CN-121978496-A - Gate oxide layer state monitoring method and circuit of field effect transistor

CN121978496ACN 121978496 ACN121978496 ACN 121978496ACN-121978496-A

Abstract

The application relates to a method and a circuit for monitoring the state of a grid oxide layer of a field effect transistor, which belong to the technical field of power electronics, and the method comprises the steps of obtaining a drain current signal of the field effect transistor to be monitored in the process of turning on a transient state; the method comprises the steps of determining the current rising time of a field effect transistor based on a drain current signal, comparing the current rising time with a preset healthy reference time, and outputting an indication signal reflecting the reliability state of a grid oxide layer based on a comparison result, wherein the current rising time is the time elapsed from the starting flowing time of the drain current to the time of the load current. According to the method provided by the application, the current rising time is used as the gate oxide degradation specificity monitoring parameter, the transient drain current signal of the device is acquired and compared with the health reference time, so that the non-invasive online real-time monitoring is realized.

Inventors

CAI YUMENG
WANG JUNYU
LI ZHUANG
SUN PENG
LI XUEBAO
ZHAO ZHIBIN

Assignees

华北电力大学

Dates

Publication Date: 20260505
Application Date: 20260212

Claims (10)

1. A method for monitoring gate oxide layer of a field effect transistor, comprising: Acquiring a drain current signal of a field effect transistor to be monitored in an on transient process; Determining a current rise time of the field effect transistor based on the drain current signal, wherein the current rise time is a time elapsed from a time when the drain current starts to flow to a time when the load current rises; And comparing the current rising time with a preset healthy reference time, and outputting an indication signal reflecting the reliability state of the gate oxide layer based on a comparison result.
2. The method of claim 1, wherein the step of obtaining the drain current signal comprises: and connecting a detection resistor in series with the source electrode of the field effect transistor, and acquiring a drain current signal proportional to the detection voltage by detecting the detection voltage signals at two ends of the detection resistor.
3. The method for monitoring the gate oxide layer state of a field effect transistor according to claim 2, wherein the method of determining the current rise time comprises: Presetting a first reference voltage and a second reference voltage, wherein the second reference voltage is set according to the value of load current; Detecting a change in the detection voltage signal by a first comparator and a second comparator; The time when the detection voltage reaches the second reference voltage is used as the time when the drain current rises to the load current; and calculating the time difference between the moment when the detection voltage reaches the first reference voltage and the moment when the detection voltage reaches the second reference voltage as the current rising time.
4. A method for monitoring the gate oxide layer state of a field effect transistor according to claim 3, comprising: The input end of the first comparator inputs the detection voltage signal and the first reference voltage signal and then outputs a first comparison signal; Triggering a monostable pulse generator through a jump edge of the first comparison signal to enable the monostable pulse generator to generate square wave pulse, wherein the pulse width of the square wave pulse is the same as the health reference time; and inputting the square wave pulse and a second comparison signal output by the second comparator into a logic AND operation circuit, wherein the logic AND operation circuit outputs an intermediate signal reflecting the reliability state of the gate oxide layer.
5. The method for monitoring the gate oxide layer state of a field effect transistor according to claim 4, characterized by comprising the following steps: when the current rising time is less than or equal to the health reference time, the rising edge of the second comparison signal falls in the high level period of the square wave pulse, and the logic AND operation circuit outputs a high level pulse intermediate signal reflecting the health of the grid oxide layer; When the current rising time is greater than a healthy reference time, the logical AND operation circuit outputs a low-level intermediate signal reflecting degradation of the gate oxide layer when a rising edge of the second comparison signal falls during a low-level period of the square wave pulse.
6. The method for monitoring the gate oxide layer state of a field effect transistor according to claim 5, characterized by comprising the following steps: Inputting the intermediate signal output by the logical AND operation circuit into a pulse shaping circuit; When the intermediate signal is a periodic transient high-level pulse, the pulse shaping circuit converts the periodic transient high-level pulse into a constant high-level intermediate signal; when the intermediate signal is continuously low, the pulse shaping circuit keeps outputting a constant low intermediate signal.
7. A method for monitoring the gate oxide layer state of a field effect transistor according to claim 3, comprising: calculating a filtered current rise time value through a digital filtering algorithm based on the detected multiple current rise times; Calculating a gate oxide degradation index of the gate oxide according to the current rise time value and the current rise time value under the healthy state of the gate oxide; And outputting an indication signal reflecting the reliability state of the gate oxide layer according to the magnitude of the gate oxide degradation index.
8. The method for monitoring the gate oxide layer state of a field effect transistor according to claim 7, characterized by comprising the following steps: Presetting a first gate oxide degradation threshold value and a second gate oxide degradation threshold value, wherein the first gate oxide degradation threshold value is smaller than the second gate oxide degradation threshold value; outputting an indication signal according to the magnitude relation between the gate oxide degradation index and the first gate oxide degradation threshold value and the second gate oxide degradation threshold value: Outputting a signal reflecting the health of the gate oxide layer when the gate oxide degradation index is less than or equal to a first gate oxide degradation threshold; outputting a signal reflecting degradation of the gate oxide layer when the gate oxide degradation index is greater than a first gate oxide degradation threshold and less than or equal to a second gate oxide degradation threshold; And outputting a signal reflecting the degradation of the gate oxide layer and a signal indicating the shutdown of a circuit where the field effect transistor is positioned when the gate oxide degradation index is larger than a second gate oxide degradation threshold value.
9. A method for monitoring the gate oxide layer state of a field effect transistor according to claim 3, comprising: The detection voltage signal is subjected to signal amplification and noise suppression processing by a differential amplifier and then is input into the first comparator and the second comparator.
10. A gate oxide state monitoring circuit for a field effect transistor for implementing the method of any of claims 1-9, comprising: The signal extraction circuit is used for obtaining a drain current signal of the field effect transistor to be monitored in the switching-on transient process; the comparison circuit is used for extracting the current rising time of the field effect transistor and comparing the current rising time with a preset healthy reference time; and the state output circuit is used for outputting an indication signal reflecting the reliability state of the gate oxide layer according to the comparison result.

Description

Gate oxide layer state monitoring method and circuit of field effect transistor Technical Field The application belongs to the technical field of power electronics, and relates to a method and a circuit for monitoring the state of a gate oxide layer of a field effect transistor. Background The field effect transistor is used as a core device of power electronics, and has wide application prospect in power electronic circuits in the fields of renewable energy power generation, rail transit, electric automobile aviation and aerospace and the like. The reliability of such devices directly determines the operational stability and lifetime of the power electronics system, wherein the reliability problem of the gate oxide layer becomes a core bottleneck that constrains the device to operate stably for a long period of time. The gate oxide layer of the field effect transistor is a key structure for controlling the on-off of drain current by gate voltage, and the degradation of the gate oxide layer mainly results from the capture of electrons and holes by interface and near-interface trap charges and the accumulation of oxide layer trap charges under high temperature and high electric field. These charges can cause threshold voltage drift, cause problems such as increase of on-resistance, increase of loss, parasitic conduction and the like, and even cause gate oxide breakdown and system failure, so the gate oxide reliability state monitoring is an important means for realizing predictive maintenance and improving the system reliability. Therefore, there is a need to develop a low-cost, on-line field effect transistor gate oxide reliability state monitoring technology to solve the deficiencies of the prior art. Disclosure of Invention The embodiment of the application provides a method and a circuit for monitoring the state of a gate oxide layer of a field effect transistor, which are used for realizing non-invasive online real-time monitoring by taking the current rising time as a gate oxide degradation specific monitoring parameter, collecting a device opening transient drain current signal and comparing the transient drain current signal with a healthy reference time, and solving the defects that the prior art needs specific test conditions, has strong invasiveness, high cost and is easy to interfere with the normal operation of a circuit. The application provides a method for monitoring a gate oxide layer state of a field effect transistor, which comprises the steps of obtaining a drain current signal of the field effect transistor to be monitored in an on transient process, determining current rising time of the field effect transistor based on the drain current signal, wherein the current rising time is time which is elapsed from the starting flowing time of drain current to the time of load current, comparing the current rising time with a preset healthy reference time, and outputting an indication signal reflecting the reliability state of the gate oxide layer based on a comparison result. In some embodiments of the present application, the method for obtaining the drain current signal includes connecting a sense resistor in series with a source of a field effect transistor, and obtaining a drain current signal proportional to the sense voltage by sensing a sense voltage signal across the sense resistor. In some embodiments of the application, the method for determining the current rising time comprises the steps of presetting a first reference voltage and a second reference voltage, setting the second reference voltage according to the value of a load current, detecting the change of a detection voltage signal through a first comparator and a second comparator, taking the moment when the detection voltage reaches the first reference voltage as the starting flowing moment of the drain current, taking the moment when the detection voltage reaches the second reference voltage as the moment when the drain current rises to the load current, and calculating the time difference between the moment when the detection voltage reaches the first reference voltage and the moment when the detection voltage reaches the second reference voltage as the current rising time. In some embodiments of the application, the method for monitoring the gate oxide layer state of the field effect transistor further comprises the steps of outputting a first comparison signal after the input end of the first comparator inputs a detection voltage signal and a first reference voltage signal, triggering a monostable pulse generator through the jump edge of the first comparison signal to enable the monostable pulse generator to generate square wave pulses, wherein the pulse width of the square wave pulses is the same as the healthy reference time, inputting a second comparison signal output by the square wave pulses and the second comparator into a logic AND operation circuit, and outputting an intermediate signal reflecting the reliability s