JP2006074129A - Temperature characteristic correction circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a temperature characteristic correction circuit which is used as circuits having various temperature dependent characteristics through an easy design change. <P>SOLUTION: The temperature characteristic correction circuit is provided with: a first current generating circuit for generating a prescribed first current independently of a temperature change; a second current generating circuit connected in series with the first current generating circuit and generating a second current that is increased when the temperature rises and is equal to the first current at a reference temperature; a third current generating circuit connected to a direct connection point between the first and second current generating circuits and generating a third current that corresponds to a difference between the first and second currents when the temperature deviates toward one side from the reference temperature; a fourth current generating circuit for generating a fourth current that increases when the temperature rises; a fifth current generating circuit connected in series with the fourth current generating circuit and generating a fifth current that is constant independently of a temperature change and equal to the fourth current at the reference temperature; a sixth current generating circuit connected to a series connection point between the fourth and fifth current generating circuits and generating a sixth current corresponding to a difference between the fourth and sixth currents when the temperature deviates toward the other side from the reference temperature; and a current output circuit that provides an output of a constant current changed by an amount of the third or sixth current. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a temperature characteristic correction circuit for canceling so-called temperature dependency that changes circuit characteristics according to temperature in various circuits.

Various circuits formed by appropriately connecting circuit elements (resistors, capacitors, transistors, etc.) have a temperature dependency in which circuit characteristics change with temperature changes. Further, some circuits having temperature dependence have a positive temperature characteristic, a negative temperature characteristic, and a positive / negative temperature characteristic. As a result, due to the above temperature characteristics, the current flowing inside the circuit may increase or decrease from the current that should flow, and the original circuit characteristics may not be obtained. Thus, conventionally, a temperature characteristic correction circuit for canceling the temperature dependence of each circuit is individually prepared and dealt with.
JP-A-10-268754

  However, in the case of a circuit having a positive temperature characteristic, the temperature range in which the positive temperature characteristic affects the circuit is not constant, and varies depending on the circuit. There are various positive temperature coefficients given to the circuit, and the ratio of the current change to the temperature change varies depending on the circuit. The same applies to circuits having negative temperature characteristics and positive and negative temperature characteristics. Therefore, when preparing a temperature characteristic correction circuit for a circuit having temperature dependence, it is difficult to make the circuit configuration common, so the temperature characteristic correction circuit must be individually designed and prepared. Had poor problems.

  Therefore, an object of the present invention is to provide a highly versatile temperature characteristic correction circuit that can be applied to a circuit having various temperature dependences by an easy design change.

  A main invention for solving the above problems is that a first current generation circuit that generates a constant first current regardless of a temperature change and a first current generation circuit that are connected in series, become larger as the temperature becomes higher and A second current generating circuit that generates a second current that is equal to the first current at a predetermined reference temperature; and a direct connection point between the first current generating circuit and the second current generating circuit; A third current generating circuit that generates a third current according to a difference between the first current and the second current when the temperature changes to one of a higher side and a lower side with respect to a reference temperature; A fourth current generating circuit for generating a fourth current and a fourth current generating circuit connected in series to generate a fifth current that is constant regardless of a temperature change and is equal to the fourth current at the reference temperature. 5th electric And the fourth current generation circuit and the fifth current generation circuit are connected to a series connection point, and when the temperature changes to the other of the higher side and the lower side with respect to the reference temperature, the fourth current and A sixth current generating circuit for generating a sixth current according to a difference from the fifth current; and a constant current output from the constant current circuit according to a temperature change, the amount of the third current or the sixth current. And a current output circuit that outputs the signal by changing only the voltage.

  ADVANTAGE OF THE INVENTION According to this invention, the versatile temperature characteristic correction circuit which can respond to the circuit which has various temperature dependence by an easy design change can be provided.

  At least the following matters will become apparent from the description of this specification and the accompanying drawings.

=== First Embodiment ===
A first embodiment of the temperature characteristic correction circuit of the present invention will be described with reference to FIGS. 1, 2, and 3. FIG. FIG. 1 is a circuit diagram showing a first embodiment of a temperature characteristic correction circuit of the present invention. 2 and 3 are characteristic diagrams showing the relationship between temperature and current in FIG. In the first embodiment, a bipolar transistor (hereinafter referred to as a transistor) is used, but the present invention is not limited to this.

<<< Configuration of First Embodiment >>>
In FIG. 1, a stabilized constant voltage VREG is applied to one input terminal (for example, + (non-inverting input) terminal) of the operational amplifier 2. As a circuit for generating the constant voltage VREG, a known band gap voltage generation circuit can be employed. The output terminal of the operational amplifier 2 is connected to the base of the transistor Q1, and the emitter of the transistor Q1 is connected to the other input terminal (for example, the-(inverting input) terminal) of the operational amplifier 2. Further, a resistor R1 is connected between the emitter of the transistor Q1 and the ground. As a result, the operational amplifier 2 operates so that the voltage across the resistor R1 becomes VREG, and the transistor Q1 operates by being biased by the output current obtained from the output terminal of the operational amplifier 2 at this time. Therefore, the output voltage and output current obtained from the output terminal of the operational amplifier 2 have characteristics independent of temperature.

  The first current generation circuit 4 is a current mirror circuit connected to the power supply VCC, and generates a current IA (first current). Specifically, the first current generating circuit 4 includes a PNP transistor Q2 connected in a diode connection, a PNP transistor Q3 connected in a current mirror, and resistors R2 and R3. The emitter of the transistor Q2 is connected to the power supply VCC via the resistor R2, the collector of the transistor Q2 is connected to the collector of the transistor Q1, and the emitter of the transistor Q3 is connected to the power supply VCC via the resistor R3. A current IA is output from the collector. That is, since the first current generation circuit 4 operates by being supplied with the collector current of the transistor Q1 controlled by the output of the operational amplifier 2, the current IA becomes a constant current regardless of the temperature change.

  The second current generation circuit 6 is connected between the output of the first current generation circuit 4 and the ground VSS, and generates a current IB (second current). Specifically, the second current generation circuit 6 includes an NPN transistor Q6 and a load resistor R6. A constant voltage VREG is applied to the base of the transistor Q6, the collector of the transistor Q6 is connected to the collector of the transistor Q3, and the emitter of the transistor Q6 is grounded via the load resistor R6. A current IB flows through the collector of the transistor Q6. Here, a stabilized constant voltage VREG is applied to the base of the transistor Q6. However, the transistor Q6 has a negative temperature characteristic in which the forward voltage between the base and emitter changes at −2 mV / ° C. Therefore, when the temperature changes, the current IB flowing through the collector and emitter of the transistor Q6 changes only due to the negative temperature characteristic applied to the forward voltage between the base and emitter of the transistor Q6. In the present application, by utilizing the temperature characteristic of the transistor Q6, a current that cancels the temperature dependence of a circuit that constitutes an amplifier, an oscillator, or the like is output.

  The third current generation circuit 8 is a current mirror circuit connected between the power supply VCC and the output of the first current generation circuit 4. Specifically, the third current generation circuit 8 includes a diode-connected PNP transistor Q10 and a current mirror-connected PNP transistor Q11. The emitter of transistor Q10 is connected to power supply VCC, and the collector of transistor Q10 is connected to the collector of transistor Q3 and the collector of transistor Q6 via diode-connected NPN transistor Q8. On the other hand, the emitter of the transistor Q11 is connected to the power supply VCC. It is assumed that the transistors Q10 and Q11 are selected so that the current mirror ratio of the transistors Q10 and Q11 is 1: m. Thereby, when the current IB becomes larger than the current IA, the difference current ΔI1 ′ between the current IB and the current IA flows through the collector of the transistor Q10, and the current ΔI1 (= mΔI1 ′: third) flows through the collector of the transistor Q11. Current) flows.

  The fourth current generation circuit 10 is a current mirror circuit connected to the power supply VCC, and generates a current IC (fourth current). Specifically, the fourth current generating circuit 10 includes a diode-connected PNP transistor Q4, a current mirror-connected PNP transistor Q5, resistors R4 and R5, and an NPN transistor Q7. And a load resistor R7. The emitter of transistor Q4 is connected to power supply VCC via resistor R4, the collector of transistor Q4 is connected to the collector of transistor Q7, the emitter of transistor Q5 is connected to power supply VCC via resistor R5, and from the collector of transistor Q5 A current IC is output. Here, a stabilized constant voltage is applied to the base of the transistor Q7 in common with the base of the transistor Q6. However, the transistor Q7 has a negative temperature characteristic in which the forward voltage between the base and emitter changes at −2 mV / ° C. Therefore, when the temperature changes, the current flowing through the collector-emitter of the transistor Q7 changes only by the negative temperature characteristic applied to the forward voltage between the base and emitter of the transistor Q7. In the present application, by further utilizing the temperature characteristic of the transistor Q7 in addition to the temperature characteristic of the transistor Q6, a current that cancels the temperature dependence of a circuit that constitutes an amplifier, an oscillator, or the like is output. That is, since the fourth current generation circuit 10 operates by being supplied with the collector current of the transistor Q7 having negative temperature characteristics, the current IC has the same negative temperature characteristics as the transistor Q7.

  The fifth current generation circuit 12 is connected between the output of the fourth current generation circuit 10 and the ground VSS, and generates a current ID (fifth current). Specifically, the fifth current generation circuit 12 includes an NPN transistor Q14 and a load resistor R8. The output voltage of the operational amplifier 2 is applied to the base of the transistor Q14, the collector of the transistor Q14 is connected to the collector of the transistor Q5, and the emitter of the transistor Q14 is grounded via the load resistor R8. A current ID flows through the collector of the transistor Q14. That is, since the fifth current generation circuit 12 operates while being controlled by the output voltage of the operational amplifier 2, the current ID becomes a constant current regardless of the temperature change.

  The sixth current generation circuit 14 is a current mirror circuit connected between the power supply VCC and the output of the fourth current generation circuit 10. Specifically, the sixth current generation circuit 14 includes a diode-connected PNP transistor Q12 and a current mirror-connected PNP transistor Q13. The emitter of transistor Q12 is connected to power supply VCC, and the collector of transistor Q12 is connected to the collector of transistor Q5 and the collector of transistor Q14 via diode-connected NPN transistor Q9. On the other hand, the emitter of the transistor Q13 is connected to the power supply VCC. It is assumed that transistors Q12 and Q13 having a size such that the current mirror ratio of transistors Q12 and Q13 is 1: n are selected. Thereby, when the current IC becomes smaller than the current ID, a difference current ΔI2 ′ between the current IC and the current ID flows through the collector of the transistor Q12, and a current ΔI2 (= nΔI2 ′: sixth) flows through the collector of the transistor Q13. Current) flows.

  The current output circuit 16 adds the currents ΔI1 and ΔI2 to the constant current Iin output from the constant current source 18 to obtain an output current Iout. By using this output current Iout, the temperature dependence of the target circuit such as an amplifier or an oscillator is canceled.

  It is assumed that at a predetermined reference temperature, current IA = current IB and current IC = current ID.

<<< Characteristics of First Embodiment >>>
The characteristics of the first embodiment of the present invention will be described below with reference to the characteristic diagrams of FIGS. In the present embodiment, at the temperature Ta = 25 ° C., the current IA = current IB and the current IC = current ID will be described first.

The current IA generated by the first current generation circuit 4 is constant regardless of the temperature change, but the current IB generated by the second current generation circuit 6 varies depending on the negative temperature characteristic between the base and emitter of the transistor Q6. Here, the negative temperature coefficient between the base and emitter of the transistor Q6 is −2 mV / ° C. When the difference temperature from 25 ° C. when the temperature is higher than 25 ° C. is ΔT,
ΔI1 ′ = IB−IA = (2 mV / R6) ΔT
ΔI1 = m (2 mV / R6) ΔT
On the other hand, the current ID generated by the fifth current generation circuit 12 is constant regardless of the temperature change, but the current IC generated by the fourth current generation circuit 10 varies depending on the negative temperature characteristic between the base and emitter of the transistor Q7. To do. Here, the negative temperature coefficient between the base and emitter of the transistor Q7 is −2 mV / ° C. When the difference temperature from 25 ° C. when the temperature is lower than 25 ° C. is ΔT,
ΔI2 ′ = ID−IC = (2 mV / R7) ΔT
ΔI2 = n (2 mV / R7) ΔT
Therefore,
Iout = Iin + ΔI1 + ΔI2
However, in detail,
When Ta> 25 ° C., Iout = Iin + m (2 mV / R6) ΔT
When Ta = 25 ° C., Iout = Iin
When Ta <25 ° C., Iout = Iin + n (2 mV / R7) ΔT Equation 1
It becomes.

  FIG. 2 shows the characteristics of the above formula 1. When the temperature Ta = 25 ° C. (reference temperature), the relationship of current IA = current IB and current IC = current ID is maintained, so that ΔI1 and ΔI2 do not occur. Therefore, the output current Iout at the temperature Ta = 25 ° C. becomes the smallest value Iin.

  When the temperature Ta> 25 ° C., ΔI1 is generated according to the difference temperature ΔT. At this time, current IC> current ID. However, since the diode-connected transistor Q9 prevents backflow of the current IC, ΔI2 does not flow. Therefore, Iout = Iin + ΔI1, and as the temperature increases, the output current Iout increases in a linear manner. That is, when the temperature Ta> 25 ° C., it is possible to provide a temperature characteristic correction circuit in which the output current Iout changes in a linear line with a positive slope as the temperature Ta increases. In FIG. 2, straight lines a1, b1, and c1 are shown as an example of temperature correction characteristics at a temperature Ta> 25 ° C. The slopes of the straight lines a1, b1, and c1 are obtained by changing the current mirror ratio 1: m of the transistors Q10 and Q11 constituting the third current generating circuit 8. Specifically, as the size ratio m of the transistor Q11 to the transistor Q10 is increased, the inclination changes from the inclination of a1 toward the inclination of c1. That is, when the temperature Ta> 25 ° C., it is possible to provide a temperature characteristic correction circuit that can change the slope of the output current Iout that increases as the temperature increases.

  On the other hand, when the temperature Ta <25 ° C., ΔI2 is generated according to the difference temperature ΔT. At this time, the current IA> the current IB, but since the diode-connected transistor Q8 prevents the backflow of the current IA, ΔI1 does not flow. Therefore, Iout = Iin + ΔI2, and as the temperature decreases, the output current Iout increases along a linear line. That is, when the temperature Ta <25 ° C., it is possible to provide a temperature characteristic correction circuit in which the output current Iout changes with a linear line with a positive slope as the temperature Ta decreases. In FIG. 2, straight lines a2, b2, and c2 are shown as an example of temperature correction characteristics at a temperature Ta <25 ° C. The slopes of the straight lines of a2, b2, and c2 are obtained by changing the current mirror ratio 1: n of the transistors Q12 and Q13 constituting the sixth current generation circuit 14. Specifically, as the size ratio n of the transistor Q13 to the transistor Q12 is increased, the inclination changes from the inclination of a2 toward the inclination of c2. In other words, at a temperature Ta <25 ° C., it is possible to provide a temperature characteristic correction circuit that can change the slope of the output current Iout that increases as the temperature decreases.

  In summary, the output current Iout becomes the minimum value at the reference temperature of 25 ° C., the output current Iout rises with an appropriate slope as the temperature Ta becomes higher than the reference temperature of 25 ° C., and the temperature Ta reaches the reference temperature of 25 ° C. It becomes possible to obtain a correction characteristic in which the output current Iout rises with an appropriate slope as the value becomes lower.

  Furthermore, the reference temperature at which the output current Iout is minimized can be made higher or lower than 25 ° C. In this case, the current IA and the current IB at 25 ° C. are not equal, and at the same time, the current IC is not equal to the current ID. This is shown in FIG. As shown in FIG. 3, since the output current Iout at 25 ° C. is changed, the reference temperature at which the output current Iout is minimum is the high temperature side (characteristic A to characteristic B) or the low temperature side (characteristic A to characteristic C). ). In order to make the current IA and the current IB not equal at a temperature of 25 ° C., for example, the resistance value of the resistor R1 or the ratio of the resistance values of the resistors R2 and R3 may be changed as appropriate. Similarly, in order to make the current IC and the current ID not equal at a temperature of 25 ° C., for example, the resistance value of the load resistor R8 or the ratio of the resistance values of the resistor R4 and the resistor R5 may be changed as appropriate.

  Further, when the temperature Ta becomes higher than the reference temperature, the output current Iout can be kept constant as Iin without being raised like the straight lines a1, b1, and c1 shown in FIG. For this purpose, the signal line through which ΔI1 ′ flows may be cut off. Specifically, the signal line may be simply cut. Alternatively, when the temperature Ta becomes higher than the reference temperature, a configuration is provided in which a control signal is generated in response to a request to keep the output current Iout constant at Iin, and the diode-connected transistor Q8 is further turned on by the control signal. A configuration for blocking may be provided. Thus, it is possible to provide a temperature characteristic correction circuit in which the output current Iout remains constant as Iin when the temperature Ta becomes higher than the reference temperature. On the other hand, when the temperature Ta becomes lower than the reference temperature, the output current Iout can be kept constant as Iin without increasing as shown by the straight lines a2, b2, and c2 shown in FIG. For this purpose, the signal line through which ΔI2 ′ flows may be cut off. Specifically, the signal line may be simply cut. Alternatively, a configuration is provided in which a control signal is generated in response to a request for keeping the output current Iout constant at Iin when the temperature Ta becomes lower than the reference temperature, and the diode-connected transistor Q9 is further turned on by the control signal. A configuration for blocking may be provided. Accordingly, it is possible to provide a temperature characteristic correction circuit in which the output current Iout remains constant as Iin when the temperature Ta becomes lower than the reference temperature.

  According to the temperature characteristic correction circuit of FIG. 1, it is possible to obtain a characteristic in which the output current Iout rises with an appropriate slope at the reference temperature, regardless of whether the temperature Ta is higher or lower than the reference temperature. In addition, the reference temperature can be changed. Since these characteristics can be realized by a small change in the circuit, it is versatile and suitable for integration. Then, according to the characteristics of the circuit 20, the setting of the current mirror ratio of the transistors Q10 and Q11, the setting of the current mirror ratio of the transistors Q12 and Q13, the current IA = current IB and the current IC = current ID according to the predetermined temperature The temperature characteristic of the circuit 20 can be effectively canceled by appropriately setting the reference temperature and switching off one of the transistors Q8 and Q9.

=== Second Embodiment ===
A second embodiment of the temperature characteristic correction circuit of the present invention will be described with reference to FIGS. 4, 5, and 6. FIG. 4 is a circuit diagram showing a second embodiment of the temperature characteristic correction circuit of the present invention. 5 and 6 are characteristic diagrams showing the relationship between temperature and current in FIG. In the second embodiment, a bipolar transistor (hereinafter referred to as a transistor) is used. However, the present invention is not limited to this. In FIG. 4, the same components as those in FIG.

<<< Configuration of Second Embodiment >>>
In FIG. 4, a stabilized constant voltage VREG is applied to one input terminal (for example, + (non-inverting input) terminal) of the operational amplifier 2. As a circuit for generating the constant voltage VREG, a known band gap voltage generation circuit can be employed. The output terminal of the operational amplifier 2 is connected to the base of the transistor Q1, and the emitter of the transistor Q1 is connected to the other input terminal (for example, the-(inverting input) terminal) of the operational amplifier 2. Further, a resistor R1 is connected between the emitter of the transistor Q1 and the ground. As a result, the operational amplifier 2 operates so that the voltage across the resistor R1 becomes VREG, and the transistor Q1 operates by being biased by the output current obtained from the output terminal of the operational amplifier 2 at this time. Therefore, the output voltage and output current obtained from the output terminal of the operational amplifier 2 have characteristics independent of temperature.

  The first current generation circuit 4 is a current mirror circuit connected to the power supply VCC, and generates a current IA (first current). Specifically, the first current generating circuit 4 includes a PNP transistor Q2 connected in a diode connection, a PNP transistor Q3 connected in a current mirror, and resistors R2 and R3. The emitter of the transistor Q2 is connected to the power supply VCC via the resistor R2, the collector of the transistor Q2 is connected to the collector of the transistor Q1, and the emitter of the transistor Q3 is connected to the power supply VCC via the resistor R3. A current IA is output from the collector. That is, since the first current generation circuit 4 operates by being supplied with the collector current of the transistor Q1 controlled by the output of the operational amplifier 2, the current IA becomes a constant current regardless of the temperature change.

  The second current generation circuit 6 is connected between the output of the first current generation circuit 4 and the ground VSS, and generates a current IB (second current). Specifically, the second current generation circuit 6 includes an NPN transistor Q6 and a load resistor R6. A constant voltage VREG is applied to the base of the transistor Q6, the collector of the transistor Q6 is connected to the collector of the transistor Q3, and the emitter of the transistor Q6 is grounded via the load resistor R6. A current IB flows through the collector of the transistor Q6. Here, a stabilized constant voltage VREG is applied to the base of the transistor Q6. However, the transistor Q6 has a negative temperature characteristic in which the forward voltage between the base and emitter changes at −2 mV / ° C. Therefore, when the temperature changes, the current IB flowing through the collector and emitter of the transistor Q6 changes only due to the negative temperature characteristic applied to the forward voltage between the base and emitter of the transistor Q6. In the present application, by utilizing the temperature characteristic of the transistor Q6, a current that cancels the temperature dependence of a circuit that constitutes an amplifier, an oscillator, or the like is output.

  The third current generation circuit 108 is a current mirror circuit connected between the output of the first current generation circuit 4 and the ground. Specifically, the third current generating circuit 108 includes a diode-connected NPN transistor Q10 and a current mirror-connected NPN transistor Q11. The emitter of the transistor Q10 is grounded, and the collector of the transistor Q10 is connected to the collector of the transistor Q3 and the collector of the transistor Q6 via a diode-connected NPN transistor Q8. On the other hand, the emitter of the transistor Q11 is grounded. It is assumed that the transistors Q10 and Q11 are selected so that the current mirror ratio of the transistors Q10 and Q11 is 1: m. Thereby, when the current IB becomes smaller than the current IA, the difference current ΔI1 ′ between the current IB and the current IA flows through the collector of the transistor Q10, and the current ΔI1 (= mΔI1 ′: third) flows through the collector of the transistor Q11. Current) flows.

  The fourth current generation circuit 10 is a current mirror circuit connected to the power supply VCC, and generates a current IC (fourth current). Specifically, the fourth current generating circuit 10 includes a diode-connected PNP transistor Q4, a current mirror-connected PNP transistor Q5, resistors R4 and R5, and an NPN transistor Q7. And a load resistor R7. The emitter of transistor Q4 is connected to power supply VCC via resistor R4, the collector of transistor Q4 is connected to the collector of transistor Q7, the emitter of transistor Q5 is connected to power supply VCC via resistor R5, and from the collector of transistor Q5 A current IC is output. Here, a stabilized constant voltage is applied to the base of the transistor Q7 in common with the base of the transistor Q6. However, the transistor Q7 has a negative temperature characteristic in which the forward voltage between the base and emitter changes at −2 mV / ° C. Therefore, when the temperature changes, the current flowing through the collector-emitter of the transistor Q7 changes only by the negative temperature characteristic applied to the forward voltage between the base and emitter of the transistor Q7. In the present application, by further utilizing the temperature characteristic of the transistor Q7 in addition to the temperature characteristic of the transistor Q6, a current that cancels the temperature dependence of a circuit that constitutes an amplifier, an oscillator, or the like is output. That is, since the fourth current generation circuit 10 operates by being supplied with the collector current of the transistor Q7 having negative temperature characteristics, the current IC has the same negative temperature characteristics as the transistor Q7.

  The fifth current generation circuit 12 is connected between the output of the fourth current generation circuit 10 and the ground VSS, and generates a current ID (fifth current). Specifically, the fifth current generation circuit 12 includes an NPN transistor Q14 and a load resistor R8. The output voltage of the operational amplifier 2 is applied to the base of the transistor Q14, the collector of the transistor Q14 is connected to the collector of the transistor Q5, and the emitter of the transistor Q14 is grounded via the load resistor R8. A current ID flows through the collector of the transistor Q14. That is, since the fifth current generation circuit 12 operates while being controlled by the output voltage of the operational amplifier 2, the current ID becomes a constant current regardless of the temperature change.

  The sixth current generation circuit 114 is a current mirror circuit connected between the output of the fourth current generation circuit 10 and the ground. Specifically, the sixth current generation circuit 114 includes a diode-connected NPN transistor Q12 and a current mirror-connected NPN transistor Q13. The emitter of the transistor Q12 is grounded, and the collector of the transistor Q12 is connected to the collector of the transistor Q5 and the collector of the transistor Q14 via a diode-connected NPN transistor Q9. On the other hand, the emitter of the transistor Q13 is grounded. It is assumed that transistors Q12 and Q13 having a size such that the current mirror ratio of transistors Q12 and Q13 is 1: n are selected. Thereby, when the current IC becomes larger than the current ID, the difference current ΔI2 ′ between the current IC and the current ID flows through the collector of the transistor Q12, and the current ΔI2 (= nΔI2 ′: sixth) flows through the collector of the transistor Q13. Current) flows.

  The current output circuit 16 subtracts the currents ΔI1 and ΔI2 from the constant current Iin output from the constant current source 18 to obtain an output current Iout. By using this output current Iout, the temperature dependence of the target circuit such as an amplifier or an oscillator is canceled.

  It is assumed that at a predetermined reference temperature, current IA = current IB and current IC = current ID.

<<< Characteristics of Second Embodiment >>>
Hereinafter, the characteristics of the second embodiment of the present invention will be described with reference to the characteristic diagrams of FIGS. 5 and 6. In the present embodiment, at the temperature Ta = 25 ° C., the current IA = current IB and the current IC = current ID will be described first.

The current IA generated by the first current generation circuit 4 is constant regardless of the temperature change, but the current IB generated by the second current generation circuit 6 varies depending on the negative temperature characteristic between the base and emitter of the transistor Q6. Here, the negative temperature coefficient between the base and emitter of the transistor Q6 is −2 mV / ° C. When the difference temperature from 25 ° C. when the temperature is lower than 25 ° C. is ΔT,
ΔI1 ′ = IA−IB = (2 mV / R6) ΔT
ΔI1 = m (2 mV / R6) ΔT
On the other hand, the current ID generated by the fifth current generation circuit 12 is constant regardless of the temperature change, but the current IC generated by the fourth current generation circuit 10 varies depending on the negative temperature characteristic between the base and emitter of the transistor Q7. To do. Here, the negative temperature coefficient between the base and emitter of the transistor Q7 is −2 mV / ° C. When the difference temperature from 25 ° C. when the temperature is higher than 25 ° C. is ΔT,
ΔI2 ′ = IC−ID = (2 mV / R7) ΔT
ΔI2 = n (2 mV / R7) ΔT
Therefore,
Iout = Iin−ΔI1−ΔI2
However, in detail,
When Ta> 25 ° C., Iout = Iin−n (2 mV / R7) ΔT
When Ta = 25 ° C., Iout = Iin
When Ta <25 ° C., Iout = Iin−m (2 mV / R6) ΔT Equation 2
It becomes.

  FIG. 5 shows the characteristic of the above equation 2. When the temperature Ta = 25 ° C. (reference temperature), the relationship of current IA = current IB and current IC = current ID is maintained, so that ΔI1 and ΔI2 do not occur. Therefore, the output current Iout at the temperature Ta = 25 ° C. is the largest value Iin.

  When the temperature Ta <25 ° C., ΔI1 is generated according to the difference temperature ΔT. At this time, although current IC <current ID, since diode-connected transistor Q9 prevents backflow to the collector of transistor Q14, ΔI2 does not flow. Therefore, Iout = Iin−ΔI1, and as the temperature decreases, the output current Iout decreases in a linear manner. That is, when the temperature Ta <25 ° C., it is possible to provide a temperature characteristic correction circuit in which the output current Iout changes in a linear line with a negative slope as the temperature Ta decreases. FIG. 5 shows, as an example, straight lines a3, b3, and c3 as temperature correction characteristics at a temperature Ta <25 ° C. The slopes of the straight lines a3, b3, and c3 are obtained by changing the current mirror ratio 1: m of the transistors Q10 and Q11 constituting the third current generation circuit 108. Specifically, as the size ratio m of the transistor Q11 to the transistor Q10 is increased, the inclination changes from the inclination of a3 toward the inclination of c3. In other words, at a temperature Ta <25 ° C., it is possible to provide a temperature characteristic correction circuit that can change the slope of the output current Iout that decreases as the temperature decreases.

  On the other hand, when the temperature Ta> 25 ° C., ΔI2 is generated according to the difference temperature ΔT. At this time, current IA <current IB, but ΔI1 does not flow because diode-connected transistor Q8 prevents backflow to the collector of transistor Q6. Therefore, Iout = Iin−ΔI2, and as the temperature increases, the output current Iout decreases in a linear manner. That is, when the temperature Ta> 25 ° C., it is possible to provide a temperature characteristic correction circuit in which the output current Iout changes in a linear manner with a negative slope as the temperature Ta increases. In FIG. 5, straight lines a4, b4, and c4 are shown as an example of temperature correction characteristics at a temperature Ta> 25 ° C. The slopes of the straight lines a4, b4, and c4 are obtained by changing the current mirror ratio 1: n of the transistors Q12 and Q13 constituting the sixth current generation circuit 114. Specifically, as the size ratio n of the transistor Q13 to the transistor Q12 is increased, the inclination changes from the inclination of a4 toward the inclination of c4. That is, when the temperature Ta> 25 ° C., it is possible to provide a temperature characteristic correction circuit that can change the slope of the output current Iout that decreases as the temperature increases.

  In summary, the output current Iout becomes the maximum value at the reference temperature of 25 ° C., the output current Iout decreases with an appropriate slope as the temperature Ta becomes higher than the reference temperature of 25 ° C., and the temperature Ta is the reference temperature of 25 ° C. Accordingly, it is possible to obtain a correction characteristic in which the output current Iout decreases with an appropriate slope as the output current becomes lower.

  Further, the reference temperature at which the output current Iout becomes maximum can be made higher or lower than 25 ° C. In this case, the current IA and the current IB at 25 ° C. are not equal, and at the same time, the current IC is not equal to the current ID. This is shown in FIG. As shown in FIG. 6, since the output current Iout at 25 ° C. is changed, the reference temperature at which the output current Iout is maximized is the high temperature side (characteristic D to characteristic E) or the low temperature side (characteristic D to characteristic F). ). In order to make the current IA and the current IB not equal at a temperature of 25 ° C., for example, the resistance value of the resistor R1 or the ratio of the resistance values of the resistors R2 and R3 may be changed as appropriate. Similarly, in order to make the current IC and the current ID not equal at a temperature of 25 ° C., for example, the resistance value of the load resistor R8 or the ratio of the resistance values of the resistor R4 and the resistor R5 may be changed as appropriate.

  Further, when the temperature Ta becomes lower than the reference temperature, the output current Iout can be kept constant as Iin without being lowered like the straight lines a3, b3, and c3 shown in FIG. For this purpose, the signal line through which ΔI1 ′ flows may be cut off. Specifically, the signal line may be simply cut. Alternatively, a configuration is provided in which a control signal is generated in response to a request for keeping the output current Iout constant at Iin when the temperature Ta becomes lower than the reference temperature, and the diode-connected transistor Q8 is further turned on by the control signal. A configuration for blocking may be provided. Accordingly, it is possible to provide a temperature characteristic correction circuit in which the output current Iout remains constant as Iin when the temperature Ta becomes lower than the reference temperature. On the other hand, when the temperature Ta becomes higher than the reference temperature, the output current Iout can be kept constant as Iin without being lowered like the straight lines a4, b4, and c4 shown in FIG. For this purpose, the signal line through which ΔI2 ′ flows may be cut off. Specifically, the signal line may be simply cut. Alternatively, a configuration is provided in which a control signal is generated in response to a request for keeping the output current Iout constant at Iin when the temperature Ta becomes higher than the reference temperature, and the diode-connected transistor Q9 is further turned on by the control signal. A configuration for blocking may be provided. Thus, it is possible to provide a temperature characteristic correction circuit in which the output current Iout remains constant as Iin when the temperature Ta becomes higher than the reference temperature.

  According to the temperature characteristic correction circuit of FIG. 4, it is possible to obtain a characteristic in which the output current Iout decreases with an appropriate slope at the reference temperature, regardless of whether the temperature Ta is higher or lower than the reference temperature. In addition, the reference temperature can be changed. Since these characteristics can be realized by a small change in the circuit, it is versatile and suitable for integration. Then, according to the characteristics of the circuit 120, the setting of the current mirror ratio of the transistors Q10 and Q11, the setting of the current mirror ratio of the transistors Q12 and Q13, the current IA = current IB and the current IC = current ID corresponding to the predetermined temperature The temperature characteristic of the circuit 120 can be effectively canceled by appropriately setting the reference temperature and switching off one of the transistors Q8 and Q9.

=== Third Embodiment ===
A third embodiment of the temperature characteristic correction circuit of the present invention will be described with reference to FIGS. FIG. 7 is a circuit diagram showing a third embodiment of the temperature characteristic correction circuit of the present invention. FIG. 8 is a characteristic diagram showing the relationship between temperature and current in FIG. The third embodiment uses a bipolar transistor (hereinafter referred to as a transistor), but is not limited to this.

<<< Configuration of Third Embodiment >>>
In FIG. 7, a stabilized constant voltage VREG is applied to one input terminal (for example, + (non-inverting input) terminal) of the operational amplifier 202. As a circuit for generating the constant voltage VREG, a known band gap voltage generation circuit can be employed. The output terminal of the operational amplifier 202 is connected to the base of the transistor Q1, and the emitter of the transistor Q1 is connected to the other input terminal (for example, the − (inverting input) terminal) of the operational amplifier 202. Further, a resistor R1 is connected between the emitter of the transistor Q1 and the ground. As a result, the operational amplifier 202 operates so that the voltage across the resistor R1 becomes VREG, and the transistor Q1 operates by being biased to the output current obtained from the output terminal of the operational amplifier 202 at this time. Therefore, the output voltage and output current obtained from the output terminal of the operational amplifier 202 have characteristics independent of temperature.

  The first current generation circuit 204 is a current mirror circuit connected to the power supply VCC, and generates a current IA (first current). Specifically, the first current generating circuit 204 includes a diode-connected PNP transistor Q2, a current mirror-connected PNP transistor Q3, and resistors R2 and R3. The emitter of the transistor Q2 is connected to the power supply VCC via the resistor R2, the collector of the transistor Q2 is connected to the collector of the transistor Q1, and the emitter of the transistor Q3 is connected to the power supply VCC via the resistor R3. A current IA is output from the collector. That is, since the first current generation circuit 204 operates by being supplied with the collector current of the transistor Q1 controlled by the output of the operational amplifier 202, the current IA becomes a constant current regardless of the temperature change.

  The second current generation circuit 206 is connected between the output of the first current generation circuit 204 and the ground VSS, and generates a current IB (second current). Specifically, the second current generation circuit 206 includes an NPN transistor Q6 and a load resistor R6. A constant voltage VREG is applied to the base of the transistor Q6, the collector of the transistor Q6 is connected to the collector of the transistor Q3, and the emitter of the transistor Q6 is grounded via the load resistor R6. A current IB flows through the collector of the transistor Q6. Here, a stabilized constant voltage VREG is applied to the base of the transistor Q6. However, the transistor Q6 has a negative temperature characteristic in which the forward voltage between the base and emitter changes at −2 mV / ° C. Therefore, when the temperature changes, the current IB flowing through the collector and emitter of the transistor Q6 changes only due to the negative temperature characteristic applied to the forward voltage between the base and emitter of the transistor Q6. In the present application, by utilizing the temperature characteristic of the transistor Q6, a current that cancels the temperature dependence of a circuit that constitutes an amplifier, an oscillator, or the like is output.

  The third current generation circuit 208 is a current mirror circuit connected between the power supply VCC and the output of the first current generation circuit 204. Specifically, the third current generation circuit 208 includes a diode-connected PNP transistor Q10, a current mirror-connected PNP transistor Q11, and resistors R10 and R11. The emitter of transistor Q10 is connected to power supply VCC via resistor R10, and the collector of transistor Q10 is connected to the collector of transistor Q3 and the collector of transistor Q6 via diode-connected NPN transistor Q8. On the other hand, the emitter of the transistor Q11 is connected to the power supply VCC via a resistor R11. It is assumed that the transistors Q10 and Q11 are selected so that the current mirror ratio of the transistors Q10 and Q11 is 1: m. Thereby, when the current IB becomes larger than the current IA, the difference current ΔI1 ′ between the current IB and the current IA flows through the collector of the transistor Q10, and the current ΔI1 (= mΔI1 ′: third) flows through the collector of the transistor Q11. Current) flows.

  The fourth current generation circuit 210 is connected between an output of a fifth current generation circuit 212 described later and the ground, and generates a current ID (fourth current). Specifically, the fourth current generation circuit 210 includes an NPN transistor Q7 and a load resistor R7. The emitter of the transistor Q7 is grounded via the load resistor R7. Here, a stabilized constant voltage is applied to the base of the transistor Q7 in common with the base of the transistor Q6. However, the transistor Q7 has a negative temperature characteristic in which the forward voltage between the base and emitter changes at −2 mV / ° C. Therefore, when the temperature changes, the current flowing through the collector-emitter of the transistor Q7 changes only by the negative temperature characteristic applied to the forward voltage between the base and emitter of the transistor Q7. In the present application, by further utilizing the temperature characteristic of the transistor Q7 in addition to the temperature characteristic of the transistor Q6, a current that cancels the temperature dependence of a circuit that constitutes an amplifier, an oscillator, or the like is output. That is, the fourth current generation circuit 210 operates by being supplied with the collector current of the transistor Q7 having the negative temperature characteristic, so that the current ID has the same negative temperature characteristic as that of the transistor Q7.

  The fifth current generation circuit 212 includes a current mirror circuit connected between the power supply VCC and the fourth current generation circuit 210, and generates a current IC (fifth current). Specifically, the fifth current generating circuit 212 includes a diode-connected PNP transistor Q5, a current mirror-connected PNP transistor Q4, resistors R4 and R5, and an NPN transistor Q14. And a load resistor R8. The emitter of transistor Q4 is connected to power supply VCC via resistor R4, the collector of transistor Q4 is connected to the collector of transistor Q7, the emitter of transistor Q5 is connected to power supply VCC via resistor R5, and the collector of transistor Q5 is Connected to the collector of transistor Q14. The output voltage of the operational amplifier 202 is applied to the base of the transistor Q14, and the emitter of the transistor Q14 is grounded via the load resistor R8. That is, since the fifth current generation circuit 212 operates under the control of the output voltage of the operational amplifier 202, the current IC flowing through the collector of the transistor Q4 becomes a constant current regardless of the temperature change.

  The sixth current generation circuit 214 is a current mirror circuit connected between the output of the fifth current generation circuit 212 and the ground. Specifically, the sixth current generation circuit 214 includes a diode-connected NPN transistor Q12, a current mirror-connected NPN transistor Q13, and resistors R12 and R13. The emitter of the transistor Q12 is electrically grounded via a resistor R12, and the collector of the transistor Q12 is connected to the collector of the transistor Q4 and the collector of the transistor Q7 via a diode-connected NPN transistor Q9. On the other hand, the emitter of the transistor Q13 is grounded via a resistor R13. It is assumed that transistors Q12 and Q13 having a size such that the current mirror ratio of transistors Q12 and Q13 is 1: n are selected. Thereby, when the current IC becomes larger than the current ID, the difference current ΔI2 ′ between the current IC and the current ID flows through the collector of the transistor Q12, and the current ΔI2 (= nΔI2 ′: sixth) flows through the collector of the transistor Q13. Current) flows.

  The current output circuit 216 outputs an output current Iout obtained by adding the current ΔI1 or subtracting the current ΔI2 to the constant current Iin output from the constant current source 218. By using this output current Iout, the temperature dependence of the target circuit such as an amplifier or an oscillator is canceled.

  It is assumed that at a predetermined reference temperature, current IA = current IB and current IC = current ID.

<<< Characteristics of Third Embodiment >>>
Hereinafter, the characteristic of the third embodiment of the present invention will be described with reference to the characteristic diagram of FIG. In the present embodiment, at the temperature Ta = 25 ° C., the current IA = current IB and the current IC = current ID will be described first.

The current IA generated by the first current generation circuit 204 is constant regardless of the temperature change, but the current IB generated by the second current generation circuit 206 changes due to the negative temperature characteristic between the base and emitter of the transistor Q6. Here, the negative temperature coefficient between the base and emitter of the transistor Q6 is −2 mV / ° C. When the difference temperature from 25 ° C. when the temperature is higher than 25 ° C. is ΔT,
ΔI1 ′ = IB−IA = (2 mV / R6) ΔT
ΔI1 = m (2 mV / R6) ΔT
On the other hand, the current IC generated by the fifth current generation circuit 212 is constant regardless of the temperature change, but the current ID generated by the fourth current generation circuit 210 changes due to the negative temperature characteristic between the base and emitter of the transistor Q7. To do. Here, the negative temperature coefficient between the base and emitter of the transistor Q7 is −2 mV / ° C. When the difference temperature from 25 ° C. when the temperature is lower than 25 ° C. is ΔT,
ΔI2 ′ = IC−ID = (2 mV / R7) ΔT
ΔI2 = n (2 mV / R7) ΔT
Therefore,
Iout = Iin + ΔI1−ΔI2
However, in detail,
When Ta> 25 ° C., Iout = Iin + m (2 mV / R6) ΔT
When Ta = 25 ° C., Iout = Iin
When Ta <25 ° C., Iout = Iin−n (2 mV / R7) ΔT Equation 3
It becomes.

  FIG. 8 shows the characteristics of the above equation 3. When the temperature Ta = 25 ° C. (reference temperature), the relationship of current IA = current IB and current IC = current ID is maintained, so that ΔI1 and ΔI2 do not occur. Therefore, the output current Iout when the temperature Ta = 25 ° C. is the constant current Iin itself.

  When the temperature Ta> 25 ° C., ΔI1 is generated according to the difference temperature ΔT. At this time, the current IC is smaller than the current ID. However, since the diode-connected transistor Q9 prevents the current from being supplied to the collector of the transistor Q7, ΔI2 does not flow. Therefore, Iout = Iin + ΔI1, and as the temperature increases, the output current Iout increases in a linear manner. That is, when the temperature Ta> 25 ° C., it is possible to provide a temperature characteristic correction circuit in which the output current Iout changes in a linear line with a positive slope as the temperature Ta increases. In FIG. 8, straight lines a5, b5, and c5 are shown as an example of temperature correction characteristics at a temperature Ta> 25 ° C. The slopes of the straight lines a5, b5, and c5 are obtained by changing the current mirror ratio 1: m of the transistors Q10 and Q11 constituting the third current generating circuit 208. Specifically, as the size ratio m of the transistor Q11 to the transistor Q10 is increased, the inclination changes from the inclination of a5 toward the inclination of c5. That is, when the temperature Ta> 25 ° C., it is possible to provide a temperature characteristic correction circuit that can change the slope of the output current Iout that increases as the temperature increases.

  On the other hand, when the temperature Ta <25 ° C., ΔI2 is generated according to the difference temperature ΔT. At this time, current IA> current IB, but since the diode-connected transistor Q8 prevents backflow of the current IA to the third current generation circuit 208, ΔI1 does not flow. Therefore, Iout = Iin−ΔI2, and as the temperature decreases, the output current Iout decreases in a linear manner. That is, when the temperature Ta <25 ° C., it is possible to provide a temperature characteristic correction circuit in which the output current Iout changes in a linear line with a negative slope as the temperature Ta decreases. In FIG. 8, straight lines a6, b6, and c6 are shown as an example of temperature correction characteristics at a temperature Ta <25 ° C. The slopes of the straight lines a6, b6, and c6 are obtained by changing the current mirror ratio 1: n of the transistors Q12 and Q13 constituting the sixth current generation circuit 214. Specifically, as the size ratio n of the transistor Q13 to the transistor Q12 is increased, the inclination changes from the inclination of a6 toward the inclination of c6. In other words, at a temperature Ta <25 ° C., it is possible to provide a temperature characteristic correction circuit that can change the slope of the output current Iout that decreases as the temperature decreases.

  In summary, the output current Iout becomes a constant current Iin at the reference temperature of 25 ° C., the output current Iout increases with an appropriate slope as the temperature Ta becomes higher than the reference temperature of 25 ° C., and the temperature Ta becomes the reference temperature of 25 It becomes possible to obtain a correction characteristic in which the output current Iout decreases with an appropriate slope as the temperature becomes lower than ° C.

  Furthermore, the reference temperature at which the output current Iout becomes equal to the constant current Iin can be made higher or lower than 25 ° C. In this case, the current IA and the current IB at 25 ° C. are not equal, and at the same time, the current IC is not equal to the current ID. Although this state is not shown, since the output current Iout at 25 ° C. is changed, the reference temperature at which the output current Iout becomes the constant current Iin is higher than 25 ° C. or lower than 25 ° C. Will shift to. In order to make the current IA and the current IB not equal at a temperature of 25 ° C., for example, the resistance value of the resistor R1 or the ratio of the resistance values of the resistors R2 and R3 may be changed as appropriate. Similarly, in order to make the current IC and the current ID not equal at a temperature of 25 ° C., for example, the resistance value of the load resistor R8 or the ratio of the resistance values of the resistor R4 and the resistor R5 may be changed as appropriate.

  Further, when the temperature Ta becomes higher than the reference temperature, the output current Iout can be kept constant as Iin without being raised like the straight lines a5, b5, and c5 shown in FIG. For this purpose, the signal line through which ΔI1 ′ flows may be cut off. Specifically, the signal line may be simply cut. Alternatively, when the temperature Ta becomes higher than the reference temperature, a configuration is provided in which a control signal is generated in response to a request to keep the output current Iout constant at Iin, and the diode-connected transistor Q8 is further turned on by the control signal A configuration for blocking may be provided. Thus, it is possible to provide a temperature characteristic correction circuit in which the output current Iout remains constant as Iin when the temperature Ta becomes higher than the reference temperature. On the other hand, when the temperature Ta becomes lower than the reference temperature, the output current Iout can be kept constant as Iin without being raised like the straight lines a6, b6, and c6 shown in FIG. For this purpose, the signal line through which ΔI2 ′ flows may be cut off. Specifically, the signal line may be simply cut. Alternatively, a configuration is provided in which a control signal is generated in response to a request for keeping the output current Iout constant at Iin when the temperature Ta becomes lower than the reference temperature, and the diode-connected transistor Q9 is further turned on by the control signal. A configuration for blocking may be provided. Accordingly, it is possible to provide a temperature characteristic correction circuit in which the output current Iout remains constant as Iin when the temperature Ta becomes lower than the reference temperature.

  According to the temperature characteristic correction circuit of FIG. 7, when the temperature Ta becomes higher than the reference temperature with the reference temperature as a boundary, the output current Iout increases with an appropriate slope, and when the temperature Ta becomes lower than the reference temperature, the output current It is possible to obtain a characteristic that Iout decreases with an appropriate inclination. In addition, the reference temperature can be changed. Since these characteristics can be realized by a small change in the circuit, it is versatile and suitable for integration. Then, according to the characteristics of the circuit 220, setting of the current mirror ratio of the transistors Q10 and Q11, setting of the current mirror ratio of the transistors Q12 and Q13, current IA = current IB and current IC = current ID corresponding to the predetermined temperature The temperature characteristic of the circuit 220 can be effectively canceled by appropriately setting the reference temperature and switching off one of the transistors Q8 and Q9.

=== Fourth Embodiment ===
A fourth embodiment of the temperature characteristic correction circuit of the present invention will be described with reference to FIGS. FIG. 9 is a circuit diagram showing a fourth embodiment of the temperature characteristic correction circuit of the present invention. FIG. 10 is a characteristic diagram showing the relationship between temperature and current in FIG. The fourth embodiment uses a bipolar transistor (hereinafter referred to as a transistor), but is not limited to this.

<<< Configuration of Fourth Embodiment >>>
In FIG. 9, a stabilized constant voltage VREG is applied to one input terminal (for example, + (non-inverting input) terminal) of the operational amplifier 302. As a circuit for generating the constant voltage VREG, a known band gap voltage generation circuit can be employed. The output terminal of the operational amplifier 302 is connected to the base of the transistor Q1, and the emitter of the transistor Q1 is connected to the other input terminal (for example, the − (inverting input) terminal) of the operational amplifier 302. Further, a resistor R1 is connected between the emitter of the transistor Q1 and the ground. Thereby, the operational amplifier 302 operates so that the voltage across the resistor R1 becomes VREG, and the transistor Q1 operates by being biased by the output current obtained from the output terminal of the operational amplifier 302 at this time. Therefore, the output voltage and output current obtained from the output terminal of the operational amplifier 302 have characteristics independent of temperature. Here, the transistor Q1 and the resistor R1 constitute a first current generation circuit 304, and a current IB (first current) that becomes constant regardless of a temperature change flows through the collector of the transistor Q1.

  The second current generation circuit 306 has a current mirror circuit connected to the power supply VCC, and generates a current IA (second current). Specifically, the second current generation circuit 306 includes a diode-connected PNP transistor Q3, a current mirror-connected PNP transistor Q2, resistors R2 and R3, a transistor Q6, and a load resistor R6. . The emitter of the transistor Q2 is connected to the power supply VCC via the resistor R2, the collector of the transistor Q2 is connected to the collector of the transistor Q1, and the emitter of the transistor Q3 is connected to the power supply VCC via the resistor R3. The emitter of the transistor Q6 is grounded via the load resistor R6. A constant voltage VREG is applied to the base of the transistor Q6, the collector of the transistor Q6 is connected to the collector of the transistor Q3, and the emitter of the transistor Q6 is grounded via the load resistor R6. A current IA flows through the collector of the transistor Q2. Here, a stabilized constant voltage VREG is applied to the base of the transistor Q6. However, the transistor Q6 has a negative temperature characteristic in which the forward voltage between the base and emitter changes at −2 mV / ° C. Therefore, when the temperature changes, the current IA flowing through the collector of the transistor Q2 changes only due to the negative temperature characteristic applied to the forward voltage between the base and emitter of the transistor Q6. In the present application, by utilizing the temperature characteristic of the transistor Q6, a current that cancels the temperature dependence of a circuit that constitutes an amplifier, an oscillator, or the like is output.

  The third current generation circuit 308 is a current mirror circuit connected between the power supply VCC and the collector of the transistor Q1 constituting the first current generation circuit 304. Specifically, the third current generation circuit 308 includes a diode-connected PNP transistor Q10, a current mirror-connected PNP transistor Q11, and resistors R10 and R11. The emitter of transistor Q10 is connected to power supply VCC via resistor R10, and the collector of transistor Q10 is connected to the collector of transistor Q1 and the collector of transistor Q2 via diode-connected NPN transistor Q8. On the other hand, the emitter of the transistor Q11 is connected to the power supply VCC via a resistor R11. It is assumed that the transistors Q10 and Q11 are selected so that the current mirror ratio of the transistors Q10 and Q11 is 1: m. Thereby, when the current IB becomes larger than the current IA, the difference current ΔI1 ′ between the current IB and the current IA flows through the collector of the transistor Q10, and the current ΔI1 (= mΔI1 ′: third) flows through the collector of the transistor Q11. Current) flows.

  The fourth current generation circuit 310 has a current mirror circuit connected between the power supply VCC and a fifth current generation circuit 312 described later, and generates a current IC (fourth current). Specifically, the fourth current generating circuit 310 includes a diode-connected PNP transistor Q4, a current mirror-connected PNP transistor Q5, resistors R4 and R5, and an NPN transistor Q7. And a load resistor R7. The emitter of transistor Q4 is connected to power supply VCC via resistor R4, the collector of transistor Q4 is connected to the collector of transistor Q7, and the emitter of transistor Q5 is connected to power supply VCC via resistor R5. The emitter of the transistor Q7 is grounded via the load resistor R7. Here, a stabilized constant voltage is applied to the base of the transistor Q7 in common with the base of the transistor Q6. However, the transistor Q7 has a negative temperature characteristic in which the forward voltage between the base and emitter changes at −2 mV / ° C. Therefore, when the temperature changes, the current flowing through the collector-emitter of the transistor Q7 changes only by the negative temperature characteristic applied to the forward voltage between the base and emitter of the transistor Q7. In the present application, by further utilizing the temperature characteristic of the transistor Q7 in addition to the temperature characteristic of the transistor Q6, a current that cancels the temperature dependence of a circuit that constitutes an amplifier, an oscillator, or the like is output. That is, the fourth current generation circuit 310 operates by being supplied with the collector current of the transistor Q7 having the negative temperature characteristic, so that the current IC flowing through the collector of the transistor Q5 has the same negative temperature characteristic as the transistor Q7. It becomes.

  The fifth current generation circuit 312 includes an NPN transistor Q14 and a load resistor R8, and generates a current ID (fifth current). Specifically, the collector of the transistor Q14 is connected to the collector of the transistor Q5, and its emitter is grounded via the load resistor R8. Here, the output voltage of the operational amplifier 302 is applied to the base of the transistor Q14. That is, since the fifth current generating circuit 312 operates under the control of the output voltage of the operational amplifier 302, the current ID flowing through the collector of the transistor Q14 becomes a constant current regardless of the temperature change.

  The sixth current generation circuit 314 is a current mirror circuit connected between the output of the fourth current generation circuit 310 and the ground. Specifically, the sixth current generation circuit 314 includes a diode-connected NPN transistor Q12, a current mirror-connected NPN transistor Q13, and resistors R12 and R13. The emitter of the transistor Q12 is electrically grounded via a resistor R12, and the collector of the transistor Q12 is connected to the collector of the transistor Q5 and the collector of the transistor Q14 via a diode-connected NPN transistor Q9. On the other hand, the emitter of the transistor Q13 is grounded via a resistor R13. It is assumed that transistors Q12 and Q13 having a size such that the current mirror ratio of transistors Q12 and Q13 is 1: n are selected. Thereby, when the current IC becomes larger than the current ID, the difference current ΔI2 ′ between the current IC and the current ID flows through the collector of the transistor Q12, and the current ΔI2 (= nΔI2 ′: sixth) flows through the collector of the transistor Q13. Current) flows.

  The current output circuit 316 outputs an output current Iout obtained by adding the current ΔI1 or subtracting the current ΔI2 to the constant current Iin output from the constant current source 318. By using this output current Iout, the temperature dependence of the target circuit such as an amplifier or an oscillator is canceled.

  It is assumed that at a predetermined reference temperature, current IA = current IB and current IC = current ID.

<<< Characteristics of Fourth Embodiment >>>
Hereinafter, the characteristic of the fourth embodiment of the present invention will be described with reference to the characteristic diagram of FIG. In the present embodiment, at the temperature Ta = 25 ° C., the current IA = current IB and the current IC = current ID will be described first.

The current IB generated by the first current generation circuit 304 is constant regardless of the temperature change, but the current IA generated by the second current generation circuit 306 varies depending on the negative temperature characteristic between the base and emitter of the transistor Q6. Here, the negative temperature coefficient between the base and emitter of the transistor Q6 is −2 mV / ° C. When the difference temperature from 25 ° C. when the temperature is lower than 25 ° C. is ΔT,
ΔI1 ′ = IB−IA = (2 mV / R6) ΔT
ΔI1 = m (2 mV / R6) ΔT
On the other hand, the current ID generated by the fifth current generation circuit 312 is constant regardless of the temperature change, but the current IC generated by the fourth current generation circuit 310 varies depending on the negative temperature characteristic between the base and emitter of the transistor Q7. To do. Here, the negative temperature coefficient between the base and emitter of the transistor Q7 is −2 mV / ° C. When the difference temperature from 25 ° C. when the temperature is higher than 25 ° C. is ΔT,
ΔI2 ′ = IC−ID = (2 mV / R7) ΔT
ΔI2 = n (2 mV / R7) ΔT
Therefore,
Iout = Iin + ΔI1−ΔI2
However, in detail,
When Ta> 25 ° C., Iout = Iin−n (2 mV / R7) ΔT
When Ta = 25 ° C., Iout = Iin
When Ta <25 ° C., Iout = Iin + m (2 mV / R6) ΔT Equation 4
It becomes.
However, ΔI1 in Equation 4 is a current that increases as the temperature becomes lower than the reference temperature of 25 ° C. Further, ΔI2 in Expression 4 is a current that increases as the temperature becomes higher than the reference temperature 25 ° C. On the other hand, ΔI1 in Equation 3 is a current that increases as the temperature becomes higher than the reference temperature 25 ° C. Further, ΔI2 in Expression 3 is a current that increases as the temperature becomes lower than the reference temperature of 25 ° C. The above is the difference between the meanings of the currents ΔI1 and ΔI2 shown in Equation 4 and Equation 3.

  FIG. 10 shows the characteristics of the above equation 4. When the temperature Ta = 25 ° C. (reference temperature), the relationship of current IA = current IB and current IC = current ID is maintained, so that ΔI1 and ΔI2 do not occur. Therefore, the output current Iout when the temperature Ta = 25 ° C. is the constant current Iin itself.

  When the temperature Ta <25 ° C., ΔI1 is generated according to the difference temperature ΔT. At this time, the current IC is smaller than the current ID. However, since the diode-connected transistor Q9 prevents the current from being supplied to the collector of the transistor Q7, ΔI2 does not flow. Therefore, Iout = Iin + ΔI1, and as the temperature decreases, the output current Iout increases in a linear manner. That is, when the temperature Ta <25 ° C., it is possible to provide a temperature characteristic correction circuit in which the output current Iout changes with a linear line with a positive slope as the temperature Ta decreases. In FIG. 10, straight lines a7, b7, and c7 are shown as an example of temperature correction characteristics at a temperature Ta <25 ° C. The slopes of the straight lines a7, b7, and c7 are obtained by changing the current mirror ratio 1: m of the transistors Q10 and Q11 constituting the third current generating circuit 308. Specifically, as the size ratio m of the transistor Q11 to the transistor Q10 is increased, the inclination changes from the inclination of a7 toward the inclination of c7. In other words, at a temperature Ta <25 ° C., it is possible to provide a temperature characteristic correction circuit that can change the slope of the output current Iout that increases as the temperature decreases.

  On the other hand, when the temperature Ta> 25 ° C., ΔI2 is generated according to the difference temperature ΔT. At this time, the current IA> the current IB, but since the diode-connected transistor Q8 prevents the current IA from flowing back to the third current generation circuit 308, ΔI1 does not flow. Therefore, Iout = Iin−ΔI2, and as the temperature increases, the output current Iout decreases in a linear manner. That is, when the temperature Ta> 25 ° C., it is possible to provide a temperature characteristic correction circuit in which the output current Iout changes in a linear manner with a negative slope as the temperature Ta increases. In FIG. 10, straight lines a8, b8, and c8 are shown as an example of temperature correction characteristics at a temperature Ta> 25 ° C. The slopes of the straight lines a8, b8, and c8 are obtained by changing the current mirror ratio 1: n of the transistors Q12 and Q13 that constitute the sixth current generation circuit 314. Specifically, as the size ratio n of the transistor Q13 to the transistor Q12 is increased, the inclination changes from the inclination of a8 toward the inclination of c8. That is, when the temperature Ta> 25 ° C., it is possible to provide a temperature characteristic correction circuit that can change the slope of the output current Iout that decreases as the temperature increases.

  In summary, the output current Iout becomes a constant current Iin at the reference temperature of 25 ° C., the output current Iout increases with an appropriate slope as the temperature Ta becomes lower than the reference temperature of 25 ° C., and the temperature Ta becomes the reference temperature of 25 It becomes possible to obtain a correction characteristic in which the output current Iout decreases with an appropriate slope as the temperature becomes higher than ° C.

  Furthermore, the reference temperature at which the output current Iout becomes equal to the constant current Iin can be made higher or lower than 25 ° C. In this case, the current IA and the current IB at 25 ° C. are not equal, and at the same time, the current IC is not equal to the current ID. Although this state is not shown, since the output current Iout at 25 ° C. is changed, the reference temperature at which the output current Iout becomes the constant current Iin is higher than 25 ° C. or lower than 25 ° C. Will shift to. In order to make the current IA and the current IB not equal at a temperature of 25 ° C., for example, the resistance value of the resistor R1 or the ratio of the resistance values of the resistors R2 and R3 may be changed as appropriate. Similarly, in order to make the current IC and the current ID not equal at a temperature of 25 ° C., for example, the resistance value of the load resistor R8 or the ratio of the resistance values of the resistor R4 and the resistor R5 may be changed as appropriate.

  Further, when the temperature Ta becomes lower than the reference temperature, the output current Iout can be kept constant as Iin without being raised like the straight lines a7, b7, and c7 shown in FIG. For this purpose, the signal line through which ΔI1 ′ flows may be cut off. Specifically, the signal line may be simply cut. Alternatively, a configuration is provided in which a control signal is generated in response to a request for keeping the output current Iout constant at Iin when the temperature Ta becomes lower than the reference temperature, and the diode-connected transistor Q8 is further turned on by the control signal. A configuration for blocking may be provided. Thus, it is possible to provide a temperature characteristic correction circuit in which the output current Iout remains constant as Iin when the temperature Ta becomes higher than the reference temperature. On the other hand, when the temperature Ta becomes higher than the reference temperature, the output current Iout can be kept constant as Iin without increasing as shown by the straight lines a8, b8, and c8 shown in FIG. For this purpose, the signal line through which ΔI2 ′ flows may be cut off. Specifically, the signal line may be simply cut. Alternatively, a configuration is provided in which a control signal is generated in response to a request for keeping the output current Iout constant at Iin when the temperature Ta becomes higher than the reference temperature, and the diode-connected transistor Q9 is further turned on by the control signal. A configuration for blocking may be provided. Thus, it is possible to provide a temperature characteristic correction circuit in which the output current Iout remains constant as Iin when the temperature Ta becomes higher than the reference temperature.

  According to the temperature characteristic correction circuit of FIG. 9, when the temperature Ta becomes lower than the reference temperature with the reference temperature as a boundary, the output current Iout rises with an appropriate slope, and when the temperature Ta becomes higher than the reference temperature, the output current It is possible to obtain a characteristic that Iout decreases with an appropriate inclination. In addition, the reference temperature can be changed. Since these characteristics can be realized by a small change in the circuit, it is versatile and suitable for integration. Then, according to the characteristics of the circuit 320, the setting of the current mirror ratio of the transistors Q10 and Q11, the setting of the current mirror ratio of the transistors Q12 and Q13, the current IA = current IB and the current IC = current ID according to the predetermined temperature The temperature characteristics of the circuit 320 can be effectively canceled by appropriately setting the reference temperature and blocking one of the transistors Q8 and Q9.

  As is apparent from the above description, the temperature characteristic correction circuit according to the present invention is a first current generation circuit (204 in FIGS. 1 and 4 and 204 in FIG. 7) that generates a constant first current regardless of temperature changes. , 304) in FIG. 9 and a first current generating circuit connected in series, and a second current generating circuit that generates a second current that increases as the temperature increases and becomes equal to the first current at a predetermined reference temperature ( 6 of FIG. 1 and FIG. 4, 206 of FIG. 7, 306 of FIG. 9 and a direct connection point of the first current generating circuit and the second current generating circuit, and the temperature is higher or lower than the reference temperature. 3, a third current generating circuit for generating a third current corresponding to the difference between the first current and the second current (8 in FIG. 1, 108 in FIG. 4, 208 in FIG. 7, 208 in FIG. 9). 308) and a fourth current that increases as the temperature increases. The fourth current generating circuit (10 in FIG. 1 and FIG. 4, 210 in FIG. 7, 310 in FIG. 9) is connected in series with the fourth current generating circuit, and is constant regardless of temperature change and at the reference temperature. A fifth current generating circuit (12 in FIGS. 1 and 4, 212 in FIG. 7, 312 in FIG. 9) that generates a fifth current equal to 4 currents, and a series connection of the fourth current generating circuit and the fifth current generating circuit And a sixth current generating circuit that generates a sixth current corresponding to the difference between the fourth current and the fifth current when the temperature is changed to the other of the higher side and the lower side with respect to the reference temperature. 14 of FIG. 1, 114 of FIG. 4, 214 of FIG. 7, 314 of FIG. 9, and a constant current circuit (18 of FIG. 1 and FIG. 2, 218 of FIG. 7, 318 of FIG. 9) according to the temperature change. A current output that is output by changing the output constant current by the amount of the third current or the sixth current. Circuit (16 in FIG. 1, 116 in FIG. 4, 216 in FIG. 7, 316 in FIG. 9) are those having a a. According to such a temperature characteristic correction circuit, it is possible to provide a highly versatile temperature characteristic correction circuit that can be applied to a circuit having various temperature dependencies by an easy design change. It is also possible to integrate the circuits shown in FIGS.

  Further, the current output circuit can change the constant current by the amount of the third current or the sixth current as follows. For example, the current output circuit adds the third current to the constant current when the temperature changes to either the higher side or the lower side (for example, the higher side) with respect to the reference temperature, and the temperature is higher than the reference temperature. In the case of changing to the other of the high side and the low side (for example, the low side), a current obtained by adding the sixth current to the constant current can be output. Further, the current output circuit adds the third current from the constant current when the temperature changes to either the higher side or the lower side (for example, the lower side) with respect to the reference temperature, and the temperature is higher than the reference temperature. In the case of changing to the other of the high side and the low side (for example, the high side), a current obtained by subtracting the sixth current from the constant current can also be output. The current output circuit adds the third current to the constant current when the temperature changes to either the higher side or the lower side (for example, the higher side) with respect to the reference temperature, and the temperature is higher than the reference temperature. In the case of changing to the other of the high side or the low side (for example, the low side), a current obtained by subtracting the sixth current from the constant current can also be output. Furthermore, the current output circuit adds the third current to the constant current when the temperature changes to either the higher side or the lower side (for example, the lower side) with respect to the reference temperature, and the temperature is higher than the reference temperature. In the case of changing to the other of the high side and the low side (for example, the high side), a current obtained by subtracting the sixth current from the constant current can also be output.

  Further, the first current generation circuit and the fifth current generation circuit are output so that the constant voltage VREG is applied to one input terminal (+ terminal) and the other input terminal (− terminal) is set to the same voltage as the constant voltage VREG. A first current and a fifth current are generated based on output voltages of operational amplifiers (2 in FIGS. 1 and 2, 202 in FIG. 7, and 302 in FIG. 9) that are fed back from the terminals. As a result, the output voltage and output current obtained from the output terminal of the operational amplifier have characteristics that do not depend on temperature, and the large current and the fifth current are constant regardless of the temperature change.

  The second current generation circuit and the fourth current generation circuit operate with the constant voltage VREG applied thereto, and the forward voltage changes with negative temperature characteristics (Q6, Q7), and the output of the transistor Each has a load resistance (R6, R7) through which current flows, and the second current and the fourth current are determined according to output currents flowing through transistors Q6, Q7 of the second current generation circuit and the fourth current generation circuit, respectively. . Here, the transistors Q6 and Q7 have a negative temperature characteristic in which the forward voltage between the base and emitter changes at −2 mV / ° C. Therefore, when the temperature changes, the currents flowing through the collectors and emitters of the transistors Q6 and Q7 change only due to the negative temperature characteristic applied to the forward voltage between the base emitters of the transistors Q6 and Q7. Therefore, currents that affect the negative temperature characteristics of the forward voltages of the transistors Q6 and Q7 can be obtained as the second current and the fourth current. Therefore, the negative temperature characteristic of the forward voltage of the transistors Q6 and Q7 appears as it is as the difference between the first current and the second current and the difference between the fourth current and the fifth current, and the target circuit (FIG. 1, 120 in FIG. 4, 220 in FIG. 7, and 320 in FIG. 9, the circuit design for canceling the temperature characteristics becomes easy.

  The third current generating circuit is a current mirror circuit that obtains a third current by multiplying the difference current between the first current and the second current by m. This m times is the mirror ratio of the current mirror circuit. Therefore, by appropriately setting the mirror ratio m, it is possible to change the rate at which the constant current changes by the third current, and to cancel the temperature characteristics of various circuits.

  The sixth current generating circuit is a current mirror circuit that obtains the sixth current by multiplying the difference current between the fourth current and the fifth current by n. This n times is the mirror ratio of the current mirror circuit. Therefore, by appropriately setting the mirror ratio n, the rate at which the constant current changes by the sixth current can be changed, and the temperature characteristics of various circuits can be canceled. If the current mirror ratios m and n in the third current generation circuit and the sixth current generation circuit are both set, the certainty of canceling the temperature characteristic of the circuit is increased.

  Further, the reference temperature when the first current and the second current are equal and the fourth current and the fifth current are equal is variable. This increases the certainty of canceling the temperature characteristics of the circuit. If the reference temperature is varied together with the setting of the current mirror ratios m and n of the third current generation circuit and the sixth current generation circuit, the certainty of canceling the temperature characteristic of the circuit is further increased.

  The temperature characteristic correction circuit according to the present invention has been described above, but the above description is intended to facilitate understanding of the present invention and is not intended to limit the present invention. The present invention can be changed and improved without departing from the gist thereof, and the present invention includes the equivalents.

1 is a circuit diagram showing a first embodiment of the present invention. It is a characteristic view which shows the relationship between the temperature in FIG. 1, and an electric current. It is another characteristic view which shows the relationship between the temperature and electric current in FIG. It is a circuit diagram which shows 2nd Embodiment of this invention. It is a characteristic view which shows the relationship between the temperature in FIG. 4, and an electric current. FIG. 6 is another characteristic diagram showing the relationship between temperature and current in FIG. 4. It is a circuit diagram which shows 3rd Embodiment of this invention. FIG. 8 is a characteristic diagram illustrating a relationship between temperature and current in FIG. 7. It is a circuit diagram which shows 4th Embodiment of this invention. FIG. 10 is a characteristic diagram illustrating a relationship between temperature and current in FIG. 9.

Explanation of symbols

2, 202, 302 Operational amplifier 4, 204, 304 First current generation circuit 6, 206, 306 Second current generation circuit 8, 108, 208, 308 Third current generation circuit 10, 210, 310 Fourth current generation circuit 12 212, 312 Fifth current generation circuit 14, 114, 214, 314 Sixth current generation circuit 18, 218, 318 Constant current source 20, 120, 220, 320 circuit

Claims (10)

A first current generating circuit for generating a constant first current regardless of a temperature change;
A second current generating circuit which is connected in series with the first current generating circuit and generates a second current that becomes larger as the temperature increases and becomes equal to the first current at a predetermined reference temperature;
When the first current generating circuit and the second current generating circuit are connected to a direct connection point and the temperature changes to one of a higher side and a lower side with respect to the reference temperature, the first current and the second current A third current generating circuit for generating a third current according to the difference between
A fourth current generating circuit for generating a fourth current that increases as the temperature increases;
A fifth current generating circuit connected in series with the fourth current generating circuit and generating a fifth current that is constant regardless of a temperature change and is equal to the fourth current at the reference temperature;
When the fourth current generating circuit and the fifth current generating circuit are connected to a series connection point, and the temperature changes to the other of the higher side and the lower side with respect to the reference temperature, the fourth current and the fifth current A sixth current generating circuit for generating a sixth current according to the difference between
A current output circuit for changing the constant current output from the constant current circuit by the amount of the third current or the sixth current in accordance with a temperature change;
A temperature characteristic correction circuit comprising: The current output circuit is
When the temperature changes to either the higher side or the lower side with respect to the reference temperature, the third current is added to the constant current, and the temperature is higher or lower than the reference temperature. The temperature characteristic correction circuit according to claim 1, wherein when the current is changed to the other, a current obtained by adding the sixth current to the constant current is output. The current output circuit is
When the temperature changes to either the higher side or the lower side with respect to the reference temperature, the third current is added from the constant current, and the temperature is higher or lower than the reference temperature. 2. The temperature characteristic correction circuit according to claim 1, wherein when the current is changed to the other, a current obtained by subtracting the sixth current from the constant current is output. The current output circuit is
When the temperature changes to either the higher side or the lower side with respect to the reference temperature, the third current is added to the constant current, and the temperature is higher or lower than the reference temperature. 2. The temperature characteristic correction circuit according to claim 1, wherein when the current is changed to the other, a current obtained by subtracting the sixth current from the constant current is output. The current output circuit is
When the temperature changes to either the higher side or the lower side with respect to the reference temperature, the third current is subtracted from the constant current, and the temperature is higher or lower than the reference temperature. The temperature characteristic correction circuit according to claim 1, wherein when the current is changed to the other, a current obtained by adding the sixth current to the constant current is output. The first current generating circuit and the fifth current generating circuit are:
A constant voltage is applied to one input terminal, and the first current and the fifth current are each based on the output voltage of an operational amplifier that feeds back from the output terminal so that the other input terminal has the same voltage as the constant voltage. The temperature characteristic correction circuit according to claim 1, wherein: The second current generation circuit and the fourth current generation circuit are operated by applying the constant voltage, and a forward resistance changes in a negative temperature characteristic, and a load resistance through which an output current of the transistor flows And each has
The temperature characteristic correction circuit according to claim 6, wherein the second current and the fourth current are determined according to an output current flowing through the transistors of the second current generation circuit and the fourth current generation circuit, respectively.   8. The current mirror circuit according to claim 1, wherein the third current generation circuit is a current mirror circuit that obtains the third current by multiplying a difference current between the first current and the second current by m. Temperature characteristic correction circuit according to the above.   9. The current mirror circuit according to claim 1, wherein the sixth current generation circuit is a current mirror circuit that obtains the sixth current by multiplying a difference current between the fourth current and the fifth current by n. Temperature characteristic correction circuit according to the above. 10. The reference temperature when the first current and the second current are equal and the fourth current and the fifth current are equal is variable. 10. Temperature characteristic correction circuit.

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