JP4222766B2 - Temperature detection circuit - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a temperature detection circuit for detecting an arbitrarily set temperature.
[0002]
[Prior art]
When an abnormally large current flows through the semiconductor integrated circuit, or when the ambient temperature rises and the semiconductor integrated circuit becomes high temperature, the semiconductor integrated circuit is destroyed. In order to prevent this destruction, it is necessary to stop the operation of the semiconductor integrated circuit when the detected temperature becomes high. A circuit having such a function includes a circuit that generates a voltage proportional to absolute temperature (PTAT), a reference voltage generation circuit, and a circuit that compares the outputs of both.
[0003]
When the detected PTAT exceeds a reference voltage (a voltage corresponding to the temperature T at which the semiconductor integrated circuit is to be stopped in advance), a signal (chip enable CE signal) for stopping the semiconductor integrated circuit is activated.
[0004]
If the accuracy of the PTAT voltage and the reference voltage is poor, the CE signal becomes active even if the semiconductor integrated circuit is within the operating temperature range, and the operation of the semiconductor integrated circuit is stopped or the operating temperature range is exceeded. In spite of this, the CE signal does not become active and causes the semiconductor circuit to be destroyed. Therefore, in this type of temperature protection circuit, the output accuracy of both the PTAT voltage and the reference voltage is important.
[0005]
As shown in FIG. 7, Japanese Patent Laid-Open No. 9-243466, “Semiconductor Temperature Sensor”, applies the same current Id to two MOS transistors N1 and N2 having different channel width W to channel length L ratios (W / L). Since the gate-source voltages Vgs1, Vgs2 of the two MOS transistors are different and the difference (Vgs1-Vgs2) is proportional to the operating temperature of both transistors, this is used as the PTAT signal. A signal having a positive or negative temperature coefficient can be obtained by adjusting the W / L ratio of the two MOS transistors.
[0006]
Further, as shown in FIG. 8, when a PNP transistor or NPN transistor is diode-connected and a constant current is passed through it, a voltage Vt having a negative temperature coefficient at both ends of the diode is obtained. When the Vt exceeds the reference voltage Vref, a predetermined signal Tout is output from the comparator.
[0007]
[Problems to be solved by the invention]
However, in the case of outputting the difference between Vgs of the two MOS transistors, the temperature range in which the PTAT voltage can be accurately extracted is limited to the range of -50 to 100 ° C., and the temperature is higher than 100 ° C. leading to the destruction of the semiconductor integrated circuit. However, accuracy is not guaranteed.
[0008]
In a circuit using a diode connection, the PTAT voltage is affected by process variations, and a highly accurate PTAT voltage cannot be output. In addition, the slope (temperature slope) proportional to the absolute temperature of the PTAT voltage is determined by the process and cannot be set freely. Therefore, a highly accurate circuit with a large temperature slope or a circuit with a low voltage operation with a small temperature slope is created. I couldn't.
[0009]
Furthermore, the reference voltage to be compared with the PTAT voltage thus detected must be a constant voltage independent of temperature, but it is not easy to create such a reference voltage.
[0010]
An object of the present invention is to realize a PTAT voltage generation circuit capable of high-temperature operation and freely setting a temperature gradient, and a reference voltage generation circuit having a temperature detection function capable of high-precision or low-voltage operation using the PTAT voltage generation circuit. Is to get.
[0011]
[Means for Solving the Problems]
The present invention is a temperature detection circuit applying the principle of work function difference of a gate disclosed in Japanese Patent Application Laid-Open No. 2001-284464. As shown in FIG. 1, this temperature detection circuit has a PTAT voltage (hereinafter referred to as Tvptat) having a positive temperature coefficient in proportion to the absolute temperature, and a positive voltage obtained by obtaining this Tvptat by a resistance voltage dividing circuit. A first voltage source circuit A that generates a voltage having a temperature coefficient (hereinafter referred to as Vptat) and a voltage having a negative temperature coefficient in proportion to the absolute temperature are generated. By adding Vptat at a predetermined ratio, the second voltage source circuit B that outputs the first reference voltage Tvref and the second reference voltage Vref independent of the temperature coefficient, the first reference voltage Tvref, And a comparison circuit C that compares Tvptat and outputs the comparison result Tout.
[0012]
Since the principle of the work function difference of the gate is applied to the first voltage source circuit A that generates Vptat, Vptat can be accurately generated up to the operating limit temperature of the semiconductor. Further, since the temperature gradient of Vptat can be adjusted by simple resistance division, a reference voltage generation circuit having a temperature detection function according to the purpose, such as a high-precision version or a low-voltage version, can be obtained. Further, since the principle of the gate work function difference is applied to the second voltage source circuit B, the reference voltages Vref and Tvref can be accurately generated up to the operating limit temperature of the semiconductor.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 2 shows an embodiment of a reference voltage generation circuit having a temperature detection function of the present invention. In this embodiment, this circuit is constructed on an n-type substrate.
The first voltage source circuit includes n-type channel field effect transistors (hereinafter simply referred to as transistors) M1, M2, and M3 and resistors R1, R2, and R5. The transistors M1 and M2 have the same substrate and channel-doped impurity concentrations, are formed in the p-well of the n-type substrate, and the substrate potential of each transistor is equal to the source potential. Further, the ratio (W / L) of the channel width W and the channel length L is equal to each other.
[0014]
The transistor M1 has a high concentration n-type gate, the transistor M2 has a low concentration n-type gate, and both transistors are connected in series. The transistor M1 has its gate connected to the source and is used as a constant current circuit. A source follower circuit is formed by connecting the transistor M3 and the resistors R1, R2, and R5 in series. The transistor M3 is a low-concentration n-type gate, Tvptat is output from the connection point between the source and the resistor R1, Vptat is output from the connection point between the resistors R1 and R2, and the potential at the connection point between the resistors R2 and R5. Is supplied to the gate of the transistor M2.
[0015]
The second voltage source circuit includes n-type channel field effect transistors M4 and M5, p-type channel field effect transistors M6, M7 and M8, and resistors R3 and R4. The transistors M4 and M5 have the same substrate and channel-doped impurity concentrations, are formed in the p-well of the n-type substrate, and the substrate potential of each transistor is equal to the source potential. Further, the ratio (W / L) of the channel width W and the channel length L is equal to each other.
[0016]
The transistor M4 is a high concentration n-type gate, and the transistor M5 is a high concentration p-type gate. The pair of transistors M4 and M5 having different conductivity types are the input transistors of the differential amplifier. Since the transistors M6 and M7 form a current mirror circuit, the same drain current flows through the transistors M4 and M5. Further, a feedback loop is formed between the differential amplifier (M4, M5) and the transistor M8. The output Vref of the gate of the transistor M5 is divided by the resistors R3 and R4 and supplied to the comparison circuit as Tvref.
[0017]
The comparison circuit includes n-type channel field effect transistors M9, M10, and M14 and p-type channel field effect transistors M11, M12, and M13. The transistors M11 and M12 constitute a current mirror circuit. The transistors M9 and M10 are input transistors of the differential amplifier. The transistor M9 has a gate Tvref from the second voltage source circuit and a gate of the transistor M10. Is supplied with Tvptat from the first voltage source circuit. This differential amplifier is used as a comparator. The output of the differential amplifier is supplied to an inverter circuit composed of a p-type channel transistor M13 and an n-type channel transistor M14, and the output of the inverter circuit becomes Tout.
[0018]
Next, the circuit operation of FIG. 2 will be described. First, in the first voltage source circuit, the same drain current flows through a pair of transistors M1 and M2 having the same conductivity type and different impurity concentrations, and the source-gate voltage of the transistor M1 is 0. As described in Japanese Patent No. -284464, the source-gate voltage difference is equal to the source-gate voltage of the transistor M2, so this becomes the PTAT voltage, which is referred to as Vptat '.
[0019]
Therefore, Vptat supplied to the transistor M4 of the second voltage source circuit is
Vptat = (R2 + R5) / R5 * Vptat '
It becomes. Also, Tvptat supplied to the transistor M10 of the comparison circuit is
Tvptat = (R1 + R2 + R5) / R5 * Vptat '(1)
It becomes. Since Vptat 'originally has a positive temperature coefficient, Vptat and Tvptat also have a positive temperature coefficient.
[0020]
Next, the second voltage source circuit uses a pair of transistors M4 and M5 of different conductivity type as input transistors of the differential amplifier, and the p-type channel transistors M6 and M7 constitute a current mirror circuit. The same current flows through M4 and M5. In addition, since a feedback loop is formed between the differential amplifier (M4, M5) and the transistor M8, the differential amplifier (M4, M5) is described in Japanese Patent Laid-Open No. 2001-284464. Has an input offset of Vpn between the gate of the transistor M4 and the gate of the transistor M5, and this Vpn has a negative temperature coefficient.
[0021]
Therefore, when Vptat from the first voltage source circuit is applied to the gate of the transistor M4, Vx obtained by adding Vpnat to Vptat is output to the gate of the transistor M5.
[0022]
This Vx has Vptat having a positive temperature characteristic and Vpn having a negative temperature characteristic, and therefore has no temperature characteristic and becomes a constant reference voltage Vref. Tvref supplied to the transistor M9 of the third voltage source circuit is
Tvref = R4 / (R3 + R4) * Vref (2)
This also has no temperature characteristics.
[0023]
Finally, the third comparison circuit forms a current mirror circuit with the p-type channel transistors M11 and M12, and has n-type channel transistors M9 and M10 as input transistors. The gate of the transistor M9 has Tvref and the transistor M10. Tvptat is input to the gate. As shown in FIG. 3, since Tvref does not have temperature characteristics, it is always constant even if the temperature changes. On the other hand, Tvpat has a positive temperature characteristic, and the voltage rises in proportion to the absolute temperature.
[0024]
If Tvref or Tvptat is set so that the lines of both characteristics intersect at the temperature T at which the semiconductor integrated circuit is to be protected, when the detected temperature is lower than the set temperature T, Tvptat <Tvref, so the comparators (M9, M10) Output becomes High, and the final output Tout becomes Low. When the detected temperature rises and becomes higher than the set temperature T, Tvptat> Tvref, so that the output of the comparator becomes Low and the final output Tout becomes High. If this Tout is used as a chip enable signal, the temperature of the semiconductor integrated circuit can be protected.
[0025]
To make Tvref the desired size, adjust the ratio of resistors R3 and R4 as shown in equation (2), and to make Tvptat the desired size, as shown in equation (1). Further, the ratio of (R1 + R2 + R5) to R5 may be adjusted.
[0026]
As shown in FIG. 4, since Tvptat is (R1 + R2 + R5) / R5 * Vptat ′, the voltage change amount ΔTvptat with respect to the temperature gradient, that is, the change in the detection temperature of 1 ° C. is also (R1 + R2 + R5) / R5 times ΔVptat ′. If this ΔTvptat is large, even if Tvref varies due to variations in the resistance ratio between the resistors R3 and R4, if the variation is smaller than ΔTvptat, the effect on accuracy is small, and higher accuracy can be expected.
[0027]
Conversely, if ΔTvptat is reduced, Tvptat does not become a high voltage even when the set temperature T is reached, so that the voltage of the circuit can be lowered. These Tvptat and Tvref can be easily adjusted by resistors R1, R2, R5 and resistors R3 and R4. These resistance ratios may be fixed at the time of manufacture, or after manufacture, the resistance value may be adjusted by trimming the x points with a laser as shown in FIG.
[0028]
As a reference voltage supplied to the semiconductor integrated circuit, Vref generated by the second voltage source circuit can be used. These voltages described above are generated by applying the principle of the work function difference of the gate, so that they are not affected by the operating temperature and are accurately output up to the operating limit temperature of the semiconductor itself.
[0029]
FIG. 6 shows a second embodiment of the present invention. In this embodiment, a reference voltage generation circuit having a temperature detection function is constructed on a p-type substrate, and includes a first voltage source circuit, a second voltage source circuit, and a comparison circuit.
[0030]
The first voltage source circuit includes p-type channel field effect transistors M1, M2, and M3 and resistors R6, R7, and R8. The transistors M1 and M2 have the same substrate and channel dope impurity concentrations, are formed in the n-well of the p-type substrate, and the substrate potential of each transistor is equal to the source potential. Further, the ratio (W / L) between the channel width W and the channel length L is the same. The transistor M2 is a low-concentration n-type gate, and the gate is connected to the source to be used as a constant current circuit.
[0031]
The transistor M1 is a high-concentration n-type gate, and a gate potential is applied by a source follower circuit including the transistor M3 and a resistor R6. Further, the potential between the source and gate of the transistor M1 is Vptat, VptatB is divided from the drain of the transistor M3, and VptatB is divided by the resistors R7 and R8 to output TvptatB.
[0032]
The second voltage source circuit includes n-type channel field effect transistors M4 and M5, p-type channel field effect transistors M6, M7 and M8, and resistors R9 and R10. The transistors M4 and M5 have the same substrate and channel-doped impurity concentration, are formed on a p-type substrate, and the substrate potential of the transistor is the GND potential. Further, the ratio (W / L) between the channel width W and the channel length L is the same.
[0033]
The transistor M4 is a high concentration n-type gate, and the transistor M5 is a high concentration p-type gate. The paired transistors M4 and M5 are input transistors of the differential amplifier. The p-type channel field effect transistors M6 and M7 constitute a current mirror circuit. A feedback loop is formed between the differential amplifier (M4, M5) and the p-type channel field effect transistor M8. The output Vref of the differential amplifier (M4, M5) is divided by the resistor R9 and the resistor R10 and output as Tvref.
[0034]
The comparison circuit includes n-type channel field effect transistors M9, M10, and M14 and p-type channel field effect transistors M11, M12, and M13. The transistors M11 and M12 constitute a current mirror circuit. The transistors M9 and M10 are input transistors of the differential amplifier. The gate of the transistor M9 has Tvref from the second voltage source circuit, and the transistor M10 has VptatB is input from the first voltage source circuit. The output of the differential amplifier (M9, M10) is input to an inverter circuit composed of a p-type channel field effect transistor M13 and an n-type channel field effect transistor M14, and the output of the inverter circuit is Tout.
[0035]
Next, the circuit operation of FIG. 6 will be described. First, since the same current flows through the paired transistors M1 and M2 in the first voltage source circuit, the voltage between the source and gate of the transistor M1 becomes Vptat as in the first embodiment. Further, since the same current as the current flowing through the resistor R6 flows also through the resistors R7 and R8, VptatB becomes ((R7 + R8) / R6) * Vptat. Further, TvptatB is (R8 / (R7 + R8)) * VptatB. Since Vptat has a positive temperature coefficient as described above, both VptatB and TvptatB have a positive temperature coefficient.
[0036]
Next, the second voltage source circuit uses a pair of transistors M4 and M5 of different conductivity type as input transistors of the differential amplifier, and the p-type channel transistors M6 and M7 constitute a current mirror circuit. The same current flows through M4 and M5. Further, since a feedback loop is formed between the differential amplifier (M4, M5) and the transistor M8, the differential amplifier (M4, M5) includes a gate of the transistor M4 and a gate of the transistor M5. It has an input offset of Vpn, and this Vpn has a negative temperature coefficient.
[0037]
Therefore, when Vptat from the first voltage source circuit is applied to the gate of the transistor M4, Vref obtained by adding Vpnat to Vptat is output to the gate of the transistor M5.
[0038]
This Vref is a constant reference voltage without temperature characteristics because Vptat having a positive temperature characteristic and Vpn having a negative temperature characteristic are added together. Tvref supplied to the transistor M9 of the third voltage source circuit is
Tvref = R10 / (R9 + R10) * Vref
This also has no temperature characteristics.
[0039]
Finally, the third comparison circuit forms a current mirror circuit with the p-type channel transistors M11 and M12, and has n-type channel transistors M9 and M10 as input transistors. The gate of the transistor M9 has Tvref and the transistor M10. Tvptat is input to the gate. Since Tvref does not have temperature characteristics, it is always constant even if the temperature changes. On the other hand, Tvpat has a positive temperature characteristic, and the voltage rises in proportion to the absolute temperature.
[0040]
Also in this case, when the detected temperature is lower than the set temperature T, since TvptatB <Tvref, the outputs of the comparators (M9, M10) become High and the final output Tout becomes Low. When the detected temperature rises and becomes higher than the set temperature T, TvptatB> Tvref, so that the output of the comparator becomes Low and the final output Tout becomes High. If this Tout is used as a chip enable signal, the temperature of the semiconductor integrated circuit can be protected.
[0041]
In order to make Tvref a desired size, the ratio of resistors R9 and R10 is adjusted, and in order to make TvptatB a desired size, the ratio of (R7 + R8) / R6 may be adjusted.
[0042]
As described above, according to the present invention, it is possible to obtain a reference voltage generation circuit having a temperature detection function capable of high-temperature operation and capable of high-precision or low-voltage operation. In addition, a voltage having a positive temperature coefficient is generated in the first voltage source circuit, and a voltage having a negative temperature coefficient is generated in the second voltage source circuit. A similar result can be obtained by generating a voltage having a negative temperature coefficient and generating a voltage having a positive temperature coefficient in the second voltage source circuit. In that case, a voltage Tvptat having a negative temperature coefficient is obtained from the first voltage source circuit.
[0043]
In addition, the “temperature detection circuit” (Japanese Patent Application No. 2002-77915) filed earlier by the present applicant eliminates the secondary temperature coefficient contained in the temperature signal and generates a high-accuracy temperature signal having only the primary temperature coefficient. If this temperature signal is used instead of the voltage Tvptat having a positive temperature coefficient obtained by the first voltage source circuit of the present invention, temperature detection with higher accuracy becomes possible.
[0044]
【The invention's effect】
The present invention relates to a reference voltage having no temperature coefficient made by adding the output voltage of the first voltage source circuit and the output voltage of the second voltage source circuit, and positive or negative from either one of the voltage source circuits. The output voltage having a negative temperature characteristic is compared, and in each of the first and second voltage source circuits, a voltage and temperature having a temperature coefficient by applying the principle of the work function difference of the gate. Since reference voltages having no coefficients are obtained, these voltages can be accurately generated up to the semiconductor operation limit temperature, and accurate temperature detection can be performed over a wide range of temperatures.
[0045]
The diffusion in the production value of the resistor that determines the magnitude of the occur voltage, since the adjustable after the film formation process, it is possible to obtain a highly accurate reference voltage having no temperature coefficient, also positive Since the temperature gradient of the voltage having the temperature coefficient can be freely set, the temperature gradient can be increased to make a more accurate circuit, or the temperature gradient can be reduced to make a circuit operating at a low voltage.
[0046]
In addition to the temperature detection signal (decision signal), since the reference voltage output to the outside, we can supply the reference voltage to the semiconductor integrated circuit to be protected by the decision signal, can reduce the size of the circuit.
[Brief description of the drawings]
FIG. 1 is a diagram corresponding to claims of a temperature detection circuit of the present invention. FIG. 2 is a circuit diagram showing a first embodiment of the present invention. FIG. 3 is a temperature change of a Tvpat voltage and a Tvref voltage created by the circuit of FIG. FIG. 4 is a graph showing temperature changes in the Tvpat voltage and Vptat voltage created by the circuit of FIG. 2. FIG. 5 is a diagram showing trimmable resistance. FIG. 6 is a second embodiment of the present invention. FIG. 7 is a circuit diagram illustrating a conventional circuit for generating a PTAT voltage. FIG. 8 is a circuit diagram illustrating a conventional circuit for obtaining a temperature determination signal.
M Field-effect transistor R Resistance Vptat, Tvptat Voltage having positive temperature coefficient Vref, Tvref Reference voltage

Claims (7)

The first field effect transistor of the high-concentration n-type gate, a second field effect transistor of the low-concentration n-type gate connected in series to the first field effect transistor, the gate to the second field effect transistor comprises a first source follower circuit for providing a voltage, a first voltage source circuit proportional voltage proportional to the first output voltage and the first output voltage having a positive or negative temperature coefficient and outputs, respectively,
The generating a first output voltage and the reverse generates a voltage having a temperature coefficient, a reference voltage having no temperature coefficient by adding the voltage and the first output voltage thus generated in the first voltage source circuit Two voltage source circuits;
And a comparator circuit for comparing the proportional voltage output from said first voltage source circuit, and a voltage corresponding to the reference voltage generated by the second voltage source circuit,
The first source follower circuit includes a third field effect transistor for outputting the first output voltage having a gate connected to a connection portion between the first field effect transistor and the second field effect transistor. A first resistor for adjusting the gate voltage of the second field effect transistor, a second resistor for adjusting the voltage of the first output voltage, and a voltage adjustment of the proportional voltage. the third consists of a series circuit of a resistor, a temperature detecting circuit, characterized in that from the first Ru comprising means for enabling adjustment of the third value of each resistor. The temperature detection circuit according to claim 1, wherein the second voltage source circuit includes a plurality of field effect transistors having gates of different conductivity types . The second voltage source circuit includes a fourth field effect transistor having a high concentration n-type gate, a fifth field effect transistor having a high concentration p type gate, and a second field voltage applying a gate voltage to the fifth field effect transistor. And a proportional reference voltage proportional to the reference voltage, and the comparison circuit compares the proportional voltage with the proportional reference voltage. Item 3. The temperature detection circuit according to Item 2. The second source follower circuit is composed of a sixth field effect transistor and a plurality of resistors, and the values of the resistors are set after the diffusion and film formation steps in manufacturing so that the reference voltage can be adjusted. 4. The temperature detection circuit according to claim 3 , further comprising means for enabling adjustment . The comparison circuit includes: a seventh field effect transistor in which an output of the first source follower circuit is input to a gate; and an eighth field effect transistor in which an output of the second source follower circuit is input to a gate; 5. The temperature detection circuit according to claim 4 , comprising a differential amplifier having an input transistor as an input transistor and comparing the magnitudes of the two input voltages and outputting a predetermined determination signal . The temperature detection circuit according to claim 1, wherein the second voltage source circuit outputs the reference voltage to the outside . The temperature detection circuit according to claim 1, wherein the means for adjusting the value of the resistance is performed after a diffusion and film formation process in manufacturing .

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