JP2003069343A - Temperature compensated oscillator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a temperature compensated oscillator that can be downsized by simplifying the circuit configuration and to attain ease of adjustment. SOLUTION: The temperature of an oscillation circuit 47 is detected by a temperature detection circuit 13, a cubic term voltage generation circuit of a control voltage generation circuit 23 generates a cubic term voltage as a control voltage based on an output voltage of the temperature detection circuit 13, and a frequency adjustment circuit 45 changes an oscillation frequency of the oscillation circuit 47 by the control voltage. The cubic term voltage generation circuit includes a first MOS transistor 37 having a source connected to a first power line 25, a second MOS transistor 35 having a source connected to a second power line 26, and digital control voltage division circuits 31, 33 for generating a first and a second gate voltage, respectively based on the output voltage of the temperature detection circuit 13, in which the first and second gate voltages are applied to gates of the first and second MOS transistors 37, 35 respectively, and a connection point 44 where respective drains are commonly connected functions as an output terminal of the control voltage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature-compensated oscillator in which the temperature characteristics of a crystal oscillator using a crystal oscillator are compensated.

[0002]

2. Description of the Related Art A crystal oscillator using a crystal oscillator is superior in frequency stability to other oscillators, but when used as a reference oscillator for mobile radio in recent years, the crystal oscillator The fluctuation of the oscillation frequency due to the temperature characteristic becomes a problem. In order to solve this problem, a so-called temperature-compensated oscillator that compensates the temperature characteristic of the crystal unit is widely used. Among the temperature-compensated oscillators, the one called the indirect method has been attempted to reduce the number of parts and improve the performance with the development of integrated circuit technology in recent years.

The temperature compensation principle of the temperature compensation oscillator by the indirect method will be described with reference to FIG. The temperature detection circuit 91 in FIG. 17 generates a temperature detection voltage that depends on the temperature.
This voltage is input to the high temperature part low temperature part circuit 92 and the gradient correction voltage generation circuit 93. High temperature part Low temperature part circuit 92
Divides the input voltage into two parts, one for the low temperature part and one for the high temperature part, and input to the low temperature part cubic curve voltage generation circuit 94 and the high temperature part cubic curve voltage generation circuit 95, respectively. The voltages output from the low temperature part cubic curve voltage generating circuit 94, the high temperature part cubic curve voltage generating circuit 95, the slope correction voltage generating circuit 93, and the standard frequency adjusting voltage generating circuit 96 are input to the adding circuit 97 and added. The frequency adjustment circuit 98
Is output to.

The frequency adjustment circuit 98 controls the oscillation frequency of the oscillation circuit 99 having the crystal oscillator 90 according to the input voltage. In addition, the standard frequency adjustment voltage generation circuit 96
The standard oscillation frequency at a predetermined temperature is adjusted by the voltage output from the. Since the cubic curve voltage generation circuit only generates a voltage that is the cube of the input voltage, it can generate only the voltage in the first quadrant, which is half the cubic curve, in the two-dimensional plane of the input voltage and the output voltage. Therefore, in order to obtain a series of cubic curve voltages, a low temperature part cubic curve voltage generating circuit 94 that inverts an input voltage and an output voltage to generate a cubic curve voltage, and a cubic curve voltage by a normal operation. The high-temperature part cubic curve voltage generating circuit 95 for generating is used to add the respective output voltages. Therefore, the high temperature part low temperature part circuit 92 and the low temperature part cubic curve voltage generation circuit 94
And the high temperature part cubic curve voltage generation circuit 95 is required.

In the series of operations described above, the low temperature part cubic curve voltage generating circuit 94 and the high temperature part cubic curve voltage generating circuit 95 have a voltage such that the frequency adjusting circuit 98 compensates the third order temperature characteristic of the AT cut crystal. Then, the gradient correction voltage generating circuit 93 generates a voltage such that the frequency adjusting circuit 98 compensates the primary temperature characteristic of the AT-cut crystal. These voltages are added by the adding circuit 97, and the frequency adjusting circuit 98 is added.
By inputting to, it compensates that the oscillation frequency of the oscillation circuit 99 changes with temperature. In this way, the oscillation frequency of the temperature compensated oscillator is kept constant even if the temperature changes.

[0006]

However, in such a conventional technique, the voltage from the temperature detection circuit is divided into a low temperature part and a high temperature part in order to compensate the temperature characteristic of the AT-cut crystal as described above. Circuit of high temperature part and low temperature part of 2
Since three cubic curve voltage generation circuits, gradient correction voltage generation circuits, and addition circuits are required, the circuit scale is increased, and in order to correct the manufacturing variations of these circuits, it is individually complicated. There is a problem that adjustment is necessary. Therefore, an object of the present invention is to solve this problem and provide a temperature-compensated oscillator having a simple circuit configuration, suitable for miniaturization, and easy to adjust.

[0007]

In order to achieve the above object, a temperature-compensated oscillator according to the present invention has an oscillation circuit, a frequency adjusting circuit for changing the oscillation frequency of the oscillation circuit by a control voltage, and an oscillation circuit for the oscillation circuit. A temperature detection circuit that detects a temperature condition in the vicinity and generates at least one output voltage based on the detected temperature, and a third-order voltage that is generated as the control voltage based on the output voltage from the temperature detection circuit 3 A temperature-compensated oscillator having a control voltage generation circuit including a next-order voltage generation circuit is characterized in that the third-order voltage generation circuit is configured as follows.

That is, the third-order voltage generation circuit has a first MOS transistor having a source connected to the first power supply line, a conductivity type different from that of the first MOS transistor, and a source of the second power supply. A second MOS transistor connected to the line, a first gate voltage generating circuit for generating a first gate voltage based on the output voltage of the temperature detecting circuit, and a second gate voltage generating circuit. And a second gate voltage generating circuit. The output terminal for outputting the first gate voltage of the first gate voltage generating circuit is connected to the first MO.
A second output terminal connected to the gate of the S-transistor for outputting the second gate voltage of the second gate voltage generation circuit
Connected to the gate of the MOS transistor of the first M
The drain of the OS transistor and the drain of the second MOS transistor are commonly connected to serve as the output terminal of the control voltage. The second power supply line may have a polarity opposite to that of the first power supply line or a ground potential.

Further, the control voltage generating circuit includes, instead of the third order voltage generating circuit, a second order voltage generating circuit for generating a second order voltage as the control voltage based on the output voltage from the temperature detecting circuit. In the case of the temperature-compensated oscillator, the configuration of the secondary term voltage generating circuit may be changed only in the following points of the configuration of the tertiary term voltage generating circuit.
That is, the second MOS transistor has the same conductivity type as the first MOS transistor, and its source is connected to the second power supply line. In this case, the second power supply line may have the same polarity as the first power supply line, or may be the same as the first power supply line. In these temperature compensated oscillators,
The output terminal of the control voltage may be connected to at least one arbitrary voltage source via a resistance element having a resistance value of 100 kΩ or more.

In the case of a temperature-compensated oscillator having a control voltage generation circuit including the third-order voltage generation circuit, the output terminal of the control voltage is connected to the first power supply line or the same polarity as the first power supply line via the first resistance element. Connect to the power line of
The second power supply line or the power supply line having the same polarity as that of the second power supply line may be connected through the resistance element. As the first resistance element and the second resistance element, those having different temperature coefficients with respect to the resistance value can be used. Further, as the first resistance element and the second resistance element, a plurality of resistance element groups having different combinations of temperature coefficients with respect to their resistance values are provided, and any one of the plurality of resistance element groups is selectively switched. It is advisable to provide a switching means to be used.

In any of the temperature-compensated oscillators described above, at least one of the first and second gate voltage generation circuits is provided with the first gate voltage generation circuit based on the difference between the output voltage of the temperature detection circuit and an arbitrary reference voltage. Alternatively, a circuit that generates the second gate voltage may be used. Alternatively, at least one of the first and second gate voltage generating circuits can be a circuit whose generated gate voltage can be controlled based on external data. Further, a memory circuit for storing the external data is provided, and at least one of the first and second gate voltage generating circuits can control the gate voltage generated based on the data stored in the memory circuit. Any circuit can be used. At least one of the first and second gate voltage generation circuits may be a voltage division circuit that divides a voltage difference between the output voltage of the temperature detection circuit and the arbitrary reference voltage. The arbitrary reference voltage may be the voltage of the first power supply line or the second power supply line.

In the case of the temperature-compensated oscillator having the control voltage generating circuit including the third order voltage generating circuit, the control voltage generating circuit uses the third order voltage generated by the third order voltage generating circuit as the first control voltage. A primary term voltage generating circuit that outputs a primary term voltage based on the output voltage of the temperature detection circuit, and outputs the primary term voltage generated by the circuit as a second control voltage; The frequency adjustment circuit may be a circuit that controls the oscillation frequency of the oscillation circuit by the first control voltage and the second control voltage. The primary term voltage generating circuit may be an operational amplifier circuit. A memory circuit that stores data from the outside and controls the amplification factor and the offset input voltage of the operational amplifier circuit by the stored digital data may be provided. Further, the temperature detection circuit has two different temperature gradients.
It may be a circuit having one temperature sensor and dividing the difference between the output voltages of the two temperature sensors into an arbitrary ratio and outputting the temperature detection voltage.

It is preferable that the frequency adjusting circuit constitutes a load capacitance of the oscillation circuit and has a voltage variable capacitance element such as a MIS type variable capacitance capacitor whose capacitance value changes according to the control voltage. In that case, the above-mentioned first control voltage may be applied to one electrode of the voltage variable capacitor, and the above-mentioned second control voltage may be applied to the other electrode. Alternatively,
The voltage variable capacitance element is configured by connecting in parallel a first voltage variable capacitance element to which the first control voltage is applied and a second voltage variable capacitance element to which the second control voltage is applied. You can also Further, it is preferable that the sources of the first and second MOS transistors in the control voltage generation circuit are connected to the first or second power supply line via resistance elements for limiting the drain current, respectively.

The resistance element may be a digitally controlled variable resistance circuit, and a memory circuit capable of controlling the resistance value of the digitally controlled variable resistance circuit based on stored digital data may be provided. It is preferable that the memory circuit can control storage and reading of digital data from the outside through a serial input / output line. As the above-mentioned temperature detection circuit, various temperature sensors and circuit configurations are used, such as one in which the temperature and output voltage are in a proportional relationship, one in which the output voltage is in an inversely proportional relationship, and one in which a plurality of temperature gradients can be selected. be able to.

Further, a preset temperature range of the operating temperature range of each of the temperature-compensated oscillators is defined as a second temperature region, and a temperature range on the lower temperature side is defined as a first temperature region and a high temperature exceeding the second temperature region. When the temperature range on the side is the third temperature region, the following is desirable. First mentioned above
Of the gate voltage generating circuit has a region in which the first gate voltage changes linearly with respect to a change in temperature in at least the third temperature region, and the second gate voltage generating circuit has
At least the first temperature region has a region in which the second gate voltage linearly changes with respect to the temperature change.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION In order to explain the present invention in more detail, preferred embodiments of the present invention will be described with reference to the accompanying drawings. [Structure of First Embodiment: FIGS. 1 to 4] FIG. 1 is a block circuit diagram showing a structure of a first embodiment of a temperature compensation oscillator according to the present invention. This temperature compensated oscillator
Power supply 11, input terminal 12, control voltage generation circuit 23
, Temperature detection circuit 13, and external control voltage input circuit 17
A frequency adjusting circuit 45, an oscillating circuit 47, and a memory circuit 19.

The control voltage generating circuit 23, as shown in FIG. 1, includes an operational amplifier circuit 29, a P channel MOS transistor 37, an N channel MOS transistor 35, and a first channel.
Resistance element 39, second resistance element 43, third resistance element 22, fourth resistance element 20, and digital control voltage division circuit 3 forming the first and second gate voltage generation circuits.
1, 33, the digital control variable resistance circuit 21, and the resistance element 27. Especially, P channel MOS
Transistor 37 and N-channel MOS transistor 35
The digital control voltage division circuits 31 and 33 constitute a third-order voltage generation circuit.

The frequency adjusting circuit 45 includes MIS type variable capacitors 41, 54, resistance elements 52, 53, 59, and
It is composed of capacitive elements 55, 57 and 58. The oscillator circuit 47 includes a crystal oscillator 49, which is a piezoelectric oscillator.
And an inverter 51 and a feedback resistance element 50. The MIS variable capacitors 41 and 54 are
Each of the capacitive elements constitutes a load capacitance of the oscillation circuit 47, and is a voltage variable capacitive element whose capacitance value changes according to a control voltage. As shown in FIG. 2, the temperature detection circuit 13 includes a power supply 100 and a P-channel MOS transistor 1
05, the resistance elements 119 and 106, and the operational amplifier circuit 11
It is composed of 1 etc. The detailed configuration will be described later.

The power supply 100 of the temperature detection circuit 13 does not have to be common to the power supply 11 of the control voltage generation circuit 23, and in an actual integrated circuit (IC), the power supply voltage is optimized for each circuit, and therefore it is different. It is generally supplied from a regulator. Specifically, the power supply 11 shown in FIG. 1 is composed of a regulator, and the power supply 100 of the temperature detection circuit 13 shown in FIG. 2 and the power supply of the external control voltage input circuit 17 (power supply 130 shown in FIG. 3 described later), The power supplies for the oscillator circuit 47 and the oscillator circuit 47 are also configured by separately prepared regulators. Therefore, in this embodiment, the temperature detection circuit 13 in FIG. 1 is shown as a circuit including a power supply in order to avoid complication of the drawing. The same applies to the external control voltage input circuit 17 described later.

As shown in FIG. 3, the external control voltage input circuit 17 includes a power source 130 and operational amplifier circuits 137 and 147.
And a digital control variable resistance circuit 141, a digital control voltage division circuit 139, and the like. The detailed configuration will be described later. The memory circuit 19 is composed of a non-volatile memory. Alternatively, a one-time memory in which data can be written only once or a mask ROM which is a read-only memory can be used.

In the control voltage generation circuit 23 shown in FIG. 1, the digital control voltage division circuits 31 and 33 are circuits for arbitrarily dividing the difference between the voltages applied to both ends thereof by a digital signal and outputting the digital signal. For example, as shown in FIG. 4, a plurality of resistance elements R1 to Rn are connected in series between the voltage input terminals A and B, and the switching elements SW1 to SWn are respectively connected between the respective connection points and the voltage output terminal C. Connect and memory circuit 1
The switch element SW1 by the digital signal from 9
By selectively turning on one or more of SWn to SWn, a voltage obtained by arbitrarily dividing the voltage applied between the voltage input terminals A and B is output to the voltage output terminal C.

Both ends (voltage input terminals A and B in FIG. 4) of one digital control voltage division circuit 31 shown in FIG. 1 are connected to the power supply 11 of the control voltage generation circuit 23.
The positive power supply line 25 (whose voltage is used as a reference voltage) connected to the positive terminal of the temperature detection circuit 13 is connected to the output voltage line 15 of the temperature detection circuit 13. Both ends (voltage input terminals A and B in FIG. 4) of the other digital control voltage division circuit 33 are respectively connected to the output voltage line 15 of the temperature detection circuit 13, the negative terminal of the power supply 11 and the ground power supply line (grounded). Alternatively, it is connected to the negative power supply line) 26. The reference voltage applied to the digital control voltage division circuits 31 and 33 does not necessarily have to be the voltage of the positive power supply line 25 and the ground power supply line 26, and a voltage from any power supply can be used. Further, in this embodiment, the digital control voltage division circuits 31, 33 are
Are first and second gate voltage generating circuits, which generate the first and second gate voltages by dividing each voltage difference based on the difference between the output voltage of the temperature detecting circuit 13 and the reference voltage. However, it is not limited to this.

The divided voltage output of the digital control voltage dividing circuit 31 is input to the gate G1 of the P-channel MOS transistor 37 as the first gate voltage through the signal line 36 connected to the voltage output terminal C of FIG. , The divided voltage output of the digital control voltage dividing circuit 33 is an N channel M as a second gate voltage through a similar signal line 30.
It is input to the gate G2 of the OS transistor 35. The digital control voltage division circuit 31 constitutes a first gate voltage generation circuit, and the digital control voltage division circuit 33 constitutes a second gate voltage generation circuit. Furthermore, P
The source S1 of the channel MOS transistor 37 is the third
Is connected to the positive power supply line 25 of the control voltage generation circuit 23 via the resistance element 22 of the N channel MOS transistor 35, and the source S2 of the N-channel MOS transistor 35 is connected to the ground power supply line 26 of the control voltage generation circuit 23 via the fourth resistance element 20. Connected to.

In addition, the P-channel MOS transistor 37
Of the N channel MOS transistor 35 is connected to the positive power supply line 25 via the first resistance element 39, and the drain D2 of the N-channel MOS transistor 35 is connected to the ground power supply line 2 via the second resistance element 43.
Connected to 6. The drain D1 of the P-channel MOS transistor 37 and the drain D2 of the N-channel MOS transistor 35 are connected to each other, and the drain connection point 4
4 is forming. In this embodiment, the positive power supply line 25 is a first power supply line having a first potential, and the ground power supply line 26 is a second power supply line having a polarity opposite to that of the first power supply line or a ground potential. Therefore, the second power supply line may be a negative power supply line that is connected to the negative terminal of the power supply 11 but is not grounded.

In FIG. 1, the first control voltage Vo1 output from the drain connection point 44 of the control voltage generation circuit 23.
Is input to the frequency adjusting circuit 45 via the signal line 46, and the second control voltage Vo2 output from the operational amplifier circuit 29 is input to the frequency adjusting circuit 45 via the signal line 48. In the temperature detection circuit 13 shown in FIG. 2, the gate G3 of the P-channel MOS transistor 105 is connected to the positive power supply line 103 of the temperature detection circuit 13 via the resistance element 101, and
It is also connected to the ground power supply line 121 via the resistance element 115. The positive power supply line 103 is connected to the positive terminal of the power supply 100, and the ground power supply line 121 is connected to the negative terminal of the power supply 100 and ground. And P-channel MOS
The source S3 of the transistor 105 is connected to the positive power supply line 103 of the temperature detection circuit 13 via the resistance element 106, and the drain D3 is connected to the ground power supply line 121 via the resistance element 119.

The output voltage at the connection point 120 between the resistance element 119 and the drain D3 of the P-channel MOS transistor 105 passes through the resistance element 107 and the operational amplifier circuit 111.
The negative input terminal of the operational amplifier circuit 111 is connected to its own output terminal via the resistance element 109. Further, the positive input terminal of the operational amplifier circuit 111 is connected to the positive power supply line 103 via the resistance element 124,
Each of them is connected to the ground power supply line 121 via the resistance element 123 to input the offset voltage. The output voltage of the operational amplifier circuit 111 is the temperature detection voltage, which is input as the output voltage of the temperature detection circuit 13 shown in FIG. 1 to the digital control voltage division circuits 31 and 33 through the signal line 15 as described above. , Is also input to the negative input terminal of the operational amplifier circuit 29 via the resistance element 27. The negative input terminal of the operational amplifier circuit 29 is connected to its own output terminal 28 via the digital control variable resistance circuit 21.

In temperature detecting circuit 13 shown in FIG. 2, resistance elements 101 and 115 form a gate voltage generating portion for P-channel MOS transistor 105. Further, the positive power supply line 103 is a first power supply line, and the ground power supply line 121 is a second power supply line having a polarity opposite to that of the first power supply line or a ground potential. The voltage generated across the resistance element 106 is the voltage between the gate G3 and the source S3 of the P-channel MOS transistor 105 (so-called gate voltage).
Since it is applied with the opposite polarity to P-channel MOS
It has a function of reducing the drain current of the transistor 105. This action is performed by the P-channel MOS transistor 10
5 becomes more prominent as the drain current (the same as the source current) of 5 increases. Therefore, a kind of negative feedback action is exerted on the drain current of the P-channel MOS transistor 105, and the drain current straight line of the P-channel MOS transistor 105 with respect to temperature. In addition to improving the performance, it also has the effect of suppressing the influence of manufacturing variations.

In this embodiment, the output voltage of the operational amplifier circuit 111 is output as the temperature detection voltage of the temperature detection circuit 13, but the present invention is not limited to this. For example, the resistance element 119 and the P-channel MOS transistor 105 are used.
Alternatively, the voltage generated at the connection point 120 with the drain D3 may be directly output as the temperature detection voltage of the temperature detection circuit 13. In the external control voltage input circuit 17 shown in FIG. 3, the external voltage is applied from the input terminal 12 to the resistance element 1
It is inputted to the negative input terminal of the operational amplifier circuit 137 via 31 and the negative input terminal of the operational amplifier circuit 137 is connected to its own output terminal via the digital control variable resistance circuit 141.

Further, the positive input terminal of the operational amplifier circuit 137 is connected to the positive power supply line 132 of the external control voltage input circuit 17 via the resistance element 133 and to the ground power supply line 138 via the resistance element 135. Also connect and input the offset voltage. The output of the operational amplifier circuit 137 is input to the negative input terminal of the operational amplifier circuit 147 via the resistance element 143, and the negative input terminal of the operational amplifier circuit 147 is connected to its own output terminal via the resistance element 145. ing. The output of the operational amplifier circuit 147 becomes the output of the external control voltage input circuit 17, and is input as an offset voltage to the positive input terminal of the operational amplifier circuit 29 of the control voltage generation circuit 23 shown in FIG. 1 through the signal line 16.

In this embodiment, the resistance elements 133 and 135 shown in FIG. 3 constitute an offset voltage generating portion of the operational amplifier circuit 137. The voltage range of the external voltage is determined by the specifications of the product, and the external voltage within the determined voltage range is directly used as the operational amplifier circuit 29.
If the offset voltage is input as the offset voltage, the matching with the voltage value required by the control voltage generation circuit 23 is poor, and a desired frequency change cannot be obtained. Therefore, generally, this external voltage variation range is compressed and an appropriate offset is added if necessary. The external control voltage input circuit 17 adjusts the compression ratio and adds the offset. The detailed operation principle will be described later.

The above-mentioned digital control voltage division circuit 31,
Digital control voltage division circuit 1 having the same function as 33
Both ends of 39 are the positive power supply line 1 of the external control voltage input circuit 17.
32 and the ground power supply line 138, the divided voltage output of the digital control voltage dividing circuit 139 is the signal line 1
The offset voltage is input to the positive input terminal of the operational amplifier circuit 147 through 40. In this embodiment, the offset input voltage to the operational amplifier circuit 147 is adjusted by the divided voltage output of the digital control voltage dividing circuit 139. The frequency adjustment circuit 45 shown in FIG. 1 inputs the first control voltage Vo1 of the control voltage generation circuit 23 to the gate side electrode which is one electrode of the MIS type variable capacitance capacitor 41 through the signal line 46 and the resistance element 52. At the same time, the signal is also input to the gate side electrode of the MIS type variable capacitor 54 through the signal line 46 and the resistance element 53.

Further, the second control voltage Vo2 of the control voltage generating circuit 23 is passed through the signal line 48 and the resistance element 59 to the MIS.
Inputs are made to the substrate side electrodes, which are the other electrodes of the mold variable capacitors 41 and 54, respectively. The gate side electrodes of the MIS type variable capacitance capacitors 41 and 54 are connected to the oscillation circuit 47 via the capacitance element 58 or 57, respectively.
Each substrate-side electrode is grounded (connected to the ground power supply line) via the capacitive element 55. The oscillator circuit 47 includes the inverter 5
1 is a crystal oscillating circuit in which a resistance element 50 and a crystal oscillator 49 are connected in parallel between the input terminal and the output terminal, and both ends of the crystal oscillator 49 are capacitive elements 58 of the frequency adjusting circuit 45.
And 57 respectively. The memory circuit 19 is connected to the serial input / output line 18 that controls storage and reading of digital data, and the three parallel output lines 14a, 14b, and 14c that output digital data, respectively.

[Operation of First Embodiment: FIGS. 1 to 8] Next, the temperature-compensated oscillator described above with reference to FIGS. 5 to 8 in addition to FIGS. 1 to 4 described above. The action of will be described. In FIG. 1, the temperature detection circuit 13 detects the temperature of the oscillation circuit 47 and outputs a voltage depending on the temperature to the control voltage generation circuit 23. Therefore, first, the principle of generation of the above-described first control voltage Vo1 by the control voltage generation circuit 23 will be described.

In the temperature detecting circuit 13, the gate G3 of the P-channel MOS transistor 105 shown in FIG. 2 has a positive power supply line 103 and a ground power supply 103 by the power supply 100 of the temperature detecting circuit 13 in order to supply a current to the drain D3. A voltage obtained by dividing the power supply voltage between the line 121 and the resistor elements 101 and 115 is input. Then, as the temperature changes from a low temperature to a high temperature, the drain current of the P-channel MOS transistor 105 increases and the resistance element 119
And the voltage at the connection point 120 between the drain D3 and the drain D3 increases linearly. Since the voltage at the connection point 120 is input to the negative input terminal of the operational amplifier circuit 111 via the resistance element 107, the operation of the operational amplifier circuit 111 becomes inverting amplification, and the output voltage thereof linearly increases as the temperature rises. Go down.

A voltage obtained by dividing the power supply voltage of the temperature detection circuit 13 by the resistance elements 124 and 123 is input to the positive input terminal of the operational amplifier circuit 111 as an offset voltage.
The source S of the P-channel MOS transistor 105
3 is replaced with a digitally controlled variable resistance circuit to replace the resistance element 106 connected between the positive power supply line 103 and the positive power supply line 103, and the drain current of the P-channel MOS transistor 105 is changed by the digital data stored in the memory circuit 19 after completion. It is also possible to perform control. The memory circuit 19 shown in FIG.
Control the storage and reading of digital data via
Digital data for control is sent via the parallel output lines 14a to 14c to the digital control variable resistance circuit 21 of the control voltage generation circuit 23, and the digital control voltage division circuit 31,
Output to 33.

As described above, the output voltage of the temperature detection circuit 13 linearly decreases with an increase in temperature, and the output voltage of the temperature detection circuit 13 and the voltage of the ground power supply line 26 of the control voltage generation circuit 23 (0 V The voltage difference between
This voltage difference is divided into a desired value by the digital control voltage dividing circuit 33, and the N-channel MOS transistor 35 is divided.
Is input as a gate input voltage to the gate G2. Now, when the temperature rises from the low temperature state to reach the temperature T1 shown in FIG. 5 and this gate input voltage becomes equal to or lower than the threshold voltage of the N-channel MOS transistor 35, the current flows between its source S2 and drain D2. The current that was being used is cut off. The temperature range until reaching the temperature T1 is the first temperature region TA1. In this region, the N-channel MOS transistor 35 is in the ON state, but the P-channel MOS transistor 37 is in the OFF state.

On the other hand, as the temperature rises, the temperature detection circuit 1
On the contrary, the voltage difference between the output voltage of No. 3 and the voltage of the positive power supply line 25 of the control voltage generating circuit 23 increases linearly. This voltage difference is divided into a desired value by the digital control voltage dividing circuit 31 and input to the gate G1 of the P-channel MOS transistor 37 as a gate input voltage. Then, when the temperature T2 shown in FIG. 5 is reached and the gate input voltage exceeds the threshold voltage of the P-channel MOS transistor 37, a current starts to flow between the source S1 and the drain D1 thereof. The temperature T2 is higher than the temperature T1 and this temperature T1
The voltage division ratios of the digital control voltage division circuits 31 and 33 are set so that the values of the temperature T2 and the temperature T2 become desired values.
It is set by the digital data stored in 9.

The temperature T1 is near the maximum point (-10 degrees to 0 degrees) on the low temperature side of the AT-cut crystal unit, and the temperature T2 is the minimum point (60 degrees to 7 degrees) on the high-temperature side of the AT-cut crystal unit.
Set around 0 degree. The temperature range between the temperature T1 and the temperature T2 is the second temperature region TA2, and in this region,
P-channel MOS transistor 37 and N-channel MOS
Both transistors 35 are turned off. In the AT-cut crystal unit, the frequency changes substantially linearly in the temperature region between the maximum point and the minimum point described above, so in the second temperature region TA2, the above-mentioned second control voltage Vo
The temperature compensation for the oscillation frequency of the oscillation circuit 47 is performed only by the change of 2.

The resistance values of the first resistance element 39 and the second resistance element 43 are both preferably set to 100 kilohms (KΩ) or more. If this resistance value is smaller than 100 KΩ, not only the current consumption of the control voltage generation circuit 23 increases, but also the effect on the equivalent resistance in the ON state of the P-channel MOS transistor 37 and the N-channel MOS transistor 35 cannot be neglected. 1 Voltage saturation occurs in the highest temperature part and the lowest temperature part of the control voltage Vo1, the voltage curve generated at the drain connection point 44 is distorted, and it is desirable that the temperature characteristics of the AT-cut crystal unit can be sufficiently compensated. The voltage curve of can not be obtained.

Until the temperature in FIG. 5 reaches T1 (first temperature region TA1), the current flowing between the source S1 and the drain D1 of the P-channel MOS transistor 37 is cut off, so that the second resistance is reached. The current flowing through the element 43 is the source S2 of the N-channel MOS transistor 35.
It is much smaller than the current flowing between the drain and the drain D2. Therefore, the current flowing from the positive power supply line 25 of the control voltage generation circuit 23 to the first resistance element 39 is the N channel M
It is almost equal to the current flowing between the source S2 and the drain D2 of the OS transistor 35. First generated at connection point 44 between drain D1 of P-channel MOS transistor 37 and drain D2 of N-channel MOS transistor 35
Control voltage Vo1 is a voltage obtained by subtracting the voltage generated across both ends of the first resistance element 39 from the voltage of the positive power supply line 25 of the control voltage generation circuit 23. Therefore, the change of the first control voltage Vo1 with respect to temperature does not change. , A curve that is upwardly convex according to the so-called square law depending on the relationship between the gate voltage and the drain current of the N-channel MOS transistor 35.

The temperature in FIG. 5 between T1 and T2 is the second temperature region TA2, the N-channel MOS transistor 35 and the P-channel MOS transistor 37 are in the cutoff state, and no current flows between the source and the drain. Therefore, the first control voltage Vo1 generated at the connection point 44 is
With the resistance ratio of the first resistance element 39 and the second resistance element 43,
It is a value obtained by dividing the power supply voltage by the power supply 11. For example,
If the resistance values of the first resistance element 39 and the second resistance element 43 are made equal, the value of the first control voltage Vo1 becomes half the value of the power supply voltage. When the temperature further rises and exceeds T2 in FIG. 5, the temperature becomes the third temperature region TA3, the N-channel MOS transistor 35 remains in the cutoff state, and the P-channel MOS transistor 37 is turned on. Therefore, the current flowing through the first resistance element 39 becomes much smaller than the current flowing between the source S1 and the drain D1 of the P-channel MOS transistor 37, and the ground power supply line 26 passes through the second resistance element 43. The current flowing into the
It is almost equal to the current flowing between the source S1 and the drain D1 of the channel MOS transistor 37.

Therefore, the first control voltage Vo1 generated at the drain connection point 44 becomes a voltage generated across both ends of the second resistance element 43. Therefore, the change of the first control voltage Vo1 with respect to the temperature changes in the P channel. The curve is a downwardly convex curve according to the so-called square law, which depends on the relationship between the gate voltage and the drain current of the MOS transistor. Therefore, the first control voltage V generated at the drain connection point 44 with respect to the temperature change
The change of o1 becomes like a curve 60 shown in the diagram of FIG. In this figure, temperature is plotted on the horizontal axis and control voltage on the vertical axis.

The range of the curve 60 below the temperature T1 (first
The temperature region TA1) is in the curved portion 67, the range from the temperature T1 to the temperature T2 (the second temperature region TA2) is in the curved portion 65,
The range exceeding the temperature T2 (third temperature region TA3) corresponds to the curved portion 61 and becomes the third-order voltage. The straight line 63 indicates a first-order term voltage that is a second control voltage Vo2 described later. The change in the first control voltage Vo1 is represented by the curve 6
As shown in 0, in principle, it is generated by the square law of the MOS transistor, but it becomes a curve of a cubic curve continuous with respect to temperature, and it is generated separately in the low temperature part and the high temperature part. You don't have to.

Therefore, if the values of the temperature T1 and the temperature T2 are properly selected, the error with respect to the actual cubic curve becomes 10 mV or less, and it is possible to sufficiently compensate the tertiary temperature characteristic of the AT-cut crystal. The digital control voltage dividing circuit 31 which is the first gate voltage generating circuit shown in FIG.
The first gate voltage output to the gate G1 of the channel MOS transistor 37 is set to at least the third temperature region TA3.
In, the temperature is changed linearly with the change in temperature. In addition, the digital control voltage divider circuit 33, which is the second gate voltage generation circuit, changes the second gate voltage output to the gate G2 of the N-channel MOS transistor 35 into a temperature change at least in the first temperature region TA1. Change linearly with respect to.

Further, the third resistance element 22 in FIG.
Is the P-channel MOS of the temperature detection circuit 13 shown in FIG.
The same operation as that described for the resistance element 106 connected to the source S3 of the transistor 105 is performed, and P
The negative feedback effect of limiting the drain current of the channel MOS transistor 37 is brought about. Therefore, by adjusting the resistance value of the third resistance element 22, the P-channel M
It is possible to control the rate of change of the voltage across the first resistance element 39 generated by the drain current of the OS transistor 37 with respect to temperature. Thereby, even if the characteristics of the MOS transistors 37 and 35 are varied, it is possible to adjust so that the compensation approximation error with respect to the third-order temperature characteristic of the AT-cut crystal is further reduced.

The fourth resistance element 20 is also an N-channel MOS.
With respect to the drain current of the transistor 35, the same operation as that of the above-described third resistance element 22 is performed. Further, the third resistance element 22 and the fourth resistance element 20 may be replaced with a digitally controlled variable resistance circuit to make a completed product, and then the above-described adjustment may be performed by digital data stored in the memory circuit 19. It is possible. In this case, the resistance value of the third resistance element 22 is adjusted so that the oscillation frequency of the oscillation circuit 47 has a desired value at the maximum temperature for temperature compensation, and the oscillation circuit has the minimum temperature for temperature compensation. The resistance value of the fourth resistance element 20 is adjusted so that the oscillation frequency of 47 has a desired value. Although temperature compensation can be performed without using the resistance elements 20 and 22, the curve shape of the first control voltage Vo1 is determined only by the temperatures T1 and T2 described above, and the variation in the temperature characteristics of the individual crystal oscillators is reduced. It will be difficult to absorb enough. In this embodiment, the temperature detection circuit 13
Although the example in which the output voltage is input to the digital control voltage division circuits 31 and 33 by using only one is described, the output voltage of the separate temperature detection circuit is input to the digital control voltage division circuits 31 and 33. However, the same effect can be obtained.

Next, the operation principle of the second control voltage Vo2 generated by the control voltage generation circuit 23 will be described. As the temperature changes from the low temperature to the high temperature, the output voltage of the temperature detection circuit 13 linearly decreases as described above. Since the output voltage of the temperature detection circuit 13 is input to the negative input terminal of the operational amplifier circuit 29 via the resistance element 27, the operation of the operational amplifier circuit 29 becomes inverting amplification, and its output voltage is linear with the rise of temperature. Increase. Therefore, the second control voltage Vo2 generated at the output terminal 28 of the operational amplifier circuit 29 increases linearly with the temperature.

The gradient of the linear change at this time depends on the amplification factor of the operational amplifier circuit 29. The amplification factor of the operational amplifier circuit 29 is inserted between the negative input terminal and the output terminal of the operational amplifier circuit 29. It is determined by the ratio between the resistance value of the digital control variable resistance circuit 21 and the resistance value of the resistance element 27. Therefore, in order to change the gradient of the second control voltage Vo2 with respect to the temperature change, the resistance value of the digital control variable resistance circuit 21 may be changed according to the digital data stored in the memory circuit 19. The change of the second control voltage Vo2 generated at the output terminal 28 of the operational amplifier circuit 29 with respect to the temperature is as follows.
In the diagram of FIG. 5 in which the temperature is plotted on the horizontal axis and the control voltage is plotted on the vertical axis, the primary term voltage is shown by a straight line 63.

Next, the adding operation of the above-mentioned first control voltage Vo1 and second control voltage Vo2 by the frequency adjusting circuit 45 will be described. The first control voltage Vo1 is input to the gate side electrode, which is one electrode of the MIS type variable capacitance capacitor 41 of the frequency adjustment circuit 45, via the resistance element 52 for blocking the outflow of the high frequency current, and It is also input to the gate side electrode of the MIS variable capacitor 54 via the resistance element 53. The second control voltage Vo2 is the MIS type variable capacitance capacitors 41, 54.
Is input to the other electrode on the substrate side via a resistance element 59 for blocking the outflow of high frequency current.

Capacitance elements 57 and 58 are inserted in order to cut off the DC voltage on the inverter side of the oscillation circuit 47, and the capacitance element 55 cuts off only the DC component, so that the MIS variable capacitors 41 and 54 are cut off at high frequencies. It is for grounding. As described above, the first control voltage Vo1 is input to the gate side electrodes of the MIS variable capacitors 41 and 54, and the second control voltage Vo2 is input to the substrate side electrode.
The voltage applied to the MIS variable capacitors 41 and 54 is from the first control voltage Vo1 to the second control voltage Vo2.
Is the voltage after subtracting. Therefore, since the gradient of the second control voltage Vo2 has the opposite effect to the first control voltage Vo1, the straight line 63 of the second control voltage Vo2 having the positive gradient shown in FIG. It acts as a negative slope for the curve 60 of the control voltage Vo1 of 1.

The change in the voltage difference (first control voltage Vo1−second control voltage Vo2) applied to both electrodes of the MIS variable capacitors 41 and 54 with respect to temperature is shown in FIG. Therefore, a curve 71 is shown in the diagram, in which the control voltage difference is plotted on the vertical axis. As can be seen from the shape, the curve 71 is a curve that approximates a curve obtained by adding a linear primary line having a negative gradient to a cubic curve. As described above, it is possible to easily add the first control voltage Vo1 that approximates a cubic curve to temperature and the second control voltage Vo2 that has a linear slope with respect to temperature without requiring a special addition circuit. You can

Next, the operating principle of the offset voltage adjustment will be described. FIG. 3 of the external control voltage input circuit 17 in FIG.
The output of the operational amplifier circuit 147 shown in (4) is input as an offset voltage to the positive input terminal of the operational amplifier circuit 29 of the control voltage generation circuit 23. Since the output voltage of the operational amplifier circuit 29 changes in response to the offset input voltage, the operational amplifier circuit 29 responds to the output voltage of the operational amplifier circuit 147.
Output voltage changes. Since the output voltage of the operational amplifier circuit 29 is the second control voltage Vo2, as a result, the second control voltage Vo2 changes in response to the output voltage of the operational amplifier circuit 147.

The output voltage of the operational amplifier circuit 147 is
It changes in response to both the input voltage of the negative input terminal and the input voltage (offset voltage) of the positive input terminal. That is,
The output voltage of this operational amplifier circuit 147 is the operational amplifier circuit 1
It changes in response to both the output voltage of 37 and the divided voltage output of the digital control voltage dividing circuit 139. The output voltage of the operational amplifier circuit 137 also changes in response to both the input voltage of its negative input terminal and the input voltage of its positive input terminal (offset input voltage). However, since the offset input voltage is a constant voltage obtained by dividing the power supply voltage of the power supply 130 by the resistance elements 133 and 135, the output voltage of the operational amplifier circuit 137 depends only on the external input voltage from the input terminal 12. Change. The offset input voltage of the operational amplifier circuit 137 has a function of adding an offset to the output voltage of the operational amplifier circuit 137 which changes depending on the external input voltage.

In conclusion, the second control voltage Vo2 is changed by both the external input voltage from the input terminal 12 and the divided voltage output of the digital control voltage dividing circuit 139. Therefore, the divided voltage output of the digital control voltage division circuit 139 is controlled by the digital data stored in the memory circuit 19 to change the second control voltage Vo2 so that the standard oscillation frequency of the temperature-compensated oscillator is changed during manufacturing. Can be adjusted.

When the customer uses the temperature compensated oscillator,
An external input voltage called AFC input voltage is input terminal 12
To adjust the oscillation frequency of the temperature-compensated oscillator to a desired value. At this time, the resistance value of the digitally controlled variable resistance circuit 141 is controlled by the digital data stored in the memory circuit 19 to change the amplification factor of the operational amplifier circuit 137, thereby compressing the change range of the external input voltage. You can set the percentage. The external input voltage input to the input terminal 12 of the external control voltage input circuit 17 shown in FIG. 3 is inverted and amplified twice by the two operational amplifier circuits 137 and 147 to obtain the external input voltage and the operational amplifier circuit. 1
The output voltage of 47 and the second control voltage Vo2 change in the same direction. When the directions of change of the external input voltage and the second control voltage Vo2 are reversed, the number of operational amplifier circuits constituting the external control voltage input circuit 17 may be odd. Whether the number of operational amplifier circuits is an even number or an odd number is selected when adjusting the forward and reverse directions of the external input voltage change direction and the oscillation frequency change direction.

Next, the operating principle of the frequency adjusting circuit 45 will be described. Since the MIS type variable capacitance capacitors 41 and 54 that form the frequency adjusting circuit 45 act as the load capacitance of the crystal resonator that forms the oscillation circuit 47, oscillation occurs when the capacitance value of the MIS type variable capacitance capacitors 41 and 54 changes. The frequency changes. MIS type variable capacitor 41,
Since the capacitance value of 54 changes depending on the difference between the control voltages applied to its both electrodes, as a result, the oscillation frequency of the oscillation circuit 47 is changed by the difference between the voltages applied to both electrodes of the MIS type variable capacitance capacitors 41 and 54. Can be controlled.

The state of the difference between the voltages applied to both electrodes of the MIS type variable capacitors 41 and 54 and the change in the oscillation frequency is shown by the line in FIG. 7 with the horizontal axis representing the voltage difference and the vertical axis representing the frequency change rate. It becomes as shown by the curve 73 in the figure. As can be seen from this figure, as the difference in voltage applied to both electrodes of the MIS variable capacitors 41 and 54 increases in the positive direction, the oscillation frequency decreases and the rate of change of the oscillation frequency changes from positive to negative. Go negative. In this embodiment, the case where the MIS variable capacitors 41 and 54 are provided on the N type silicon substrate is taken as an example. Therefore, although the change direction is as described above, the MIS variable capacitors 41 and 54 are changed. Is P
When it is provided on the mold silicon substrate, the change is in the opposite direction. That is, the MIS variable capacitors 41, 54
The oscillation frequency increases and the sign of the rate of change of the oscillation frequency changes from negative to positive as the difference between the voltages applied to the two poles increases in the positive direction.

As described in the description of the relationship between the external input voltage input to the input terminal 12, the output voltage of the operational amplifier circuit 147 and the second control voltage Vo2 in FIG. Output voltage and second control voltage V
o2 changes in the same direction. And the voltage rise is
Since the MIS variable capacitors 41 and 54 act to reduce the difference between the voltages applied to the both electrodes, the external input voltage and the oscillation frequency of the temperature compensation oscillator change proportionally. Since the middle portion of the curve 73 shown in FIG. 7 is almost a straight line, if the frequency is adjusted by the voltage difference in this range, the difference between the voltage applied to the both electrodes of the MIS type variable capacitors 41 and 54 will be obtained. The rate of change of the oscillation frequency has a substantially linear relationship.

Therefore, the curve 71 of FIG.
When the voltage difference as shown in (4) is applied, the state of the frequency change rate with respect to the temperature becomes like a curve 75 in the diagram in which the horizontal axis represents temperature and the vertical axis represents frequency change rate in FIG.
Since the shape of this curve is the inverse of the frequency change rate characteristic of the AT-cut crystal unit with respect to the temperature with respect to the temperature axis, the temperature characteristic of the AT-cut crystal unit can be compensated.

[Modification of First Embodiment: FIGS. 9 to 1]
4] Here, an embodiment in which a part of the above-described first embodiment is modified will be described. In the first embodiment, the temperature detection circuit 13 uses the P-channel MOS transistor, and the one in which the relationship between the temperature and the output voltage is inversely proportional is used, but the same effect can be obtained by using the N-channel MOS transistor. To be For example, FIG. 9 shows an example of the circuit.
This temperature detecting circuit 13 'has an N channel MOS transistor 12 in place of the P channel MOS transistor 105.
5 has the same circuit configuration as that of the temperature detection circuit 13 shown in FIG. 2, and elements corresponding to those in FIG. 2 are designated by the same reference numerals.

In the temperature detecting circuit 13 ', the gate G4 of the N-channel MOS transistor 125 is connected to the power source 1
00 is connected in series between the positive power supply line 103 and the ground power supply line 121, and is connected to the connection point of the resistance elements 115 and 101. The source S4 is connected to the ground power supply line 121 via the resistance element 106, the drain D4 is connected to the positive power supply line 103 via the resistance element 119, and a connection point 120 between the resistance element 119 and the drain D4 of the N-channel MOS transistor 125 is formed. Is output to the negative input terminal of the operational amplifier circuit 111 via the resistance element 107. Other configurations and operations are the same as those of the temperature detection circuit 13 shown in FIG. 2, and therefore description thereof will be omitted. Then, the operational amplifier circuit 1
The output voltage of 11 is the output of the temperature detection circuit 13 ', and the relationship between the temperature and the output voltage is in a proportional relationship.

Instead of generating the second control voltage Vo2 by the temperature detection circuit 13 and the operational amplifier circuit 29 shown in FIG. 1, two temperature sensors 155 and 158 having different temperature gradients are provided as shown in FIG. It is also possible to use the temperature detection circuit 160 provided. This temperature detection circuit 160
The voltage dividing circuit 159 divides the difference between the output voltages of the two temperature sensors 155 and 158 into an arbitrary ratio to select an arbitrary temperature gradient between the temperature gradients of the two temperature sensors 155 and 158. To The output voltage of the voltage division circuit 159 is used as the second control signal Vo2. The division ratio of the voltage division circuit 159 can be changed by a digital signal from the memory circuit 19.

Further, the first resistance element 39 in FIG.
In place of the second resistance element 43 and the resistance element 213 and the resistance element 215 having different temperature coefficients with respect to the resistance values as shown in FIG. 11, the same effect can be obtained. That is, in the above-mentioned second temperature region (temperature region TA2 in FIG. 5), the first control voltage Vo1 is generated by the resistance element 213 and the resistance element 215 in the control voltage generation circuit 23.
Is a value obtained by dividing the power supply voltage of, the resistance elements 213 and 215 have different temperature coefficients of resistance,
The first control voltage Vo1 changes linearly with changes in temperature. At this time, in order to change the temperature gradient, a plurality of sets of resistance elements having different combinations of temperature coefficients of resistance values of these two resistance elements may be prepared and switched by a switch.

In the example shown in FIG. 11, three sets of resistance elements 213 and 2 having different combinations of temperature coefficients of resistance values are used.
Any one of 15, 219, 221, 225 and 227 is provided with three switches 211, 217 and 2 as switching means.
It is selectively used by turning ON / OFF 23. ON / OFF of these switches 211, 217, 223
It is also possible to perform the OFF control with a digital signal from the memory circuit. As a switching means, this switch 211,
When switching transistors are used instead of 217 and 223, as shown in FIG. 12, switching transistors 231, 233, and 235 are inserted between the positive power supply line 25 and the resistance elements 213, 219, and 225, and grounded. Switching transistors 232, 234, 236 may be inserted between the power supply line 26 and the resistance elements 215, 221, 227. As a result, the ON resistance of the switching transistor can be reduced. Further, in this case, by supplying the control voltage of each switching transistor 231-236 from the regulator circuit,
It is possible to prevent the ON resistance of the switching transistor from changing due to fluctuations in the power supply voltage.

A frequency adjusting circuit 45 'shown in FIG. 13 may be used instead of the frequency adjusting circuit 45 shown in FIG. In FIG. 13, the frequency adjusting circuit 45 of FIG.
The same parts as those in FIG. In the frequency adjusting circuit 45 'shown in FIG. 13, the second MIS variable capacitor 15 is provided in parallel with each series circuit of the MIS variable capacitors 41 and 54 and the capacitive elements 58 and 57.
1, 153 and capacitance elements 152, 154 are provided in each series circuit. In this case, as in the case of the first embodiment shown in FIG. 1, the first control voltage Vo1 passes through the signal line 46 and the resistance element 52 or 53 through the gate side electrodes of the MIS variable capacitors 41 and 54. The second control voltage Vo2 is applied to the signal line 48 and the resistance element 156 or 1
The second MIS type variable capacitance capacitor 15 via 57
It is applied to each gate side electrode of 1,153. Even in this case, the same result as in the case of the first embodiment described above can be obtained.

Further, regarding the adjustment of the standard oscillation frequency of the temperature-compensated oscillator at the time of manufacture and the adjustment of the frequency of the temperature-compensated oscillator by the external input voltage called AFC input voltage, a kind of resistor as shown in FIG. A similar effect can be obtained by the circuit network. In FIG. 14, a digital control voltage division circuit 251 controlled by a digital signal from the memory circuit 19 divides an external input voltage from the input terminal 12 and is controlled by a digital signal from the memory circuit 19. It is added to one terminal of the division circuit 253. Further, the digital control voltage division circuit 255 controlled by the digital signal from the memory circuit 19 divides the output voltage of the constant voltage source 250 and applies it to the other terminal of the digital control voltage division circuit 253. The divided voltage output to the output line 256 of the digital control voltage division circuit 253 is used as the second control voltage Vo2. This voltage is divided by the external input voltage from the input terminal 12 and the digital control voltage division circuit 255. Varies with both voltage. Further, the output of this divided voltage has a dependency on the external input voltage from the input terminal 12 and the divided voltage from the digital control voltage dividing circuit 255 depending on the division ratio of the digital control voltage dividing circuit 253.

[Second Embodiment: FIGS. 15 and 16]
Next, a second embodiment of the temperature-compensated oscillator according to the present invention will be described with reference to FIGS. FIG. 15 is a block circuit diagram showing the configuration of the temperature-compensated oscillator. Elements corresponding to those of the first embodiment shown in FIG. 1 are designated by the same reference numerals, and their description will be omitted or simply described. To do. The components of the temperature-compensated oscillator shown in FIG. 15 are that a temperature detection circuit 201 is newly added, and instead of the operational amplifier circuit 29, the resistance element 27, and the digital control variable resistance circuit 21 in FIG. Except that the digital control voltage dividing circuits 205 and 207 are provided,
It is almost the same as the component of FIG.

The control voltage generating circuit 23 'includes a P-channel MOS transistor 37 shown in FIG.
The transistor 38 is replaced and both ends of the digital control voltage division circuit 33 are connected to the output voltage line 203 of the newly provided temperature detection circuit 201 and the ground power supply line 26 of the control voltage generation circuit 23 '. And the operational amplifier circuit 2 instead of the operational amplifier circuit 29 as described above.
9. Digitally controlled voltage division circuit 205 that operates in the same manner as 9
The circuit configuration is the same as that of the control voltage generation circuit 23 shown in FIG. Frequency adjustment circuit 4
5 and the circuit configuration of the oscillation circuit 47 and their functions are
Since it is the same as the embodiment described above, the description thereof will be omitted. The circuit configuration and the function of the temperature detection circuit 13 are the same as the circuit configuration of the temperature detection circuit 13 shown in FIG. 2 in the first embodiment.

The temperature detection circuit 201 is composed of an N-channel MOS transistor 125, resistance elements 119 and 106, an operational amplifier circuit 111 and the like, like the temperature detection circuit 13 'shown in FIG. External control voltage input circuit 1
Since the circuit configuration and the function of 7 are the same as those of the external control voltage input circuit 17 shown in FIG. 3 in the first embodiment, the description thereof will be omitted. The configuration of the memory circuit 19 is also the first
Is the same as the embodiment of.

In the control voltage generating circuit 23 ', the connection of the digital control voltage dividing circuit 31 is exactly the same as that of the first embodiment shown in FIG. Both ends of the digital control voltage division circuit 33 are connected to the output voltage line 203 of the temperature detection circuit 201 and the control voltage generation circuit 23 'as described above.
Is connected to the ground power supply line 26. The divided voltage output of the digital control voltage dividing circuit 31 is input to the gate G5 of the N-channel MOS transistor 38 as a gate voltage,
The divided voltage output of the digital control voltage dividing circuit 33 is input to the gate G2 of the N-channel MOS transistor 35 as a gate voltage. Also in this embodiment, the digital control voltage division circuit 31 constitutes a first gate voltage generation circuit, and the digital control voltage division circuit 33 constitutes a second gate voltage generation circuit.

The source S5 of the N-channel MOS transistor 38 is connected to the ground power supply line 26 via the third resistance element 22.
The source S2 of the N-channel MOS transistor 35 is connected to the ground power supply line 26 via the fourth resistance element 20. N-channel MOS transistors 35 and 3
The drains D2 and D5 of 8 are commonly connected, and the drain connection point 44 is connected to the positive power supply line 25 via the first resistance element 39 and the ground power supply line 26 via the second resistance element 43. Is also connected to.

In this embodiment, the N-channel MOS transistor 38 forming the first MOS transistor and the second MOS transistor 38
The N-channel MOS transistor 35 and the digital control voltage dividing circuits 31 and 33, which form the MOS transistor of FIG. Further, in this embodiment, unlike the case of the first embodiment shown in FIG. 1, the ground power supply line 26 is the first power supply line. The source sides of both the transistors 38 and 35 are both connected to the ground power supply line 26 which is the first power supply line, but if the power supply lines have the same polarity, one of them will be connected to another power supply line (second power supply line). Power line)
You may connect to. The first control voltage Vo1 output from the drain connection point 44 of the control voltage generation circuit 23 ',
The second control voltage Vo2 based on the division voltage output from the digital control voltage division circuit 205 is input to the frequency adjustment circuit 45 through the signal lines 46 and 48, respectively.

Next, the operation of the temperature-compensated oscillator of the second embodiment will be described. In FIG. 15, the temperature detection circuit 13 detects the temperature of the oscillation circuit 47 and outputs a voltage depending on the temperature to the control voltage generation circuit 23 '.
The temperature detection circuit 201 also detects the temperature of the oscillation circuit 47,
The voltage depending on the temperature is output to the control voltage generating circuit 23 '.

First, the principle of operation of generating the first control voltage Vo1 will be described. Since the operation of the temperature detection circuit 13 is the same as that of the first embodiment, its description is omitted. The temperature detection circuit 201 is configured similarly to the temperature detection circuit 13 'shown in FIG. 9, and the gate G4 of the N-channel MOS transistor 125 has a power supply voltage from the power supply 100 for supplying a current to the drain D4. Resistor element 115 and 1
When the voltage divided by 01 is input and the temperature changes from low temperature to high temperature, the current of the drain D4 of the N-channel MOS transistor 125 increases and the resistance element 119
And the drain D4 of the N-channel MOS transistor 125
The voltage at the connection point 120 between and decreases linearly.

Since the voltage at the connection point 120 is input to the negative input terminal of the operational amplifier circuit 111 via the resistance element 107, the operation of the operational amplifier circuit 111 is inverting amplification, and the output voltage is linear with the rise in temperature. Go up to. That is, the temperature and the output voltage have a proportional relationship. A power supply voltage is applied to the positive input terminal of the operational amplifier circuit 111 by the resistor element 1.
The voltage divided by 23 and 124 is input as the offset voltage. It is also possible to replace the resistance element 106 with a digitally controlled variable resistance circuit, complete the completed body, and then control the drain current of the N-channel MOS transistor 125 by the digital data stored in the memory circuit 19. Since the operation of the memory circuit 19 is the same as that of the first embodiment, its description is omitted.

As described above, the output voltage of the temperature detection circuit 13 shown in FIG. 15 linearly decreases with an increase in temperature, and the output voltage of the temperature detection circuit 201 linearly increases with an increase in temperature. go. Since the basic operation principle of the N-channel MOS transistor 35 and the N-channel MOS transistor 38 with respect to the temperature change is the same as that described in the first embodiment, the temperature range is as described in the first embodiment. Will be described using temperature region divisions of a first temperature region, a second temperature region, and a third temperature region that are sequentially divided from the low temperature side.

In the first temperature region on the low temperature side, the N channel M
The OS transistor 35 is ON, the N-channel MOS transistor 38 is OFF, both the N-channel MOS transistors 35 and 38 are OFF in the middle second temperature region, and the N-channel MOS transistor 35 is OFF in the third temperature region on the high temperature side. N channel MOS transistor 38 is O
N. FIG. 16 shows how the first control voltage Vo1 generated at the drain connection point 44 changes with respect to the temperature at that time.
In addition, a curve 277 is shown in which the temperature is plotted on the horizontal axis and the control voltage is plotted on the vertical axis.

The range (temperature range TA1) below the temperature T1 of the curve 277 is in the curve part 271, the range from the temperature T1 to the temperature T2 (temperature range TA2) is in the curve part 273, and the range exceeding the temperature T2 (temperature range TA3). ) Is the curved portion 27
5 corresponds to the secondary term voltage. This change in the first control voltage Vo1 is, in principle, generated by the square law of the MOS transistor as shown by the curve 277, so that it becomes a quadratic curve that is continuous with respect to temperature, and It is not necessary to generate it separately in the high temperature part and the high temperature part.
By properly selecting the values of the temperature T1 and the temperature T2, it is possible to accurately compensate the secondary temperature characteristic of the tuning fork vibrator.

Also in this case, the digital control voltage dividing circuit 31 which is the first gate voltage generating circuit shown in FIG.
The first gate voltage output to the gate G5 of the N-channel MOS transistor 38 is set to at least the third temperature region TA.
In No. 3, the temperature is changed linearly.
In addition, the digital control voltage dividing circuit 33, which is the second gate voltage generating circuit, includes an N-channel MOS transistor 35.
The second gate voltage output to the gate G2 of the above is linearly changed with respect to the temperature change at least in the first temperature region TA1. Since the operations of the third resistance element 22 and the fourth resistance element 20 are exactly the same as those of the first embodiment, the description thereof will be omitted. In the second embodiment, the tuning fork type vibrator
Since the next temperature characteristic is compensated, it is not necessary to provide the second control voltage Vo2 with a temperature gradient in order to correct the gradient of the third temperature characteristic of the AT-cut crystal, as described in the first embodiment. The operation principle of the offset voltage adjustment and the operation principle of the frequency adjustment circuit 45 are the same as those in the first embodiment, and therefore the description thereof will be omitted.

[0080]

As described above, the temperature-compensated oscillator according to the present invention includes a high temperature part low temperature part circuit, a low temperature part cubic curve voltage generating circuit, and a high temperature part cubic curve voltage generating circuit. P-channel MOS transistor and N-channel MOS without complicated and difficult circuit adjustment
A series of third-order approximate curve-shaped control voltages can be generated only from the electrical characteristics of the transistor. Further, since the addition of the cubic approximation curve and the linear straight line for performing the gradient correction can be performed without using the adder circuit, the circuit configuration becomes very simple, and the integration into a semiconductor integrated circuit is easy, and the semiconductor is integrated. The area of the integrated circuit chip can be greatly reduced, which is very effective in improving the yield and reducing the price. Further, the same effect as in the case of the compensation of the cubic curve is exhibited even for the temperature-compensated oscillator having the temperature characteristic of the quadratic curve.

[Brief description of drawings]

FIG. 1 is a block circuit diagram showing a configuration of a first embodiment of a temperature compensation oscillator according to the present invention.

2 is a circuit diagram showing a specific configuration example of a temperature detection circuit 13 in FIG.

3 is a block circuit diagram showing a specific configuration example of an external control voltage input circuit 17 in FIG.

FIG. 4 is a digital control voltage division circuit 31 in FIG.
FIG. 33 is a block circuit diagram showing a specific configuration example of 33.

FIG. 5 is a diagram showing a relationship between temperature and first and second control voltages in the first embodiment of the present invention.

FIG. 6 is a diagram similarly showing a relationship between temperature and a difference between the first control voltage and the second control voltage.

FIG. 7 is a diagram similarly showing the relationship between the voltage difference and the frequency change rate.

FIG. 8 is a diagram showing the relationship between temperature and frequency change rate.

FIG. 9 is a circuit diagram showing another configuration example of the temperature detection circuit used in the present invention.

FIG. 10 is a block circuit diagram showing still another configuration example of the temperature detection circuit.

FIG. 11 is a circuit diagram showing another configuration example of the circuit that generates the first control voltage in FIG.

FIG. 12 is a circuit diagram showing still another configuration example of the circuit which similarly generates the first control voltage.

FIG. 13 is a circuit diagram showing the oscillator circuit in FIG. 1 and a partially modified frequency adjusting circuit.

FIG. 14 is a block circuit diagram showing another example of the external control voltage input circuit used in the present invention.

FIG. 15 is a block circuit diagram showing a second embodiment of the temperature-compensated oscillator according to the present invention.

FIG. 16 is a diagram showing a relationship between the temperature generated by the control voltage generating circuit and the first control voltage.

FIG. 17 is a block diagram showing a configuration example of a conventional temperature compensation oscillator.

[Explanation of symbols]

11: Power supply 13, 13 ', 160, 201: Temperature detection circuit 17: External control voltage input circuit 19: Memory circuit 23, 23': Control voltage generation circuit 25, 103: Positive power supply line 26, 121: Ground power supply line 31 , 33, 139: Digital control voltage dividing circuits 35, 38, 125: N-channel MOS transistors 37, 105: P-channel MOS transistor 39: First resistance element 41, 54: MIS variable capacitor 43: Second resistance Elements 45, 45 ': Frequency adjustment circuit 47: Oscillation circuits 106, 119, 213, 215, 219, 221, 2
25,227: Resistance element 111: Operational amplifier circuit 120: Connection points 151, 153: Second MIS type variable capacitance capacitors 155, 158: Temperature sensors 211, 217, 223: Switches 231-236: Switching transistor TA1: First Temperature region TA2: second temperature region TA3: third temperature region

Claims (33)

[Claims] 1. An oscillating circuit, a frequency adjusting circuit for changing an oscillating frequency of the oscillating circuit by a control voltage, a temperature in the vicinity of the oscillating circuit, and at least one output voltage based on the detected temperature. A temperature-compensated oscillator having: a temperature detection circuit that generates a temperature; and a control voltage generation circuit that includes a third-order voltage generation circuit that generates a third-order voltage as the control voltage based on an output voltage from the temperature detection circuit. The third-order voltage generation circuit has a first MOS transistor whose source is connected to a first power supply line, and a conductivity type different from that of the first MOS transistor,
A second MOS transistor whose source is connected to a second power supply line; a first gate voltage generation circuit which generates a first gate voltage based on the output voltage of the temperature detection circuit; A second gate voltage generating circuit for generating a second gate voltage based on the output voltage of the detection circuit, the first gate of the first gate voltage generating circuit An output terminal for outputting a voltage is connected to the gate of the first MOS transistor, and an output terminal for outputting the second gate voltage of the second gate voltage generating circuit is connected to the second MOS transistor. And a drain of the first MOS transistor and a drain of the second MOS transistor are commonly connected to serve as an output terminal of the control voltage. 2. An oscillating circuit, a frequency adjusting circuit for changing an oscillating frequency of the oscillating circuit by a control voltage, a temperature in the vicinity of the oscillating circuit is detected, and at least one output voltage is generated based on the detected temperature. And a control voltage generating circuit including a quadratic term voltage generating circuit that generates a quadratic term voltage as the control voltage based on an output voltage from the temperature detecting circuit. The secondary term voltage generating circuit has a first MOS transistor having a source connected to a first power supply line, a first MOS transistor having the same conductivity type as the first MOS transistor, and a source connected to a second power supply line. No. 2 MOS transistor, a first gate voltage generating circuit for generating a first gate voltage based on the output voltage of the temperature detecting circuit, and an output voltage of the temperature detecting circuit. A second gate voltage generating circuit for generating a second gate voltage based on the output of the first gate voltage generating circuit, and an output for outputting the first gate voltage of the first gate voltage generating circuit. An end is connected to the gate of the first MOS transistor, and an output end of the second gate voltage generating circuit for outputting the second gate voltage is connected to the gate of the second MOS transistor. A temperature-compensated oscillator, wherein the drain of the first MOS transistor and the drain of the second MOS transistor are commonly connected to serve as an output terminal of the control voltage. 3. The temperature-compensated oscillator according to claim 1, wherein the output terminal of the control voltage is further connected to at least one arbitrary voltage source via a resistance element. 4. The temperature-compensated oscillator according to claim 3, wherein the resistance element has a resistance value of 100 kilohms or more. 5. The temperature-compensated oscillator according to claim 1, wherein the control voltage output terminal is further connected to the first power supply line or a power supply line having the same polarity as the first power supply line via a first resistance element. A temperature-compensated oscillator connected to the second power supply line or a power supply line having the same polarity as the second power supply line via a second resistance element. 6. The temperature-compensated oscillator according to claim 5, wherein the first resistance element and the second resistance element have different temperature coefficients with respect to a resistance value. 7. The temperature-compensated oscillator according to claim 6, wherein the first resistance element and the second resistance element are provided with a plurality of sets of resistance elements having different combinations of temperature coefficients with respect to their resistance values. A temperature-compensated oscillator, comprising switching means for selectively switching and using any one of the plurality of resistance elements. 8. The temperature-compensated oscillator according to claim 1, wherein at least one of the first and second gate voltage generation circuits has a difference between an output voltage of the temperature detection circuit and an arbitrary reference voltage. A temperature-compensated oscillator, which is a circuit for generating the first or second gate voltage based on 9. The temperature-compensated oscillator according to claim 1, wherein at least one of the first and second gate voltage generation circuits is a circuit capable of controlling a generated gate voltage based on external data. A temperature-compensated oscillator characterized by being present. 10. The temperature-compensated oscillator according to claim 9, further comprising a memory circuit that stores the external data,
At least one of the second gate voltage generation circuit and the second gate voltage generation circuit is a circuit capable of controlling the generated gate voltage based on the data stored in the memory circuit. 11. The temperature-compensated oscillator according to claim 8, wherein at least one of the first and second gate voltage generation circuits has a voltage difference between an output voltage of the temperature detection circuit and the arbitrary reference voltage. A temperature-compensated oscillator characterized by being a voltage division circuit for dividing the temperature. 12. The temperature-compensated oscillator according to claim 8, wherein the reference voltage applied to at least one of the first and second gate voltage generation circuits is the first power line or the first power line. A temperature-compensated oscillator characterized in that it is the voltage of the second power supply line. 13. The temperature-compensated oscillator according to claim 1, wherein the control voltage generation circuit outputs a third-order voltage generated by the third-order voltage generation circuit as a first control voltage, and further, the temperature detection circuit. A primary term voltage generation circuit that generates a primary term voltage based on an output voltage of the circuit, and outputs the primary term voltage generated by the circuit as a second control voltage; Control voltage and the second
A temperature-compensated oscillator which is a circuit for controlling the oscillation frequency of the oscillation circuit according to the control voltage of 1. 14. The temperature-compensated oscillator according to claim 13, wherein the first-order voltage generation circuit is an operational amplifier circuit. 15. The temperature-compensated oscillator according to claim 14, further comprising a memory circuit that stores data from the outside and controls an amplification factor and an offset input voltage of the operational amplifier circuit by the stored digital data. A temperature-compensated oscillator characterized by the following. 16. The temperature-compensated oscillator according to claim 1, wherein the temperature detection circuit has two temperature sensors having different temperature gradients, and a difference between output voltages of the two temperature sensors is set to an arbitrary ratio. A temperature-compensated oscillator, which is a circuit that divides and outputs as a temperature detection voltage. 17. The temperature-compensated oscillator according to claim 1, wherein the frequency adjustment circuit is a capacitive element that constitutes a load capacitance of the oscillation circuit, and its capacitance value changes according to the control voltage. A temperature compensated oscillator having a voltage variable capacitance element. 18. The temperature-compensated oscillator according to claim 13, wherein the frequency adjustment circuit is a capacitive element that constitutes a load capacitance of the oscillation circuit, and the voltage variable whose capacitance value changes according to the control voltage. A capacitive element, wherein the first control voltage is applied to one electrode of the voltage variable capacitance element, and the second control voltage is applied to the other electrode of the voltage variable capacitance element. Characteristic temperature compensated oscillator. 19. The temperature compensated oscillator according to claim 17, wherein the voltage variable capacitance element is a MIS type variable capacitance capacitor. 20. The temperature-compensated oscillator according to claim 13, wherein the frequency adjustment circuit is a capacitive element that constitutes a load capacitance of the oscillation circuit, and the variable voltage of which the capacitance value changes according to the control voltage. A first voltage variable capacitance element to which the first control voltage is applied, and a second voltage variable capacitance element to which the second control voltage is applied are arranged in parallel. A temperature-compensated oscillator characterized by being connected to. 21. The temperature-compensated oscillator according to claim 1, wherein the sources of the first and second MOS transistors are:
A temperature-compensated oscillator characterized in that the temperature-compensated oscillator is connected to the first or second power supply line via a resistance element for limiting a drain current, respectively. 22. The temperature-compensated oscillator according to claim 21, wherein the resistance element is a digital control variable resistance circuit, and the resistance value of the digital control variable resistance circuit can be controlled based on stored digital data. A temperature-compensated oscillator having a memory circuit. 23. The temperature-compensated oscillator according to claim 10, wherein the memory circuit is capable of externally controlling storage and reading of digital data via a serial input / output line. A temperature-compensated oscillator characterized by being present. 24. The temperature-compensated oscillator according to claim 1, wherein the temperature detection circuit has a source connected to a first power supply line of the temperature detection circuit and a drain connected to a second power supply line via a resistance element. Connected to the power line of P
A channel MOS transistor and a gate voltage generator that supplies a gate voltage exceeding the threshold voltage of the P-channel MOS transistor to the gate of the P-channel MOS transistor, and a drain of the P-channel MOS transistor. A temperature compensation oscillator, which is a circuit for outputting a voltage generated at a connection point with the resistance element as a temperature detection voltage. 25. The temperature-compensated oscillator according to claim 24, wherein the source of the P-channel MOS transistor is connected to the first power supply line via a resistance element. Oscillator. 26. The temperature-compensated oscillator according to claim 24, wherein the temperature detection circuit outputs a voltage generated at a connection point between the drain of the P-channel MOS transistor and the resistance element through an operational amplifier circuit. A temperature-compensated oscillator that outputs as a detection voltage. 27. The temperature-compensated oscillator according to claim 1, wherein the temperature detection circuit has a drain terminal via a resistance element, and the first of the temperature detection circuits.
And an N-channel MOS transistor whose source is connected to the second power supply line and a gate voltage of the N-channel MOS transistor exceeding the threshold voltage of the N-channel MOS transistor. A temperature-compensated oscillator comprising a gate voltage generator and outputting a voltage generated at a connection point between the drain of the N-channel MOS transistor and the resistance element as a temperature detection voltage. 28. The temperature-compensated oscillator according to claim 27, wherein the source of the N-channel MOS transistor is connected to the first power supply line via a resistance element. Oscillator. 29. The temperature-compensated oscillator according to claim 27, wherein the temperature detection circuit outputs a voltage generated at a connection point between the drain of the N-channel MOS transistor and the resistance element through an operational amplifier circuit. A temperature-compensated oscillator that outputs as a detection voltage. 30. The temperature-compensated oscillator according to claim 1, wherein the control voltage generation circuit outputs a third-order voltage generated by the third-order voltage generation circuit as a first control voltage, and further, the temperature detection circuit. A primary term voltage generation circuit that generates a primary term voltage based on the output voltage of the circuit is output, the primary term voltage generated by the circuit is output as a second control voltage, and an external voltage for frequency adjustment is input from the outside. And an output voltage output from the external control voltage input circuit as an offset input voltage of the operational amplifier circuit forming the first-order voltage generation circuit. , And the amplification factor and offset input voltage of the operational amplifier circuit that constitutes the external control voltage input circuit are controlled by digital data stored in the memory circuit. That a circuit, the frequency adjustment circuit, said first control voltage and the second
A temperature-compensated oscillator which is a circuit for controlling the oscillation frequency of the oscillation circuit according to the control voltage of 1. 31. The temperature-compensated oscillator according to claim 2, wherein the output terminal of the quadratic voltage generation circuit is further connected to at least one arbitrary voltage source via a resistance element. Temperature compensated oscillator. 32. The temperature-compensated oscillator according to claim 31, wherein the resistance element has a resistance value of 100 kilohms or more. 33. The temperature-compensated oscillator according to claim 1, wherein the preset temperature range of the operating temperature range is the second temperature region, and the temperature range on the lower temperature side is the first temperature region, When the temperature range on the high temperature side exceeding the second temperature range is set to the third temperature range, the first gate voltage generation circuit is at least the third temperature range.
In the temperature region, there is a region in which the first gate voltage linearly changes with respect to a change in temperature, and the second gate voltage generation circuit includes at least the first gate voltage generation circuit.
A temperature-compensated oscillator having a region in which the second gate voltage changes linearly with respect to temperature changes in the temperature region.