JP2005142279A - Resistor element and temperature detecting circuit using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resistor element capable of realizing a temperature detecting circuit that can output a voltage having highly linear temperature characteristics by amplifying the voltage. <P>SOLUTION: The resistor element 10 is constituted of a plurality of polysilicon resistors 12. The resistors 12 are provided on an oxidized film 24 (insulator) formed on a substrate 22 (a first resistor biasing conductor). Above the polysilicon resistors 12, on the other hand, a thin metallic plate 28 (second resistor biasing conductor) is disposed in parallel with the substrate 22 through an interlayer film 26 (insulator). Upon the substrate 22 and the thin metallic plate 28, independent voltages are respectively impressed. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a resistor element, and also relates to a voltage temperature detection circuit that outputs a voltage having a temperature characteristic that enables highly accurate temperature detection using the resistor element.

  Conventionally, there is a temperature detection circuit described in Patent Document 1 (see FIG. 1). This temperature detection circuit has a first field effect transistor pair composed of a first field effect transistor M1 and a second field effect transistor M2 having gates of different conductivity types, and the same polarity conductivity type. A reference voltage for obtaining a reference voltage by using a work function difference between the gate electrodes of each of the second field effect transistor pair composed of the third field effect transistor M3 and the fourth field effect transistor M4 having gates with different impurity concentrations. The temperature characteristic of the voltage output from the source circuit is used.

  More specifically, the reference voltage source circuit is composed of three circuit blocks. In the circuit block on the left side of the drawing, the first electric field having a high-concentration n-type gate by connecting the gate and the source. An effect transistor M1 and a second field transistor M2 (encircled in the figure) having a high-concentration p-type gate are connected in series between the power supply Vcc and the ground GND. Next, in the circuit block in the center of the drawing, a fifth field effect transistor M5 having a gate and a source connected, and resistors R1 and R2 are connected in series in order from the power supply Vcc to the ground GND. In the circuit on the right side of the drawing, a third transistor M3 having a high-concentration n-type gate and a fourth field effect transistor M4 having a low-concentration n-type gate by connecting the gate and the source (Δ in the figure) Are connected in series between the power supply Vcc and the ground GND. In these configurations, the gates of the first field effect transistor M1 and the fifth field effect transistor M5 are connected, and the gate of the second field effect transistor M2 is between the fifth field effect transistor M5 and the resistor R1. The gate of the third field effect transistor M3 is connected to a node between the resistors R1 and R2. All field effect transistors are of the same polarity channel type. In particular, the channel of the field effect transistor M1 and the channel of M2 are the same (channel ratio is equal), and the channel of the field effect transistor M3 and M4 Have the same channel (equal channel ratio). Further, all the field effect transistors are provided in independent wells, and the potentials of the substrate and the source are made equal.

In the circuit having the above-described configuration, the gate and source of the first field effect transistor M1 are connected, and the same current flows through the first and second field effect transistors M1 and M2. The work function difference between the respective gate electrodes of the field effect transistors M1 and M2 is represented by a gate-source voltage V1 of the second field effect transistor M2 (hereinafter referred to as “Vpn”). Next, the gate voltage V2 of the third field effect transistor M3 can be expressed by [Equation 1].
[Equation 1]
V2 = {R2 / (R1 + R2)} × V1 = {R2 / (R1 + R2)} × Vpn

Next, since the gate and the source of the fourth field effect transistor M4 are connected and the same current flows through the third and fourth field effect transistors M3 and M4, the third and fourth field effect transistors. The work function difference between the gate electrodes of M3 and M4 is represented by the gate-source voltage Vnn of the third field effect transistor M3. Therefore, the source voltage V3 of the third field effect transistor M3 used as the reference voltage can be expressed by [Equation 2].
[Equation 2]
V3 = {R2 / (R1 + R2)} × Vpn + Vnn

In the above circuit, the voltage Vnn indicating the work function difference between the gate electrodes of the third field effect transistor M3 and the fourth field effect transistor M4 has a positive temperature characteristic as shown in FIG. In the figure, the black dots represent measured values, while the solid line represents a relational expression (temperature characteristic of Vnn) between Vnn and temperature calculated from the measured values. By using this voltage Vnn, a temperature detection circuit having a positive temperature characteristic can be obtained.
JP 2001-284464 A

However, the equation indicating the temperature characteristic of the voltage Vnn includes a second-order coefficient, and therefore a highly accurate temperature detection circuit cannot be obtained. For example, in order to obtain a temperature characteristic having linearity with an accuracy of ± 0.3 ° C., the second order coefficient needs to be 7.0 × 10 ⁻⁵ or less. The voltage Vnn may be amplified and used as the final output of the temperature detection circuit.

  Accordingly, an object of the present invention is to provide an amplifier circuit (element) that reduces (corrects) a second-order coefficient included in the temperature characteristic of the voltage Vnn. Moreover, the temperature detection circuit which can output the voltage which has the temperature characteristic excellent in linearity using it is provided.

The resistor element of the present invention that solves the problem has a plurality of resistors connected in series via a plurality of nodes,
One of the plurality of nodes is set as a voltage input node,
In the resistor element having any one or more of the plurality of nodes as a voltage output node,
It is characterized by having at least one resistor biasing conductor disposed adjacent to at least a part of the plurality of resistors via an insulator.

  In the resistor element of the present invention, the resistor is made of polycrystalline silicon.

Furthermore, the temperature detection circuit of the present invention includes
A voltage source circuit composed of first and second field effect transistors having the same conductivity type and different impurity concentrations;
A temperature detection circuit including a source follower circuit including a third field effect transistor, a first resistor, and a second resistor;
The resistor element includes any one of a first voltage output node and a second voltage output node at each of terminals of the plurality of resistors connected in series, and a plurality of nodes between the plurality of resistors. A voltage input node,
The first resistor is formed between the first voltage output node and the voltage input node,
The second resistor is formed between the second voltage output node and the voltage input node,
The output of the temperature detection circuit is input to the input voltage node, and the voltage output from the output node is used.

  According to the present invention, there is provided a temperature detection circuit capable of outputting a highly accurate output voltage with a reduced second-order coefficient of temperature characteristics. The output voltage is output in the form of an amplified input voltage.

  As shown in FIG. 3, the resistor element 10 according to the present invention includes a plurality of resistors, for example, a polysilicon resistor 12. Each of the plurality of polysilicon resistors 12 is arranged in parallel and connected by a plurality of nodes (conductors) 14 so that current paths are in a meandering series, thereby reducing the size of the entire resistor element 10. Yes. In this embodiment, these polysilicon resistors 12 are doped to a low concentration n-type. Terminals 16 and 18 for inputting and outputting voltage are connected to both ends of the plurality of polysilicon resistors 12 connected in series.

  The resistor element 10 is used as a part of an amplifier circuit of a temperature detection circuit as shown in FIG. Specifically, one of the plurality of nodes 14 of the resistor element 10 is connected to the input voltage terminal 20 to which the amplified voltage Vnn is input, while the terminals 16 and 18 amplify the voltage Vnn. The output voltage Vout is used as an output voltage terminal and a ground GND terminal. The group of polysilicon resistors 12 between the input voltage Vnn terminal 20 and the output voltage Vout terminal 16 are connected to the resistor R1, and the group of polysilicon resistors between the input voltage Vnn terminal 20 and the ground GND terminal 18. When the body 12 is a resistor R2, the resistor element 10 can be used as an amplifier circuit composed of resistors R1 and R2. The resistors R1 and R2 of the resistor element 10 can be variously set by changing the number of the polysilicon resistors 12 and the arrangement of the input voltage terminals. The output voltage Vout output from the resistor element 10 configured as described above is amplified to (R1 + R2) / R2 times the input voltage Vnn.

  The plurality of polysilicon resistors 12 are provided in the configuration shown in FIG. 3 on an oxide film 24 (insulator) formed on a substrate 22 (first resistor bias conductor) (see FIG. 4). .) In this embodiment, the oxide film 24 has a thickness of about 5,000 mm. The first conductor may not be the substrate 22 and may be, for example, a well formed on the substrate. In this embodiment, the substrate 22 is an n-type substrate. On the other hand, a thin metal plate 28 (second resistor biasing conductor) is disposed above the plurality of polysilicon resistors 12 in parallel with the substrate 22 via an interlayer film 26 (insulator). In this embodiment, the interlayer film 26 has a thickness of about 10,000 mm. The second conductor may not be a thin metal plate but may be a metal film. Independent voltages are applied to the substrate 22 and the metal thin plate 28, respectively.

  The amplification factor (R1 + R2) / R2 of the resistor element 10 configured as described above is the voltage of the input voltage Vnn terminal 20, the output voltage Vout terminal 16, the ground GND terminal 18, the substrate 22, and the metal thin plate 28. It is determined by the application state. More specifically, a predetermined voltage is applied to the resistors R1 and R2 by the input voltage Vnn terminal 20, the output voltage Vout terminal 16, and the ground GND terminal 18. Since the resistors R1 and R2 to which a predetermined voltage is applied are configured by a plurality of n-type polysilicon resistors 12, the potential difference between the substrate 22 and the metal thin plate 28 to which the predetermined voltage is applied, respectively. The resistance value is biased. For example, considering the influence of the bias from the substrate 22 on the plurality of polysilicon resistors 12 constituting the resistor R1, the voltage applied to the substrate 22 is higher than the voltage applied to the plurality of polysilicon resistors 12 of the resistor R1. When the applied voltage is high, a carrier accumulation layer is induced inside the polysilicon resistor 12, and the resistance value of the resistor R1 is reduced as compared with that before being biased. On the contrary, when the voltage applied to the substrate 22 is low, a depletion layer is induced inside the polysilicon resistor 12, and the resistance value of the resistor R1 increases. As a matter of course, this also occurs in the resistor R2, and the resistance value similarly changes even when the metal thin plate 28 is used for biasing. Therefore, the resistor element 10 of the present invention changes the voltage application state of the input voltage Vnn terminal 20, the output voltage Vout terminal 16, the ground GND terminal 18, the substrate 22, and the metal thin plate 28 to obtain a desired element. Amplification factor (R1 + R2) / R2.

  As shown in FIG. 5, the temperature detection circuit including the resistor element 10 of the present invention is composed of two circuit blocks. In the circuit block (first circuit block) on the left side of the drawing, the first field effect transistor M1 having a high-concentration n-type gate by connecting the gate and the source, and the second having a low-concentration n-type gate. The field transistor M2 (enclosed by Δ in the figure) is connected in series between the power supply Vcc and the ground GND. The first field effect transistor M1 and the second field effect transistor M2 have the same gate width, gate length, and gate oxide film thickness, the gate width is 50 μm, the gate length is 100 μm, and the gate oxide film thickness. Is 300 mm and has the same channel with the same polarity channel type. On the other hand, in the circuit block (second circuit block) on the right side of the drawing, a third field effect transistor M3 having a gate and a source connected in order from the power source Vcc to the ground GND and resistors R1 and R2 are connected in series. ing. Of course, the resistors R1 and R2 are resistors configured in the resistor element 10. The third field effect transistor M3 is a channel type having the same polarity as the first and second field effect transistors M1 and M2. Furthermore, all these field effect transistors have the same substrate and source potentials. In these configurations, the gates of the first field effect transistor M1 and the third field effect transistor M3 are connected, and the gate of the second field effect transistor M2 is connected to the node between the resistors R1 and R2. Has been. The final output of this temperature detection circuit is given from the source voltage of the third field effect transistor M3.

In the temperature detection circuit, since the gate and source of the first field effect transistor M1 are connected and the same current flows through the first and second field effect transistors M1 and M2, the first and second field effect transistors M1 and M2 are connected. The work function difference between the gate electrodes of the field effect transistors M1 and M2 is represented by the gate-source voltage Vnn of the second field effect transistor M2. At this time, the final output voltage Vout of the temperature detection circuit can be expressed by [Equation 3].
[Equation 3]
Vout = {(R1 + R2) / R2} × Vnn

  In order to amplify the input voltage Vnn by 30 times, for example, the input voltage Vnn is approximately under the condition (bias condition) in which 0 volt is applied to the ground GND terminal 18, 5 volt is applied to the substrate 22, and 0 volt is applied to the metal thin plate 28. A temperature detection circuit using the resistor element 10 in which the resistance values of the resistors R1 and R2 are set so that the output voltage Vout is biased to about 0.05 volts and about 30 times the input voltage Vnn. The temperature characteristics of the amplification magnification are shown in FIG. In the figure, the output voltage Vout and the input voltage Vnn are measured in the measurement temperature range of 0 to 100 ° C., and the ratio (amplification magnification) is obtained to show the result. As shown in the figure, the amplification magnification obtained by measurement in all temperature ranges exceeds 30 times the set amplification magnification. This occurs because carriers accumulate due to the bias conditions as described above, and the resistance value of the resistor R2 becomes smaller than the original value. Further, the amplification factor of the resistor element 10 has a so-called negative temperature characteristic that decreases as the temperature rises.

  Next, the mechanism by which the linearity of the temperature characteristic of the output voltage Vout of the temperature detection circuit is improved by these phenomena will be described. FIG. 7 is a graph showing the output voltage Vout with respect to temperature before amplification (indicated by a dotted line in the figure) and after amplification by 30 times (indicated by a solid line in the figure). First, before amplification, the amount of increase in the output voltage accompanying the temperature rise is small in the low temperature range, substantially constant in the intermediate range, and large in the high temperature range. These changes in the increase amount of the output voltage Vout between the low temperature range and the high temperature range cause a curve in the temperature characteristic graph, and as a result, increase the second order coefficient. On the other hand, when amplification is performed 30 times, it is necessary to consider the resistance ratio of [Equation 3]. In general, since the accumulation of carriers is inversely proportional to the temperature, as shown in FIG. 6, the accumulation of carriers becomes remarkable in a low temperature region, and has a temperature characteristic with a negative amplification factor. Therefore, the amplification factor becomes larger than the original amplification factor in the low temperature range, and the amplification amount gradually decreases as the temperature increases. As a result, due to the temperature characteristics of carrier accumulation and resistance ratio, the increase amount of the output voltage Vout accompanying the temperature rise becomes substantially constant in all temperature regions compared to before amplification, and the decrease of the second order coefficient, that is, the temperature characteristics. Improvement of linearity is realized.

Specifically, it shows that the linearity of the temperature characteristic of the output voltage Vout is improved by increasing the amplification factor. The amplification factor of the resistor element 10 incorporated in the temperature detection circuit of the present invention is changed, the output voltage Vout and the temperature at each amplification factor are measured, and the relational expression between the output voltage Vout and the temperature (the temperature of Vout) Characteristic). The measurement temperature range at this time is 0-100 degreeC. FIG. 8 shows the relationship between the secondary coefficient of the relational expression between the output voltage Vout and the temperature and the amplification factor. As shown in the figure, the second-order coefficient increases from 4.5 × 10 ⁻⁴ to 1.3 × 10 ⁻⁵ by increasing the amplification factor of the resistor element 10 from 1 × to 61 ×. It has been reduced to 35. In addition, in order for the temperature characteristic of the output voltage Vout to have a linearity with an accuracy of ± 0.3 ° C. or less (the second-order coefficient of the temperature characteristic is 7.0 × 10 ⁻⁵ or less), the resistor element 10 It can be seen that the amplification magnification of 2 should be 2 or more. Further, it can be seen that the output voltage Vout can obtain a temperature characteristic having linearity with an accuracy of ± 0.2 ° C. or less when the amplification magnification is 61 times.

  In the resistor element of the above form, the plurality of polysilicon resistors constituting the resistors R1 and R2 of the temperature detection circuit are biased with the same substrate and the same metal thin plate, but for each of the resistors R1 and R2. A substrate and a thin metal plate may be provided. For example, the first substrate of the first conductor is disposed below the plurality of polysilicon resistors constituting the resistor R1, and the first metal thin plate of the second conductor is disposed above. On the other hand, the second substrate of the third conductor is disposed below the plurality of polysilicon resistors constituting the resistor R2, and the second metal thin plate of the fourth conductor is disposed above. As a result, the amplification factor of the resistor element can be set more finely by the four conductors. Of course, the amplification factor of the resistor element can be set even with one conductor.

It is a circuit diagram of the conventional temperature detection circuit. It is a figure which shows the temperature characteristic of the voltage Vnn. It is a front view of the resistor element of the present invention. It is sectional drawing of the resistor element shown by the AA line of FIG. It is a circuit diagram of the temperature detection circuit of this invention. It is a figure which shows the temperature characteristic of the amplification magnification of the resistor element of this invention. It is a figure which shows the temperature characteristic of the output voltage Vout before amplification and after amplification. It is a figure which shows the relationship between the secondary coefficient of the temperature characteristic of the output voltage of the temperature detection circuit of this invention, and amplification magnification.

Explanation of symbols

10 resistor element, 12 polysilicon resistor, 14 node, 16 terminal, 18 terminal, 20 input voltage terminal, 22 substrate, 24 oxide film, 26 interlayer film, 28 metal thin plate,
M1, M2, M3, M4, M5 Field effect transistors R1, R2 Resistance

Claims (3)

Having a plurality of resistors connected in series via a plurality of nodes;
One of the plurality of nodes is set as a voltage input node,
In the resistor element having any one or more of the plurality of nodes as a voltage output node,
A resistor element comprising at least one resistor biasing conductor disposed adjacent to at least a part of the plurality of resistors via an insulator.   The resistor element according to claim 1, wherein the resistor is made of polycrystalline silicon. A voltage source circuit composed of first and second field effect transistors having the same conductivity type and different impurity concentrations;
A temperature detection circuit including a source follower circuit including a third field effect transistor, a first resistor, and a second resistor;
The resistor element includes any one of a first voltage output node and a second voltage output node at each of terminals of the plurality of resistors connected in series, and a plurality of nodes between the plurality of resistors. A voltage input node,
The first resistor is formed between the first voltage output node and the voltage input node,
The second resistor is formed between the second voltage output node and the voltage input node,
An output of the temperature detection circuit is input to the input voltage node, and a voltage output from the output node is used.

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