JPH0972755A - Circuit for compensating temperature dependency of signal value - Google Patents

Abstract

PROBLEM TO BE SOLVED: To compensate for the temperature dependency in the value of analog signal, e.g. a detection signal of sensor, accurately through simple circuitry. SOLUTION: A proportional amplifier circuit comprises an operational amplifier 10 receiving an input signal Si, to be compensated for the temperature dependency, through an input resistor 20 with a feedback resistor 30 being connected between the input and output thereof. A compensation resistor 32 having specified temperature dependency is built in at least one of the input resistor 20 or feedback resistor 30, e.g. the feedback resistor 30. According to the circuitry, the amplification factor of proportional amplification circuit is provided with temperature dependency and the temperature dependency in the value Vi of input signal Si is compensated or canceled accurately by the temperature dependency in the amplification factor of proportional amplification circuit being set by the resistance of compensation resistor 32. Consequently, an output signal So having a temperature independent value Vo can be taken out on the output side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature dependency compensating circuit suitable for incorporation in an integrated circuit device for compensating the temperature dependency of an analog signal value from a sensor or the like.

[0002]

2. Description of the Related Art In various electronic circuits, a detection signal from a sensor or the like is received from the outside and a predetermined operation or the like is performed in accordance with an analog signal value thereof. Since there is no exception depending on temperature,
It is necessary to compensate it as accurately as possible before using it as a reference for control operation or the like, and for this reason, the temperature dependence compensation circuit targeted by the present invention is used.

To compensate for this temperature dependence, it has been customary to use a constant current or a constant voltage having a predetermined temperature dependence. For example, in an integrated circuit device, a well-known bandgap circuit is used to make a positive correction. It is customary to compensate or cancel the temperature dependence of the signal value by creating a constant current or constant voltage with negative or accurate temperature dependence and superimposing these with the detection signal of the sensor in a circuit. .

[0004]

However, it is necessary to incorporate a constant current circuit and a constant voltage circuit in such a conventional temperature dependence compensating circuit, and not only each has a considerably complicated circuit configuration, but also compensation is required. It is necessary to accurately adapt the temperature dependence of constant current and constant voltage for each required signal. Therefore, in an integrated circuit device in which the number of input signals for which temperature dependence needs to be compensated is particularly large, a considerable amount of chip area is consumed due to the constant current circuit or constant voltage circuit, and each input signal is allocated to them. There is a problem that it takes a lot of time to set or adjust the temperature dependency.

Under these circumstances, an object of the present invention is to provide a temperature dependence compensating circuit capable of compensating for the temperature dependence of an analog signal value of an input signal with a simple circuit configuration without using a constant current circuit or a constant voltage circuit. To do.

[0006]

According to the temperature dependence compensating circuit of the present invention, an input signal to be compensated for the temperature dependence of a signal value is given to a proportional amplification circuit through an input resistor, and its input side and output are provided. A feedback resistor is connected between the input side and the feedback side, and a compensating resistor whose resistance value depends on temperature is incorporated in at least part of the input resistance and feedback resistance to make the amplification factor of the proportional amplification circuit have a predetermined temperature dependence. In addition, the above-mentioned object is achieved by taking out the output signal in which the temperature dependence of the signal value of the input signal is compensated from the output side of the proportional amplification circuit.

It should be noted that the input resistance and the feedback resistance excluding the above-mentioned compensating resistors are the ones having very little or the same temperature dependency of the resistance value, and the compensation resistors having the different temperature dependency of the resistance value are used. Is advantageous. As a proportional amplification circuit, it is preferable to connect an input resistance and a feedback resistance to one input side that receives an input signal using an operational amplifier as usual and to give a reference voltage of a predetermined value to the other input side. . Further, it is preferable that the input signal is given to this in the form of a voltage signal and the output signal is also taken out in the form of a voltage signal.

As the compensation resistance, a resistance having a positive temperature dependence,
In the case of an integrated circuit device, it is convenient to use a so-called diffusion resistance. When the signal value of the input signal has a negative temperature dependence, a compensation resistance is incorporated in the feedback resistance to increase the positive temperature of the amplification factor of the proportional amplification circuit. When the signal value of the input signal has a positive temperature dependency, it is compensated by the dependency, and a compensation resistor is incorporated in the input resistor to compensate it by the negative temperature dependency of the amplification factor of the proportional amplification circuit. It is advantageous. The temperature dependence of the diffusion resistance can be adjusted over a wide range by the impurity concentration of the resistance layer diffusing from the semiconductor surface and the type of impurities.

[0009]

According to the present invention, it is desirable that an input signal received by an electronic circuit such as an integrated circuit device is made uniform in signal value level by amplification, and if the amplification factor at that time has an appropriate temperature dependency, a very simple circuit is provided. Focusing on the fact that the temperature dependency of the signal value of the input signal can be compensated for in the configuration, a proportional amplification circuit having a feedback resistor between the input resistance and the input / output is used for this amplification as described in the configuration in the previous section. Temperature dependence that can compensate the temperature dependence of the signal value of the input signal to the amplification factor of the proportional amplification circuit by incorporating a compensation resistance whose resistance value depends on the temperature in at least one of the input resistance and feedback resistance. It is intended to have. Therefore, in the circuit of the present invention, the signal value of the input signal can be adjusted to a desired level by amplification, and at the same time, its temperature dependence can be accurately compensated.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit diagram of an embodiment in which a compensation resistor is incorporated in a feedback resistor, and FIG. 2 is a circuit diagram of an embodiment in which a compensation resistor is incorporated in an input resistor. In the embodiments of FIGS. 1 and 2, the signal values of input signals are respectively Suitable for negative and positive temperature dependence.
In these embodiments, an operational amplifier is used for proportional amplification, and diffused resistors are incorporated in the integrated circuit device as resistors.

In the embodiment as shown in FIG.
Since the input operational amplifier 10 is used, as usual, the input signal Si is applied to its inverting input through the input resistor 20, the reference voltage Vr of a predetermined value is applied to its non-inverting input, and the operational amplifier is
A feedback resistor 30 is connected between the inverting input of 10 and the output to take out the output signal So from the output side. As is well known, this proportional amplification circuit is a voltage amplification type, and the voltage values that are the signal values of the input signal Si and the output signal So are Vi and Vo, respectively. The voltage value Vo of the input signal Si has a negative temperature dependency of, for example, −3 × 10 ⁻⁴ / degree, and its temperature coefficient is represented by α.

As is well known when the amplification factor or gain of this proportional amplification circuit is G, the voltage value of the output signal So is
Vo is represented by Vo = Vr + G (Vi-Vr), and if the resistance values of the input resistance 20 and the feedback resistance 30 are Ri and Rf, respectively, (1) G = Rf / Ri is established. When it is incorporated in an integrated circuit device, Ri is several kΩ and Rf is ten and several k so that the amplification factor G becomes several times, for example.
It is better to set each to Ω.

In the embodiment shown in FIG. 1, the feedback resistor 30 is provided with a compensating resistor 32 having a predetermined temperature dependence, so that the above-mentioned amplification factor G of the proportional amplification circuit depends on the temperature Vi of the voltage value Vi of the input signal Si. It has a temperature dependence that can exactly compensate for the sex. In order to make this compensation accurate, it is advantageous to make the feedback resistance portion 31 in the input resistance 20 and the feedback resistance 30 excluding the compensation resistance 32 have the same temperature dependence. As a diffusion resistance of a sheet resistance of about 130Ω that is simultaneously diffused, the temperature coefficient β should be set to about + 1 × 10 ^-3 / degree. On the other hand, as the compensation resistor 32, a diffusion resistor having a sheet resistance different in impurity concentration or type, for example, 3 kΩ is used, and its temperature coefficient γ is preferably set to several times or more, for example, + 7 × 10 ⁻³ / degree. .

In the embodiment of FIG. 1 configured as described above, the input signal is adjusted by appropriately setting the resistance value of the compensation resistor 32.
The temperature dependence of the Si voltage value Vi can be compensated, and the resistance value for accurate compensation at this time should be determined by a strict equation, but since it becomes complicated, it is assumed here by approximate calculation. Assuming that the ratio of the resistance value of the compensation resistor 32 to the total resistance Rf of the feedback resistor 30 is represented by k (where k = 0 to 1) for convenience, the resistance value of the compensation resistor 32 is kRf and the remainder of the feedback resistor 30. The resistance value of the feedback resistor part 31 is (1-k) Rf
Can be represented by

Further, if the temperature rise is dT, the voltage value Vi of the input signal Si changes to Vi (1 + αdT) due to the above-mentioned temperature coefficient, but at the same time, the resistance value Ri of the input resistor 20 becomes Ri (1 + βdT),
The resistance value (1-k) Rf of the feedback resistor part 31 is (1-k) Rf (1 + βdT)
Since the resistance value kRf of the compensating resistor 32 changes to kRf (1 + γdT) respectively, if the resistance values after these changes are added to the formula of the amplification factor G in (1) and the first-order approximation is taken, the temperature rise (2) G _T / G = 1 + k (γ−β) dT is established, where the amplification factor at time is G _T. This is an expression showing the temperature dependence of the amplification factor G. In the present invention, the temperature dependence of the voltage value Vi of the input signal Si is compensated by the temperature dependence of the amplification factor G, and therefore the following formula is established. To do.

-Α = k (γ-β) If the positive temperature coefficient γ of the resistance value of the compensation resistor 32 is larger than the temperature coefficient β of the resistance value of the input resistor 20 or the feedback resistor portion 31, the voltage of the input signal Si is It can be seen that the negative temperature coefficient α of the value Vi can be compensated. The resistance value of the compensation resistor 32 required for this purpose can be determined by the equation (3) k = -α / (γ-β). As described above, α = −3x
^{10 -4, β = + 1x10 -3} , when a gamma = + 7x10 ^-3 is k
= 0.05, that is, the resistance value kRf of the compensation resistor 32 should be set to 5% of the total resistance value Rf of the feedback resistor 30.

In the next embodiment shown in FIG. 2, the voltage value of the input signal Si is set by incorporating the compensation resistor 22 into the input resistor 20.
Compensate the temperature dependence of Vi. Also in this embodiment, the input resistance 20
If the same temperature coefficient β of resistance value is used for the remaining input resistance portion 21 and feedback resistance 30 in the above and the positive temperature coefficient γ of resistance value is larger than that for the compensation resistance 21, Assuming that the ratio of the resistance value of 22 to the total resistance Ri of the input resistance 20 is k, the amplification factor G at the time of temperature rise is the same as in the previous embodiment.
_T is approximately represented by (4) G _T / G = 1-k (γ-β) dT, and the temperature dependence of the voltage value Vi of the input signal Si is compensated by the temperature dependence of the amplification factor G. Therefore, α
= K (γ−β) holds. From this, the resistance value of the compensation resistor 32 necessary for temperature compensation in the embodiment of FIG. 2 can be determined by (5) k = α / (γ−β).

As can be seen from the above, in the embodiment of FIG. 2, when the positive temperature coefficient γ of the resistance value of the compensation resistor 22 is set to be larger than the temperature coefficient β of the resistance value of the input resistance portion 21 and the feedback resistor 30, It is possible to compensate the positive temperature coefficient α of the voltage value Vi of the input signal Si, which is the reverse of the embodiment shown in FIG. Temperature coefficient α
Similar to the previous embodiment, the resistance value kRi of the compensation resistor 22 may be set to 5% of the total resistance value Ri of the input resistor 20 when β and γ are the above values.

The present invention is not limited to the embodiments described above, and can be implemented in various modes. For example, although the compensation resistors 22 and 32 have the positive temperature coefficient γ in the embodiment, on the contrary, by giving the negative temperature coefficient to the positive temperature coefficient Vi of the voltage value Vi of the input signal Si in the circuit example of FIG. The dependency, in the circuit example of FIG. 2, can be compensated for the negative temperature dependency. In the case of an integrated circuit device, for example, n-type polycrystalline silicon resistors can be used as the compensation resistors 22 and 32.

Further, in the above-mentioned numerical example, the compensation resistors 22 and 32 are
Since the temperature coefficient γ of is larger than the temperature coefficient β of other resistors by several times or more, the ratio k of the resistance values of the compensating resistors 22 and 32 to the total resistance values of the input resistor 20 and the feedback resistor 30 can be small.
The difference between the temperature coefficients γ and β is small and the voltage value Vi of the input signal Si is
Has a large temperature coefficient α and the ratio k according to Eqs. (3) and (5) is 1
In the case of exceeding, the compensation resistors 22 and 32 can be incorporated in the input resistor 20 and the feedback resistor 30, respectively, by using those having positive and negative temperature coefficients. In this case, the temperature coefficients of the resistance values of the compensating resistors 22 and 32 are γ _i and γ _f , respectively.
If the ratio of the feedback resistance 30 and the total resistance of the feedback resistor 30 is k, the ratio k can be determined by (6) k = α / (γ _i −γ _f ) regardless of the temperature coefficient β.

[0021]

As described above, in the temperature dependence compensation circuit of the present invention, a proportional amplification circuit in which an input signal whose signal value has temperature dependence is received via an input resistance and a feedback resistance is connected between the input and output is provided. Incorporating a compensating resistor whose resistance value has temperature dependence in at least one of the input resistance and feedback resistance to give a predetermined temperature dependence to the amplification factor of the proportional amplification circuit. The following effects can be obtained by taking out the output signal in which the temperature dependence of the value is compensated from the proportional amplification circuit.

(A) By setting the resistance value of the compensation resistor according to its temperature coefficient and the temperature coefficient of the signal value of the input signal very simply, the temperature dependence to be given to the amplification factor of the proportional amplification circuit is set. As a result, the temperature dependence of the input signal can be accurately compensated, and the output signal can be extracted with a signal value having no temperature dependence. (b) Since the temperature dependence of the signal value of the input signal is compensated for by using the amplifier circuit that is usually required to adjust the signal value of the input signal to a predetermined level, the constant current circuit or constant voltage circuit as in the conventional technology is used. It is not necessary to add a circuit, and the signal value of the input signal can be temperature-compensated with a very simple circuit configuration.

(C) Since the proportional amplification circuit is used for temperature compensation, the temperature dependence of the signal value of the input signal can be compensated, and at the same time, the output signal obtained by accurately proportionally amplifying it can be taken out. Moreover, as can be seen from equations (3), (5), and (6) above, the resistance values of the input resistance and feedback resistance are not particularly related to temperature compensation, so amplification of the proportional amplification circuit is independent of the compensation conditions. You can set the rate.

It should be noted that the embodiment of the present invention in which the input resistance and the feedback resistance other than the compensation resistance have the same temperature dependence of the resistance value and the compensation resistance whose resistance value has a different temperature dependence is used. The advantage is that the resistance value given to the compensation resistor can be set very easily. Further, an embodiment in which an input amplifier and a feedback resistor are connected to one input side of the proportional amplification circuit that receives an input signal using an operational amplifier and a reference voltage of a predetermined value is applied to the other input side is a proportional amplification circuit. There is an advantage that the signal value level of the output signal can be freely selected according to the reference voltage value so as to be convenient for signal processing by the circuit receiving it.

Further, a mode in which a compensating resistor having a positive temperature coefficient is incorporated in the feedback resistor so that the amplification factor of the proportional amplification circuit has a positive temperature dependency, when the signal value of the input signal has a negative temperature dependency, The mode in which this is incorporated into the input resistor to make the amplification factor of the proportional amplification circuit have a negative temperature dependence is particularly advantageous in the case where the signal value of the input signal has a positive temperature dependence, and in the case of an integrated circuit device, There is an advantage that the diffusion resistance for the compensation resistance can easily and accurately have a positive temperature coefficient by selecting the impurity concentration and the like.

[Brief description of drawings]

FIG. 1 is a circuit diagram of an embodiment of the present invention in which a compensation resistor is incorporated in a feedback resistor.

FIG. 2 is a circuit diagram of an embodiment of the present invention in which a compensation resistor is incorporated in an input resistor.

[Explanation of symbols]

 10 Operational amplifier 20 Input resistance 22 Compensation resistance incorporated in input resistance 30 Feedback resistance 32 Compensation resistance incorporated in feedback resistance Ri Input resistance value kRi Compensation resistance resistance value incorporated in input resistance Rf Feedback resistance resistance Value kRf Resistance value of compensation resistor incorporated in feedback resistor Si input signal So output signal Vi Input signal voltage value Vo Output signal voltage value Vr Reference voltage

Claims (5)

[Claims] 1. A proportional amplification circuit configured to receive an input signal whose signal value depends on temperature via an input resistor, wherein a feedback resistor is connected between an input side and an output side of the input resistor and the feedback resistor. An output that compensates the temperature dependence of the signal value of the input signal by the temperature dependence of the amplification factor from the output side of the proportional amplification circuit by incorporating a compensation resistance whose resistance value has a predetermined temperature dependence in at least one part of A temperature-dependent compensation circuit for signal values, which is characterized in that a signal is taken out. 2. The circuit according to claim 1, wherein a compensation resistor having a positive temperature dependency is incorporated in a feedback resistor, and a positive temperature dependency of an amplification factor of a proportional amplification circuit causes a negative temperature of a signal value of an input signal. A temperature dependency compensating circuit for a signal value, wherein an output signal whose dependency is compensated is taken out. 3. The circuit according to claim 1, wherein a compensation resistor having a positive temperature dependency is incorporated in the input resistor, and the positive temperature of the signal value of the input signal is increased by the negative temperature dependency of the amplification factor of the proportional amplification circuit. A temperature dependency compensating circuit for a signal value, wherein an output signal whose dependency is compensated is taken out. 4. The circuit according to claim 1, wherein the input resistance and the feedback resistance excluding the compensation resistance have the same temperature dependence of resistance value, and the compensation resistance has the temperature dependence of resistance value. A circuit for compensating for temperature dependence of signal value, characterized in that a circuit different from the above is used. 5. The circuit according to claim 1, wherein an operational amplifier is used in the proportional amplification circuit and an input resistance and a feedback resistance are connected to one input side of the input side for receiving an input signal, and the other input side has a predetermined value. A temperature-dependent compensation circuit for a signal value, characterized in that a reference voltage is applied.