JP2009204422A - Semiconductor temperature sensor circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a temperature sensor circuit, having a characteristic depending only on an absolute temperature T, even when a saturation current I<SB>S</SB>of a bipolar transistor fluctuates by dispersion, in a manufacturing process, regarding a temperature sensor circuit constituted of a plurality of bipolar transistors. <P>SOLUTION: Two constant currents set to have an optional current ratio are supplied respectively at two different timings to one bipolar transistor, and each voltage difference generated in an emitter of the bipolar transistor is removed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a temperature sensor circuit, and more particularly to a semiconductor temperature sensor circuit using a semiconductor temperature sensor having a MOS structure.

  2. Description of the Related Art Conventionally, as a semiconductor temperature sensor circuit configured with a MOS structure in particular, a circuit configured with a plurality of bipolar transistors is known (see Patent Document 1).

  A conventional semiconductor temperature sensor circuit is configured by connecting a plurality of bipolar transistors each having a MOS structure and supplying a constant current to each emitter electrode. FIG. 3 is a circuit diagram of a conventional semiconductor temperature sensor circuit. The conventional semiconductor temperature sensor circuit shown in FIG. 3 has a plurality of PNP bipolar transistors each having a connector connected to a first constant potential point, and a plurality of constant currents connected to a second constant potential point. A constant current circuit composed of a plurality of MOS transistors, each emitter of the bipolar transistor being connected to receive one constant current, and the base of the first bipolar transistor being the first constant potential The base of the nth bipolar transistor is connected to the point, and the base of the nth bipolar transistor is connected to the emitter of the (n-1) th bipolar transistor so that an output is obtained from the emitter of the nth bipolar transistor. This is a semiconductor temperature sensor circuit.

In a conventional semiconductor temperature sensor circuit, when a constant current supplied to each emitter electrode from a constant current circuit constituted by a plurality of MOS transistors is I, the base-emitter voltage V _BE of one bipolar transistor is expressed by the following equation (1). The characteristic to be expressed is shown.

V _BE = kT / q ln (I / I _S ) (Formula 1)
Where k: Boltzmann constant, q: unit charge, T: total temperature, I _S : saturation current, I: current supplied to the emitter electrode of the bipolar transistor.

From the constant current circuit to the emitter electrode of the bipolar transistor, when the temperature dependency is supplied a constant current I almost negligible, the saturation current I _S V _BE from the above equation, if constant is one parameter characteristic of the bipolar transistor The voltage becomes a value dependent only on the absolute temperature T, and high-precision temperature sensing is possible.
Japanese Patent No. 3128013

However, conventional semiconductor temperature sensor circuit as described above, actually will be variations due to variations in the saturation current I _S is the manufacturing process, V _BE voltage is dependent only on the absolute temperature T as shown in Equation 1 It does not become a characteristic.

  In other words, the conventional semiconductor temperature sensor circuit has a problem that the characteristics of the bipolar transistor fluctuate due to variations in the manufacturing process, and the output of the semiconductor temperature sensor circuit obtained from the emitter of the nth bipolar transistor varies. It was.

  An object of the present invention is to provide a semiconductor temperature sensor circuit that solves the above-described problems of the prior art and obtains an output that depends only on the absolute temperature T.

  In order to solve the conventional problems, the semiconductor temperature sensor circuit of the present invention has the following configuration.

The semiconductor temperature sensor circuit has one bipolar transistor whose collector is connected to a first constant potential point and a second constant potential point, and a constant current I1 is sent to the emitter of the bipolar transistor at a first timing. The first constant current circuit composed of the supplied MOS transistor generates a base-emitter voltage V _BE 1 depending on the constant current I1 at the emitter of the bipolar transistor at the first timing. Further, at the first timing, the base-emitter voltage V _BE 1 is held by the holding means.

Similarly, the second constant current circuit composed of a bipolar transistor and a MOS transistor connected to the second constant potential point and configured to supply a constant current I2 to the emitter of the bipolar transistor at the second timing is used as the second constant current circuit. At this timing, the base-emitter voltage V _BE2 depending on the constant current I2 is generated at the emitter of the bipolar transistor. In addition, at the second timing, the base-emitter voltage V _BE2 is held by the holding means. Further, the constant currents I1 and I2 are set in a circuit with an arbitrary current ratio. Then, the differential voltage between the voltage V _BE 1 and the voltage V _BE 2 held at the first and second timings is taken and output.

  According to the semiconductor temperature sensor circuit of the present invention as described above, two constant currents set at arbitrary current ratios are supplied to one bipolar transistor at two different timings, respectively. Thus, the voltage difference value is a voltage that depends only on the constant current ratio and the absolute temperature, and there is an effect that a voltage that does not depend on variations in saturation current in the manufacturing process can be realized.

  Furthermore, manufacturing variations in the constant current ratio can be easily adjusted with a simple circuit if a constant current adjustment circuit that adjusts the constant current ratio to have a desired value is provided.

(1) Outline of Embodiment FIG. 1 is a block diagram showing an outline of a semiconductor temperature sensor circuit of the present embodiment.

  The semiconductor temperature sensor circuit of this embodiment includes a bipolar transistor 107 that is the semiconductor temperature sensor 2, a first constant current circuit 3, a second constant current circuit 4, and a voltage difference output circuit 5.

The first constant current circuit 3 supplies the constant current I1 to the emitter of the bipolar transistor 107 at the first timing. The first constant current circuit 3 is composed of, for example, a MOS transistor. The second constant current circuit 4 supplies a constant current I2 to the emitter of the bipolar transistor 107 at a second timing different from the first timing. The first constant current circuit 3 is composed of, for example, a MOS transistor. In the voltage difference output circuit 5, the emitter of the bipolar transistor 107 and the input terminal IN1 are connected, and the difference between the voltage V _BE 1 and the voltage V _BE 2 generated at the emitter of the bipolar transistor 107 at the first timing and the second timing. And output from the output terminal OUT1.

The base-emitter voltage V _BE 1 and the voltage V _BE 2 of the bipolar transistor 107 generated at the first timing and the second timing are expressed by the following equations.

V _BE 1 = kT / q ln (I1 / I _S ) (Formula 2)
V _BE 2 = kT / q ln (I2 / I _S ) (Formula 3)
However, k: Boltzmann constant, q: unit charge, T: total temperature, I _S : saturation current, I1: current supplied to the emitter of the bipolar transistor 107 at the first timing, I2: bipolar transistor 107 at the second timing Current supplied to the emitter. Here, since the saturation current I _S is a parameter determined by the characteristics of one bipolar transistor 107, it has the same value at the first and second timings.

Since the voltage V _BE 1 is input to the input terminal IN1 of the voltage difference output circuit 5 at the first timing and the voltage V _BE 2 is input at the second timing, the following expression is obtained from the output terminal OUT1. Output voltage VOUT is output.

_{VOUT1 = V BE 1-V BE} 2 = kT / q ln (I1 / I2) ··· ( Equation 4)
As can be seen from Equation 4, the voltage VOUT1 is a voltage that depends only on the current ratio (I1 / I2) and the absolute temperature T.

Therefore, the value of one parameter is a saturation current I _S of the bipolar transistor 107, even when having a variation in the manufacturing process, the variation can be obtained an output voltage VOUT1 of the temperature sensor which is independent (2) conducted FIG. 2 is a circuit diagram showing an example of the semiconductor temperature sensor circuit of the present embodiment.

  The transistor 101 which is an Nch depletion type transistor and the transistors 102, 103 and 104 which are Pch enhancement type transistors constitute a constant current circuit. The transistor 103 constitutes the first constant current circuit 3, and the transistor 104 constitutes the second constant current circuit 4.

  The temperature sensor 2 includes a bipolar transistor 107. The transistors 105 and 106 switch the low currents I1 and I2 by the signals T1X and T2X and supply them to the temperature sensor 2.

  Transistors 108 and 109, capacitive elements C1 and C2, buffer circuits 111 and 112, resistance elements R1, R2, R3 and R4, and operational amplifier circuit 110 constitute a voltage difference output circuit.

The transistor 101 in which the gate electrode and the source electrode are connected to the first constant potential point GND constitutes a constant current generating circuit that generates a constant current I _REF . The drain electrode of the transistor 101 is connected to the gate electrode and the drain electrode of the transistor 102 whose source electrode is connected to the second constant potential point VDD, and the transistor 103 whose source electrode is connected to the second constant potential point VDD. , 104 are connected to the gate electrodes. The transistors 102, 103, and 104 constitute a current mirror circuit that mirrors a current corresponding to the size ratio of each transistor.

  Here, a case where the current mirror ratio from the transistor 102 to the transistor 103 is 1 and the current mirror ratio from the transistor 102 to the transistor 104 is 100 will be described.

  The transistor 102 has a drain electrode connected to the drain electrode of the transistor 105, and a gate electrode to which a signal T1X from a timing generation circuit (not shown) is input, and conduction and cutoff are controlled by the signal T1X. At the first timing, the transistor 105 is set to be conductive, and is set to be cut off at other timings. Similarly, the transistor 104 has a drain electrode connected to the drain electrode of the transistor 106, a gate electrode that receives a signal T2X from a timing generation circuit (not shown), and conduction and cutoff are controlled by the signal T2X. At the second timing, the transistor 106 is set to be conductive, and is set to be cut off at other timings. The drain electrodes of the transistors 105 and 106 are connected to the emitter electrode of the bipolar transistor 107 whose base electrode and collector electrode are connected to the first constant potential point GND.

By performing the configuration and control as described above, a constant current (1 × I _REF ) is supplied to the emitter electrode of the bipolar transistor 107 at the first timing, and the voltage V _BE 1 is applied to the emitter-base voltage of the bipolar transistor 107. Will occur. At the second timing, a constant current (100 × I _REF ) is supplied to the emitter electrode of the bipolar transistor 107, and a voltage V _BE2 is generated as the emitter-base voltage of the bipolar transistor 107.

  The emitter electrode of the bipolar transistor 107 is connected to the source electrodes of the transistor 108 and the transistor 109. In the transistor 108, a signal T1 from a timing generation circuit (not shown) is input to the gate electrode, and conduction and interruption are controlled by the signal T1. The transistor 108 is set to be conductive at the first timing, and to be cut off at other timings. In the transistor 109, a signal T2 from a timing generation circuit (not shown) is input to the gate electrode, and conduction and interruption are controlled by the signal T2. In the second timing, the transistor 109 is set to be conductive, and is set to be cut off at other timings.

  The drain electrode of the transistor 108 is connected to one electrode of the capacitor C1. One electrode of the capacitive element C1 is connected to the inverting input terminal of the operational amplifier circuit 110 through the buffer circuit 111 and the resistive element R1. The drain electrode of the transistor 109 is connected to one electrode of the capacitor C2. One electrode of the capacitive element C2 is connected to the non-inverting input terminal of the operational amplifier circuit 110 through the buffer circuit 112 and the resistive element R2. The non-inverting input terminal of the operational amplifier circuit 110 is further connected to the first constant potential point GND via the resistance element R3. The inverting input terminal of the operational amplifier circuit 110 is further connected to the output terminal of the operational amplifier circuit 110 via the resistance element R4. The operational amplifier circuit 110 and the resistance elements R1, R2, R3, and R4 constitute a differential amplifier circuit.

By performing the configuration and control as described above, the voltage V _BE 1 generated at the emitter electrode of the bipolar transistor is charged to the capacitor element C1 at the first timing, and the capacitor element C1 even when the first timing ends. Holds the voltage V _BE 1. Similarly, at the second timing, the voltage V _BE 2 generated at the emitter electrode of the bipolar transistor is charged to the capacitive element C2, and the voltage V _BE 2 is held in the capacitive element C2 even when the second timing ends. The

  When the resistance values of the resistance elements R1, R2, R3, and R4 are set as R3 = R4 = A × R1 = A × R2, a voltage VOUT1 as shown in Expression 5 is output to the output terminal of the operational amplifier circuit 110. Is done.

_{VOUT1 = A {V BE 1-} V BE 2} = A {kT / q ln (100I REF / I REF)}
= A {kT / qln (100)} (Formula 5)
Therefore, the output VOUT1 of the operational amplifier circuit 110 can output a voltage that depends only on the constant current ratio, the resistance ratio A, and the absolute temperature T.

  In the present embodiment, the case where the current mirror ratio from the transistor 102 to the transistor 103 is 1 and the current mirror ratio from the transistor 102 to the transistor 104 is 100, that is, the current ratio is 100 times, the difference voltage is small. Therefore, a larger current ratio is advantageous for processing the voltage VOUT1. However, if the current ratio is increased too much, the influence on the current consumption increases, so that the effective range is approximately 100,000 times.

  Furthermore, when the ratio between the constant current I1 of the first constant current circuit and the constant current I2 of the second constant current circuit varies depending on the manufacturing process, the first constant current circuit and the second constant current A constant current ratio adjusting circuit may be added to the circuit to adjust the current ratio to a desired value.

  As described above, in the conventional semiconductor temperature sensor circuit, since the saturation current of the bipolar transistor varies depending on the manufacturing process, the output varies. However, the semiconductor temperature sensor circuit of the present invention has a difference in the saturation current of the bipolar transistor. Independent output can be obtained.

It is a block diagram which shows the outline of the semiconductor temperature sensor of this embodiment. It is a circuit diagram which shows an example of the semiconductor temperature sensor of this embodiment. It is a circuit diagram of the conventional semiconductor temperature sensor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Temperature sensor 2 Semiconductor temperature sensor 3 1st constant current circuit 4 2nd constant current circuit 5 Voltage difference output circuit 110 Operational amplifier circuits 111 and 112 Buffer circuit

Claims (4)

A semiconductor temperature sensor circuit including a bipolar transistor having a collector and a base connected as a temperature sensor,
A first constant current circuit connected to the emitter of the bipolar transistor via a first switch circuit and outputting a first constant current;
A second constant current circuit for outputting a second constant current connected to the emitter of the bipolar transistor via a second switch circuit;
An input terminal is connected to the emitter of the bipolar transistor, and an emitter voltage when the first constant current flows to the bipolar transistor and an emitter voltage when the second constant current flows to the emitter of the bipolar transistor A voltage difference output circuit that outputs a voltage difference between
A semiconductor temperature sensor circuit comprising: The voltage difference output circuit is
First holding means connected to the input terminal via a third switch circuit;
A second holding means connected to the input terminal via a fourth switch circuit;
An operational amplifier circuit having an inverting input terminal and a non-inverting input terminal and an output terminal,
The operational amplifier circuit includes:
The inverting input terminal is connected to the first holding means via a first resistance element, and is connected to the output terminal via a fourth resistance element;
The non-inverting input terminal is connected to the second holding means via a second resistance element, and is connected to the ground terminal via a third resistance element;
The semiconductor temperature sensor circuit according to claim 1.   3. The semiconductor temperature sensor circuit according to claim 1, wherein a current ratio between the first constant current and the second constant current is set to 100 times or more and 100000 times or less.   The constant current ratio adjustment circuit for adjusting the current ratio of the first constant current and the second constant current to a desired current ratio is provided. Semiconductor temperature sensor circuit.

Images