JP2702407B2 - Temperature compensation circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature compensating circuit for generating a temperature compensating voltage corresponding to a temperature change in order to perform temperature compensation of a device having a temperature fluctuation, and more particularly to a temperature compensating circuit which is not necessarily proportional to the temperature. The present invention relates to a temperature compensation circuit suitable for a required device.

[0002]

2. Description of the Related Art A conventional temperature compensating circuit of this kind is disclosed in Japanese Patent Laid-Open Publication No. 63-296506. The temperature compensating circuit includes a variable voltage generating unit that outputs a voltage that changes according to a temperature change in order to generate a temperature compensation voltage to be applied to a voltage-controlled variable attenuator for correcting a gain variation of the amplifier. A constant voltage generating means for constantly generating a constant voltage regardless of a temperature change, and an output voltage of the variable voltage generating means as a temperature compensation voltage in a certain temperature range, and a constant voltage generation at a temperature outside this temperature range. A switching circuit for setting the output voltage of the means to a temperature compensation voltage.

[0003]

The temperature compensation voltage generated by the above-described prior art temperature compensation circuit is the inflection point of the temperature compensation voltage characteristic (that is, the temperature at which the rate of change of the temperature compensation voltage changes). However, there is a drawback that it is inflexible for various devices having different bending points, since the device is fixed at the above-mentioned constant voltage.

Further, there is a disadvantage that the variable voltage generating means requires fine adjustment of circuit constants in order to change the rate of change (gradient) of the temperature compensation voltage with respect to temperature.

[0005]

According to the present invention, there is provided a temperature compensating circuit comprising: a temperature-sensitive element for generating a first voltage whose voltage decreases with a rise in temperature; a first inverting amplifier for inverting and amplifying the first voltage; A second inverting amplifier for inverting and amplifying the first voltage so as to generate a predetermined voltage corresponding to the predetermined voltage when the first voltage is equal to or higher than a predetermined voltage; an output of the first inverting amplifier; An adder for adding the output of the inverting amplifier.

[0006] One of the temperature compensation circuits may be configured such that when the first voltage is equal to or lower than a predetermined voltage, the first inverting amplifier and the second inverting amplifier have substantially the same amplification. it can.

Another one of the temperature compensation circuits is that the temperature-sensitive element generates the first voltage substantially proportional to an absolute temperature,
The second inverting amplifier includes a constant voltage diode circuit that limits the first voltage to the predetermined voltage or less, and the adder inverts and adds an output of the first inverting amplifier and an output of the second inverting amplifier. A configuration that is an operational amplifier can be employed.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings.

FIG. 1 is a circuit diagram of one embodiment of the present invention.
FIGS. 2A and 2B are diagrams showing main characteristics of the present embodiment, wherein FIG. 2A shows a relative gain-temperature characteristic when the multistage amplifier 1 does not have temperature compensation, FIG. 2B shows an output voltage-temperature characteristic of the temperature sensitive element 2, and FIG. (C)
Is the relative attenuation-voltage characteristic of the variable attenuator 13, (d) is the output voltage-temperature characteristic of the inverting amplifiers 4 and 5, (e) is the output voltage-temperature characteristic of the inverting amplifier 3, and (f) is the multistage amplifier 1. 5 shows the relative output-temperature characteristics of FIG.

Referring to FIGS. 1 and 2, a multi-stage amplifier 1 of this embodiment amplifies a microwave input signal Pi supplied from an input terminal 1 while compensating for a gain variation due to a temperature change, and outputs the amplified signal. An output signal Po is generated at the terminal 16. The multistage amplifier 1 includes a plurality of amplifiers 12, 14,..., 15 connected in cascade between an input terminal 11 and an output terminal 16.
And a variable attenuator 13 provided at an appropriate position between the amplifiers and performing gain temperature compensation of the amplifiers. The variable attenuator 13 changes the amount of attenuation of the microwave signal under the control of the temperature compensation voltage V3, and controls the gain of the multi-stage amplifier 1. Further, the temperature sensing element 2, the inverting amplifiers 3, 4 and 5, and the constant voltage diode (Zener diode) D1
And resistors R1 to R12 determine the gain of multi-stage amplifier 1.
A temperature compensating circuit for generating a temperature compensating voltage V3 suitable for temperature compensation of the temperature characteristic to make it substantially flat.

When the amplifier element of the amplifier is an FET (field effect transistor), each of these amplifiers
It has gain-temperature characteristics of about -0.015 dB / ° C. This gain-temperature characteristic does not necessarily have a primary slope depending on the design of the amplifier, but has a characteristic having a bending point. FIG. 2A shows a 20-stage amplifier 1 in the multi-stage amplifier 1.
, 15 (that is, the circuit excluding the variable attenuator 13) shows the relative gain-temperature characteristics. This relative gain-temperature characteristic has a primary slope of −5 dB / 25 ° C. between -25 ° C. and 0 ° C. of the temperature T, where 0 ° C. is a bending point, and 0 ° C. to 25 ° C. -10dB / 2 between
It has a primary slope of 5 ° C. Also, the variable attenuator 13
This is a voltage-controlled variable attenuator using a PIN diode, and as shown in a relative attenuation-voltage characteristic of FIG.
In the temperature compensation voltage V3 range from 5.0 V to 6.0 V, the attenuation change of the primary slope of 20 dB / 1 V is shown.

Therefore, in order to obtain a flat relative output ΔPo having a gain-temperature characteristic at the output terminal 16 of the multistage amplifier 1 as shown in FIG. 2 (f), the temperature compensation voltage V 3 applied to the variable attenuator 12 must be adjusted. FIG. 2 shows the output voltage-temperature characteristics.
As shown in (e), the range between −25 ° C. and 0 ° C. is −0.2.
It is necessary to have a primary slope of 5V / 25 ° C, a bending point of 0 ° C, and a primary slope of -0.5V / 25 ° C between 0 ° C and 25 ° C. FIG. 2E shows the temperature compensation circuit of this embodiment.
And a circuit for obtaining a temperature compensation voltage V3 having an output voltage-temperature characteristic having different inclinations with respect to the inflection point.

In the temperature compensation circuit of this embodiment, the temperature sensing element 2 generates a first voltage V2 corresponding to a change in temperature T as shown in FIG. The first voltage V <b> 2 decreases as the temperature rises, and exhibits a primary slope of −0.5 V / 50 ° C. (= ° K) between −25 ° C. and 25 ° C. As the temperature sensing element 2 that generates the first voltage V2 having the primary slope, the LM3911 type Temperature Co.
ntroller (National Semiconductor)
ductor, USA). In order to obtain the first voltage V2 whose output voltage-temperature characteristic shows a primary slope, as shown in the above-mentioned publication (FIGS. 1 and 4), the output voltage of the thermistor circuit is inverted by an operational amplifier or the like. It can also be used.

The first voltage V2 is supplied to an input terminal of a first inverting amplifier comprising an inverting amplifier 4 and resistors R5, R6, and R7 (having a resistance value of 1 KΩ), an inverting amplifier 5, a resistor R8,
R9, R10, R11 (above, resistance value 1 KΩ), R12
(A resistance value of 100 KΩ) and a constant voltage diode D1 (zener voltage Vz is 2.75 V) and is supplied to an input terminal of a second inverting amplifier. Here, the first voltage V2 is directly applied to the minus input terminal of the inverting amplifier 4 via the resistor R6, while the minus voltage terminal is applied to the minus input terminal of the inverting amplifier 5 via the resistors R11 and R9. It should be noted that the first voltage V2 whose voltage is equal to or higher than the zener voltage Vz is clipped by D1. When the first voltage V2 is equal to or lower than the zener voltage Vz, the voltage drop of the first voltage V2 due to the resistor R11 is negligible.

The first inverting amplifier and the second inverting amplifier invert and amplify the first voltage V2 with an amplification factor of 1, and output output voltages V4 and V5, respectively. However, when the first voltage V2 is equal to or higher than the zener voltage Vz, the second inverting amplifier sets the input first voltage V2 to the zener voltage Vz.
And is applied to the-input terminal, thereby generating an output voltage V5 of a constant voltage of -2.75 V which is an inversion of the zener voltage Vz (see FIG. 2D). This output voltage V5
Has an inflection point at the temperature T = 0 ° C., that is, −2.75 V which is the inversion of the zener voltage Vz.

The output voltages V4 and V5 correspond to the inverting amplifier 3 and the resistors R1, R3, R4 (the resistance value is 2 KΩ), R
2 (a resistance value of 2 KΩ), and the adder generates a temperature compensation voltage V3. That is, the resistor R3
Output voltage V4 through resistor R4 and output voltage V4 through resistor R4
5 are supplied to the minus input terminal of the inverting amplifier 3 and added together. Then, the inverting amplifier 3 and the resistors R1 and R2 constitute an operational amplifier having an amplification degree of -1, and generate a temperature compensation voltage V3 as shown in FIG. In addition,
The temperature compensation voltage V3 output from the adder is derived from the following equation. Here, each of R1, R3, and R4 in the equation indicates the resistance value of the same sign resistor.

V4 / R3 + V5 / R4 = -V5 / R1 Therefore, V5 = -R1 (V4 / R3 + V5 / R4) As described above, the variable attenuator 13 uses the temperature compensation voltage V3
As a result, the multi-stage amplifier 1
(F), the relative output Δ of flat gain-temperature characteristics
An output signal Po indicating Po can be obtained at the output terminal 16. The voltage V3x shown in FIG. 2E indicates the output voltage of the inverting amplifier 5 when the constant voltage diode D1 is omitted, and the relative output ΔPox shown in FIG.
The relative output at the output terminal 16 of the multistage amplifier 1 when the variable attenuator 13 is controlled by 3x is shown. As described above, when the temperature characteristic of the output voltage from the inverting amplifier 3 has no bending, if the temperature T is appropriately compensated from 0 ° C. to 25 ° C., on the contrary, the temperature from −25 ° C. to 0 ° C. In the range, it becomes overcompensated.

Here, the first inverting amplifier and the second
Each of the inverting amplifier and the adder has been described with reference to the example of the inverting amplifier having the amplification degree of -1. However, the amplification degree of these inverting amplifiers can be changed by appropriately setting the feedback resistors R5, R8, and R1. As a result, the temperature compensation voltage V3 having a desired temperature-temperature compensation voltage characteristic (gradient) can be easily generated. The inflection point of the temperature compensation voltage V3 can be easily adjusted by changing the zener voltage Vz of the constant voltage diode D1.

In this embodiment, an inverting adder is used as the adder and a negative temperature characteristic element is used as the temperature-sensitive element. However, a positive adder may be used as the adder or the temperature-sensitive element 2 may be used as described above. Using a thermistor circuit having a positive temperature characteristic such as the thermistor circuit described above, it is possible to obtain a gradient temperature compensation voltage V3 whose temperature versus temperature compensation characteristic is opposite to that of the present embodiment with respect to the inflection point.

[0020]

As described above, according to the present invention, the first voltage generated by the temperature sensing element is inverted and amplified by the first inverting amplifier and the second inverting amplifier which generates a voltage corresponding to the predetermined voltage when the voltage is equal to or higher than the predetermined voltage. Since the output of the first inverting amplifier and the output of the second inverting amplifier are added by an adder to generate a temperature compensation voltage, a temperature compensation voltage having a desired temperature-temperature compensation voltage characteristic and its slope inflection point can be obtained. There is an effect that it can be easily generated.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of one embodiment of the present invention.

FIGS. 2A and 2B are diagrams showing main characteristics of the present embodiment, in which FIG. 2A shows a relative gain-temperature characteristic when the multistage amplifier 1 does not have temperature compensation, and FIG. 2B shows an output voltage-temperature characteristic of the thermosensitive element 2; , (C)
Is a relative attenuation-voltage characteristic of the variable attenuator 13, (d) is an output voltage-temperature characteristic of the inverting amplifiers 4 and 5, (e) is an output voltage-temperature characteristic of the inverting amplifier 3, and (f) is a multistage amplifier 1. 5 shows the relative output-temperature characteristics of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Multistage amplifier 2 Temperature sensing element 3-5 Inverting amplifier circuit 11 Input terminal 12,14,15 Amplifier 13 Variable attenuator 16 Output terminal R1-R12 Resistor D1 Constant voltage diode

Claims (3)

(57) [Claims] 1. A temperature-sensitive element for generating a first voltage corresponding to a temperature change, a first inverting amplifier for inverting and amplifying the first voltage, and, when the first voltage is equal to or higher than a predetermined voltage, corresponding to the predetermined voltage. A second inverting amplifier for inverting and amplifying the first voltage so as to generate the predetermined voltage, and an adder for adding an output of the first inverting amplifier and an output of the second inverting amplifier. Temperature compensation circuit. 2. When the first voltage is equal to or less than the predetermined voltage, the first inverting amplifier and the second inverting amplifier include:
2. The temperature compensation circuit according to claim 1, wherein the temperature compensation circuit has substantially the same amplification degree. 3. The constant-voltage diode circuit, wherein the temperature-sensitive element generates the first voltage whose voltage decreases as the temperature rises, and wherein the second inverting amplifier limits the first voltage to the predetermined voltage or less. The temperature compensating circuit according to claim 1, wherein the adder is an operational amplifier that inverts and adds the output of the first inverting amplifier and the output of the second inverting amplifier.