TW201619585A - Thermal detection circuits - Google Patents

Abstract

According to one embodiment of a temperature detecting circuit, comprising: a reference voltage circuit of positive temperature coefficient, a reference voltage circuit of negative temperature coefficient and a comparator. The reference voltage circuit of positive temperature coefficient uses positive temperature coefficient of voltage difference (Vgs) between the gate electrode and the source electrode of transistor to generate a voltage of positive temperature coefficient, and the reference voltage circuit of negative temperature coefficient uses negative temperature characteristic of BJT to produce a voltage of negative temperature coefficient. Thereby the voltage of positive temperature coefficient and the voltage with a negative temperature coefficient produce a temperature detection voltage of less variation with power supply voltage via a comparator.

Description

Temperature detection circuit

The disclosure relates to a temperature detecting circuit.

Semiconductor components are used in various systems, such as an optical system and a drive system, the characteristics of which vary depending on the temperature. Therefore, in order to accurately measure the temperature to control the change in the characteristics of the semiconductor element, a temperature detector is usually mounted. Although these temperature detectors require high detection efficiency, these temperature detectors are also required to be small and inexpensive. For example, a temperature detecting circuit is constructed using a constant current flowing through a PN diode and is determined by utilizing the characteristic that the forward bias of the PN diode increases with temperature (ie, positive temperature coefficient). temperature.

In general, the temperature coefficient refers to the degree to which the voltage and current output by the voltage and current circuit vary with the external operating temperature, and may be a positive temperature coefficient or a negative temperature coefficient. The positive temperature coefficient means that the voltage and current of the output increase with the increase of the external operating temperature, and the negative temperature coefficient means that the voltage and current of the output decrease with the increase of the external operating temperature.

Another temperature sensing circuit architecture uses metal oxide semiconductors (Metal Oxide Semiconductor, MOS) The threshold voltage Vth and the drain current Ids of the transistor are temperature dependent parameters. This technique uses a potential control circuit to provide a control voltage to the gate of the MOS transistor such that the gate voltage of the transistor remains constant and independent of temperature, and the temperature is measured by utilizing the temperature characteristics of the drain current Ids. .

The disclosed embodiments can provide a temperature detecting circuit, and more particularly, a temperature detecting circuit suitable for a semiconductor integrated circuit.

One disclosed embodiment relates to a temperature detecting circuit including a positive temperature coefficient reference voltage circuit, a negative temperature coefficient reference voltage circuit, and a comparator. Wherein, the positive temperature coefficient reference voltage circuit generates a positive temperature coefficient voltage by using a positive temperature coefficient of a potential (Vgs) difference between a gate and a source of the transistor, and the negative temperature The coefficient reference voltage circuit uses the negative temperature characteristic of the BJT to generate a voltage with a negative temperature coefficient. Further, the voltage of the positive temperature coefficient and the voltage of the negative temperature coefficient are passed through the comparator to generate a temperature detection voltage that is less variable with the power supply voltage.

The above described features and advantages of the present invention will be more apparent from the following description.

100‧‧‧ Temperature detection circuit design architecture

101‧‧‧ positive temperature coefficient reference voltage circuit

102‧‧‧Negative temperature coefficient reference voltage circuit

103‧‧‧ comparator

201‧‧‧current mirror

202‧‧‧current mirror

The first figure is a schematic diagram consistent with an embodiment of the disclosure to illustrate the temperature sensing circuit design architecture of the present invention.

The second figure is a schematic diagram consistent with an embodiment of the disclosure to illustrate the temperature sensing circuit of the present invention.

The third figure is a schematic diagram consistent with an embodiment of the disclosure, illustrating the voltage V1 and voltage V2 calculated by the circuit of the second figure, and the voltage V3 output by the comparator.

The fourth figure is a schematic diagram consistent with an embodiment of the disclosure, illustrating that the output voltage V3 of the comparator is calculated from various supply voltages in accordance with the circuit of the second figure.

The present disclosure proposes a technique of a temperature detecting circuit that can be applied to a semiconductor integrated circuit.

The first figure is a schematic diagram consistent with an embodiment of the disclosure, illustrating a temperature detection circuit design architecture. As shown in the first figure, the temperature detecting circuit design architecture 100 includes a positive temperature coefficient reference voltage circuit 101 for outputting a positive temperature coefficient voltage V1, a negative temperature coefficient reference voltage circuit 102 to output a negative temperature coefficient voltage V2, and A comparator 103 generates a temperature detection voltage V3 by receiving the voltage V1 and the voltage V2. The above positive temperature coefficient means that the voltage of its output increases as the operating temperature increases, and the negative temperature coefficient means that the voltage of its output decreases as the operating temperature increases.

The second figure is a schematic diagram consistent with an embodiment of the disclosure, illustrating a temperature detecting circuit. As shown in the second figure, the temperature detecting circuit includes a positive temperature coefficient reference voltage circuit 101, a negative temperature coefficient reference voltage circuit 102, and a comparator 103. The positive temperature coefficient reference voltage circuit 101 is implemented by a PMOS current mirror 201. The current mirror 201 is composed of a transistor M _N1 , a transistor M _N4 , a transistor M _N2 , a transistor M _N3 , a transistor M _N5 , and a resistor R ₁ . The source of the transistor M _N4 , the transistor M _N3 and the transistor M _N5 are respectively connected to the current source, and the current flowing in is represented by I ₁ , I ₂ and I _{5 respectively} ; the transistor M _N4 , the transistor M _N3 and the electricity The gate of the crystal M _N5 is connected to the source of the transistor M _N5 and outputs a voltage V1 of positive temperature coefficient; the source of the transistor M _N1 is connected to the drain of the transistor M _N4 ; the source of the transistor M _N2 Connected to the gate of the transistor M _N3 ; the transistor M _N1 is connected to the gate of the transistor M _N2 and is connected to the source of the transistor M _N3 ; the gate of the transistor M _N2 and the transistor M _N5 are grounded, and The drain of the transistor M _N1 is connected to the series resistor R ₁ and then grounded.

The negative temperature coefficient reference voltage circuit 102 is implemented by a PMOS current mirror 202. The current mirror 202 is composed of a Bipolar Junction Transistor (BJT) Q ₃ , Q ₄ , and resistors R ₂ and R ₃ . Wherein, the transistor Q ₃ emitter series resistors R ₂ , R _{3 are} connected to the current source, the current flowing in is represented by I ₃ , and the voltage V2 of the negative temperature coefficient is output at the junction of the resistors R ₂ and R ₃ ; The base of the crystal Q ₃ is connected to the emitter of the transistor Q ₄ ; the transistor Q ₃ and the collector of the transistor Q _{4 are} grounded and connected to the base of the transistor Q ₄ .

The positive terminal input of comparator 103 is a positive temperature coefficient reference voltage The path 101 outputs a voltage V1, and its negative terminal input is a voltage V2 output from the negative temperature coefficient reference voltage circuit 102. The voltage V1 and the voltage V2 are input to the comparator 103 to generate the temperature detecting voltage V3. The comparator 103 can also have hysteresis characteristics, such as setting the hysteresis voltage at the input terminal to ±100 mV, that is, when the voltage V1 is greater than the voltage V2 exceeding 100 mV, the voltage V3 is at a high potential (for example, 5 V), and the voltage V2 is greater than the voltage V1. At 100 mV, the voltage V3 is low (for example, 0 V).

In the embodiment of the second figure, the voltage V1 and the voltage V2 output by the positive temperature coefficient reference voltage circuit 101 and the negative temperature coefficient reference voltage circuit 102 can be described by the following equations.

Suppose I ₁ = I ₂ , Vtn _{MN 2} = Vtn _{MN 1} Hypothesis then Assume Vtn _{MN 1} = Vtn _{MN 5}

Since Vtn has a negative temperature coefficient characteristic (its negative temperature coefficient is about -2mV/°C), , then V1 is the positive temperature coefficient voltage T ₀ : reference temperature (usually 25 degrees C), T _J : junction temperature, and κ is a junction energy gap constant, A ₀ is the junction area

when , then V2 is the negative temperature coefficient voltage.

It can be known from the above equation, the voltage V1 and the related I _5, and I ₅ I ₁ being a multiple of about ₁ and a resistor R, and therefore variation in the resistance R ₁ may change with temperature variation rate of the voltage V1. The voltage V2 is related to the resistance R ₂ , and the fluctuation resistance R ₂ can change the rate of change of the voltage V2 with temperature.

The third figure is a schematic diagram consistent with an embodiment of the disclosure, illustrating the voltage V1 and voltage V2 calculated by the circuit of the second figure, and the voltage V3 output by the comparator 103. The X-axis is a temperature value, which is from -40 ° C to 200 ° C, and the Y-axis is a voltage value (the upper graph is the voltage value of the voltage V1 and the voltage V2, and the lower graph is the voltage value of the voltage V3). As shown in the third figure, the voltage value of the voltage V1 increases as the temperature rises, and the voltage value of the voltage V2 decreases as the temperature rises. The temperature detecting circuit sets the voltage V2 to be greater than the voltage V1 when the temperature is high. As the temperature rises from a low temperature, for example, -40 ° C, the voltage V1 continues to rise, and the voltage V2 continues to drop. When the temperature reaches a predetermined temperature, for example, 150 ° C, when the voltage V1 is greater than the voltage V2 exceeding the hysteresis voltage of the comparator by 100 mV, the output voltage V3 of the comparator is 5 V (high potential). Another situation is that the temperature is high (for example 200 ° C) drops to a low temperature, at which time the voltage V1 continues to drop, and the voltage V2 continues to rise. When the temperature reaches a predetermined temperature, for example, 105 ° C, when the voltage V2 is greater than the voltage V1 exceeding the hysteresis voltage of the comparator by 100 mV, the output voltage V3 of the comparator is 0 V (low potential).

The fourth figure is a schematic diagram consistent with an embodiment of the disclosure, illustrating that the output voltage V3 of the comparator is calculated from various supply voltages in accordance with the circuit of the second figure. Among them, the X axis is the temperature value, which is from -40 ° C to 200 ° C, and the Y axis is the voltage value. As shown in the fourth figure, the voltage value of the output voltage V3 of the comparator is simulated by the power supply voltage from 2V to 6V for each 0.5V increase. In the fourth figure, for various power supply voltages, the results of the simulation calculation are as follows: As the temperature rises from -40 ° C, when the temperature reaches 150 ° C, the output voltage V3 of the comparator changes from a low potential to a high potential. Furthermore, the temperature drops from 200 ° C. When the temperature reaches 105 ° C, the output voltage of the comparator changes from a high potential to a low potential. As a result of calculating the output voltage V3 of the comparator from the simulation of the fourth figure, it can be known that the voltage V1 of the positive temperature coefficient and the voltage V2 of the negative temperature coefficient can generate a temperature detection voltage that does not vary with the power supply voltage via the comparator.

In summary, the present disclosure proposes a temperature detecting circuit that uses a positive temperature coefficient of a potential difference between a gate and a source of a transistor to generate a positive temperature coefficient voltage, and uses a negative temperature characteristic of the BJT to generate a a voltage of a negative temperature coefficient, and changing a temperature change rate of the two voltages by adjusting some resistance values of the temperature detecting circuit, and comparing the two by using a comparator The voltage is used to generate a detectable voltage that is less than the settable temperature that varies with the supply voltage.

The above is only the embodiment according to the disclosure, and the scope of the disclosure is not limited thereto. That is, the equivalent changes and modifications made by the scope of the patent application should remain within the scope of the disclosure.

100‧‧‧ Temperature detection circuit design architecture

101‧‧‧ positive temperature coefficient reference voltage circuit

102‧‧‧Negative temperature coefficient reference voltage circuit

103‧‧‧ comparator

Claims (7)

A temperature detecting circuit comprising: a positive temperature coefficient reference voltage circuit, which is a positive temperature coefficient of a potential (Vgs) difference between a gate and a source of a metal oxide semiconductor (MOS) transistor To generate a positive temperature coefficient voltage; a negative temperature coefficient reference voltage circuit utilizing a negative temperature characteristic of a bipolar transistor (BJT) to generate a negative temperature coefficient voltage; and a comparator; wherein the positive temperature coefficient The voltage and the voltage of the negative temperature coefficient are passed through the comparator to generate a temperature detection voltage that is less variable with the power supply voltage. The temperature detecting circuit of claim 1, wherein the positive temperature coefficient reference voltage circuit is a current mirror, wherein the current mirror is composed of a transistor M _N1 , a transistor M _N4 , a transistor M _N2 , a transistor M _N3 , a transistor M _N5 , and a resistor R ₁ are formed. The transistor M _N4 , the transistor M _N3 and the source of the transistor M _N5 are respectively connected to a current source; the transistor M _N4 , the transistor M _{N3 is} connected to the gate of the transistor M _N5 , and Connected to the source of the transistor M _{N5 ;} the source of the transistor M _N1 is connected to the drain of the transistor M _N4 ; the source of the transistor M _N2 is connected to the drain of the transistor M _N3 ; M _{N1 is} connected to the gate of the transistor M _N2 and is connected to the source of the transistor M _N3 ; the transistor M _N2 is grounded to the drain of the transistor M _N5 , and the drain of the transistor M _N1 Then, the resistor R ₁ is connected in series and then grounded. The temperature detecting circuit of claim 1, wherein the negative temperature coefficient reference voltage circuit is a current mirror, wherein the current mirror is composed of a transistor Q ₃ , a transistor Q ₄ , and a resistor R ₂ and a R ₃ are formed. The transistor Q ₃ emitter is connected in series with the resistor R ₂ , and the resistor R _{3 is} connected to a current source; the transistor Q ₃ is connected to the transistor Q ₄ emitter; the transistor Q ₃ and the transistor The crystal Q ₄ collector is grounded and connected to the base of the transistor Q ₄ . The temperature detecting circuit of claim 1, wherein the voltage of the positive temperature coefficient and the voltage of the negative temperature coefficient are input to the positive input and the negative terminal of the comparator to generate the temperature detecting voltage. The temperature detecting circuit of claim 1, wherein the comparator has hysteresis characteristics. The temperature detecting circuit of claim 2, wherein the resistor R ₁ is varied to change a positive temperature coefficient of a voltage of a source of the transistor M _N5 . The temperature detecting circuit of claim 3, wherein the resistor R ₂ is varied to change a negative temperature coefficient of a connection point voltage of the resistor R ₂ and the resistor R ₃ .