JP2750886B2 - Temperature sensitive voltage generating circuit and temperature compensating element using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial application field) The present invention relates to a temperature-sensitive voltage generation circuit that detects the ambient temperature of a partial area and generates a sensitive voltage. The present invention relates to a temperature compensating element applied to a compensation voltage generating circuit in the case of double compensation.

BACKGROUND OF THE INVENTION Temperature-compensated oscillators have become widespread, particularly for compensating for frequency changes due to temperature characteristics caused by quartz oscillators. In recent years, there has been a demand for a temperature-compensated oscillator that is even more stable with respect to temperature due to increasingly severe communication situations and the like.

(Prior Art) FIG. 13 is a block diagram of a temperature-compensated oscillator for explaining a conventional example of this kind.

The temperature compensation oscillator includes an oscillation circuit 1 and a temperature compensation circuit 2. The oscillation circuit 1 uses the crystal oscillator 3 as an oscillator, and connects one end of the crystal oscillator 3 to, for example, the oscillation transistor 5 on the circuit side 4. Then, together with other circuit elements such as a capacitor (not shown), for example, a Colpitts-type circuit network is formed. The crystal resonator 3 has a thickness shear vibration mode in which the cutting angle is, for example, an AT cut. Note that V _CC in the figure is a power supply, and V _O is an output. In such an oscillator circuit 1, the curve (a) in FIG.
The temperature characteristics are as shown in FIG. In other words, a cubic curve having an inflection point near normal temperature of 25 ° C., which is the main cause of the crystal resonator 3, is obtained.

The temperature compensation circuit 2 includes a compensation voltage generation circuit 6 (hereinafter, referred to as a voltage generation circuit 6) and a voltage variable capacitance element 7. The voltage generating circuit 6 is composed of a serial / parallel network (not shown) including a temperature sensing element (for example, a thermistor 8) and a resistor 9 connected between the power supply V _CC and the ground potential. Then, the compensation voltage V _S1 responsive to the ambient temperature is obtained at the output terminal a by the resistance value of the thermistor 8. The voltage variable capacitance element 7 is, for example, a voltage variable capacitance diode (hereinafter, referred to as a variable capacitance diode). The cathode side is grounded to the output terminal a of the voltage generation circuit 6, and the anode side is grounded to the ground potential. Then, a connection point between the voltage generation circuit 6 and the variable diode 7 is connected to one end of the crystal unit 3.
In such a case, the compensation voltage V _S1 is set to a value that compensates for the temperature characteristic of the oscillation circuit 1 to obtain a compensation temperature characteristic satisfying the standard (the curve (b) in FIG. 14).

(Problems of the Related Art) However, the temperature compensated oscillator having the above configuration has the following problems that cannot be theoretically avoided.

That is, as is clear from the curve (C) connecting the circles in FIG. 15 in which the above-mentioned compensation temperature characteristics are enlarged, for example, the temperature tolerance ΔT ₁ is -30 to 70 ° C. and the frequency tolerance (hereinafter referred to as tolerance) Assuming that Δf / f is ± 2 ppm, this compensation temperature characteristic satisfies the standard. However, the standard is the same temperature range ΔT ₁
-20 ° C indicated by the dotted line frame when the tolerance is ± 1ppm
And at 60 ° C, outside the standard.

Conventionally, in such a case, the value of each resistor 9 is corrected by recalculation based on the compensation temperature characteristic. Thus, the voltage generating circuit 6 was newly manufactured and replaced, thereby satisfying the standard of the allowable deviation ± 1 ppm. However, in general, even a resistor having a good value has an error of 1 to 2%.
Strictly speaking, regarding the thermistor, the error of the resistance value and the B constant at each temperature also change. Therefore, even if the value of each resistor 9 is corrected, an error of about ± 0.5 ppm occurs with respect to the compensation temperature characteristic by theoretical calculation. For this reason, in the conventional temperature compensated oscillator, even if the voltage generation circuit 6 is remanufactured, it is theoretically difficult to reduce the allowable deviation to ± 1 ppm or less due to the accuracy problem of each element. When the allowable deviation Δf / f is set to ± 1 ppm or less, there is a problem that the yield is extremely deteriorated and the productivity is reduced.

(Points and Objects of the Invention) The present invention focuses on the point that the temperature specification can be satisfied by further compensating only for a part of the temperature region exceeding the allowable deviation in the temperature within the standard. It is an object of the present invention to provide a temperature-sensitive voltage generating circuit for generating a sensitive voltage and a temperature compensation element using the same.

(SOLUTION) The present invention is set to the first transistor to be ON from OFF at temperatures T ₁ is set to the bias voltage by the first temperature sensitive device sensitive to the ambient temperature, the bias voltage by the second temperature sensitive device and connects the second transistor from oN to OFF at temperature T ₂ Te, that the formation of the temperature-sensitive voltage generation circuit from the switching circuit to operation period when the temperature T ₁ of the T _2, and which from the temperature compensation element Is a solution. Hereinafter, an embodiment of the present invention will be described.

(Embodiment) FIG. 1 is a diagram of a temperature-sensitive voltage generating circuit for explaining an embodiment of the present invention.

The compensation voltage generating circuit 10 includes a switching circuit in which first and second transistors Tr ₁ and Tr ₂ are provided in series with the power supply V _CC (+ DC) on the collector side and the ground potential on the emitter side. The load resistor R ₁ to the collector side of the transistor Tr ₁ in the switching circuits, between the emitter of the collector and Tr ₂ of Tr ₁ provided by cascade a resistor R ₂ and R _3. And
The connection point between the resistor R ₂ and R ₃ to the output terminal b. The resistance of the thermistor RT ₁ and the resistance R ₄ as bias dividing resistance of the transistor Tr _1, for the same resistance Tr ₂ R ₅ and the thermistor RT ₂
Are provided on the base side. Thermistors RT ₁ and R
Temperature voltage characteristic of T ₂ are, resistance in response thereto in accordance with the transition from low to high temperature side as shown in FIG. 2 decreases exponentially. Then, as shown in FIG. 3, the thermistor RT ₁ and the resistance R ₄ is set to be ON from OFF at temperatures T ₁ and transistor TR ₁ "figure (a)." The resistance R ₅ and the thermistor RT ₂ is turned ON, the temperature T ₂ of the transistor Tr ₂
FIG. 3 (b) is set so as to be turned off.

In such a case, the first and second transistors T
r _1, Tr ₂ turned ON, the OFF, the period from temperatures T ₁ to T ₂ and the operation period of the switching circuit (Tr _1, Tr ₂₎ "FIG. 3 (c)". Therefore, during the operation period of the switching circuit as shown in FIG. 4 by the voltage drop across the load resistance R _1,
The output voltage between the resistor R ₂ and R ₃ are reduced. That is, in some region between temperatures T ₁ to T ₂ are a sensitive voltage V ₂ in response to this, a higher normal voltages V ₁ priority than sensitive voltage V ₂ except some areas. In addition, normal voltage V ₁ pressure and sensitive voltage
The value of V ₂ can be set freely by resistors _{R 1, R 2, R 3} .

Therefore, as shown in FIG. 5, if a variable-capacitance diode 11 is connected to the output terminal of the temperature-sensitive voltage generating circuit 10 and a DC blocking capacitor 12 is provided, a part of FIG. A voltage variable capacitance element as the temperature compensation element 13 whose capacitance value changes only in the temperature region can be obtained as shown in FIG. Then, as shown in FIG. 6, if this temperature compensating element is connected to the above-described temperature compensating oscillator (see FIG. 13), the temperature in the compensating temperature characteristic is changed from T ₁ to T _2.
The part exceeding -1 ppm of time is further compensated for and the part
As shown in the p portion of the curve (d) in FIG. 15, the concentration can be within ± 1 ppm. However, in this case, the frequency change the sensitivity voltage V ₂ as the compensation voltage is set to a value such that within ± 1 ppm. Further, at the time of application of the normal voltages V ₁ compensation temperature characteristics must be adjusted by, for example, the variable capacitor so as not to change. In such a device, it is not necessary to remanufacture and replace the voltage generating circuit 6 (temperature compensating circuit 2) as in the prior art, and it is sufficient to add this temperature compensating element to the conventional temperature compensating oscillator. To improve the productivity.

(Another Embodiment) FIG. 7 is a diagram of a temperature-sensitive voltage generating circuit for explaining another embodiment of the present invention.

The temperature-sensitive voltage generating circuit 14 of this embodiment is
_It consists of a switching circuit in which transistors Tr ₃ and Tr ₄ are provided in parallel with _CC (+ DC) on the collector side and earth potential on the emitter side. In the switching circuit, the collector of the transistor Tr ₃ (Tr ₄₎ is a load resistor R _6, between the collector of Tr ₃ and the emitter (ground potential) provided by cascade a resistor R ₇ and R _8. Then, the connection point between the resistor R ₇ and R ₈ and the output terminal c. Further, the thermistor RT ₃ and a resistor R ₉ as bias dividing resistance of the transistor Tr _3, provided a resistor R ₁₀ and the thermistor RT ₄ for the same resistance Tr ₄ to the base side. Then, Samita RT ₃ and the resistor R ₉ is, OFF at a temperature T ₄ of the transistor Tr _3, as shown in Figure 8 (a)
It is set to turn ON from. The resistance R ₁₀ and the thermistor RT ₄ is set to be OFF from ON the transistor Tr ₄ to a temperature T ₃ "Figure 8 (b)".

In such a case, the third and fourth transistors T
ON the r _3, Tr _4, the OFF, the period from the temperature T ₃ to T ₄ the operation period of the switching circuit (Tr _3, Tr ₄₎ "Figure 8 (c)". Therefore, the operating period Tr of the switching circuit
_{Since 3} and Tr ₄ are turned off, the output voltage between the resistors R ₃ and R ₄ increases. That is, as shown in FIG.
In some region between T ₃ to T ₄ and sensing voltage V ₄ in response to this, the normal voltage V ₃ lower level than the sensitive voltage V ₄ except partial region. Note that the normal voltage V ₃ and the sensitive voltage V ₄
Can be freely set by the resistors R ₁ , R ₂ and R ₃ as described above.

Therefore, also in this embodiment, as shown in FIG. 10, a variable capacitance diode is connected to the output terminal of the temperature-sensitive voltage generation circuit 14.
If a DC blocking capacitor 16 is provided by connecting the capacitor 15 as shown in FIG. 3A, a voltage variable capacitor as a temperature compensating device 17 whose capacitance changes only in a partial temperature region can be obtained. "FIG. (B)". Then, this temperature compensating element is
As shown in FIG. 11, do it connects to the temperature compensated oscillator described above, the compensation temperature from the temperature T ₃ in the characteristics and further compensate the portion exceeding 1ppm o'clock T _4, the FIG. 13 prior to the partial curve It can be within ± 1 pmm as shown in the p part of (d). However, also in this case, the sensitive voltage V ₄ as the compensation voltage
Is set to a value such that the frequency change is within ± 1 ppm.
Further, at the time of the application of normal voltage V ₃ compensation temperature characteristics must be adjusted by, for example, the variable capacitor so as not to change. In such a case, the voltage generation circuit 6 (temperature compensation circuit 2) does not need to be remanufactured and replaced as in the related art, so that the yield is improved and the productivity is improved.

(Other Matters) In the above embodiment, the case where the portion deviating to the + side or the − side in the conventional compensation temperature characteristic is separately compensated has been described. However, as shown in FIG. It goes without saying that the off-side portion may be compensated for together. Basically, it is possible to compensate for a portion exceeding the standard regardless of the form of the temperature compensation characteristic.
Although the conventional compensation temperature characteristic is based on voltage control, the compensation temperature characteristic is, for example, directly connected to a thermistor, a capacitor, and a resistor.
The present invention can be applied even when a so-called direct compensation method including a parallel circuit is used.

The present invention has the following additional effects. In other words, the temperature characteristic of the crystal unit 3 is theoretically a cubic curve having an inflection point near room temperature of 25 ° C. However, in practice, even if the temperature characteristic is designed with the theoretical temperature characteristic as a target, The temperature characteristic is distorted by a slight influence such as a difference in cutting angle.
Among these, there is a crystal oscillator for a temperature-compensated oscillator that cannot be used because its temperature characteristics cannot be fully compensated. However, if the present invention is applied, even if the temperature characteristic deviates somewhat from the theoretical value, the temperature characteristic can be partially compensated and sufficiently used, and this has an effect of making the manufacturer very economically advantageous.

Further, the temperature-sensitive voltage generating circuit has been described as a temperature compensating element of the temperature-compensating oscillator, but it is needless to say that the temperature-sensitive voltage generating circuit can be applied as a sensor for detecting the temperature of a partial area.

(Effect of the Invention) According to the present invention, the temperature-sensitive voltage generating circuit is set with the bias voltage by the first temperature-sensitive element that senses the ambient temperature, and the temperature T ₁
A first transistor which becomes ON from OFF at, OF from ON at temperature T ₂ is set to the bias voltage by the second temperature sensitive device
By connecting to the second transistor which becomes F, the temperature T ₁ to T ₂
In this case, since the switching circuit is formed as an operation period, a sensitive voltage is generated only in a part of the temperature range and can be used as a compensation voltage of a temperature-compensated oscillator. In this case, the effect of improving productivity can be obtained. .

[Brief description of the drawings]

FIG. 1 is a diagram of a temperature-sensitive voltage generating circuit illustrating one embodiment of the present invention, FIG. 2 is a diagram of a temperature resistance characteristic of a thermistor, FIG.
5A, 5B, and 5C are switching characteristic diagrams for explaining the operation of the temperature-sensitive voltage generating circuit of the embodiment, FIG. 4 is a temperature-voltage characteristic diagram of the embodiment, and FIG. FIG. 5 (b) is a diagram of a temperature compensating element utilizing the embodiment, FIG. 5 (b) is a temperature capacity characteristic diagram of the temperature compensating element, and FIG. 6 is a schematic configuration diagram of a temperature compensating oscillator using the temperature compensating element. FIG. 7 is a diagram of a temperature-sensitive voltage generating circuit illustrating another embodiment of the present invention, and FIGS. 8 (a), (b) and (c) are switching diagrams illustrating the operation of the temperature-sensitive voltage generating circuit of the embodiment. FIG. 9 is a temperature-voltage characteristic diagram of the embodiment, and FIG.
FIG. 10 (b) is a diagram of a temperature compensation element using the same embodiment.
FIG. 11 is a temperature capacity characteristic diagram of the temperature compensation element, and FIG. 11 is a schematic configuration diagram of a temperature compensation oscillator using the temperature compensation element. FIG. 12 is a schematic configuration diagram of a temperature compensated oscillator for explaining another embodiment of the present invention. FIG. 13 is a schematic configuration diagram of a temperature compensated oscillator for explaining a conventional example, FIG. 14 is a temperature characteristic diagram, and FIG. 15 is a curve (a) in FIG.
FIG.

Claims (3)

(57) [Claims] A first resistor whose resistance value changes in response to an ambient temperature;
OFF at temperatures T ₁ by setting the bias voltage by the temperature sensitive element
A first transistor becomes ON from and a second transistor from ON to OFF at temperature T ₂ to set the bias voltage by the second temperature sensitive element that changes the resistance value by responding to the ambient temperature, the by the first transistor and the second transistor forming a switching circuit as a operation period when the temperature T ₁ of the T _2, the temperature-sensitive voltage, characterized in that so as to generate only sensitive voltage operation period of the switching circuit Generator circuit. 2. The apparatus according to claim 1, wherein said sensitive voltage is a compensation voltage applied to a voltage variable capacitance element connected to a crystal resonator of a temperature-compensated crystal oscillator to compensate for a frequency-temperature characteristic of the crystal oscillator. 2. The temperature-sensitive voltage generation circuit according to claim 1. 3. A temperature compensating element, wherein a voltage variable capacitance element is connected to an output terminal of the temperature-sensitive voltage generating circuit according to claim 1 for compensating frequency temperature characteristics of a crystal oscillator. .