation voltage generation circuits 210 and 220.

  The secondary compensation voltage generation circuit 210 includes a reference voltage generation circuit 211, operational amplifiers OP2, OPba, OPbb, OPbc, OPbd, resistors R26, R27, Rba1, Rba2, Rba3, Rbb1, Rbb2, Rbb3, Rbc1, Rbc2, It consists of Rbc3, Rbd1, Rbd2, Rbd3, Rs, and Rt.

  The reference voltage generation circuit 211 is configured by connecting resistors Rb1, Rb2, Rb3, Rb4, Rb5, and Rb6 in series between the internal voltage Vref and the ground potential GND. The voltage Vbc1 from the connection point of the resistors Rb1 and Rb2, the voltage Vbb1 from the connection point of the resistors Rb2 and Rb3, the voltage Vb01 from the connection point of the resistors Rb3 and Rb4, the voltage Vbd1 from the connection point of the resistors Rb4 and Rb5, and the resistor Rb5 And the voltage Vba1 is output from the connection point of Rb6.

  In the operational amplifier OP2, the voltage Vb01 is input to the + terminal, the voltage Vt1 is input to the − terminal via the resistor R26, and the resistor R27 is connected between the output terminal and the − terminal.

  In the operational amplifier OPba, the voltage Vba1 is input to the + terminal, the voltage Vt2 is input to the − terminal via the resistor Rba1, the resistor Rba2 is connected between the output terminal and the − terminal, and one end of the resistor Rba3 is connected to the output terminal. Has been.

  In the operational amplifier OPbb, the voltage Vbb1 is input to the + terminal, the voltage Vt1 is input to the − terminal via the resistor Rbb1, the resistor Rbb2 is connected between the output terminal and the − terminal, and one end of the resistor Rbb3 is connected to the output terminal. Has been.

  In the operational amplifier OPbc, the voltage Vbc1 is input to the + terminal, the voltage Vt2 is input to the − terminal via the resistor Rbc1, the resistor Rbc2 is connected between the output terminal and the − terminal, and one end of the resistor Rbc3 is connected to the output terminal. Has been.

  In the operational amplifier OPbd, the voltage Vbd1 is input to the + terminal, the voltage Vt1 is input to the − terminal via the resistor Rbd1, the resistor Rbd2 is connected between the output terminal and the − terminal, and one end of the resistor Rbd3 is connected to the output terminal. Has been.

  The other end of the resistor Rba3, the other end of the resistor Rbb3, the other end of the resistor Rbc3, and the other end of the resistor Rbd3 are connected to each other and connected to one end of the resistor Rs. The other end of the resistor Rs is connected to one end of a resistor Rt whose other end is connected to the ground potential GND, and outputs an output potential VCbk.

  The secondary compensation voltage generation circuit 220 includes an operational amplifier OPbe and resistors Rbe1 and Rbe2. The operational amplifier OPbe has a positive terminal connected to the ground potential GND and a negative terminal connected to the internal potential Vref via the resistor Rbe1. Has been. A resistor Rbe2 is connected between the output terminal and the negative terminal of the operational amplifier OPbe. Output potential VCba of secondary compensation voltage generation circuit 220 is always at ground potential GND.

  The secondary compensation voltage generator 200 compensates the primary temperature compensation result shown in the graph G3 of FIG. 6C by applying the compensation voltage VCbk to the cathode terminal of the variable capacitor VCb of FIG. 1 and the compensation voltage VCba. The voltage is applied to the anode terminal of the variable capacitor VCb in FIG. The primary temperature compensation result of the graph G3 is compensated by the capacitance change shown in the graph G4 of FIG. 6C obtained as a result, and the secondary temperature compensation result shown in the graph G5 of FIG. 6C is obtained.

  6A is a graph showing changes in the output voltage Vt1 from the temperature sensor unit 120 and the potentials Vt2, Vba2, Vbb2, Vbc2, and Vbd2 in FIG. 5 corresponding to the temperature change.

  The output voltage Vt2 of the operational amplifier OP2 is determined by adjusting the voltage Vb01 at the + terminal and the gain R26 / R27 of the operational amplifier OP2, and as shown in FIG. 6A, the voltage Vt1 is inverted with respect to the voltage Vb01. Graph.

  The output voltage Vba2 of the operational amplifier OPba is determined by adjusting the voltage Vba1 at the + terminal and the gain Rba1 / Rba2 of the operational amplifier OPba. As shown in FIG. 6A, the internal voltage Vref and the temperature are reduced below the temperature t1. It falls linearly from the internal voltage Vref to the ground potential GND from t1 to t2, and at the temperature t2 or higher, the ground potential GND is maintained.

  The output voltage Vbb2 of the operational amplifier OPbb is determined by adjusting the voltage Vbb1 at the + terminal and the gain Rbb1 / Rbb2 of the operational amplifier OPbb. As shown in FIG. 6A, at the temperature t3 or lower, the ground potential GND, From t3 to t4, the voltage rises linearly from the ground potential GND to the internal voltage Vref, and at the temperature t4 or higher, the internal voltage Vref is maintained.

  The output voltage Vbc2 of the operational amplifier OPbc is determined by adjusting the voltage Vbc1 at the + terminal and the gain Rbc1 / Rbc2 of the operational amplifier OPbc. As shown in FIG. 6A, the internal voltage Vref and the temperature are reduced below the temperature t10. From t10 to t11, the voltage falls linearly from the internal voltage Vref to the ground potential GND, and at the temperature t11 or higher, the ground potential GND is maintained.

  The output voltage Vbd2 of the operational amplifier OPbd is determined by adjusting the voltage Vbd1 at the + terminal and the gain Rbd1 / Rbd2 of the operational amplifier OPbd. As shown in FIG. 6A, the ground potential GND and the temperature are reduced below the temperature t8. From t8 to t9, the voltage rises linearly from the ground potential GND to the internal voltage Vref, and at the temperature t9 or higher, the internal voltage Vref is maintained.

  FIG. 6B is a graph showing a change in the output voltage VCbk, which is a combined result of the output voltages Vba2, Vbb2, Vbc2, and Vbd2 in FIG. 6A, corresponding to the temperature change. Since the output voltage VCba is fixed to the ground potential GND, the voltage difference ΔVb = VCbk between the cathode and the anode of the variable capacitance element VCb.

Since Vba2 = Vbc2 = Vref and Vbb2 = Vbd2 = 0 V at the temperature t1, the voltage value V1 of the output voltage VCbk is obtained by the following equation (1).
V1 = Vref × Rbb3 × Rbd3 × (Rba3 + Rbc3) / (Rba3 × Rbc3 × (Rbb3 + Rbd3) + Rbb3 × Rbd3 × (Rba3 + Rbc3)) (1)

Since Vbc2 = Vref and Vba2 = Vbb2 = Vbd2 = 0 V at the temperature t2, the voltage value V2 of the output voltage VCbk is obtained by the following equation (2).
V2 = Vref × Rba3 × Rbb3 × Rbd3 / (Rbc3 × (Rba3 × Rbb3 + Rbb3 × Rbd3 + Rba3 × Rbd3) + Rba3 × Rbb3 × Rbd3) (2)

Since Vbc2 = Vbd2 = Vref and Vba2 = Vbb2 = 0 V at the temperature t4, the voltage value V3 of the output voltage VCbk can be obtained by the following equation (3).
V3 = Vref × Rba3 × Rbd3 × (Rbb3 + Rbc3) / (Rbb3 × Rbc3 × (Rba3 + Rbd3) + Rba3 × Rbd3 × (Rbb3 + Rbc3)) (3)

Since Vbb2 = Vbc2 = Vbd2 = Vref and Vba2 = 0 V at the temperature t9, the voltage value V4 of the output voltage VCbk is obtained by the following equation (4).
V4 = Vref × Rba3 × (Rbb3 × Rbc3 + Rbc3 × Rbd3 + Rbb3 × Rbd3) / (Rba3 × (Rbb3 × Rbc3 + Rbc3 × Rbd3 + Rbb3 × Rbd3) + Rbb3 × Rb3) (Rbc3 × Rb4)

Since Vbb2 = Vbd2 = Vref and Vba2 = Vbc2 = 0 V at the temperature t11, the voltage value V5 of the output voltage VCbk is obtained by the following equation (5).
V5 = Vref × Rba3 × Rbc3 × (Rbb3 + Rbd3) / (Rbb3 × Rbd3 × (Rba3 + Rbc3) + Rba3 × Rbc3 × (Rbb3 + Rbd3)) (5)

  Note that the values of Rba3, Rbb3, Rbc3, and Rbd3 can be obtained by simultaneously solving the equations (1) to (5).

  By applying ΔVb (= VCbk) between the cathode and anode of the variable capacitor VCb in FIG. 1, the capacitance change shown in the graph G4 in FIG. 6C is applied to the external control terminal VCONT. The primary temperature compensation result is compensated, and the secondary temperature compensation result shown in graph G5 is obtained.

  According to the embodiment described above, the following effects can be obtained.

  In the present embodiment, in the temperature compensation waveform (graph G3 in FIG. 6C) of the compensation result by the frequency temperature compensation circuit, the waveform in the temperature region (temperature t4 or less and temperature t8 or more) that could not be stabilized. By applying and compensating for the trapezoidal capacitance change shown in the graph G5 of FIG. 6C, which is an inverted equivalent waveform, it is possible to provide a temperature compensated piezoelectric oscillation circuit with stable temperature characteristics in all temperature regions.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to such embodiment at all, In the range which does not deviate from the meaning of this invention, it can be implemented with various forms. Hereinafter, a modification will be described.

  (Modification 1) A first modification of the temperature compensated piezoelectric oscillation circuit according to the present invention will be described. In the first embodiment, as shown in FIG. 5, the case where the voltage VCba applied to the anode side of the variable capacitor VCb is fixed to the ground potential GND has been described. However, as shown in FIG. A circuit for outputting the side voltage VCba may be configured by a secondary compensation voltage generation circuit 210a in which each resistance value is changed in the same configuration as the secondary compensation voltage generation circuit 210. With such a configuration, as shown in FIG. 7B, the voltage ΔVb between the cathode and the anode of the variable capacitor VCb can be formed into a more complicated trapezoidal waveform.

  (Modification 2) A second modification of the temperature compensated piezoelectric oscillation circuit according to the present invention will be described. In the first embodiment, as shown in FIG. 1, there is a problem that the external control terminal VCONT is occupied by the secondary compensation voltage generator 200 and external control cannot be performed. In the second modification, as shown in FIG. 8, an operational amplifier OP3 is provided between the output voltage VCbk of the secondary compensation voltage generator 200 and the external control terminal VCONT, and an external control signal VCONT1 is applied to the + terminal of the operational amplifier OP3. By inputting, control by an external control signal can be enabled.

The circuit diagram explaining the composition of the temperature compensation type piezoelectric oscillation circuit concerning a 1st embodiment. The circuit diagram explaining the structure of a temperature sensor part. The circuit diagram explaining the structure of a primary compensation voltage generation circuit. The graph explaining operation | movement of a primary compensation voltage generation circuit. The circuit diagram explaining the structure of a secondary compensation voltage generation part. The graph explaining operation | movement of a secondary compensation voltage generation part. The figure explaining the structure of the secondary compensation voltage generation part of the modification 2. FIG. 9 is a circuit diagram illustrating a configuration of a temperature compensated piezoelectric oscillation circuit according to Modification 3. The graph which shows the temperature characteristic by the difference in the cutting angle of the crystal oscillator (At-Cut) currently used for the mobile telephone. The circuit diagram explaining the structure of the conventional temperature compensation type | mold piezoelectric oscillation circuit.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Temperature compensation type piezoelectric oscillation circuit, 100 ... Conventional temperature compensation type piezoelectric oscillation circuit, 110 ... Constant voltage circuit, 120 ... Temperature sensor part, 130 ... Primary compensation voltage generation circuit, 131 ... Reference voltage generation circuit, 140 ... Crystal oscillator circuit 141... Crystal oscillator 142 Amplifier amplifier 200 Secondary compensation voltage generator 210 Secondary compensation voltage generator 211 Reference voltage generator 220 Secondary compensation voltage generator

Claims (3)

  In order to compensate for the temperature characteristic of the oscillation frequency in an oscillation signal whose oscillation frequency can be changed by temperature, it comprises one or more inverted trapezoids in which one or more trapezoids that can be regarded as substantially equivalent to the temperature characteristics are inverted. A temperature compensation method for a temperature compensated piezoelectric oscillation circuit, comprising a step of adding a compensation characteristic to the temperature characteristic. A piezoelectric vibrator including a piezoelectric element excited at a predetermined frequency, an oscillation amplifier that excites the piezoelectric element by passing a current, and a frequency temperature compensation circuit that compensates for a change in oscillation frequency due to a temperature change. In the temperature compensation method of the temperature compensated piezoelectric oscillation circuit,
Generating one or more trapezoidal equivalent waveforms that can be considered substantially equivalent to a temperature compensation waveform corresponding to a temperature change output from the frequency temperature compensation circuit;
By applying an inverted equivalent waveform obtained by inverting the equivalent waveform to the output terminal of the frequency temperature compensation circuit, the temperature compensation waveform is compensated.
A temperature compensation method for a temperature compensated piezoelectric oscillation circuit. A piezoelectric vibrator including a piezoelectric element excited at a predetermined frequency, an oscillation amplifier that excites the piezoelectric element by passing a current, and a frequency temperature compensation circuit that compensates for a change in oscillation frequency due to a temperature change. In a temperature compensated piezoelectric oscillation circuit,
The temperature compensated piezoelectric oscillation circuit is an inverted equivalent waveform obtained by inverting an equivalent waveform having one or more trapezoidal shapes that can be regarded as substantially equivalent to a temperature compensation waveform corresponding to a temperature change output from the frequency temperature compensation circuit. A secondary compensation voltage generation circuit for generating
Compensating the temperature compensation waveform by applying the inverted equivalent waveform to the output terminal of the frequency temperature compensation circuit;
A temperature compensated piezoelectric oscillation circuit characterized by the above.

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