Power transistor aging detection

Abstract

The invention relates to a power transistor aging detection circuit. The power transistor aging detection circuit allows end-of-life detection of a power transistor. The circuit includes a power transistor and a comparator. In a test phase, a test current may flow through the turned-on power transistor, thereby leading out an input voltage at an input node of the power transistor through its on-resistance. The comparator then compares the burn-in test voltage (depending on the input voltage present on the input node of the power transistor) with a reference voltage provided by a reference voltage source. If the power transistor has significantly aged during the test phase to an extent that the input voltage present at the power transistor increases to a certain proportion of the reference voltage, the comparator will output an end-of-life indication signal indicating that the power transistor has reached or is approaching its end-of-life state.

Description

Background Art

[0001] Electronic circuits often include transistors that act as electronic switches to regulate or control the flow of current in various parts of the circuit. One type of transistor is a field effect transistor, in which a voltage is applied to a gate terminal to turn the transistor on and off. A semiconductor channel region is disposed between a drain terminal and a source terminal. When the transistor is on, current flows through the semiconductor channel region between the source terminal and the drain terminal. When the transistor is off, less or no current flows through the semiconductor channel region between the source terminal and the drain terminal. A gate terminal is disposed above the semiconductor channel region between the source terminal and the drain terminal. The voltage on the gate terminal generates an electric field that affects whether the semiconductor channel region conducts current, hence the term "field effect transistor."

[0002] However, there are other types of transistors. In each transistor, when the transistor is turned on by applying sufficient voltage to the control node, current flows from the input node to the output node through the channel. For example, in a field effect transistor, the control node will be the gate terminal, the input node will be one of the source terminal or the drain terminal, and the output node will be the other of the source terminal or the drain terminal.

[0003] Typical transistors are used in electronic circuits for amplification and switching purposes. Power transistors, on the other hand, are used to transfer larger currents, have higher voltage ratings, and may be more typically used in power supplies, battery charging, etc. Power transistors may typically operate at currents from over 1 amp up to 100 amps, or even more. Power transistors may transfer power from over 1 watt up to hundreds of watts, or even more.

[0004] The subject matter claimed herein is not limited to embodiments that solve any disadvantages or work only in environments such as those described above. Rather, this background technology is provided only to illustrate an exemplary technology area in which some embodiments described herein may be practiced. Summary of the invention

[0005] This summary is provided to introduce some concepts in a simplified form that are further described in the following detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

[0006] Embodiments described herein relate to a power transistor aging detection circuit that allows end-of-life detection of a power transistor. The power transistor aging detection circuit includes a power transistor and a comparator. When the power transistor is turned on, current is allowed to pass between an input node and an output node of the power transistor. The comparator has a first comparator input node (e.g., a negative input node) that receives a reference voltage from a reference voltage source. The comparator also has a second comparator input node (e.g., a positive input node) that is coupled to an input node of the power transistor so that it can receive an aging test voltage that depends on an input voltage present at the input node of the power transistor. Finally, the comparator has a comparator output node at which an end-of-life indication signal can be output.

[0007] When a power transistor is turned on, power current is caused to flow through the power transistor, which has a certain internal resistance (called the "on-resistance"). When the power transistor is turned off, there is a much larger voltage drop (which may be hundreds of volts) between the input node and the output node of the power transistor. Due to the high electric fields caused by such a large voltage drop, power transistors are prone to "aging" over time. As a power transistor ages, its on-resistance may increase. This causes the power transistor to transfer current less efficiently because more power is lost due to heat. In some cases, the power transistor fails. The principles described in this article detect aging before the transistor fails so that remedial measures (such as replacing the power transistor) can be taken.

[0008] In order to determine whether the power transistor is approaching its end-of-life state, a test phase can be initiated when the power transistor aging detection circuit is turned on. In this test phase, a test current can be made to flow through the turned-on power transistor, thereby drawing an input voltage at the input node of the power transistor through its on-resistance. The comparator then compares the aging test voltage (depending on the input voltage present at the input node of the power transistor) with a reference voltage provided by a reference voltage source. The reference voltage is selected when the power transistor aging detection circuit is manufactured, and can take into account fine-tuning due to process variations encountered by the power transistor during the manufacturing process.

[0009] If the input voltage at the power transistor has not increased by at least a certain threshold amount above the reference voltage during the test phase due to an increase in on-resistance caused by aging, the comparator will not output an end-of-life indication signal. However, if the power transistor has aged significantly during the test phase to the extent that the input voltage present at the power transistor has increased by at least a threshold amount above the reference voltage, the comparator will output an end-of-life indication signal indicating that the power transistor has reached or is approaching its end-of-life state.

[0010] Thus, the embodiments described herein allow the power transistor aging detection circuit to accurately detect aging of a power transistor before the power transistor fails. Such failures can lead to problems such as overheating, junction breakdown, or insulation breakdown, which can damage not only the power transistor itself, but also other components contained within or coupled to the circuit containing the power transistor. Thus, by utilizing the power transistor aging detection circuit to accurately detect aging of a power transistor before the power transistor fails, remedial measures (e.g., replacing the power transistor) can be taken to prevent damage to the power transistor and any related components or circuits.

[0011] Other features and advantages will be set forth in the following description and will be partially apparent from the description or can be understood by practicing the teachings herein. The features and advantages of the present invention can be realized and obtained by the instruments and combinations specifically pointed out in the appended claims. The features of the present invention will become more apparent from the following description and the appended claims or can be understood by practicing the present invention as described below. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to describe the manner in which the advantages and features of the systems and methods described herein can be obtained, a more particular description of the embodiments briefly described above will be presented in conjunction with specific embodiments shown in the accompanying drawings. It should be understood that these drawings depict only typical embodiments of the systems and methods described herein and are therefore not to be considered limiting of their scope. Certain systems and methods will be described and explained more specifically and in more detail through the use of the accompanying drawings, in which:

[0013] Figure 1 A power transistor aging detection circuit according to the principles described herein is shown, wherein the principles described herein can be practiced and wherein an input voltage of a power transistor is compared with a reference voltage in order to detect aging of the power transistor; and

[0014] Figure 2 An exemplary power transistor aging detection circuit is shown, which is Figure 1 An example of a power transistor aging detection circuit. DETAILED DESCRIPTION

[0015] Embodiments described herein relate to a power transistor aging detection circuit that allows end-of-life detection of a power transistor. The power transistor aging detection circuit includes a power transistor and a comparator. When the power transistor is turned on, current is allowed to pass between an input node and an output node of the power transistor. The comparator has a first comparator input node (e.g., a negative input node) that receives a reference voltage from a reference voltage source. The comparator also has a second comparator input node (e.g., a positive input node) that is coupled to an input node of the power transistor so that it can receive an aging test voltage that depends on an input voltage present at the input node of the power transistor. Finally, the comparator has a comparator output node at which an end-of-life indication signal can be output.

[0016] When a power transistor is turned on, power current is caused to flow through the power transistor, which has a certain internal resistance (called the "on-resistance"). When the power transistor is turned off, there is a much larger voltage drop (which may be hundreds of volts) between the input node and the output node of the power transistor. Due to the high electric fields caused by such a large voltage drop, power transistors are prone to "aging" over time. As a power transistor ages, its on-resistance may increase. This causes the power transistor to transfer current less efficiently because more power is lost due to heat. In some cases, the power transistor fails. The principles described in this article detect aging before the transistor fails so that remedial measures (such as replacing the power transistor) can be taken.

[0017] In order to determine whether the power transistor is approaching its end-of-life state, a test phase can be initiated when the power transistor aging detection circuit is turned on. In this test phase, a test current can be made to flow through the turned-on power transistor, thereby drawing an input voltage at the input node of the power transistor through its on-resistance. The comparator then compares the aging test voltage (depending on the input voltage present at the input node of the power transistor) with a reference voltage provided by a reference voltage source. The reference voltage is selected when the power transistor aging detection circuit is manufactured, and can take into account fine-tuning due to process variations encountered by the power transistor during the manufacturing process.

[0018] If the input voltage at the power transistor has not increased by at least a certain threshold amount above the reference voltage during the test phase due to an increase in on-resistance caused by aging, the comparator will not output an end-of-life indication signal. However, if the power transistor has aged significantly during the test phase to the extent that the input voltage present at the power transistor has increased by at least a threshold amount above the reference voltage, the comparator will output an end-of-life indication signal indicating that the power transistor has reached or is approaching its end-of-life state.

[0019] Thus, the embodiments described herein allow the power transistor aging detection circuit to accurately detect aging of a power transistor before the power transistor fails. Such failures can lead to problems such as overheating, junction breakdown, or insulation breakdown, which can damage not only the power transistor itself, but also other components contained within or coupled to the circuit containing the power transistor. Thus, by utilizing the power transistor aging detection circuit to accurately detect aging of a power transistor before the power transistor fails, remedial measures (e.g., replacing the power transistor) can be taken to prevent damage to the power transistor and any related components or circuits.

[0020] Figure 1 A power transistor aging detection circuit 100 is shown that can practice the principles described herein and is only one example of a power transistor aging detection circuit that is consistent with the principles described herein. The power transistor aging detection circuit 100 includes a power transistor 110 and a comparator 120. The comparator 120 and its operation will be described later.

[0021] exist Figure 1 , power transistor 110 is illustrated using symbols commonly used for field effect transistors. However, the principles described herein are not limited to power transistor 110 being a field effect transistor. Power transistor 110 can be any transistor capable of transmitting current when turned on. For example, power transistor 110 can be any transistor capable of transmitting more than 1 Watt of power when turned on. If a field effect transistor, power transistor 110 is not limited to any particular type of field effect transistor. By way of example only, power transistor 110 can be a gallium nitride field effect transistor or a high electron mobility transistor. However, the principles described herein are not limited to power transistor 110 being any particular type of transistor, or even necessarily a field effect transistor.

[0022] When the power transistor 110 is turned on, for example, by switching the control voltage V C is applied to the control node 111 of the power transistor 110, so that the power current I POWER The current flows through the power transistor 110 from the input node 112 of the power transistor 110 to the output node 113. This is because the input voltage V IN Higher than the voltage present on the output node 113. For example, the power transistor output node 113 may be grounded. For the remainder of this specification, for illustration purposes, the operation of the power transistor aging detection circuit 100 will be described assuming that the output node 113 is grounded.

[0023] The power transistor 110 has a certain on-resistance. Therefore, assuming that the output node 113 is grounded, when the power transistor 110 is turned on, the on-resistance will lead to the input voltage V IN , the input voltage is equal to the product of the on-resistance and the current flowing through the power transistor 110. The on-resistance can be very low, so the input voltage V when the power transistor 110 is turned on is IN It can also be relatively low (for example, less than 5V). However, as the power transistor 110 ages, the on-resistance increases, so the input voltage V IN will increase proportionally.

[0024] When the power transistor 110 is turned off, for example, due to the control voltage V C is lower, the current no longer flows through the power transistor 110, and the input voltage V IN The input voltage V when the power transistor 110 is turned on may be increased by the pull-up network (not shown) connected to the input node 112 of the power transistor 110. The higher voltage difference between the input node 112 and the output node 113 of the power transistor 110 when the power transistor 110 is turned off may cause the power transistor 110 to age over time, thereby increasing the internal on-resistance of the power transistor 110. Therefore, when the internal on-resistance of the power transistor 110 increases, the input voltage V when the power transistor 110 is turned on may be increased by the pull-up network (not shown) connected to the input node 112 of the power transistor 110. IN Also increases proportionally.

[0025] The comparator 120 has a first comparator input node 121 (eg, a negative input node), a second comparator input node 122 (eg, a positive input node), and a comparator output node 123. The first comparator input node 121 is connected to a reference voltage source 130, which provides a reference voltage V R The second comparator input node 122 is coupled to the input node 112 of the power transistor 110 through the intermediate circuit 140, so that the intermediate circuit 140 outputs the aging test voltage V TEST , the aging test voltage depends on the input voltage V applied to the power transistor input node 112 IN .

[0026] For example, if the intermediate circuit 140 is a voltage divider, the aging test voltage V TEST will be with the input voltage V IN In the remainder of this specification, for illustrative purposes only, the intermediate circuit 140 will be described as outputting N times the input voltage V IN Aging test voltage V TESTA voltage divider 140 is shown, wherein N is a fraction between 0 and 1. N may even be 1, in which case the second comparator input node 122 will be directly connected to the input node 112 of the power transistor 110 .

[0027] The power transistor aging detection circuit 100 further includes an aging detection circuit 150, which is connected to the comparator output node 123. The aging detection circuit 150 interprets the signal from the comparator output node 123, which will be described later.

[0028] During operation, the power transistor aging detection circuit 100 may enter a test phase. In this test phase, the test power current I POWER (e.g., 1 ampere) flows through the power transistor 110, thereby drawing an input voltage VIN at the input node 112 of the power transistor 110 when the power transistor 110 is turned on. The output of the voltage divider 140 depends on the input voltage V IN Aging test voltage V TEST For example, the output of the voltage divider 140 is equal to N×V IN Aging test voltage V TEST . Select N and V R value, so that when the input voltage V IN becomes the reference voltage V R When the power transistor 110 reaches or is approaching the end of its life, V R The value of may be a trimming value set after the characteristics of the power transistor 110 are determined during manufacturing.

[0029] The comparator 120 converts the aging test voltage V present at the second comparator input node 122 into TEST The reference voltage V R If the input voltage V IN There is no increase in on-resistance due to aging at least to the reference voltage V R , the comparator 120 outputs a low signal to the comparator output node 123. The aging detection circuit 150 can translate the low signal from the comparator output node 123 into an indication that the power transistor 110 has not aged to its end-of-life state. Alternatively, if the positive input terminal 121 of the comparator is connected to receive the reference voltage V R The negative input terminal 122 of the comparator is connected to receive the aging test voltage V TEST , the aging detection circuit 150 may translate the high signal from the comparator output node 123 into an indication that the power transistor 110 has not aged to its end-of-life state.

[0030] However, if the power transistor 110 has aged significantly to the input voltage V IN At least the reference voltage V R If the comparator 120 outputs a high signal to the comparator output node 123 to a certain extent that the power transistor 110 has reached or is at least approaching its end-of-life state, the comparator 120 outputs a high signal to the comparator output node 123. The aging detection circuit 150 can translate the high signal from the comparator output node 123 into an indication that the power transistor 110 has reached or is at least approaching its end-of-life state. Alternatively, if the positive input terminal 121 of the comparator is connected to receive the reference voltage V R The negative input terminal 122 of the comparator is connected to receive the aging test voltage V TEST , the aging detection circuit 150 can translate the low signal from the comparator output node 123 into an indication that the power transistor 110 has reached or is at least approaching its end-of-life state. Therefore, the power transistor aging detection circuit 100 detects aging of the power transistor 110 before the power transistor 110 fails so that remedial measures (such as replacing the power transistor 110) can be taken.

[0031] Figure 2 An exemplary power transistor aging detection circuit 200 is shown. Figure 1 An example of a power transistor aging detection circuit 100 is shown. Specifically, Figure 2 The power transistor 210, the comparator 220, the voltage divider 240 and the aging detection circuit 250 are respectively Figure 1 1. However, the power transistor aging detection circuit 200 also includes a reference transistor 260 and a reference current source 270, which together act as Figure 1 An example of a reference voltage source 130 in FIG. 1 is shown in FIG.

[0032] The control node 261 of the reference transistor 260 and the control node 211 of the power transistor 210 are connected to each other. The output node 263 of the reference transistor 260 and the output node 213 of the power transistor 210 are also connected to each other. The input node 262 of the reference transistor 260 is connected to the first comparator input node 221 and receives the reference current I from the reference current source 270. R .

[0033] In one embodiment, reference transistor 260 is substantially identical to power transistor 210, except that the current flow area of ​​power transistor 210 is M times larger than the current flow area of ​​reference transistor 260. M is a number representing the ratio of the magnitude of the current flow area of ​​power transistor 210 to the current flow area of ​​reference transistor 260, and may be, for example, 500 or greater. For example, when the active regions of both transistors are fabricated using the same epitaxial stack, reference transistor 260 may be a miniaturized version of power transistor 210, except that the current flow area of ​​power transistor 210 is M times larger.

[0034] If the same epitaxial stack is used, in the case where the power transistor 210 is a field effect transistor, the reference transistor 260 can also be a field effect transistor of the same type but smaller. Similarly, in the case where the power transistor 210 is a gallium nitride transistor, the reference transistor 260 can also be a gallium nitride transistor of the same type but smaller. In addition, in the case where the power transistor 210 is a high electron mobility transistor, the reference transistor 260 can also be a high electron mobility transistor of the same type but smaller. By using the same epitaxial stack to form the power transistor 210 and the reference transistor 260, the circuit can be manufactured without overly complicating the manufacturing process.

[0035] Both the power transistor 210 and the reference transistor 260 have a certain on-resistance. That is, when the power transistor 210 is turned on, its on-resistance will lead to the input voltage V IN , the input voltage is equal to the product of its on-resistance and the current flowing through the power transistor 210. Similarly, when the reference transistor 260 is turned on, its on-resistance will lead to the input voltage (ie, the reference voltage V R ), the input voltage is equal to its on-resistance and the reference current I flowing through the reference transistor 260 R Therefore, in Figure 2 In the embodiment of the present invention, the reference transistor 260 and the reference current source 270 work together to provide a reference voltage V R .

[0036] As previously mentioned Figure 1 As expressed, when the power transistor 210 is turned off, a large voltage drop (e.g., hundreds of volts) may occur between its input node 212 and output node 213. However, when the reference transistor 260 is turned off, the reference transistor 260 may not have a large voltage drop between its input node 262 and output node 263. Therefore, the reference transistor 260 will not age like the power transistor 210, so the reference voltage V R Relatively stable.

[0037] The output of the voltage divider 240 depends on the input voltage V IN Aging test voltage V TEST For example, the output of the voltage divider 240 is equal to N×V IN Aging test voltage V TEST . Select N and V R value, so that when the input voltage V IN becomes the reference voltage V R When N is in the range between 0 and 1 (e.g., the test voltage V TEST is the input voltage V IN In the case of a fraction of N), the voltage divider is a suitable intermediate element between the input node 212 of the power transistor 210 and the second comparator terminal 222. Once a suitable value of N is selected, the resistance values ​​of the resistors 241 and 242 can be appropriately selected, such as R2 / (R1+R2)=N (where R1 is the resistance value of the resistor 241 and R2 is the resistance value of the resistor 242). That is, the voltage divider can be formed by circuit elements other than resistors, so the principles described herein are not limited to Figure 2 The voltage divider 240 in FIG.

[0038] Remove the reference voltage V R way and from the input voltage V IN Generate test voltage V TEST way, Figure 2 The power transistor aging detection circuit 200 in the embodiment can be implemented in other ways as described above. Figure 1 The power transistor aging detection circuit 100 operates as described in the drawings.

[0039] Thus, the embodiments described herein allow the power transistor aging detection circuit to accurately detect aging of a power transistor before the power transistor fails. Such failures can lead to problems such as overheating, junction breakdown, or insulation breakdown, which can damage not only the power transistor itself, but also other components contained within or coupled to the circuit containing the power transistor. Thus, by utilizing the power transistor aging detection circuit to accurately detect aging of a power transistor before the power transistor fails, remedial measures (e.g., replacing the power transistor) can be taken to prevent damage to the power transistor and any related components or circuits.

[0040] Literal support clause

[0041] Item 1. A power transistor aging detection circuit, comprising: a power transistor, configured to pass current from a power transistor input node to a power transistor output node when the power transistor is turned on, an input voltage is present at the power transistor input node, and an output voltage lower than the input voltage is present at the power transistor output node; a comparator, having a first comparator input node and a second comparator input node, the first comparator input node being configured to receive a reference voltage, the second comparator input node being coupled to the power transistor input node so as to be configured to receive an aging test voltage, the aging test voltage depending on the input voltage applied to the power transistor input node, the comparator being further configured to output a signal indicating a state of the reference voltage relative to the aging test voltage; and an aging detection circuit, configured to receive a signal output from the comparator and to detect aging of the power transistor when the comparator outputs a signal indicating a specific state of the reference voltage relative to the aging test voltage when the power transistor is turned on.

[0042] Item 2. The power transistor aging detection circuit according to Item 1, wherein the specific state refers to an aging test voltage being greater than a reference voltage.

[0043] Item 3. The power transistor aging detection circuit according to Item 1, wherein the aging test voltage is proportional to the input voltage of the power transistor.

[0044] Item 4. The power transistor aging detection circuit according to Item 3, further comprising: a voltage divider whose output is connected to the second comparator input node so that the aging test voltage is less than the input voltage of the power transistor.

[0045] Item 5. The power transistor aging detection circuit of Item 1, wherein the power transistor is a field effect transistor.

[0046] Item 6. The power transistor aging detection circuit of Item 5, wherein the power transistor is a gallium nitride transistor.

[0047] Item 7. The power transistor aging detection circuit of Item 1, wherein the power transistor is a high electron mobility transistor.

[0048] Item 8. The power transistor aging detection circuit according to Item 1 further includes: a reference current source configured to provide a reference current through a voltage divider to generate a reference voltage at an output end of the voltage divider.

[0049] Clause 9. The power transistor aging detection circuit of clause 8, wherein the resistor of the voltage divider includes a reference transistor in an on state.

[0050] Item 10. The power transistor aging detection circuit of Item 9, wherein the second comparator input node is coupled to the power transistor input node such that the aging test voltage is less than 90% of the input voltage at the power transistor input node.

[0051] Item 11. The power transistor aging detection circuit of Item 9, the second comparator input node being coupled to the power transistor input node such that the aging test voltage is less than 75% of the input voltage at the power transistor input node.

[0052] Clause 12. The power transistor aging detection circuit of Clause 9, wherein the power transistor and the reference transistor are field effect transistors.

[0053] Clause 13. The power transistor aging detection circuit of Clause 12, wherein the power transistor and the reference transistor are gallium nitride transistors.

[0054] Clause 14. The power transistor aging detection circuit of Clause 12, wherein the power transistor and the reference transistor are high electron mobility transistors.

[0055] Item 15. The power transistor aging detection circuit of Item 12, wherein the power transistor and the reference transistor both have active regions formed of the same epitaxial stack.

[0056] Item 16. The power transistor aging detection circuit of Item 12, wherein a ratio of a current flow area of ​​the power transistor to a current flow area of ​​the reference transistor is 500 or greater.

[0057] Although the subject matter has been described in language directed to structural features and / or methodological acts, it should be understood that the subject matter defined in the appended claims is not necessarily limited to the features or acts or the order of the acts described above. Instead, the features and acts are disclosed as exemplary forms of implementing the claims.

[0058] The present invention may be implemented in other specific forms without departing from the essential features of the present invention. The described embodiments are considered to be illustrative and non-restrictive in all respects. All changes within the meaning and scope of the equivalents of the claims should be included within the scope of the claims.

[0059] When introducing elements in the appended claims, the articles "a," "an," "the," and "said" mean that there are one or more of the elements. The terms "comprising," "including," and "having" are intended to be inclusive and mean that there may be additional elements other than the listed elements.

Claims

1. A power transistor aging detection circuit, comprising: a power transistor configured to pass current from the power transistor input node to the power transistor output node when the power transistor is turned on, an input voltage is present at the power transistor input node, and an output voltage lower than the input voltage is present at the power transistor output node; a comparator having a first comparator input node and a second comparator input node, the first comparator input node being configured to receive a reference voltage, the second comparator input node being coupled to the power transistor input node so as to be configured to receive a burn-in test voltage, the burn-in test voltage being dependent on an input voltage applied to the power transistor input node, the comparator being further configured to output a signal indicating a state of the reference voltage relative to the burn-in test voltage; as well as An aging detection circuit is configured to receive a signal output from the comparator and detect aging of the power transistor when the comparator outputs a signal indicating a specific state of the reference voltage relative to the aging test voltage when the power transistor is turned on. 2 . The power transistor aging detection circuit according to claim 1 , wherein the specific state refers to that the aging test voltage is greater than the reference voltage. 3 . The power transistor aging detection circuit according to claim 1 , wherein the aging test voltage is proportional to an input voltage of the power transistor.

4. The power transistor aging detection circuit according to claim 3, further comprising: A voltage divider, wherein an output terminal of the voltage divider is connected to the second comparator input node, so that the aging test voltage is less than the input voltage of the power transistor. 5 . The power transistor aging detection circuit according to claim 1 , wherein the power transistor is a field effect transistor. 6 . The power transistor aging detection circuit according to claim 5 , wherein the power transistor is a gallium nitride transistor. 7 . The power transistor aging detection circuit according to claim 1 , wherein the power transistor is a high electron mobility transistor.

8. The power transistor aging detection circuit according to claim 1, further comprising: The reference current source is configured to provide a reference current through a voltage divider to generate the reference voltage at an output terminal of the voltage divider. 9 . The power transistor aging detection circuit of claim 8 , wherein the resistor of the voltage divider comprises a reference transistor in an on state. 10 . The power transistor aging detection circuit of claim 9 , wherein the second comparator input node is coupled to the power transistor input node such that the aging test voltage is less than 90% of the input voltage at the power transistor input node.

11. The power transistor aging detection circuit of claim 9, wherein the second comparator input node is coupled to the power transistor input node such that the aging test voltage is less than 75% of the input voltage at the power transistor input node. 12 . The power transistor aging detection circuit according to claim 9 , wherein the power transistor and the reference transistor are field effect transistors. 13 . The power transistor aging detection circuit according to claim 12 , wherein the power transistor and the reference transistor are gallium nitride transistors. 14 . The power transistor aging detection circuit according to claim 12 , wherein the power transistor and the reference transistor are high electron mobility transistors. 15 . The power transistor aging detection circuit according to claim 12 , wherein active regions of the power transistor and the reference transistor are both formed by the same epitaxial stack. 16 . The power transistor aging detection circuit according to claim 12 , wherein a size ratio of a current flow area of ​​the power transistor to a current flow area of ​​the reference transistor is 500 or more.

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