JP4642364B2 - Temperature detection circuit, temperature detection device, and photoelectric conversion device - Google Patents

Description

  The present invention relates to a temperature detection circuit, in particular, a temperature detection circuit that achieves a high temperature coefficient at a low power supply voltage and enables highly accurate temperature detection, a temperature detection device using such a temperature detection circuit, and such The present invention relates to a photoelectric conversion device capable of obtaining a sensor signal that is stable with respect to temperature based on temperature information obtained using a temperature detection device.

  2. Description of the Related Art Conventionally, there is a temperature detection circuit that detects temperature using temperature characteristics of a semiconductor element. An example thereof is proposed in Patent Document 1. The configuration generates a current proportional to the absolute temperature composed of the first and second bipolar transistors having different emitter areas, a resistor, and a current mirror circuit composed of the first, second, and third MOS transistors. And a circuit for converting the output current of the first current source into a voltage using a resistor and outputting the voltage. Further, Patent Document 2 proposes a technique that makes it possible to drive the first current source with a low power supply voltage. FIG. 7 shows a temperature detection circuit using the first current source proposed in Patent Document 2.

The temperature detection circuit 710 includes a bipolar transistor 704 and 706 having an emitter area ratio of N: 1 that is grounded by commonly connecting a collector and a base, one end connected to the emitter of the bipolar transistor 704, and the other end connected to the operational amplifier 701. A resistor 703 having a resistance value R ₁ connected to the inverting input terminal, a drain and a gate are commonly connected to the inverting input terminal of the operational amplifier 701, and a source is connected to the output terminal of the operational amplifier 701 and the current source 707 MOS transistor 702, the gate is connected to the gate of MOS transistor 702, the source is connected to the source of MOS transistor 702 and current source 707, the drain is the non-inverting input terminal of operational amplifier 701, and the emitter of bipolar transistor 706 The MOS transistor 705 connected to the gate and the gate are connected to the gates of the MOS transistor 702 and the MOS transistor 705, Over scan it is commonly connected to the source of the MOS transistor 702 and the MOS transistor 705, drain the first current source from the connected MOS transistor 708 Metropolitan is formed on the output terminal 711 and one end of a resistor 709. From this first current source, an absolute temperature proportional current is generated, and the resistance value with the other end grounded is converted into a voltage at the resistor 709 of _Rx and output. The current source 707 is a current source that supplies a current to each element, and can be realized as a current mirror circuit coupled to a voltage source such as a power supply voltage _VDD . The MOS transistor 702 and the MOS transistor 705 are connected so as to form a current mirror circuit, and the current ratio between the currents I ₁ and I ₂ flowing through each MOS transistor is adjusted by adjusting the size of each transistor. I can do it. The potentials of the contacts V ₁ and V ₂ are the same due to the virtual ground of the operational amplifier. Here, assuming that the reverse saturation currents of the bipolar transistor 704 and the bipolar transistor 706 are equal, the voltage equation relating to the resistor 703, the bipolar transistor 704, and the bipolar transistor 706 can be expressed by equation (1).

Here, V _T is the thermal voltage of the bipolar transistor, I _S is the reverse saturation current of the bipolar transistor. If the current ratio I ₂ / I ₁ determined by the size of the MOS transistor is M, the current I ₁ can be expressed by the equation (2) from the equation (1).

Further, when the current ratio I ₃ / I ₁ determined by the size of the MOS transistor 702 and the MOS transistor 708 is G, the voltage V _{PTAT at the} output terminal 711 can be expressed by Expression (3).

Here, since there is a relationship V _T = kT / q among V _T , Boltzmann constant k, absolute temperature T, and elementary charge q, the relationship between the output voltage V _PTAT and the absolute temperature T is expressed by Equation (4). Can be expressed.

Equation (4) means that the current I ₁ can be expressed by I ₁ (T) that changes in proportion to the absolute temperature T, as shown in the parenthesized equation.

Further, in Patent Document 2, in order to operate with a low power supply voltage, the operational amplifier 701 is a P.A. Gray and R.A. It is made up of a folding cascode operational amplifier described on pages 752-755 of the text “Analysis and Design of Analog Integrated Circuits (Second Edition)” by Meyer.
Japanese Patent Laid-Open No. 10-332494 Japanese Patent Laid-Open No. 8-234533

In order to realize highly accurate temperature detection, it is necessary to increase the temperature coefficient (V / ° C.), which is a change in output voltage per unit temperature. However, although Patent Document 2 considers temperature detection using the first current source at a low power supply voltage, there are the following problems. That is, since there is a relationship of T = t + 273 between the absolute temperature T and the Celsius temperature t, the expression (4) can be expressed by the expression of the output voltage V and the temperature t as shown in the expression (5). Become.

Here, as shown in the expression in parentheses, the equation (5) is obtained by changing the current I ₁ that changes in proportion to the absolute temperature into the I ₁ (t) component that changes in proportion to the temperature t and the temperature t. On the other hand, it is expressed by a constant offset component Offset.

FIG. 8 is a graph showing the relationship of Equation (5) as a change in output voltage with respect to temperature. Here, reference numeral 803 in FIG. 8 indicates the power supply voltage level of the temperature detection circuit 710, and reference numeral 804 indicates the operating temperature range of the temperature detection circuit 710. The first term of equation (5) corresponds to the slope of the graph of FIG. 8, and the second term corresponds to the offset. As can be seen from equation (5), since the same coefficient is related to the temperature t and the constant 273, the temperature coefficient corresponding to the slope in FIG. 8 and the offset cannot be adjusted independently. That is, when the resistance ratio R _x / R ₁ , the bipolar transistor size ratio N: 1, and the current ratios M and G are changed to increase the temperature coefficient, the offset also increases. As a result, if a high temperature coefficient is to be realized, the characteristic curve 802 represented by a broken line in FIG. 8 changes to a characteristic curve 801 represented by a solid line. As a result, the output voltage is saturated within the operating temperature range of the temperature detection circuit 710, and temperature detection within the operating temperature range becomes impossible. The phenomenon in which the output voltage is saturated within the operating temperature range in an attempt to increase the temperature coefficient becomes more prominent as the power supply voltage is lowered when the same temperature coefficient is realized.

  Furthermore, in the temperature detection circuit using the temperature characteristics of the semiconductor element, there is a problem that the output voltage fluctuates due to fluctuations in characteristics at the time of manufacture, battery consumption, noise, etc., and a temperature detection error occurs. Since the influence due to the characteristic variation and the fluctuation of the power supply voltage becomes more conspicuous under a low power supply voltage and a high temperature coefficient, it is important to stably detect the temperature by correcting the temperature detection error due to the influence.

  The present invention has been made in view of the above circumstances, a temperature detection circuit capable of detecting a temperature with a high temperature coefficient even with a low power supply voltage, a temperature detection device using such a temperature detection circuit, and this An object of the present invention is to provide a photoelectric conversion device capable of obtaining a sensor signal stable with respect to temperature based on temperature information obtained by using such a temperature detection / detection device.

In order to achieve the above object, a temperature detection circuit according to a first aspect of the present invention includes a first current mirror circuit having a first current path and a second current path, and a current proportional to an absolute temperature. and outputs as a first current, a first current source, a second current mirror circuit having a third current path and the fourth current path, a substantially constant with temperature current second and outputs as a current, a second current source, wherein the first current a second current and is input, the current third proportional to the difference of said first current and said second current A third current mirror circuit that outputs current, and a read circuit that converts the third current into a voltage by passing the third current through a first resistor, and the current flowing through the first current path is a second current The current flowing through the third current path flows through the third resistor, Serial first resistor, the temperature characteristic of the second resistor and the third resistor is characterized by matching.

  According to the first aspect, the temperature coefficient can be increased within the operating temperature range by taking a substantially constant current difference with respect to the temperature from the first current proportional to the absolute temperature.

  According to the present invention, a temperature detection circuit capable of detecting a temperature with a high temperature coefficient even with a low power supply voltage, a temperature detection device using such a temperature detection circuit, and such a temperature detection detection device are used. A photoelectric conversion device capable of obtaining a sensor signal stable with respect to temperature based on the obtained temperature information can be provided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[First Embodiment]
First, a conceptual configuration of the temperature detection circuit according to the first embodiment of the present invention will be described. FIG. 1 is a block diagram of a temperature detection circuit according to the first embodiment.

  That is, the temperature detection circuit of FIG. 1 controls the first current source 101 that generates the absolute temperature proportional current, the second current source 103 that generates the temperature stable current, and the second current source 103. A control voltage generation circuit 102 that generates a control voltage, and a current mirror circuit 104 that combines the currents generated from the first current source 101 and the second current source 103, and that has a high output resistance and a wide output voltage dynamic range. And a readout circuit 105 that converts the output current of the current mirror circuit 104 into a voltage.

In the above configuration, if the absolute temperature proportional current is I _PTAT , the temperature stable current is I _const , a resistor is used for the readout circuit, the resistance value is R, and the current amplification factor of the current mirror circuit 104 is G ₃ , the output voltage V _PTAT can be expressed by equation (6).

Here, as can be seen from the equation (5), the equation (6) is calculated from the sum of I _PTAT (t) that changes in proportion to the temperature t (° C.) and the constant offset with respect to the temperature t. It means that it can be expressed by subtracting a constant I _const from t. Here, the magnitude of I _const can be controlled by the control voltage of the control voltage generation circuit 102.

FIG. 2 shows a graph of change in output voltage with respect to temperature (° C.) based on the relationship of Expression (6). In Expression (6), by controlling the magnitude of the temperature stable current I _const of the second term in parentheses, the output voltage V _PTAT is the absolute temperature proportional current I _PTAT of the first term of Expression (6). Can be adjusted independently. Therefore, the characteristic curve 201 in which the output voltage is saturated exceeding the power supply voltage 203 within the operating temperature range 204 can be level shifted to the characteristic curve 202 by appropriately controlling the temperature stable current I _const . As a result, it is possible to detect the temperature with a high temperature coefficient without saturating the output voltage within the operating temperature range.

Further, since the current mirror circuit 104 of FIG. 1 has a high output resistance and operates in a wide dynamic range, the absolute temperature proportional output voltage V _PTAT can be obtained stably and accurately even when the power supply voltage is low. .

  Next, the configuration of FIG. 1 will be described in more detail. FIG. 3 is an electric circuit diagram of the configuration of FIG. In FIG. 3, a first current source 101, a control voltage generation circuit 102, a second current source 103, a current mirror circuit 104, and a readout circuit 105 are provided. The first current source 101 is connected to a startup circuit 301 for operating the operating point of the temperature detection circuit at a stable operating point. The startup circuit 301 is connected to the power supply voltage terminal 329, the ground terminal 330, and the drain of the MOS transistor 304 in the first current source 101.

The first current source 101 includes a bipolar transistor 302 and 305 to the base and collector connected to the supply voltage terminal 329, the resistance value of which one end is connected to the emitter of the bipolar transistor 305 and the resistor 306 of the R _6, A MOS transistor 303 having a source connected to the emitter of the bipolar transistor 302, a source connected to the other end of the resistor 306, a gate and a drain connected to the gate of the MOS transistor 303, and a transistor having the same transistor size as the MOS transistor 303 The transistor 307 has a gate and drain connected to the drain of the MOS transistor 303, a source connected to the ground terminal 330, a drain connected to the drain of the MOS transistor 307, and a gate connected to the gate of the MOS transistor 304. Connected, source connected to ground terminal 330 A MOS transistor 308 having the same transistor size as that of the MOS transistor 304, a MOS transistor 325 having a gate connected to the gate of the MOS transistor 308, a source connected to the ground terminal 330, and a gate connected to the gate of the MOS transistor 325. And a MOS transistor 322 having a source connected to a ground terminal 330.

Further, the control voltage generation circuit 102 has one end connected to the reference voltage terminal 331, a resistance value 309 having a resistance value of R ₁₀ , and one end connected to the other end of the resistance 309 and the non-inverting input terminal of the operational amplifier 314. resistance other end of which is connected to the ground terminal 330 and the resistor 310 of the R _12, one end is connected to one end of the resistor 310 and the other end connected to resistance to the inverting input terminal of the operational amplifier 314 is R ₁₁ a resistor 312, one end is connected to the correction signal input terminal 332, connected to the resistance to the inverting input terminal of the other end operational amplifier 314 and the resistor 311 of R _8, one end is connected to the other end of the resistor 311, the other end is connected to the output terminal of the operational amplifier 314, the resistance value is composed of the resistor 313 of the R _9,. A control voltage V _{REF_IN} is generated from the control voltage generation circuit 102.

The control voltage V _{REF_IN} generated in the control voltage generation circuit 102 is input to the second current source 103. The second current source 103 includes an operational amplifier 315 having a non-inverting input terminal connected to the output terminal of the operational amplifier 314, a gate connected to the output terminal of the operational amplifier 315, and a source connected to the non-inverting input terminal of the operational amplifier 315. a MOS transistor 317 connected to the one end connected to the source of the MOS transistor 317, the resistance value other end of which is connected to the ground terminal 330 and the resistor 318 of the R _13, drain and gate to the drain of the MOS transistor 317 The MOS transistor 316 is connected, the source is connected to the power supply voltage terminal 329, the gate is connected to the gate of the MOS transistor 316, the drain is connected to the drain of the MOS transistor 325, and the transistor size is the same as the MOS transistor 316. The MOS transistor 319 has a gate connected to the gate of the MOS transistor 319 and a source connected to the power supply voltage terminal 329. The MOS transistor 320 is connected to the drain of the MOS transistor 322 and has the same transistor size as the MOS transistor 319.

  The current mirror circuit 104 includes a MOS transistor 323 whose source is connected to the power supply voltage terminal 329, a MOS transistor 326 whose source is connected to the source of the MOS transistor 323, and whose gate is connected to the gate of the MOS transistor 323; The source is connected to the drain of the MOS transistor 323, the drain is connected to the gate of the MOS transistor 323 and the drain of the MOS transistor 325, the transistor size is the same as the MOS transistor 323, and the source is the drain of the MOS transistor 326. Is connected to the gate of the MOS transistor 324, the drain is connected to the absolute temperature proportional voltage output terminal 333, the source is connected to the power supply voltage terminal 329, and the gate and drain are connected to the MOS transistor 322. Drey The gate width of the transistor is 1/4 of the gate width of the transistor of the MOS transistor 324 and the gate length is the same as that of the MOS transistor 324 (that is, the transistor size is 1/4 of the MOS transistor 324). MOS transistor 321.

The current mirror circuit 104 adjusts the size and the like of the MOS transistor in order to increase the output resistance and keep a wide dynamic range. That is, in the first embodiment, the transistor size of the MOS transistor 326, which is the second MOS transistor, is set to m times that of the MOS transistor 323, which is the first MOS transistor (m = 1 in the first embodiment). The transistor size of the MOS transistor 324, which is the third MOS transistor, is 1 / n ² times that of the MOS transistor 323 (n = 1 in the first embodiment), and the transistor size of the MOS transistor 327, which is the fourth MOS transistor, is MOS and m / n ² times the transistor 323 (= 1 ×), as 1 / a transistor size of the MOS transistor 321 is a fifth MOS transistor MOS transistor 323 (n + 1) ² times (= 1/4 times) Yes.

Thus by adjusting the transistor size, it is possible to adjust the temperature coefficient by changing the current amplification factor G ₃ of the current mirror circuit 104. That is, temperature detection can be performed with a high temperature coefficient even at a low power supply voltage within the operating temperature range, and highly accurate temperature detection can be achieved. In the first embodiment, since the current mirror 104 is used as a circuit for calculating the difference between the output of the first current source 101 and the output of the second current source 103, the output of each current source is converted into a voltage. Therefore, the circuit configuration can be simplified compared to the case where the differential circuit is configured by an operational amplifier or the like.

The read circuit 105 includes a resistor 328 having an R ₁₆ resistance value, one end connected to the absolute temperature proportional voltage output terminal 333 and the other end connected to the ground terminal 330.

Here, since the transistor sizes of the MOS transistors 304 and 308 that are mirror-connected are the same, the path formed by the bipolar transistor 302, the MOS transistor 303, and the MOS transistor 304, the bipolar transistor 305, the resistor 306, and the MOS transistor The current I _PTAT having the same magnitude is generated in the path formed by 307 and the MOS transistor 308. Further, since the MOS transistor 303 and the MOS transistor 307 have the same transistor size, the gate-source voltages Vgs of the respective MOS transistors are equal. Accordingly, when a voltage equation is established in the loop of the bipolar transistor 305, the resistor 306, the MOS transistor 307, the MOS transistor 308, the MOS transistor 304, the MOS transistor 303, and the bipolar transistor 302, the following equation (7) is obtained.

Here, it is assumed that the emitter area ratio of the bipolar transistors 302 and 305 is N: 1.

From equation (7), the absolute temperature proportional current I _PTAT can be expressed by equation (8).

Incidentally, the current amplification factor of the current mirror circuit formed by MOS transistors 304,308,322,325 and G _1. Further, the control voltage generation circuit 102 is composed of a combination of a resistance divider circuit composed of resistors 309 to 313 and an operational amplifier 314 and an addition circuit, so that the output of the operational amplifier 314, that is, the control voltage generation circuit 102 The generated control voltage V _{REF_IN} can be expressed by Expression (9).

In the second current source 103, the temperature stable current I _const of the constant current circuit including the operational amplifier 315, the MOS transistor 317, and the resistor 318 is expressed by Expression (10).

Incidentally, the current amplification factor of the current mirror circuit formed by MOS transistors 316,319,320 and G _2. Further, the current amplification factor of the current mirror circuit 104 comprised of MOS transistors 321,323,324,326,327, and G _3. At this time, the absolute temperature proportional current I _PTAT represented by the equation (8) and the temperature stable current I _const represented by the equation (10) are input to the current mirror circuit 104 and synthesized, The current output is converted into a voltage by the resistor 328 of the read circuit 105 and read. The absolute temperature proportional output voltage V _{PTAT at} this time is expressed by Expression (11).

  Therefore, if the offset component of the first term is level-shifted by the temperature stable current of the second term of the parenthesized formula as in the formula (6), the output is within the operating temperature range even if the temperature coefficient is low and the temperature coefficient is high. It can be operated as a temperature detection circuit capable of detecting temperature without voltage saturation. That is, highly accurate temperature detection can be realized even with a low power supply voltage.

Furthermore, in the first embodiment, R ₁₆ and R ₆ , and R ₁₆ and R ₁₃ are expressed in the form of a fractional numerator and denominator, respectively, as shown in Equation (11). By combining these, the effects of the temperature characteristics of the resistances varying with temperature can be canceled out. That is, it is possible to remove an error in output voltage caused by a change in resistance characteristics due to a temperature change.

  In the first embodiment, the bipolar transistor is formed of a parasitic bipolar transistor, and can be manufactured by a standard CMOS process. It goes without saying that the same operation and effect can be obtained even if the polarity of the entire circuit of FIG. 3 is reversed. The values of m and n described above are examples and can be changed.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. The second embodiment of the present invention is a temperature detection apparatus using the temperature detection circuit of FIG. FIG. 4 shows the configuration of the temperature detection device.

An assembly 400 of FIG. 4, generates a first current source 101, a control voltage generation circuit 102 for generating a control voltage V _{REF_IN} as input the correction signal V _{REF_AD,} the temperature stabilized current is controlled by a control voltage V _{REF_IN} The second current source 103, the current mirror circuit 104 that combines the output currents of the first current source 101 and the second current source 103, and the read circuit 105 that converts the output current of the current mirror circuit 104 into a voltage. , An output terminal 406 for outputting an output signal from the temperature detection circuit 405, an A / D converter 404 for converting the output signal of the temperature detection circuit 405 into a digital signal, and an A / D The CPU 401 connected to the output of the converter 404, the memory 402 connected to the CPU 401 and recording necessary information, and the CPU 401 and the control voltage generation circuit 102 in the temperature detection circuit 405 are connected to the analog output signal from the CPU 401. Signal And a D / A converter 403 for outputting a correction signal V _{REF_AD} and conversion.

  In the temperature detection device having the above-described configuration, a method for correcting manufacturing variations and the like of the temperature detection device based on the output signal of the temperature detection circuit obtained in an environment controlled to the set temperature will be described.

That is, in this case, with the temperature detection circuit 405 placed in an environment controlled to the set temperature, the output signal of the temperature detection circuit 405 is converted into a digital signal by the A / D converter 404 and input to the CPU 401. The Then, the CPU 401 compares the output signal from the A / D converter 404 with the standard output recorded in the memory 402, and calculates a correction value. Thereafter, the calculated correction value is converted into an analog correction signal by the D / A converter 403 and input to the control voltage generation circuit 102. In the control voltage generation circuit 102, a control voltage V _{REF_IN} for controlling the second current source 103 is generated. Due to the generated control voltage V _{REF_IN} , the second current source 103 generates a temperature stable current that is constant with respect to temperature. The generated temperature stable current and the absolute temperature proportional current generated by the first current source 101 are combined by the current mirror circuit 104, converted into current / voltage by the read circuit 105, and then output by the output terminal 406. Output as absolute temperature proportional voltage.

As described above, in the second embodiment, the current mirror circuit 104 subtracts the temperature stable current generated in the second current source 103 from the absolute temperature proportional current generated in the first current source 101. It is possible to detect the temperature without saturating the output voltage within the operating temperature range. Further, the output voltage in a standard state, for example, a temperature of 25 ° C. and a power supply voltage of 5 V, is stored as a standard output in the memory 402, and the correction signal V _{REF_AD} is controlled by comparing the standard output with the output of the temperature detection circuit. In addition, by adjusting and correcting the level shift amount, errors in temperature detection due to manufacturing variations among a plurality of temperature detection devices and fluctuations in power supply voltage can be corrected.

  In addition, in order to obtain more accuracy, in addition to the above correction, an output at another controlled temperature environment, for example, a temperature of 50 ° C. and a power supply voltage of 5 V is obtained, and this output and an output at 25 ° C. The temperature coefficient is obtained from the temperature, and when detecting the temperature, correction based on the obtained temperature coefficient can correct the manufacturing variation of the temperature coefficient of the temperature detection circuit and the power supply voltage dependency more accurately. .

  Next, a method for correcting a temperature detection error due to manufacturing variations among a plurality of temperature detection devices and fluctuations in power supply voltage will be described in more detail. FIG. 5A is a flowchart showing a processing procedure of a method (referred to as a temperature one-point correction method) in which only the output for one temperature is measured and corrected, and FIG. 5B is the output for two temperatures. It is a flowchart which shows the process sequence of the method (it calls a temperature two point correction method) which measures and corrects.

First, with reference to FIG. 5A, the processing of the temperature single point correction method will be described. First, the power supply voltage terminal of the temperature detection circuit 405 is connected to a stabilized power supply, and the power supply voltage is set to a standard voltage, for example, 5V. Furthermore, a temperature detection circuit 405 is placed in a constant temperature layer or the like so that the standard temperature is set to, for example, 25 ° C. Then, the correction signal V _{REF_AD} input to the control voltage generation circuit 102 is _set to zero (step S1).

Next, the output signal of the output terminal 406 is converted into a digital signal by the A / D converter 404 and input to the CPU 401, and a difference ΔV between the output digital signal and the standard output stored in the memory 402 is obtained (step S2). ). Next, it is determined whether or not the difference ΔV is equal to or less than 1 LSB which is the minimum resolution of the A / D converter 404 and the D / A converter 403 set in advance (step S3). If the difference ΔV is larger than 1 _LSB in the determination in step S3, the correction voltage V _{REF_AD} is calculated from the difference ΔV (step S4). Next, the correction voltage V _{REF_AD} obtained by calculation is _added to the previous correction voltage V _{REF_AD} (step S5). The added value is D / A converted by the D / A converter 403, and a correction signal is input to the control voltage generation circuit 102 (step S6). Thereafter, the process returns to step S2, and the processes from step S2 to step S6 are repeated until ΔV becomes 1 LSB or less.

On the other hand, if it is determined in step S3 that the difference ΔV is smaller than 1 _LSB , the value of V _{REF_AD} finally calculated and added is stored in the memory 402. The value of V _{REF_AD} is D / A converted by the D / A converter 403 and input to the control voltage generation circuit 102 to operate the temperature detection circuit 405 (step S7).

Next, the temperature two-point correction method will be described with reference to FIG. First, the correction signal V _{REF_AD} is obtained by the temperature single point correction method described in FIG. 5A (step S11). Next, the temperature detection circuit 405 is put in a constant temperature layer set to a temperature different from the standard temperature, for example, 50 ° C., and the output voltage from the output terminal 406 is A / D converted (step S12).

  Thereafter, a temperature coefficient (V / ° C.) is obtained from the final output voltage obtained at 25 ° C. and the output voltage at 50 ° C., and the value of the standard temperature coefficient in the memory 402 is updated with this value ( Step S13). Temperature detection is performed using the updated temperature coefficient (step S14).

  By performing temperature detection using the correction method of the temperature detection circuit 405 described above, a high temperature coefficient can be realized even with a low power supply voltage, and power supply voltage fluctuations and manufacturing variations can also be corrected. As a result, highly accurate temperature detection is possible with a low power supply voltage.

[Third Embodiment]
Next, a third embodiment of the present invention will be described. The third embodiment of the present invention is a photoelectric conversion device using the temperature detection circuit of FIG. 3 or the temperature detection device of FIG. The structure of this photoelectric conversion device is shown in FIG.

  The photoelectric conversion device 600 in FIG. 6 is a temperature detection unit that includes, for example, a sensor unit 601 that is formed of an image sensor, a distance measurement sensor, a photometry sensor, and the like and outputs an observation signal related to a detection target, and a temperature detection device in FIG. And a correction unit 603 that corrects a change in characteristics due to a temperature change of the sensor unit 601 based on temperature information obtained from the temperature detection unit 602 and obtains a final output.

  For example, in a distance measuring sensor used in an autofocus camera or the like, a sensor signal fluctuates because a photographing lens, a lens frame, or the like expands or contracts depending on temperature, or the dark current of the sensor signal changes depending on temperature. As a result, correct distance detection may not be possible. In the third embodiment, even if the sensor signal or the information detected using the sensor signal changes due to a change in temperature, the sensor signal or the like is corrected based on the temperature information obtained from the temperature detection unit 602. Thus, it is possible to detect the distance with high accuracy by correcting the characteristic change. In particular, recently, it is desired to lower the power supply voltage of the sensor unit 601 for the purpose of reducing power consumption. However, by applying a temperature detection device as shown in FIG. It becomes possible to detect the temperature of the temperature coefficient, and it is possible to correct the change in characteristics due to the temperature change of the sensor unit 601 with high accuracy.

  Although the present invention has been described based on the above embodiments, the present invention is not limited to the above-described embodiments, and various modifications and applications are naturally possible within the scope of the gist of the present invention.

  Further, the above-described embodiments include various stages of the invention, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements. For example, even if some constituent requirements are deleted from all the constituent requirements shown in the embodiment, the problem described in the column of the problem to be solved by the invention can be solved, and the effect described in the column of the effect of the invention Can be extracted as an invention.

It is a block diagram shown about the conceptual structure of the temperature detection circuit which concerns on the 1st Embodiment of this invention. It is a figure which shows the graph of the change of the output voltage with respect to the temperature of the temperature detection circuit which concerns on the 1st Embodiment of this invention. 1 is an electrical circuit diagram of a temperature detection circuit according to a first embodiment of the present invention. It is a block diagram of the temperature detection apparatus which concerns on the 2nd Embodiment of this invention. FIG. 5A is a flowchart for explaining a temperature correction method of the temperature detection device according to the second embodiment of the present invention, and FIG. 5A is a flowchart showing a temperature one-point correction method, and FIG. ) Is a flowchart showing processing of the temperature two-point correction method. It is a block diagram of the photoelectric conversion apparatus which concerns on the 3rd Embodiment of this invention. It is an electric circuit diagram of a conventional temperature detection circuit. It is a figure which shows the graph of the change of the output voltage with respect to the temperature of the temperature detection circuit of a prior art example.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 101 ... 1st current source, 102 ... Control voltage generation circuit, 103 ... 2nd current source, 104 ... Current mirror circuit, 105 ... Read-out circuit, 321-327 ... MOS transistor, 401 ... CPU, 402 ... Memory, 403 ... D / A converter, 404 ... A / D converter, 405 ... temperature detection circuit, 406 ... output terminal, 601 ... sensor unit, 602 ... temperature detection unit, 603 ... correction unit

Claims (5)

Comprising a first current mirror circuit having a first current path and second current path, and outputs a current proportional to absolute temperature as the first current, a first current source,
A second current mirror circuit having a third current path and the fourth current path to output a substantially constant current as a second current with respect to temperature, a second current source,
A third current mirror circuit that receives the first current and the second current and outputs a current proportional to the difference between the first current and the second current as a third current;
A read circuit that converts the third current into a voltage by flowing the first current;
Equipped with,
A current flowing through the first current path flows through a second resistor;
A current flowing through the third current path flows through a third resistor;
The temperature detection circuit according to claim 1, wherein temperature characteristics of the first resistor, the second resistor, and the third resistor are matched .   The temperature detection circuit according to claim 1, further comprising a control voltage generation circuit that generates a control voltage for controlling a current output from the second current source. The third current mirror circuit includes:
A first MOS transistor having a source connected to a power supply voltage terminal;
A second MOS transistor having a source connected to the power supply voltage terminal and a gate connected to the gate of the first MOS transistor, the transistor size being m times that of the first MOS transistor; ,
A MOS transistor having a source connected to the drain of the first MOS transistor, a drain connected to the gates of the first MOS transistor and the second MOS transistor, and a transistor size of the first MOS transistor; A third MOS transistor that is 1 / n ² times the
A MOS transistor having a source connected to the drain of the second MOS transistor, a drain connected to an output terminal, and a gate connected to the gate of the third MOS transistor, the transistor size being the first MOS transistor A fourth MOS transistor which is m / n ² times the transistor;
The MOS transistor has a source connected to the power supply voltage terminal, a drain and a gate connected to the gates of the third MOS transistor and the fourth MOS transistor, and the transistor size is 1 of that of the first MOS transistor. a fifth MOS transistor is a / (n + 1) ² times,
Consisting of
The output of the first current mirror circuit is connected to the drain of the third MOS transistor and the drain of the fifth transistor,
The output of the second current mirror circuit is connected to the drain of the third MOS transistor and the drain of the fifth transistor,
3. The temperature detection circuit according to claim 1, wherein currents of the same magnitude are respectively supplied to drains of the third MOS transistor and the fifth MOS transistor. (Where m and n are each a positive integer) A temperature detection circuit according to claim 2;
An analog / digital converter that converts the output from the temperature detection circuit into a digital signal;
A CPU for generating a correction signal for correcting a control voltage generated by the control voltage generation circuit based on a digital signal from the analog / digital converter;
A memory for storing parameters used for generating the correction signal;
A digital / analog converter that converts the correction signal into an analog signal and supplies the analog signal to the control voltage generation circuit;
A temperature detection apparatus comprising: A sensor unit that outputs an observation signal related to the detected object;
The temperature detection device according to claim 4, which detects a temperature in the vicinity of the sensor unit;
A correction unit for correcting the observation signal based on an output from the temperature detection unit;
A photoelectric conversion device comprising:

Images