JP3180409B2 - Semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a MOSFET having an overtemperature protection function.

[0002]

2. Description of the Related Art As a conventional semiconductor device having an over-temperature protection function, there is, for example, a device as shown in FIG. 14, 1 is a MOSFET having a large current capacity (so-called power MOSFET), 4 is a gate terminal, 9 is a power supply circuit, 10 is an input terminal of a signal for controlling the MOSFET 1, 11 is an output terminal to which a load is connected, Reference numeral 12 denotes a reference voltage circuit that outputs a reference voltage VR that does not change with temperature, 13 denotes a temperature detection circuit that outputs a voltage VK that changes with temperature, 14 denotes a comparison circuit, and 15 denotes a NOR gate.

[0003] The MOSFET 1 is susceptible to heat and must not be used above about 170 ° C. Therefore, an element which may generate a very large amount of self-heating, such as an element used in a severe environment such as a vehicle or a power element, needs some kind of over-temperature protection function. Conventionally, as shown in FIG. 14, a comparison circuit 14 compares a reference voltage VR, which does not change with temperature, and a voltage VK, which changes with a rise in temperature. The configuration is such that the input signal is shut off by closing the switch 15 and the MOSFET 1 is stopped. As the reference voltage circuit 12, for example, a bandgap reference voltage source or the like is used.
As 3, a circuit or the like that outputs a diffusion potential of a PN junction of a semiconductor that changes according to temperature as VK is used. The power supply circuit 9 is required to operate these circuits.

As a conventional semiconductor device having an over-temperature protection function, there is a high-side switch circuit as shown in FIG. In a switching circuit that drives a load such as an actuator, when a load is connected to the power supply side such as “power supply-load-semiconductor switching element-ground”,
In the event of a short circuit, etc., the load remains directly grounded,
There is a fear of overheating and breakage. Therefore, a high-side switch structure in which the load is connected to the ground side and the semiconductor switching element is connected to the power supply side, such as “power supply-semiconductor switching element-load-ground”, is used. When a power MOSFET is used as a switching element of the high side switch circuit as described above, a case where an NMOS transistor is used and a case where a PMOS transistor is used are considered. However, in order to obtain the same characteristics as the NMOS in the PMOS, a chip area about three times as large as that of the NMOS is required. Therefore, the NMOS is used in many cases.

FIG. 15 shows an example in which an NMOS is used as the MOSFET 1.
6 is a circuit example in the case of using. NMOS MOSFET
To turn on 1 sufficiently, it is necessary to apply a considerably large voltage to its gate terminal 4. Therefore, the input signal needs to be boosted by the booster circuit 42 before being applied to the gate 4. As the booster circuit 42, for example, there is a charge pump type booster circuit as shown in FIG. This circuit supplies charges only in one direction through a diode, and sends charges to the gate terminal 4 through a capacitor 44 when the output of the CR oscillation circuit 43 rises. In this case, the electric charge is sent to the gate terminal 4 side in one direction because it passes through the diode. Also, the circuit of FIG. 15 is provided with the same overtemperature protection function as that of FIG. That is, the over-temperature protection circuit 41 has the same configuration as that of FIG. When an over-temperature condition is detected by this circuit, PM
At the same time that the switch of the OS transistor 45 is turned off and the supply of the power supply voltage is stopped, the NMOS transistor 46 is turned off.
Is turned on, the gate terminal 4 is grounded to release the electric charge of the gate, and the MOSFET 1 is turned off to realize over-temperature protection.

[0006]

In the above-mentioned conventional semiconductor device having an over-temperature protection function, a fairly large-scale circuit is required to realize an accurate protection function. For example, the configuration of the conventional example requires about 30 transistors. Therefore, there is a problem that the chip area is increased and the cost is increased. In addition, even if such a large-scale circuit is used, since the setting of the circuit constant is delicate, it is easily affected by variations in circuit operating conditions such as variations in each element and power supply voltage variations, and the reproducibility is not very good. There was a problem.

SUMMARY OF THE INVENTION The present invention has been made to solve the problems of the prior art as described above, and has as its object to provide a semiconductor device capable of performing effective overtemperature protection with a simple circuit.

[0008]

Means for Solving the Problems In order to achieve the above object, the present invention is configured as described in the claims. That is, according to the first aspect of the present invention, an insulated gate field effect transistor and a ferroelectric
Body, the capacitance greatly increases near its Curie point.
Temperature-sensitive variable capacitor with
And a temperature-sensitive variable capacitor
Is the source terminal of the insulated gate field effect transistor
And the fixed capacitor capacitor connected between
A sensor is connected between the gate terminal and the input terminal of the insulated gate field effect transistor .

[0009] In the invention described in claims 2 to 4, a capacitor changes the electrostatic capacitance with temperature, the resistance to change in resistance with temperature, the gate potential of the insulated gate field effect transistor A first temperature at which the capacitance of the capacitor changes rapidly and a second temperature at which the resistance of the resistor changes suddenly. Is set to a different value.

Further, in the invention according to claim 5 ,
A booster circuit that operates in response to an input signal, including a capacitor whose capacitance changes according to temperature, a CR oscillation circuit using the capacitor as C, and a part of a gate charge of an insulated gate field effect transistor that is grounded. And a circuit that flows to the gate terminal of the insulated gate field effect transistor.

[0011]

According to the first aspect of the present invention, the ferroelectric substance is
And the capacitance greatly increases near the Curie point.
Variable capacitor with fixed characteristics and fixed capacitance
The over-temperature protection function is realized by changing the gate-source voltage of the insulated gate field effect transistor using a capacitor . That is, when the temperature reaches a predetermined value, the capacitance of the temperature-sensitive variable capacitor rapidly increases,
As a result, the gate potential of the insulated gate field effect transistor is reduced, the insulated gate field effect transistor is turned off, and the temperature is reduced.

In the inventions according to the second to fourth aspects of the present invention, when the second temperature is reached, the insulated gate field effect transistor is turned off. A configuration in which the gate type field effect transistor is turned on (for example, a third embodiment described later, in this case, first temperature <second temperature), or conversely,
When the first temperature is reached, the insulated gate field effect transistor is turned off, and when the temperature is lowered to the second temperature, the insulated gate field effect transistor is turned on (for example, a fourth embodiment to be described later. If the first
Temperature> second temperature), the ON / OFF operation has a hysteresis characteristic.

Further, in the invention according to claim 5 ,
By configuring the oscillation circuit in the gate booster circuit using a capacitor whose capacitance changes with temperature, a voltage higher than the input signal voltage can be used as the gate voltage of the insulated gate field effect transistor, as in a high-side switch circuit. The overtemperature protection function is realized in the required circuit.

[0014]

FIG. 1 is a diagram showing a first embodiment of the present invention. FIG.
, A temperature-sensitive variable capacitor 2 is connected between the gate terminal 4 and the source terminal 5 of the MOSFET 1. Further, the fixed capacitor 3 is connected between the gate terminal 4 and the input terminal 10. Reference numeral 6 denotes a power supply terminal.

Next, the operation will be described. The capacitor has a structure in which a dielectric is sandwiched between electrodes. The capacitance of a so-called parallel plate capacitor is expressed as follows: dielectric constant ε, electrode area A,
Assuming that the electrode interval is t, it is expressed by the following (Equation 1).

[0016]

(Equation 1)

Therefore, if the dielectric constant ε changes, the capacitance also changes. For example, a ferroelectric material such as BaTiO _3, as shown in FIG. 2, the dielectric constant is largely changed by temperature, it is known that takes a maximum value in particular in Curie point Tc. Its value is about 6000 for BaTiO ₃ , which is more than three times the normal temperature. Therefore, if the dielectric material of the temperature-sensitive variable capacitor 2 of FIG. 1 is made of BaTiO ₃ or the like, the capacitor has a significantly increased capacitance near the Curie point. Here, the capacitance between the gate and the source of the MOSFET 1 is Cm, the capacitance of the temperature-sensitive variable capacitor 2 at room temperature is Cb, the maximum value near the Curie point is Cbm, and the capacitance of the fixed capacitor 3 is Let it be Ca. Since the gate-source capacitance Cm and the temperature-sensitive variable capacitor 2 are connected in parallel, their combined capacitance is Cd = Cm + Cb at room temperature, and the combined capacitance near the Curie point. Cdm = Cm + Cbm. Considering the case where the voltage Vx is applied between the input terminal 10 and the source terminal 5,
A voltage Vgs expressed by the following equation (2) is applied to the gate terminal 4 and the source terminal 5 of the MOSFET 1.

[0018]

(Equation 2)

If the temperature rises and the capacitance of the temperature-sensitive variable capacitor 2 changes from Cb to Cbm,
The above voltage Vgs is equal to the voltage Vgs as shown in the following equation (3).
changes to s.

[0020]

(Equation 3)

The above Vgss is the threshold value Vt of the MOSFET.
Determine each constant so that it is smaller than h. For example,
Ca = 1000 pF, Cm = 1000 pF, Cb = 300
Assuming that 0 pF and Cbm = 3.2 Cb, Vgs and Vgss are as shown in the following (Formula 4).

[0022]

(Equation 4)

If Vth = 1V, Vgs = 2V, and therefore Vx = about 10V.

When the constants are set as described above, when the temperature rises and the capacitance of the temperature-sensitive variable capacitor 2 increases, Vgss falls below Vth and the MOSFET 1 is turned off. Therefore, the heat generation of the MOSFET 1 stops, and the temperature decreases.

FIG. 3 is a diagram showing a reference example of the present invention. In this reference example, the gate terminal 4 and the source terminal 5 of the MOSFET 1 are connected by a MOSFET 7 having a small current capacity, and the gate terminal 8 and the gate terminal 4 of the MOSFET 1 are connected.
Are connected by a temperature-sensitive variable capacitor 2. Here, the capacitance between the gate and the source of the MOSFET 7 is assumed to be Cm2. The voltage V is applied to the gate terminal 4 and the source terminal 5.
When gs is applied, a voltage Vgs2 expressed by the following equation (5) is applied between the gate and the source of the MOSFET 7.

[0026]

(Equation 5)

At room temperature, the MOSFET 7 is turned off if it is set so that Vgs2 <Vth2 (where Vth2 is the threshold value of the MOSFET 7). When the temperature rises and the capacitance Cb of the temperature-sensitive variable capacitor 2 increases to Cbm, the voltage Vgs2 rises and becomes equal to or higher than the threshold value Vth2, so that the MOSFET 7 is turned on. As a result, MO
The gate-source voltage Vgs of the SFET 1 decreases and becomes lower than the threshold value Vth, so that the SFET 1 is turned off. Therefore MOSF
The heat generation of ET1 stops, and the temperature decreases. In this embodiment, a circuit operating at the same gate-source voltage as a normal MOSFET can be provided with the same overtemperature protection function as described above.

FIG. 4 is a diagram showing a second embodiment of the present invention. In FIG. 4, reference numeral 16 denotes a load of an actuator or the like;
2 is a booster circuit similar to that shown in FIG.
In addition, the same reference numerals as those in FIG. This example is
This is an example in which the first embodiment is applied to a high-side switch. In the case of the high-side switch, since the load 16 is connected between the source and the ground, the source potential when a current flows through the load becomes very close to the power supply voltage Vdd. Therefore, in order to turn on the MOSFET 1 sufficiently, the gate potential needs to be equal to or higher than the power supply voltage Vdd. The booster circuit 42 outputs a voltage higher than the power supply voltage Vdd, boosts the signal input from the input terminal 10 to the power supply voltage or higher, and
It has a role to turn on SFET1.

The operation of this embodiment is similar to that of the first embodiment described above. As the temperature rises, the capacitance of the temperature-sensitive variable capacitor 2 increases and the MOSFET 1
The potential of the gate terminal 4 becomes low, and the MOSFET 1 is turned off. Therefore, the heat generation of the MOSFET 1 stops, and the temperature decreases. In this embodiment, by boosting the voltage input to the input terminal,
The MOSFET of the high-side switch can be sufficiently turned on. It should be noted that a MOSFET
1 is not only applied to the high-side switch, but is effective when the threshold voltage Vth of the MOSFET 1 is high and a considerably high voltage needs to be applied to the input terminal 10 to turn on sufficiently. It is.

FIG. 5 shows a third embodiment of the present invention. In FIG. 5, a MOSFET 17 having a small current capacity is connected between the gate terminal 4 and the source terminal 5 of the MOSFET 1, and a MOSFET 7 having a small current capacity is connected between the gate terminal 18 and the source terminal 5 of the MOSFET 1. Further, the anode of the diode 21 is connected to the gate terminal 18, the cathode of the diode 21 and the source terminal 5 are connected via the temperature-sensitive variable resistor 19,
And the gate terminal 4 are connected via a fixed resistor 20. Further, the gate terminal 8 and the source terminal 5 of the MOSFET 7 are connected via the temperature-sensitive variable capacitor 2,
The gate terminal 8 and the gate terminal 4 are connected via the fixed capacitor 3.

Next, the operation will be described. As in the case of the first embodiment, the temperature-sensitive variable capacitor 2 is made of BaTiO _3.
The dielectric constant of the temperature-sensitive variable capacitor 2 significantly increases in accordance with the temperature, particularly near the Curie point, and accordingly, the capacitance of the temperature-sensitive variable capacitor 2 significantly increases. Further, the temperature-sensitive variable resistor 19 is a semiconductor obtained by doping a ferroelectric such as BaTiO ₃ with a dopant such as Mn. In such a semiconductor, as shown in FIG. 6, the resistivity ρ greatly changes depending on the temperature, and particularly greatly changes near the Curie point. The amount of change in the resistivity ρ also changes depending on the substance, dopant, and structure, but when BaTiO ₃ is doped with Mn, the amount increases by six orders of magnitude. Also, as shown in FIG.
The temperature T2 at which the resistivity ρ starts to change is generally higher than the temperature T1 at which the permittivity ε of the temperature-sensitive variable capacitor 2 starts to change. The capacitance between the gate and source of the MOSFET 7 is Cm2, and the capacitance of the temperature-sensitive variable capacitor 2 is Cm2.
b, Let the capacitance of the fixed capacitor 3 be Cs. When a voltage Vgs is applied to the gate terminal 4 and the source terminal 5, a voltage Vgs2 expressed by the following (Formula 6) is applied between the gate and the source of the MOSFET 7.

[0032]

(Equation 6)

At room temperature, if it is set so that Vgs2> Vth2 (where Vth2 is the threshold value of the MOSFET 7), the MOSFET 7 is turned on.
The gate charge of the SFET 17 is zero. When the temperature rises and the capacitance Cb of the temperature-sensitive variable capacitor 2 increases, Vgs2 decreases and becomes lower than the threshold value Vth2.
Although the FET 7 is turned off, the potential of the gate terminal 18 is low and M
The gate charge of OSFET 17 remains zero. On the other hand, the gate terminal 18 of the MOSFET 17
A divided voltage Vgs3 of the gate-source voltage Vgs of ET1 is applied. Assuming that the resistance value of the fixed resistor 20 is Rs and the resistance value of the temperature-sensitive variable resistor 19 is Rv, the divided voltage value Vgs3 is represented by the following equation (7).

[0034]

(Equation 7)

When the temperature T is in the range of T <T2 with respect to T2 in FIG. 6, Vgs3−Vf <Vth3 (where Vth3 is MOS
If the threshold value and Vf of the FET 17 are set to be equal to the forward voltage drop of the diode 21, the MOSFET
17 is off. Then, when the temperature rises and reaches T2, Rv increases and Vgs3 rises, and the threshold Vt
Since it is h3 or more, the MOSFET 17 is turned on. As a result, the MOSFET 1 is turned off, and the heat generation stops.
Next, consider the case where the temperature decreases. When T <T2, the voltage at the voltage dividing point 22 decreases, but is clamped by the reverse voltage of the diode 21, so that the voltage at the gate terminal 18 does not decrease and the MOSFET 17 remains on, that is, the MOSFET 1 remains off. Become. When the temperature T further falls and T <T1, the MOSFET 7 is turned on, so that the gate charge of the MOSFET 17 becomes 0 and M
OSFET 17 is turned off. As a result, MOSFET1
Recovers to the ON state. FIG. 7 is an operation waveform diagram showing the above ON / OFF operation. As shown in FIG. 7, the circuit of FIG. 5 performs a hysteresis operation between temperatures T1 and T2.

FIG. 8 is a diagram showing a fourth embodiment of the present invention. 8, reference numeral 23 denotes a temperature-sensitive variable capacitor, 2
Reference numeral 4 denotes a temperature-sensitive variable resistor, reference numerals 25 and 26 denote diodes, and the same reference numerals as those in FIG. The temperature-sensitive variable capacitor 23 and the temperature-sensitive variable resistor 24 have the same structure as 2 and 19 in FIG.
As shown in FIG. 9, the temperature T2 at which the resistivity ρ of the temperature-sensitive variable resistor 24 starts to change is set to a value lower than the temperature T1 at which the dielectric constant ε of the temperature-sensitive variable capacitor 23 starts to change. In the circuit of FIG. 8, when the temperature T is T <T2,
The temperature-sensitive variable resistor 24 and the temperature-sensitive variable capacitance capacitor 23
Both perform normal operations with normal values. Temperature T is T2 <T
In the case of <T1, since the resistance value R of the temperature-sensitive variable resistor 24 becomes very large, the time constant τ = RCm + Cb of the gate electrode becomes very large. This time constant τ is set to be larger than the time constant of the temperature change.

When the temperature further rises and reaches T1, the capacitance of the temperature-sensitive variable capacitor 23 increases, and the gate and gate of the MOSFET 1 are increased in the same manner as in the first embodiment.
The source-to-source voltage decreases from Vgs to Vgss. Vgss in this case is expressed by the following equation (8).

[0038]

(Equation 8)

Here, Vgss <Vth (where Vth is MO
(The threshold of SFET1)
MOSFET 1 is turned off. As a result, heat is eliminated, so that the temperature drops, and the capacitance of the temperature-sensitive variable capacitor 23 returns to its original value, and the voltage applied to both ends increases again.
The charge does not return to the gate terminal 4 of the MOSFET 1 due to the diode 25, but passes through the diode 26 to the input terminal 1.
Flowing to zero. Since the time constant τ of charging the gate electrode of MOSFET 1 is very large as described above,
ET1 remains off, and when the temperature drops to T2 in this state, the resistance value of the temperature-sensitive variable resistor 24 returns to its original state, the gate is quickly recharged, and the MOSFET 1 turns on.
Therefore, when the situation is not improved, a hysteresis operation of repeating ON / OFF is performed as shown in FIG.

FIG. 11 is a diagram showing a fifth embodiment of the present invention, and FIG. 12 is a detailed circuit diagram of FIG. First, in FIG. 11, the other end of the load 16 whose one end is grounded is
The source terminal 5 of OSFET1 (NMOS) is connected. The gate terminal 4 of the MOSFET 1 is connected to the booster circuit 31. The gate terminal 4 is grounded through a resistor 30. The booster circuit 31 uses a temperature-sensitive variable capacitor 33 whose capacitance changes with temperature.
An R oscillation circuit 32 is included. FIG. 12 shows the above CR
2 shows a detailed circuit example of a booster circuit 31 including an oscillation circuit 32. The booster circuit 31 has a charge pump system configuration including a capacitor 34 and a diode 35, as in the conventional example shown in FIG. Between the power supply Vdd and the capacitor 34, a PMOSFET 36 and a diode 3
7 is connected. The capacitor 34 and the MOSF
A diode 38 is also connected between the gate terminals 4 of ET1. Temperature-sensitive variable capacitors 33 and 33 ′ are used as C of the CR oscillation circuit 32, and the output side of the CR oscillation circuit 32 is connected to a capacitor 34.

Next, the operation will be described.

[0042] As in the case of the first embodiment, the temperature-sensitive variable capacitor 33, 33 'are formed in the BaTiO ₃ HitoshiTsutomu dielectric, depending on the temperature, in particular the dielectric constant in the vicinity Curie point This greatly increases the capacitance of the temperature-sensitive variable capacitors 33 and 33 '. FIG.
The switching of the PMOSFET 36 by the input signal given from the input terminal 10
A charge is supplied to the capacitor 34. When the temperature is lower than the Curie point, the value of C of the CR oscillation circuit 32, that is, the capacitance of the temperature-sensitive variable capacitors 33 and 33 'is small, so that the oscillation frequency proportional to 1 / CR is large.
Therefore, the frequency of charging by the capacitor 34 in the charge pump operation of the booster circuit 31 increases. If the amount of leaked charge through the resistor 30 is set smaller than the amount of charge charged by the charge pump operation, charges are accumulated in the gate 4 and the MOSFET 1 is turned on. Next, when the temperature approaches the Curie point, the capacitances of the temperature-sensitive variable capacitors 33 and 33 ′ increase remarkably.
The value of C of the R oscillation circuit 32 increases, and the oscillation frequency decreases. Therefore, the charge current by the capacitor 34 in the charge pump operation of the booster circuit 31 decreases,
Since the amount of leaked charge through the resistor 30 increases and the charge is not accumulated in the gate 4, the MOSFET 1 is turned off. Therefore, no current flows to the load 16, and the overtemperature protection function can be realized. FIG.
FIG. 3 is a diagram showing the state of the potential of the gate terminal 4 in the case of a normal temperature and in the case of a high temperature. In FIG. 13, the characteristic A is a case of a normal temperature, shows a state where the frequency is large, the charge amount due to the boosting operation is larger than the leak charge amount, and the potential of the gate terminal 4 increases. Further, the characteristic B is a case of a high temperature, in which the frequency is small, the amount of leaked charge is larger than the amount of charged charge, and the potential of the gate terminal 4 does not increase. As described above, in the fifth embodiment, even in a circuit such as a high-side switch circuit that requires the gate voltage of the MOSFET to be higher than the input signal, it is possible to effectively provide the overtemperature protection function with a simple circuit. I can do it.

[0043]

As described above, according to the present invention, an over-temperature protection function is realized by changing the gate-source voltage of a MOSFET using a capacitor whose capacitance changes with temperature. As a result, an accurate overtemperature protection function can be added without using a complicated circuit, so that the chip area can be significantly reduced. In addition, an effect is obtained that a protection function with good reproducibility, which is less susceptible to element variations and changes in operating conditions, can be added. In addition, Claim 2 to Claim
In the invention described in Item 4 , an over-temperature protection function that performs a hysteresis operation with a simple circuit by utilizing a difference in the changing temperature between a capacitor whose capacitance changes with temperature and a resistor whose resistance changes with temperature. Can be realized. According to the fifth aspect of the present invention, the oscillation circuit in the gate booster circuit is configured by using a capacitor whose capacitance changes depending on the temperature, so that the input voltage is input as the gate voltage of the MOSFET as in a high-side switch circuit. Even in a circuit requiring a voltage higher than the signal voltage, the overtemperature protection function can be realized with a simple circuit.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a first embodiment of the present invention.

FIG. 2 is a characteristic diagram showing a relationship between a dielectric constant and a temperature in a ferroelectric.

FIG. 3 is a circuit diagram of a reference example of the present invention.

FIG. 4 is a circuit diagram of a second embodiment of the present invention.

FIG. 5 is a circuit diagram of a third embodiment of the present invention.

FIG. 6 is a characteristic diagram showing a relationship between resistivity and temperature of a temperature-sensitive resistor according to a third embodiment.

FIG. 7 is an operation waveform diagram showing an on / off operation in the third embodiment.

FIG. 8 is a circuit diagram of a fourth embodiment of the present invention.

FIG. 9 is a characteristic diagram showing a relationship between resistivity and temperature of a temperature-sensitive resistor according to a fourth embodiment.

FIG. 10 is an operation waveform diagram showing an on / off operation in the fourth embodiment.

FIG. 11 is a circuit diagram of a fifth embodiment of the present invention.

FIG. 12 is a detailed circuit diagram of FIG. 11;

FIG. 13 is an operation waveform diagram in the fifth embodiment.

FIG. 14 is a circuit diagram of an example of a conventional semiconductor device having an over-temperature protection function.

FIG. 15 is a circuit diagram of another example of a conventional semiconductor device having an overtemperature protection function.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... MOSFET 2 ... Temperature-sensitive variable capacitor 3 ... Fixed capacitor 4 ... Gate terminal 5 ... Source terminal 6 ... Power supply terminal 7 ... MOSFET with small current capacity 8 ... Gate terminal of 7 9 ... Power supply circuit 10 ... Input terminal 11 ... Output 12: Reference voltage circuit 13: Temperature detection circuit 14: Comparison circuit 15: NOR gate 16: Load 17: MOSFET having small current capacity 18: Gate terminal of 17 19: Temperature-sensitive variable resistor 20: Fixed resistor 21: Diode 22: Connection Point 23: Temperature-sensitive variable capacitor 24 ... Temperature-sensitive variable resistor 25, 26 diode 30 ... Fixed resistor 31 ... Step-up circuit 32 ... CR oscillation circuit 33, 33 '... Temperature-sensitive variable capacitor 34 ... Capacitor 35 ... Diode 36 ... MOS
FET 37, 38 Diode 40 Load 41 Over-temperature protection circuit 42 Boost circuit 43 CR oscillation circuit 44 Capacitor 45, 46 MOSFET

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-224368 (JP, A) JP-A-58-173867 (JP, A) JP-A-2-166916 (JP, A) 19312 (JP, B1) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 29/78 H01L 21/822 H01L 21/8234 H01L 27/04 H01L 27/088

Claims (5)

(57) [Claims] An insulated gate field effect transistor and a ferroelectric are used, and the capacitance is large near the Curie point.
A temperature-sensitive variable capacitor having a characteristic that increases in width, and a fixed capacitor, wherein the temperature-sensitive variable capacitor is connected between a source terminal and a gate terminal of the insulated gate field effect transistor , and The fixed capacitance capacitor is the above insulated gate type
Connected between the gate terminal and input terminal of the field effect transistor
Semiconductor devices. 2. An insulated gate type field effect transistor and a ferroelectric material having a large capacitance near the Curie point.
Uses a temperature-sensitive variable capacitor with a characteristic that increases in width and a ferroelectric, and the resistance value greatly increases near its Curie point
And a gate potential of the insulated gate field effect transistor according to the capacitance of the temperature-sensitive variable capacitor and the resistance value of the temperature-sensitive variable resistor. And a ferroelectric material forming the temperature-sensitive variable capacitor.
The first temperature corresponding to the vicinity of the Curie point of
It corresponds to the vicinity of the Curie point of a ferroelectric that forms a variable resistance.
By setting the second temperature different from the first temperature, a semiconductor configured such that the on / off operation of the insulated gate field effect transistor has a hysteresis characteristic between the first temperature and the second temperature. apparatus. (3)First insulated gate field effect transistor
When, The first insulated gate field-effect transistor has a lower electric
Second insulated gate field effect transistor with small current capacity
And The first insulated gate field-effect transistor has a lower electric current than the first insulated gate field-effect transistor.
The third with small flow capacity Insulated gate field effect transistor
And Using ferroelectric material, large capacitance near its Curie point
A temperature-sensitive variable capacitor having a characteristic that increases in width; Fixed capacitance capacitors, Using a ferroelectric, the resistance value is large near the Curie point
A temperature-sensitive variable resistor having a characteristic of increasing to Fixed resistance, And a diode, Gate of the first insulated gate field effect transistor
The second insulated gate field effect between the terminal and the source terminal
Connecting a transistor, further comprising the second insulated gate
Terminal of the gate type field effect transistor and the first insulation
Between the source terminal of the gate type field effect transistor.
3. Connect the insulated gate field effect transistor of No. 3
Gate terminal of second insulated gate field effect transistor
Connect the anode of the diode to
Sword and the first, second and third insulated gate field effect
Connects to the source terminal of the transistor via a temperature-sensitive variable resistor.
Connecting the cathode of the diode to the first insulating gate.
A fixed resistor is connected to the gate terminal of the
Through the third insulated gate type electric field effect device.
The gate and source terminals of the transistor are temperature sensitive
Connected through a variable capacitance capacitor,
The gate terminal of
Connected to the input terminal via a capacitor,
The input terminal to the gate terminal of the
3. The semiconductor device according to claim 2, wherein the semiconductor device is connected to the semiconductor device. (4)An insulated gate field effect transistor; Using ferroelectric material, large capacitance near its Curie point
A temperature-sensitive variable capacitor having a characteristic that increases in width; Using a ferroelectric, the resistance value is large near the Curie point
A temperature-sensitive variable resistor having a characteristic of increasing to A first diode; A second diode; With the gate terminal of the insulated gate field effect transistor
Connect to the input terminal via the above temperature-sensitive variable resistor,
With the gate terminal of the insulated gate field effect transistor
A source terminal connected to the first diode and the temperature-sensitive variable element;
Connected through a series circuit with a capacitor,
The connection point between the diode of
Connected to the input terminal via the second diode
3. The semiconductor device according to claim 2, wherein: 5. Use of an insulated gate field effect transistor and a ferroelectric, and a large capacitance near the Curie point.
A temperature-sensitive variable capacitor having a characteristic of increasing in width, a booster circuit including a CR oscillation circuit using the temperature-sensitive variable capacitor as C, and operating in response to an input signal; A circuit for flowing a part of the gate charge to a ground terminal, wherein an output of the booster circuit is connected to a gate terminal of the insulated gate field effect transistor.