JPH03139873A - Temperature detecting circuit - Google Patents

Abstract

PURPOSE:To realize a temperature detecting circuit cheaply and highly stably through usual MOS manufacturing process by providing a circuit with a constant current source and at least one set of field effect transistors connected in series to the output terminals of the constant current source, and a drain terminal and a gate terminal of at least one stage are connected with each other, as a temperature detecting means. CONSTITUTION:In a P-type MOS field effect transistor 11 constituting a temperature detecting means 1, the source and a + power source, the gate and the drain gate connection of a P-type MOS field effect transistor 31, the drain and an output terminal 13, are connected respectively. In N-type MOS field effect transistors 121-12m connected in series in (m) stages, the drain gate connection of the transistor 121 of the first stage is connected to the output terminal 13 and the drain of the P-type MOS field effect transistor 11. The source is connected to the drain gate connection of the transistor 122 of the second stage. Hereafter, it goes the same, and for the transistor 12m at the last m stage, the drain gate connection is connected to the source of the transistor 12m-1 of the preceding stage, and the source of the transistor 12m is earthed.

Description

[Detailed description of the invention]

(Field of Industrial Application) The present invention is applicable to electronic devices integrated on the same semiconductor substrate that are required to be stable against ambient temperature.
! 1 Compensation method, particularly regarding a temperature detection circuit for a system that detects ambient temperature and performs temperature compensation using a digitized value [Prior art] Conventionally, this type of temperature detection circuit has been connected to the outside of a semiconductor device. An analog/digital converter was used to digitize the voltage temperature changes generated by passing a constant current through a thermistor or a diode integrated in a semiconductor substrate. [Problems to be Solved by the Invention] When the conventional humidity detection circuit described above is realized in one process using a metal-oxide film-semiconductor (hereinafter referred to as MO8) 'II fabrication process, there are the following drawbacks. First, there is no 1m process for integrating thermistors on semiconductor substrates. Second, the humidity coefficient of the voltage generated when a constant current is passed through the diode is about 2IIv/℃, for example -40 to 8
Because it does not change by 250mvL for a temperature change of 5℃,
Due to the resolution limit of the analog/digital converter, only 5 bits of accuracy can be obtained, which is insufficient for temperature compensation. Third, as a diode, when the base and collector terminals of a bipolar transistor are shorted,
Using emitter-to-emitter voltage, multiple bipolar
A method of connecting transistors in series has been realized, but
In the MO8 manufacturing process, the provision of multiple stages of bipolar transistors means that the manufacturing process becomes more complex, longer, and increases the manufacturing cost. Fourth, when making a diode using the MO3 manufacturing process,
For example, an island-shaped P-type head region (P-well) is provided on an N-type semiconductor substrate, and an N-type region is provided within the P-well again to form a diode. However, the P-well is usually connected to a low potential, and connecting diodes in series, like multiple bipolar transistors connected in series, will cause a latch-up phenomenon that is specific to the MO8 manufacturing process, which may destroy the semiconductor device. This method cannot be used because of the connection. As described above, the problem in integrating the temperature detection circuit on the MO3 semiconductor substrate is how to realize the temperature detection means at low cost. An object of the present invention is to provide a temperature detection circuit that can be manufactured at low cost in one normal manufacturing process. [Means for Solving the Problems] The temperature detecting circuit of the present invention includes a constant current source and at least one stage of drain terminal and gate terminal connected in series to the output terminal of the constant current source. has at least one set of field effect transistors connected to each other. [Operation] Since there is no bipolar transistor process in 0MO3, the temperature detection means can be realized at low cost. [Example] Next, an example of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a general configuration of a temperature detection circuit. An output terminal of the temperature detection means 1 whose output voltage changes depending on the surrounding temperature S degrees is connected to an analog input terminal of the analog/digital converter 3. An output terminal of the constant voltage generation circuit 2 is connected to a reference voltage input terminal of the analog/digital converter 3. The analog/digital converter 3 outputs an N-bit digital value obtained by converting the output voltage of the temperature detecting means 1 from analog to digital with the output voltage of the constant voltage generating circuit 2 as 11. FIG. 2 is a circuit diagram of a specific circuit according to an embodiment of the present invention. Of the temperature detection circuits, only the temperature detection means 1 and the constant voltage generation circuit 2 are shown here. One end of the constant current source 32 is grounded, and the other end is connected to the drain-gate connection point of the P-type MO3 field effect transistor 31. The source of the P-type MO8N field effect transistor 31 is connected to the power supply terminal. The P-type MO8 field effect transistor 11 constituting the temperature detection means 1 has a source connected to the power supply terminal, a gate connected to the drain-gate connection point of the P-type MO8 field effect transistor 31, and a drain connected to the output terminal 13. N-type MO8 field effect transistors 12 connected in series
1 to 12m, the drain/gate connection point of the first stage transistor 121 is connected to the output terminal 13 and the drain of the P-type MO8 field effect transistor 11, and the source thereof is connected to the drain/gate of the second stage transistor 122. connected to a connection point. Similarly, the drain-gate connection point of the transistor in each stage is connected to the source of the transistor in the previous stage, and the source is connected to the drain-gate connection point of the transistor in the next stage. The drain-gate connection point of the last m-th transistor 12m is connected to the source of the previous transistor 12m-+, and the source of the transistor 12m is grounded. Next, the P-type MO8 field effect transistors 21 and 24 constituting the constant voltage generation circuit 2 have their sources connected to the Juden #1 terminal,
The gate is connected to the drain-gate connection point of a P-type MO8 field effect transistor 31, the drain of the transistor 21 is connected to the output terminal 23 and the resistor 22, the drain of the transistor 24 is connected to the output terminal 26 and the resistor 25, and the drain of the transistor 24 is connected to the output terminal 26 and the resistor 25. The other end of 22°25 is grounded. FIG. 3 is a graph showing temperature changes in the characteristics of gate-source voltage versus drain current when the drain and gate of an MO3 field effect transistor are connected to each other. When a voltage exceeding the threshold voltage (hereinafter referred to as VT) of a transistor is applied between the gate and source, a drain current (hereinafter referred to as 1 os) begins to flow. In region A where the current is small, the temperature characteristics of VT are dominant. When the gate-source voltage (hereinafter referred to as Vcs) is further increased, there is a region B where the temperature characteristics of mobility and VT, which are parameters indicating the current supply ability of the transistor, cancel each other out, and when Vcs is higher than that, When , the temperature characteristic of mobility becomes a dominant region. In the temperature detection means 1 of FIG. 2, an N-type MO3 field effect transistor 121 whose gate and drain are connected to each other
~12m, the output voltage at room temperature (25° C.) and its temperature coefficient change depending on the current value passed by the P-type MO8 field effect transistor 11, which is a constant current source. In the region where the current is small (Fig. 3A), the temperature coefficient of the output voltage appearing at the terminal 13 is almost equal to the temperature coefficient of VT, which is approximately -2mV/''C per stage of N-type MO8 field effect transistor. When the current value flowing through the P-type MO8 field effect transistor 11 is increased, and in the region where the temperature characteristics of the mobility and the temperature characteristics of the VT cancel each other out (FIG. 3B), the temperature coefficient of the output voltage appearing at the terminal 13 becomes becomes O.P'(2M) When the current flowing through the OS field effect transistor 11 is further increased (Fig. 3D), the temperature coefficient of the output voltage appearing at the terminal 13 is reversed and becomes approximately 211V/'C. However, in order to achieve a temperature coefficient of 2 vJ/'C, the output voltage appearing at terminal 13 will be approximately 3 V per stage of N-type MO8 field effect transistor at room temperature, so connecting multiple stages in series will require the power supply voltage. Furthermore, as a function of the temperature detection means 1, if the temperature characteristic is as large as possible, it becomes possible to relax the requirements on the resolution of the analog/digital converter 30 connected at the next stage. Therefore, the current flowing through the N-type MO8 field effect transistors 121 to 12m must be kept small (region shown in FIG. 3) and must be set so that the absolute value of the temperature coefficient is maximized. The drain-source voltage per stage of a field effect transistor is approximately VT, and its temperature 1σ
The characteristic is -2+IV/"C. By stacking this in m stages, the temperature coefficient of -2X m (av/"C) is (9).If the power supply voltage is 5V, an N-type MO8 field effect transistor is Even if four stages are connected in series, there is sufficient voltage margin, so P-type MO8 field effect transistor 1
1 operates in the normal phase region and can guarantee constant current property, and the output voltage of terminal 13 has a temperature coefficient of -8 mv/"C. At this time, the output voltage is , at an ambient temperature of -40 to 85°C, the output voltage at terminal 13 is 2
．． The range is 8v±0.5■. Therefore, the constant voltage generating circuit 2 must output 3.3 V to the terminal 23 as the reference voltage of the analog/digital converter 3. However, even if the resolution of the analog/digital converter 3 is 8 bits, when the analog input voltage range is 0 to 3.3 square meters, the quantization step (1LS[3) is about 13 mV. Even if the ambient temperature changes from -40 to 85°C, the analog input voltage changes by only 1 inch, so it is quantized in only 77 ways, and the resolution is only equivalent to 6 bits. Therefore, in the constant voltage generation circuit 2, the base rI! on the high voltage side!
3.3V as voltage, 2.3 as reference voltage on low voltage side
■ Outputs the difference between the two male quasi voltages to the analog/digital converter 3.

[1G input voltage range (2.3V to 3.3V)
By setting it to l, it becomes possible to use the performance of the analog/digital converter 3 to the maximum. In the constant voltage generating circuit 2 of FIG. 2, if the dimensions of the P-type MO8ff field effect transistors 21.24 are made equal, the currents flowing through the resistors 22.25 are equal. Therefore, it is possible to design the resistance value of the resistor 22 so that the output voltage at the terminal 23 is 3.3■, and the resistance value of the resistor 25 so that the output voltage at the terminal 26 is 2.3■. can. Furthermore, due to variations in the semiconductor manufacturing process, Ir! 1 The output voltage of the detection means 1 changes, but the resistance 2
2.25 can absorb variations in the manufacturing process by trimming with a laser or fuse. FIG. 4 shows a specific circuit of the second embodiment of the present invention. Of the temperature detection circuits, only the temperature detection means 1 and the constant voltage generation circuit 2 are shown. The temperature detection means 1 includes P-type MO8'Jtii field effect transistors 11 and 14 whose sources are connected to the power supply terminal and whose gates are connected to the P-type MO8'Jtii field effect transistors 11 and 14.
It is connected to the drain/gate connection point of the MO3 field effect transistor 31. The drain of the P-type MO8 field effect transistor 11 is connected to the train-gate connection point of the transistor 121 in the first stage of the four stages of N-type MO8 field effect transistors connected in series. Hereinafter, the source of the transistor 121 is connected to the drain-gate connection point of the transistor 122, the source of the transistor 122 is connected to the drain-gate connection point of the transistor 123, and the source of the transistor 123 is connected to the drain-gate connection point of the transistor 124.
The source of the transistor 124 is connected to the gate connection point, and the source of the transistor 124 is grounded. P-type MO8 field effect transistor 1
The drain of transistor 15 is connected to the drain-gate connection point of transistor 151 in the first stage of N-type MO8 voltage effect transistors 151 and 152 connected in series in two stages.
The source of 1 is the drain of the second stage transistor 152.
The source of the transistor 152 is connected to the gate connection point, and the source of the transistor 152 is grounded. The drain connection point a of transistors 11 and 121 is operationally amplified via resistor R1! The inverting input of S16 is connected to the drain connection point of transistors 14 and 15 via a resistor R2 to the non-inverting input of operational amplifier 16. Further, the non-inverting input of the operational amplifier 16 is grounded via a resistor R4, and the inverting input is connected to the output terminal of the operational amplifier 16 and the terminal 13 via a resistor R3. The P-type MO8 voltage effect transistor 11 is set so that a small current, for example 1 μA, flows therethrough (region 8 in FIG. 3). The voltage at the drain connection point a of the transistors 11 and 121 is in the range of 2.8v±0.5v in the ambient temperature range of -40 to 85°C, assuming that VT is 0.7v. The P-type MO8 field effect transistor 14 has the mobility temperature characteristics of the N-type MO3m field effect transistor 151,152,
The setting is made so that a slightly larger current flows than the region where the temperature characteristics of the VT cancel each other out (region C in FIG. 3). The drain-source voltage per stage of the switching transistors 151 and 152 is greater than 2XVT, and its temperature characteristics have a slightly positive temperature coefficient. Therefore, f of the P-type MO8 field effect transistor 14
f1l value and N-type MO8 field effect transistor 151
By appropriately selecting the dimensions of transistor 152,
The voltage at the drain connection points of 4 and 151 can be 3.4v±0.7■ at an ambient temperature of -40 to 85°C. Operational amplifier 16 and resistors R1 to R4 constitute a subtraction circuit. When rfcR is set as 2R1=2R2-R3==R4, a voltage twice as high as the differential voltage at the connection point a is output to the terminal 713. A P-type MO8 field effect transistor 21 constituting the constant voltage generation circuit 2 has a source connected to a power supply terminal and a gate connected to a P-type MO8 field effect transistor 21.
It is connected to the drain/gate connection point of the O8 field effect transistor 31. The drain of the P-type MO8 field effect transistor 21 is connected to the drain-gate connection point of two N-type MO8 field-effect transistors 271 connected in series, and the source of the transistor 271 is connected to the drain-gate connection point of the transistor 272. The source of is grounded. The P-type MO3 field effect transistor 21 is connected to the N-type MO8 field effect transistor 271.
The If flow is set so that 272 is a region (region 8 in FIG. 3) where the temperature characteristics of mobility and the temperature characteristics of VT cancel each other out. At this time, the drain-source voltage per stage of the transistors 271 and 272 becomes approximately 2·VT, and the temperature characteristic becomes 0. Therefore, the output terminal 23 drawn from the drain connection point of the transistor 21.271 has approximately 2.8
The voltage of V is stably output in the range of 140 to 85 degrees Celsius. The temperature detection circuit 1 and the constant voltage generation circuit 2 are P-type MO8 field effect transistors 11.1 made in the same process.
4.21 allows a constant current to flow, so relative errors can be suppressed to a negligible level. In addition, N-type MO3 field effect transistors 121 to 1 made by the same process.
Since a constant current is passed through 24.151152.27t and 272 to generate a voltage, the only variation due to the manufacturing process is a relative error, and trimming is not necessary. FIG. 5 is a diagram showing the temperature characteristics of the output voltage of the second embodiment. The voltage at connection point a is denoted by a, the voltage at connection point S is denoted by C9, the voltage at terminal 13 is denoted by C9, and the voltage at terminal 23 is denoted by d. The output voltage of the temperature detection means 1 is about 0 to 2.4V, and the Ml voltage of the analog/digital converter 3 only needs to be on the high voltage side, so the constant voltage generation circuit 2 can have only one output terminal. can. As mentioned above, the current flowing through the N-type MO8 field effect transistor can be controlled in a very small region and in a region where the temperature coefficient is canceled out (Fig. 3A).
, B), it is possible to realize a temperature detection circuit that is highly stable against variations in the manufacturing process. [Effects of the Invention] As explained above, the present invention uses a constant current source and at least one stage connected in series to the output terminal of the constant current source, the drain terminal and the gate terminal of which are connected to each other. By having at least one set of field effect transistors, there is an effect that it can be realized at low cost and with high stability using a normal MO8 manufacturing process.

[Brief explanation of the drawing]

FIG. 1 is a general configuration diagram of a temperature detection circuit, FIG. 2 is a circuit diagram of a temperature detection circuit according to a first embodiment of the present invention, FIG. 3 is a voltage-current characteristic diagram of an MO8 field effect transistor, and FIG. 4 is a circuit diagram of a temperature detection circuit according to a second embodiment of the present invention, and FIG.
The figure is a temperature characteristic diagram of the output voltage of the second embodiment. DESCRIPTION OF SYMBOLS 1... Temperature detection means, 2... Constant voltage generation circuit, 3.
・・N-bit alog/digital converter, 11°14
．． 21.24.31...P-type MO8 field effect transistor, 121-12a, 151,152°271.27
2...N-type MO8 field effect transistor, 13.23
．． 26...Output terminal, 22.25°R1, R2, R3
, R4...Resistor, 16...Operation amplifier, 32...
Constant current source.

Claims (1)

[Claims] 1. A temperature detection means integrated on a semiconductor substrate, a constant voltage generation circuit, an output terminal of the temperature detection means being an analog input terminal, and an output terminal of the constant voltage generation circuit being a reference voltage terminal. In a temperature detection circuit that has an analog/digital converter connected and outputs a digital value obtained by converting the output voltage of the temperature detection means from analog to digital, the temperature detection means includes a constant current source and an output of the constant current source. 1. A temperature detection circuit comprising at least one set of field effect transistors in at least one stage connected in series to terminals, each having a drain terminal and a gate terminal connected to each other.