JPH04315932A - Temperature sensor - Google Patents

Abstract

PURPOSE:To provide a temperature sensor circuit in a semiconductor integrated circuit capable of setting the output voltage and temperature coefficient freely without being subjected to influence of fluctuation in a negative power source. CONSTITUTION:Fluctuation in temperature is detected by the use of temperature characteristic of bipolar transistors 1, 2, 3 and it is converted into fluctuation in current by a constant current circuit composed of an amplifier 12, MOS transistors 9, 10 and resistance element 14. This current fluctuates according to fluctuation in temperature without being affected by the influence of fluctuation in a negative power source is copied to a MOS transistor 11 by a current mirror circuit, and converted into voltage and output to an output terminal 19 by an inverter amplifier composed of an amplifier 13 and resistance elements 15, 16. As a result, temperature coefficient can be set freely by arbitrarily setting the ratio between the low resistance elements 14, 16 and similarly voltage can be set freely by arbitrarily setting first and second reference voltages, and output of temperature sensor which is not affected by fluctuation in a negative power source 8 can be obtained.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature sensor circuit, and more particularly to a temperature sensor in a semiconductor integrated circuit.

0002

2. Description of the Related Art A circuit shown in FIG. 2 is known as a conventional example of a temperature sensor circuit that detects temperature and outputs the temperature change as a voltage change. In FIG. 2, in the conventional circuit, the emitter of a bipolar transistor 1 whose collector and base are connected to a negative power supply is connected to a constant current source 4 and the base of a bipolar transistor 2 whose collector is connected to a negative power supply. The emitter of 2 is connected to the constant current source 5 and the base of the bipolar transistor 3,
The emitter of the bipolar transistor 3 whose collector was connected to a negative power supply was connected to a constant current source 6 and an output terminal 19 in a circuit configuration.

The voltage at the output terminal 19 in FIG. 2, which is an example of a conventional circuit, is expressed by the equation (1), and the change in the voltage at the output terminal 19 with respect to temperature is expressed by the equation (2).

0004

[Equation 1] Vout=Vss+3×Vbe

[Equation 2] Here, Vout is the voltage at the output terminal, dVout/
dT represents the change in voltage at the output terminal with respect to temperature, Vss represents the negative power supply voltage, Vbe represents the base-emitter voltage of the bipolar transistor, and dVbe/dT represents the temperature coefficient of the base-emitter voltage Vbe. In the conventional temperature sensor circuit, as can be seen from equations 1 and 2, the voltage at the output terminal 19 is
Base-emitter voltage Vbe3 with respect to negative power supply voltage Vss
The voltage is for each stage, and the temperature coefficient is the base-emitter voltage V.
The circuit configuration was such that the temperature coefficient of be was three times that of be.

[0005]

[Problems to be Solved by the Invention] In the conventional circuit described above, the voltage at the output terminal is three times the base-emitter voltage Vbe of the bipolar transistor, and the temperature coefficient is also limited to three times the temperature coefficient of the base-emitter voltage Vbe. Moreover, it has the disadvantage that it is greatly affected by fluctuations in the negative power supply voltage Vss.

The present invention has been made in view of the above-mentioned conventional circumstances, and therefore, an object of the present invention is to provide a novel temperature sensor circuit that makes it possible to eliminate the above-mentioned drawbacks inherent in the conventional technology. It's about doing.

[0007]

[Means for Solving the Problems] In order to achieve the above object, the temperature sensor circuit according to the present invention has the emitter of the first bipolar transistor whose base and collector are connected to the negative power supply, and the collector connected to the negative power supply. The base of a second bipolar transistor connected to the first constant current source connected to a positive power supply, and the emitter of the second bipolar transistor connected to the base of a third bipolar transistor whose collector was connected to a negative power supply. and a second constant current source connected to a positive power source, and the emitter of the third bipolar transistor is connected to the third constant current source connected to the positive power source and a positive input of the first amplifier, A negative input of the first amplifier is connected to a source of a first MOS transistor and a first terminal of a first resistor, a second terminal of the first resistor is connected to a negative power supply, and a second terminal of the first resistor is connected to a negative power supply. The gate of the first MOS transistor is connected to the output of the first amplifier, the drain is connected to the drain and gate of the second MOS transistor and the gate of the third MOS transistor, and the gate of the first MOS transistor is connected to the output of the first amplifier. The sources of the transistors are each connected to the positive power supply, and the drain of the third MOS transistor is connected to the first terminal of the second resistor, the first terminal of the third resistor and the negative input of the second amplifier. , a second terminal of the second resistor is connected to an input terminal of a reference voltage 1, a positive input of the second amplifier is connected to an input terminal of a second reference voltage 2, and an output has a circuit configuration connected to the second terminal and output terminal of the third resistor.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a preferred embodiment of the present invention will be specifically explained with reference to the drawings.

FIG. 1 is a circuit diagram showing an embodiment of a temperature sensor circuit according to the present invention.

To explain the circuit configuration in FIG. 1,
The emitter of a bipolar transistor 1 whose base and collector are connected to a negative power supply is connected to the base of a bipolar transistor 2 whose collector is connected to a negative power supply and to a constant current source 4 which is connected to a positive power supply. The emitter of the bipolar transistor 2 is connected to the base of a bipolar transistor 3 whose collector is connected to a negative power supply, and to a constant current source 5 connected to a positive power supply. The emitter of the bipolar transistor 3 is connected to a constant current source 6 connected to a positive current source.
is connected to the positive input of the amplifier 12, and the negative input of the amplifier 12 is connected to the source of the MOS transistor 9 and the first resistor 14.
is connected to the terminal. The second terminal of the resistor 14 is connected to a negative power supply, the gate of the MOS transistor 9 is connected to the output of the amplifier 12, and the drain of the MOS transistor 9 is connected to the drain and gate of the MOS transistor 10 and the gate of the MOS transistor 11. has been done. M
The sources of the OS transistors 10 and 11 are each connected to a positive power supply, and the drain of the MOS transistor 11 is connected to a first terminal of a resistor 15, a first terminal of a resistor 16, and a negative input of an amplifier 13, respectively. ing. The second terminal of the resistor 15 is connected to the input terminal 17 of the first reference voltage, the positive input of the amplifier 13 is connected to the input terminal 18 of the second reference voltage, and the output is connected to the second input terminal 17 of the resistor 16. and the output terminal 19.

In order to explain the circuit operation, each current flowing through the circuit will be calculated using equations. The amplifier 12, MOS transistor 9, and resistor 14 constitute a constant current circuit,
The positive input of the amplifier 12 receives a differential voltage corresponding to three stages of the base-emitter voltage Vbe of the bipolar transistor with respect to the negative power supply 8 . Further, the negative input of the amplifier 12 is at the same potential as the positive input which is in a virtual ground relationship, and the resistor 14 connected between the negative power supply 8 and the negative input always has a base emitter voltage Vbe of three stages. Voltage is applied.

Current I0 flowing through resistor 14, resistor 14
Assuming that the resistance value of is R14, the power supply I0 is expressed by Equation 3. Equation 3 indicates that the current flowing through the resistor 14 is not affected by fluctuations in the negative power supply 8.

Furthermore, P channel MOS transistor 10 and P channel M
The OS transistor 11 is connected in a current mirror, and the transistor size of the P-channel MOS transistor 10 is W10/L10, the transistor size of the P-channel MOS transistor 11 is W11/L11, and the current flowing through the P-channel MOS transistor 11 is I1. , the current I1 is expressed by Equation 4.

[0014]

[Equation 5] I1=I0 The resistor 15 connects the first reference voltage input terminal 17 and the amplifier 1
Connected to the negative input of 3. Since the positive and negative inputs of the amplifier 13, which constitutes an inverting amplifier, are in a virtual ground relationship, the negative input has the same voltage as the second reference voltage input to the positive input. When the current flowing through the resistor 15 is I2, the resistance value is R15, the first reference voltage is Vref1, and the second reference voltage is Vref2, the current I2 is expressed by Equation 6.

[0015]

[Equation 6] The resistor 16 is connected between the output terminal 19 and the negative input of the amplifier 13, and the current flowing through the resistor 16 is I3,
Assuming that the resistance value is R16, the current I3 is expressed by Equation 7.

[0016]

[Equation 7] Applying Kirchhoff's law to the negative input contact of the amplifier 13 and calculating the voltage Vout at the output terminal 19 using Equations 3 to 7, Vout is given by Equation 8.

[0017]Furthermore, the change in Vout with respect to the change in temperature is given by Equation 9.

[0018]

[Equation 9] As can be seen from Equation 8 above, the voltage at the output terminal 19 can be determined by setting the resistance value of the resistor 15, the first reference voltage, or the second reference voltage to an arbitrary value. Can be set freely. Similarly, the temperature coefficient of the output terminal 19 can be freely set by setting the resistance value of the resistor 16 or the resistor 14 to an arbitrary value, as can be seen from Equation 9. Furthermore, the reference voltage is not affected by the fluctuations in the negative power supply 8, and as is clear from the fact that there is no term for the negative power supply voltage Vss in Equations 8 and 9, the voltage at the output terminal 19 is not affected by the fluctuations in the negative power supply 8. Not affected by

In one embodiment of the present invention, a series circuit of a bipolar transistor and a constant current source is connected in series in three stages, but instead, a series circuit of a bipolar transistor and a constant current source is connected in one stage. In the case of two stages,
Of course, the present invention can also be applied to three or more stages.

[0020]

As explained above, according to the temperature sensor circuit of the present invention, the voltage and temperature coefficient of the output terminal are determined by the base emitter voltage Vbe and V of the bipolar transistor.
It can be set freely without being restricted by the temperature coefficient of be.
Moreover, the effect of not being affected by fluctuations in the negative power supply voltage Vss can be obtained.

[Brief explanation of drawings]

FIG. 1 is a circuit block configuration diagram showing an embodiment of a temperature sensor circuit according to the present invention.

FIG. 2 is a circuit diagram showing an example of a conventional temperature sensor circuit.

[Explanation of symbols]

1 to 3...Bipolar transistor 4 to 6...constant current source 7...Positive power supply 8...Negative power supply 9-11...MOS transistor 12, 13...Amplifier 14-16...Resistor 17...First reference voltage input terminal 18...Second reference voltage input terminal 19...Output terminal

Claims (3)

[Claims] 1. A first bipolar transistor having a base and a collector connected to a negative power supply and an emitter connected to a first constant current source connected to a positive power supply, and a first bipolar transistor having a positive input and a negative input. an amplifier, the negative input of the first amplifier is connected to the source of the first N-channel MOS transistor and the first terminal of the first resistor, and the negative input of the first amplifier is connected to the second terminal of the first resistor. The terminal is connected to a negative power supply, the gate of the first N-channel MOS transistor is connected to the output of the first amplifier, and the drain is connected to the drain and gate of the second P-channel MOS transistor, and the third P-channel MOS transistor. M
connected to the gate of the OS transistor, and the second and third
The sources of the P-channel MOS transistors are respectively connected to a positive power supply, and the drains of the third P-channel MOS transistor are connected to the first terminal of the second resistor, the first terminal of the third resistor, and the third resistor. The second terminal of the second resistor is connected to the input terminal of the first reference voltage, and the positive input of the second amplifier is connected to the input terminal of the second reference voltage. A constant current source is connected between the emitter of the bipolar transistor, which is connected to the input terminal, whose output is connected to the second terminal and the output terminal of the third resistor, and whose collector is connected to the negative power source and the positive power source. At least one circuit whose base is connected to the emitter of a preceding bipolar transistor is connected between the emitter of the first bipolar transistor and the positive input of the first amplifier. circuit. 2. The emitter of a first bipolar transistor whose base and collector are connected to a negative power supply is connected to the base of a second bipolar transistor whose collector is connected to a negative power supply and the emitter of a first bipolar transistor whose base and collector are connected to a positive power supply. The emitter of the second bipolar transistor connected to a constant current source is connected to the base of a third bipolar transistor whose collector is connected to a negative power source, and the second constant current source connected to a positive power source, The emitter of the third bipolar transistor is connected to a third constant current source connected to a positive power supply and the positive input of the first amplifier, and the negative input of the first amplifier is connected to the first N-channel MOS transistor. is connected to the source of the first resistor and the first terminal of the first resistor;
is connected to a negative power supply, and the terminal of the first N-channel MO
The gate of the S transistor is connected to the output of the first amplifier, the drain is connected to the drain and gate of the second P channel MOS transistor, and the gate of the third P channel MOS transistor, The sources of the P-channel MOS transistors are respectively connected to a positive power supply, and the drains of the third P-channel MOS transistor are connected to the first terminal of the second resistor, the first terminal of the third resistor, and the third resistor. The second terminal of the second resistor is connected to the input terminal of the first reference voltage, and the positive input of the second amplifier is connected to the input terminal of the second reference voltage. A temperature sensor circuit characterized in that the circuit is connected to an input terminal, and an output is connected to a second terminal and an output terminal of the third resistor. 3. The series circuit of the second bipolar transistor and the second constant current source and the series circuit of the third bipolar transistor and the third constant current source are removed, and the first bipolar transistor and the third constant current source are removed. 3. The temperature sensor circuit according to claim 2, further comprising an emitter of a transistor connected to the positive input of the first amplifier.