ESD active protection diode with scr structure

Abstract

This invention relates to the field of semiconductor device technology, specifically to an ESD active protection diode with an SCR structure. The diode comprises: acquiring a trend term signal and a periodic term signal from the current signal during the SCR's on-state; determining a corrected main energy decay factor for the current moment based on the current amplitude at each instant in the trend term signal and the difference in current amplitude between adjacent instants; and determining a ringing decay factor for the current moment based on the current amplitude at each instant in the periodic term signal, thereby determining the ESD termination probability for the current moment, used to control the switching on and off of the MOS transistor. This invention can significantly reduce the risks of voltage bounce, current surge, and secondary stress, improving the reliability, stability, and engineering applicability of ESD protection circuits.

Description

Technical Field

[0001] This invention relates to the field of semiconductor device technology, and more specifically to an SCR structure for active ESD protection diode. Background Technology

[0002] With the rapid development of integrated circuit technology, modern electronic products are becoming increasingly sensitive to electrostatic discharge (ESD) at input / output ports and power lines. ESD events can generate high voltage and high current in a very short time; if not effectively controlled, they can cause permanent damage to internal chip circuits and peripheral devices. Therefore, various ESD protection devices are widely used in the field of electronic component design to ensure the safety and reliability of chips during production, assembly, transportation, and use. Existing SCR (Selective Cushion Receiver) ESD protection devices not only need to respond quickly to ESD events but also require sufficient capacity to withstand peak discharge currents without interfering with the normal operation of the chip. They have significant engineering value and broad application prospects in integrated circuit design.

[0003] Existing problems: While traditional SCR structures offer advantages such as fast response speed and high current withstand capability in ESD protection, they still have shortcomings in certain situations. For example, after an electrostatic discharge event ends, if the current in the SCR remains sufficient to maintain its conduction, the SCR will not automatically turn off. In this case, even without an electrostatic event, the continued conduction of the SCR may affect the protected circuit, reduce system stability, or even cause a failure. Summary of the Invention

[0004] This invention provides an SCR structure for active ESD protection diode to solve existing problems.

[0005] The SCR structure of the present invention provides an ESD active protection diode using the following technical solution: One embodiment of the present invention provides an SCR structure for active ESD protection diode, which includes the following steps: Obtain the current signal when the SCR is on; The trend term signal and the periodic term signal are decomposed from the current signal; based on the magnitude of the current amplitude at each moment in the trend term signal and the difference in the current amplitude at adjacent moments, the corrected main energy decay factor at the current moment is determined. The ringing attenuation factor at the current moment is determined based on the magnitude of the current amplitude at each moment in the periodic signal. Based on the magnitudes of the modified main energy decay factor and the ringing decay factor at the current moment, the ESD termination probability at the current moment is determined; based on the magnitude of the ESD termination probability at the current moment, the MOS is controlled to turn off and on.

[0006] Furthermore, the specific steps for determining the corrected principal energy decay factor at the current moment are as follows: In the trend term signal, obtain the inverse proportional normalized value of the current amplitude at the current moment, and denot it as the main energy decay factor at the current moment; The target time period corresponding to the current moment is determined based on the preset number of adjacent moments before the current moment and the time period formed by the current moment; Based on the difference in current amplitude between adjacent times within the target time period corresponding to the current time of the trend term signal, and combined with the main energy attenuation factor at the current time, the corrected main energy attenuation factor at the current time is determined.

[0007] Furthermore, the specific steps for determining the corrected main energy attenuation factor at the current moment, based on the difference in current amplitude between adjacent moments within the target time period corresponding to the current moment and in conjunction with the main energy attenuation factor at the current moment, are as follows: The time interval between any two adjacent moments is denoted as the standard duration. For trend signal, within the target time period corresponding to the current moment, the absolute value of the difference between the current amplitude at each moment and the current amplitude at the previous moment is recorded as the current difference value at each moment. The ratio of the current difference value at each moment to the standard duration is recorded as the current change per unit time at each moment. The product of the inversely proportional normalized value of the current change per unit time at each moment and the main energy decay factor is recorded as the first product at each moment. The mean of the first products at all moments is recorded as the corrected main energy decay factor at the current moment.

[0008] Furthermore, the specific steps for determining the ringing attenuation factor at the current moment are as follows: For periodic signals, within the target time period corresponding to the current moment, at least two effective peak values ​​are obtained using a peak detection algorithm based on the current amplitude at all times. In chronological order, all effective peak values ​​are used to form an effective peak sequence. WMA prediction is performed on the effective peak sequence to obtain a predicted peak value. The inversely proportional normalized value of the predicted peak value at the current moment is denoted as the ringing safety level at the current moment. Based on the effective peak value of the periodic signal within the target time period corresponding to the current moment, determine the ringing attenuation stability coefficient at the current moment; The ringing attenuation factor at the current moment is determined based on the ringing safety factor and the ringing attenuation stability coefficient at the current moment.

[0009] Furthermore, the specific steps for determining the ringing attenuation stability coefficient at the current moment are as follows: For a periodic signal, within the target time period corresponding to the current moment, the inversely proportional normalized value of the standard deviation of all effective peak values ​​is recorded as the ringing attenuation stability coefficient at the current moment.

[0010] Furthermore, the specific steps for determining the ringing attenuation factor at the current moment based on the ringing safety factor and the ringing attenuation stability coefficient at the current moment are as follows: The product of the ringing safety factor and the ringing attenuation stability factor at the current moment is denoted as the ringing attenuation factor at the current moment.

[0011] Furthermore, the specific steps for determining the ESD termination probability at the current moment are as follows: Determine the main energy decay weight at the current moment based on the magnitude of the corrected main energy decay factor at the current moment; The ESD termination probability at the current moment is determined based on the magnitude of the modified main energy decay factor, the main energy decay weight, and the ringing decay factor at the current moment.

[0012] Furthermore, the specific steps for determining the primary energy decay weight at the current moment are as follows: The product of the corrected primary energy decay factor at the current moment and the preset constant is denoted as the second product. The sum of the second product and the preset constant is denoted as the primary energy decay weight at the current moment.

[0013] Furthermore, the specific steps for determining the ESD termination probability at the current moment based on the magnitude of the corrected main energy attenuation factor, the main energy attenuation weight, and the ringing attenuation factor are as follows: At the current moment, the product of the modified main energy decay factor and the main energy decay weight is denoted as the third product, and the product of the inverse proportional value of the main energy decay weight and the ringing decay factor is denoted as the fourth product. The sum of the third product and the fourth product is denoted as the ESD termination probability at the current moment.

[0014] Furthermore, the specific steps for controlling the MOS to turn on and off based on the current ESD termination probability are as follows: If the probability of ESD termination at the current moment is less than or equal to the preset shutdown threshold, then MOS is turned off; If the probability of ESD ending at the current moment is greater than the preset shutdown threshold and less than the preset enable threshold, then MOS is allowed to enter the gradual enable region. If the probability of ESD termination at the current moment is greater than or equal to the preset activation threshold, then MOS is allowed to enter the fully activated region.

[0015] The beneficial effects of the technical solution of the present invention are: In this embodiment of the invention, the current signal under the SCR conduction state is acquired, and a trend term signal and a periodic term signal are decomposed from the current signal. Based on the magnitude of the current amplitude at each moment in the trend term signal and the difference in current amplitude at adjacent moments, the corrected main energy attenuation factor at the current moment is determined. Based on the magnitude of the current amplitude at each moment in the periodic term signal, the ringing attenuation factor at the current moment is determined. Based on the magnitudes of the corrected main energy attenuation factor and the ringing attenuation factor at the current moment, the ESD termination probability at the current moment is determined. Thus, by decomposing and modeling the SCR discharge current into trend and periodic terms, the ESD termination judgment is upgraded from instantaneous amplitude judgment to a comprehensive probability assessment of the main energy release process and the parasitic ringing attenuation process. This not only accurately identifies whether the main discharge energy has been basically exhausted, but also effectively avoids misjudgment caused by the incomplete attenuation of parasitic oscillations. Therefore, while ensuring the safety of the protected node, the smooth turn-off of the SCR and the gradual takeover of the MOS transistor channel are achieved, significantly reducing the risks of voltage rebound, current surge and secondary stress, and improving the reliability, stability and engineering applicability of the ESD protection circuit. Finally, based on the probability of ESD termination at the current moment, the MOS is controlled to turn on or off. Thus, this invention accurately determines the end time of electrostatic discharge by real-time monitoring and analysis of the current, voltage, and signal characteristics of the protected port. It provides protection when needed and promptly shuts off the SCR when not needed, thereby ensuring ESD protection while avoiding interference with normal circuits. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a flowchart illustrating the steps of an SCR structure ESD active protection diode according to the present invention. Figure 2 This is a schematic diagram of a composite ESD protection circuit for SCR and MOS with an ESD detection unit. Detailed Implementation

[0018] To further illustrate the technical means and effects adopted by the present invention to achieve its intended purpose, the following, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation, structure, features, and effects of an ESD active protection diode with an SCR structure proposed according to the present invention. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0019] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0020] The following description, in conjunction with the accompanying drawings, details a specific solution for an SCR structure-based ESD active protection diode provided by this invention.

[0021] Please see Figure 1 The diagram illustrates a flowchart of the steps of an SCR structure ESD active protection diode according to an embodiment of the present invention, the diode comprising the following steps: Step S001: Obtain the current signal when the SCR is in the on state.

[0022] The SCR structure of the active ESD protection diode in this embodiment monitors and analyzes the current, voltage and signal form of the protected port in real time to accurately determine the end time of electrostatic discharge. It provides protection when needed and turns off the SCR in time when not needed, thus ensuring the ESD protection effect and avoiding interference with normal circuits.

[0023] It should be noted that the active protection diode for ESD (Electrostatic Discharge) in the SCR (Silicon Controlled Rectifier) ​​structure includes: (1) Protected node: the external ESD entry point, the trigger source of the SCR and the detection reference point; (2) SCR protection unit: passively turned on when ESD occurs, providing a low-resistance conduction path to quickly release the electrostatic discharge current; (3) ESD detection unit: internally coupled with the main path of the SCR to obtain characteristic information in the conduction state; (4) MOS (Metal-Oxide-Semiconductor) modulation unit: connected in parallel with the SCR, controlled by the control signal, which can change the equivalent current of the SCR after the ESD ends, and realize the active turn-off control of the SCR protection unit. The protected node is connected to the SCR protection unit and the MOS modulation unit respectively. The other end of the SCR protection unit and the MOS modulation unit are both connected to the ground terminal. In the initial stage, it is necessary to obtain the working status data of the SCR structure. In the SCR main conduction path or its parallel path between the protected node and the ground terminal, the current and voltage data related to the SCR conduction state are obtained through the ESD detection device, and the obtained data is transmitted to the control analysis module to determine the end of electrostatic discharge.

[0024] Further explanation is needed regarding the schematic diagram of the SCR and MOS combined ESD protection circuit with ESD detection unit, as shown below. Figure 2 As shown, Figure 2 In this system, the protected node is the chip's input or output pin, a core node requiring protection against electrostatic discharge (ESD). The MOSFET discharge path is from the protected node to the MOSFET (drain in, source out) and then to GND (Ground). The SCR protection unit is from the protected node to the SCR (PNPN path) and then to GND. The ESD detection unit triggers the SCR through internal coupling or modulation, and is crucial for active protection. The PNPN path is the core structure of the SCR, referring to the current conduction path formed by four alternating layers of doped P-type semiconductor to N-type semiconductor to P-type semiconductor to N-type semiconductor.

[0025] Therefore, the current signal under SCR conduction state is first acquired in real time. The horizontal axis of the current signal represents time, the vertical axis represents current amplitude, and the acquisition frequency is 20 kHz.

[0026] It should be noted that the SCR is in its initial stage within the first second after conduction, during which its current, voltage, and internal carrier distribution have not yet reached a stable state, and may exhibit oscillations, spikes, or atypical dynamic characteristics. To avoid interference from the initial transient process on the analysis results, this embodiment begins subsequent analysis after one second to ensure that the analysis is based on the stable conduction state of the SCR, thereby improving the accuracy and reliability of the results. Furthermore, the data collected in the first second can be used as the basis for subsequent analysis.

[0027] Step S002: Decompose the trend term signal and the periodic term signal from the current signal; determine the corrected main energy attenuation factor at the current moment based on the magnitude of the current amplitude at each moment in the trend term signal and the difference in the current amplitude at adjacent moments.

[0028] It should be noted that in existing ESD protection processes, ESD protection is often passively detected, based on passive triggering and recovery methods, without analyzing or judging the ESD discharge process. This approach, when the operating current is high, or when the discharge process is strongly coupled with the system's operating state (e.g., active systems operating online with high operating current), can lead to continued conduction after discharge. Prolonged conduction can affect the normal operation of the protected circuit after the ESD event. Therefore, in addition to the traditional approach, we consider real-time detection of the SCR current to further analyze the end time of the ESD event, allowing for timely shutdown of the SCR after the ESD event to minimize the impact on the protected circuit. However, the ESD discharge process is characterized by strong transients, multiple peak values, and oscillating decay. If judgment is based solely on whether the current amplitude in the protection channel drops below a preset threshold, relying on the instantaneous current magnitude, it is easy to misjudge the ESD discharge as complete before it is fully finished or when there is a risk of secondary discharge. Furthermore, protective devices such as SCRs are affected by temperature changes, parasitic parameters, and manufacturing processes during conduction. Their sustaining current threshold is not fixed, and a single threshold criterion is insufficient to adapt to different operating conditions and discharge patterns, leading to inaccurate judgments. Therefore, this study considers using STL decomposition to analyze the real-time current signal acquired during SCR conduction. This allows for the differentiation of the energy release trend, oscillation behavior, and random disturbances contained within the signal, reflecting the true physical characteristics of the current change and obtaining trend, periodic, and residual signals.

[0029] Further explanation is needed: the trend term characterizes the main energy release process of ESD, the periodic term characterizes the attenuation characteristics of parasitic ringing, and the residual term mainly characterizes local disturbances. The main energy release process is the primary energy injected into the protected node by the human body model, capacitor discharge model, or external static power source during an ESD event. This energy is rapidly discharged in the form of a large current after the SCR is turned on, and gradually decays as the discharge process progresses. When the trend term continues to decrease and enters a stable low-energy region, the ESD electrostatic energy in the system is basically exhausted. The subsequent discharge current is no longer dominated by the external static power source, but gradually transitions to the residual current caused by the device's own parasitic effects or recovery process. Therefore, the real-time main energy attenuation factor is first determined based on the changes in the current trend term.

[0030] Preferably, in one embodiment of the present invention, the method for obtaining the corrected principal energy decay factor at the current moment includes: The current signal is decomposed using STL to obtain the trend term signal, periodic term signal, and residual term signal.

[0031] Among them, STL decomposition (Seasonal and Trend decomposition using Loess) is a well-known technique, and the specific method will not be introduced here.

[0032] In the trend term signal, obtain the inverse proportional normalized value of the current amplitude at the current moment, and denote it as the main energy decay factor at the current moment. .

[0033] It should be noted that in this embodiment, the current time is denoted as... Timing. Obtain the sustaining current amplitude from the diode's datasheet. This is the minimum current required for the SCR to remain on; below this value, the SCR will automatically turn off. It also specifies the maximum withstand current amplitude. This is the maximum transient current that an SCR can safely discharge without damage. Therefore, with The current amplitude at the current moment is a trend signal. The inverse proportional normalized value is used to obtain the principal energy decay factor at the current moment. .in, Should be greater than and less than Otherwise, the SCR will be turned off, therefore In the range Inside. The closer Then the principal energy decay factor The larger it is, the closer it is to 1.

[0034] Following the above method, the primary energy decay factor at each moment can be obtained.

[0035] It should be noted that, in real-time judgment, considering that the slower the trend term changes, the higher the probability that the main energy release is nearing completion, based on a single moment, the influence of the trend term change rate on the degree of completion of the main energy release is further considered over a period of time prior to the current moment, and the real-time correction main energy decay factor is determined.

[0036] The time interval between any two adjacent moments is denoted as the standard duration.

[0037] In this embodiment, the sampling frequency is 20 kHz, so the standard duration is 50 microseconds.

[0038] Preset quantity threshold Let's take 10 as an example.

[0039] Based on a preset threshold number of adjacent times preceding the current time and the time period formed by the current time, the target time period corresponding to the current time is determined. Specifically, the target time period corresponding to the current time is... Time's up The time interval between moments (including) Time and time).

[0040] Using the method described above, the target time period corresponding to each moment can be obtained.

[0041] For trend signals, within the target time period corresponding to the current moment, the absolute value of the difference between the current amplitude at each moment and the current amplitude at the previous moment is recorded as the current difference value at each moment. The ratio of the current difference value at each moment to the standard duration is recorded as the current change per unit time at each moment. The product of the inversely proportional normalized value and the principal energy decay factor is denoted as the first product at each time step. The mean of the first products at all time steps is denoted as the corrected principal energy decay factor at the current time step. .

[0042] It should be noted that: for the first moment within the target time period corresponding to the current moment, i.e. At that moment, with Current amplitude at time t and The absolute value of the difference in current amplitude at time t is used as The current difference value corresponding to each moment can be obtained by using the data collected in the first second after the SCR is turned on as the basic data in this embodiment, and starting the analysis from the second onwards. Therefore, the complete target time period corresponding to each moment and the current difference value corresponding to each moment can be obtained. Since... Since it is a non-negative data value, in this embodiment it is used as... As The inverse proportional normalized value, its range is Inside, among which As an exponential function with the natural constant as its base, the closer the difference in current amplitude at adjacent moments is to 0, the more complete the main energy release is, meaning the main energy decay has reached its maximum. A value close to 1 is used as a correction weight for the main energy decay factor. Therefore, by introducing the inversely proportional normalized value of the rate of change of current in the trend term as a weight, a comprehensive quantitative evaluation of the main energy release decay is achieved. This considers both the magnitude of the current amplitude and the stability of the trend, thus enabling a more accurate judgment of the completion of the ESD main energy release process. The closer it is to 1, the more likely the ESD main energy release has been completed.

[0043] Step S003: Determine the ringing attenuation factor at the current moment based on the magnitude of the current amplitude at each moment in the periodic signal.

[0044] It should be noted that after completing the quantitative analysis of the trend term, the periodic term of the SCR current can be further analyzed to characterize the attenuation characteristics of parasitic ringing and help determine the end time of the ESD tail segment. The change of the trend term mainly reflects the overall attenuation characteristics of the discharge current borne by the SCR. When ESD occurs, even if the main energy is exhausted, there will still be oscillations in the current signal caused by the parasitic effects of devices such as parasitic capacitance and inductance. These oscillations will cause the current amplitude to change repeatedly after the main energy is consumed. If only the main energy trend term is relied upon to determine whether ESD has ended, the impact of high-frequency parasitic ringing on the circuit will be ignored. Moreover, the trend term cannot reflect the attenuation process of multi-cycle oscillation or secondary energy release. Although this process is not obvious in the overall trend, it may still have a transient impact on sensitive circuits. If the SCR is turned off too early, it will still cause an impact on the protected node. Therefore, in this embodiment, we consider analyzing the periodic term of the SCR current. Within a set time period, we extract multiple consecutive effective peaks and use the amplitude corresponding to each peak as a characterization parameter of the ringing intensity. This allows for the acquisition of a valid peak sequence, which can then be used to calculate subsequent ringing attenuation.

[0045] It should be further noted that, regarding the decay behavior of the obtained effective peak sequence, when the amplitude of the continuous peak sequence gradually shows a stable and continuous decay trend, and the decay rate continues to slow down, it indicates that the parasitic oscillation process has entered the tail stage, and the residual energy in the system is within a controllable range.

[0046] Preferably, in one embodiment of the present invention, the method for obtaining the ringing attenuation factor at the current moment includes: For periodic signals, within the target time period corresponding to the current moment, at least two valid peak values ​​are obtained using a peak detection algorithm based on the current amplitude at all times. These valid peak values ​​are then arranged in chronological order to form a valid peak sequence. WMA prediction is performed on this valid peak sequence to obtain a predicted peak value. This is the predicted peak value corresponding to the current moment.

[0047] It should be noted that both the peak detection algorithm and WMA (Weighted Moving Average) prediction are well-known techniques, and their specific methods will not be described here. In peak detection of current signals, the essence of an effective peak is the local maximum of the current amplitude within a specified neighborhood. WMA prediction is used to obtain the predicted current amplitude of the ringing peak corresponding to subsequent parasitic oscillations. Here, WMA prediction does not rely on complex models and is suitable for the short-term, rapid decay process of ESD. In this embodiment, if at least two effective peaks cannot be obtained within the target time period corresponding to any given moment, the preset number threshold is increased. This ensures that there are at least two valid peaks within the target time period corresponding to each moment, thereby ensuring that WMA prediction can be performed.

[0048] The predicted peak value for each moment is obtained using the method described above.

[0049] The predicted peak value at the current moment The inversely proportional normalized value is denoted as the ringing safety factor at the current moment.

[0050] Among them, the predicted peak It is the current amplitude, and the current amplitude is non-negative, therefore it is... As The inverse proportional normalized value, its range is That is, predicting the peak value. The closer the value is to 0, the more likely the parasitic oscillation process has entered its final stage, the more the residual energy in the system is within a controllable range, and the higher the safety level of ringing. The closer it is to 1.

[0051] For periodic signals, within the target time period corresponding to the current moment, the standard deviation of all effective peak values ​​is calculated. The inversely proportional normalized value is denoted as the ringing attenuation stability coefficient at the current moment.

[0052] It should be noted that the standard deviation is non-negative, therefore it is... As The inverse proportional normalized value, its range is .Right now The closer a value is to 0, the more consistent the effective peak values ​​are within the target time period corresponding to the current moment, meaning that the ringing attenuation tends to stabilize. The closer it is to 1. After obtaining the ringing safety factor corresponding to the predicted ringing peak, a measure of the dispersion of historical effective ringing peak is introduced to reflect the fluctuation of the ringing amplitude in that time period. When the standard deviation is large, it indicates that the ringing amplitude changes drastically and the parasitic oscillation has not yet entered the stable decay stage. When the standard deviation gradually decreases and tends to stabilize, the parasitic oscillation has basically dissipated.

[0053] The product of the ringing safety factor and the ringing attenuation stability factor at the current moment is denoted as the ringing attenuation factor at the current moment. .

[0054] It should be noted that if the ringing attenuation tends to stabilize within the target time period corresponding to the current moment (the closer the ringing attenuation stability coefficient is to 1), and the smaller the predicted ringing peak value corresponding to the subsequent parasitic oscillation (the closer the ringing safety factor is to 1), then the ringing attenuation factor at the current moment is larger, that is, closer to 1.

[0055] Step S004: Determine the ESD termination probability at the current moment based on the magnitude of the corrected main energy attenuation factor and the ringing attenuation factor; adjust the MOS to turn off or on based on the magnitude of the ESD termination probability at the current moment.

[0056] It should be noted that in the early stages of an ESD event, the main energy injected by the external static power source dominates. However, in the later stages of an ESD event, as the main energy is basically exhausted, the system behavior gradually becomes dominated by parasitic parameters. Therefore, the main energy decay factor is used to determine the end of the ESD event. When the main energy decay factor is large, the magnitude of the ringing decay factor is mainly considered.

[0057] Preferably, in one embodiment of the present invention, the method for obtaining the ESD termination probability at the current moment includes: The default constant is 0.5, and this will be used as an example for explanation.

[0058] The product of the current corrected primary energy decay factor and the preset constant is denoted as the second product. The sum of the second product and the preset constant is denoted as the primary energy decay weight at the current moment. .

[0059] Therefore, the modified main energy decay factor is normalized to between 0.5 and 1 and used as the main energy decay weight to avoid the modified main energy decay factor from becoming completely ineffective.

[0060] At the current moment, the principal energy decay factor will be corrected. With main energy decay weight The product of these is denoted as the third product, which represents the inverse proportional value of the principal energy decay weight. With ringing attenuation factor The product of the first and second products is denoted as the fourth product. The sum of the third and fourth products is denoted as the ESD termination probability at the current time. .

[0061] It should be noted that when the system's main energy is still relatively high, the main energy decay state plays a dominant role in the system's decision. As the main energy gradually decays, its weight automatically decreases, causing the ringing feature to gradually dominate the decision, thereby achieving adaptive judgment of the ringing end state. This allows us to obtain the probability of the real-time ESD event ending.

[0062] The preset closing threshold is 0.6, and the preset opening threshold is 0.9. This will be used as an example for explanation.

[0063] It should be noted that: if the probability of ESD ending at the current moment... If the value approaches 0, it indicates that the SCR device is clearly in a strong discharge phase. If the ESD termination probability at the current moment... If the value approaches 1, it indicates that both ESD discharge and parasitic ringing are nearing completion. Therefore, the specific control method for the MOS is as follows: If the probability of ESD ending at the current moment is... If the current threshold is less than or equal to the preset shutdown threshold, the MOSFET will be turned off. This means that at the current moment, the SCR is completely dominant, the parallel MOSFET channel remains off, and any current transfer is prohibited.

[0064] If the probability of ESD ending at the current moment is... If the threshold value is greater than the preset shutdown threshold and less than the preset turn-on threshold, the MOSFET enters the gradual turn-on region. That is, at the current moment, the MOSFET channel begins to turn on linearly or in stages. The MOSFET's equivalent conduction capability is... There is a positive correlation, and the conduction ratio of the MOSFET is... .

[0065] If the probability of ESD ending at the current moment is... If the value is greater than or equal to the preset turn-on threshold, the MOS will enter the fully turn-on region. That is, at the current moment, both the main power and ringing have entered the controllable tail section, the SCR enters the active turn-off state or maintains the minimum holding current state, and the system can safely return to the normal power supply and load state.

[0066] It should be noted that when the ESD termination probability obtained by fusing the aforementioned main energy decay characteristics and ringing characteristics reaches the preset judgment condition, the control unit triggers a gradual turn-on control strategy for the MOSFET channel. By adopting a gradual channel control method, voltage rebound, current surge, or local stress concentration problems caused by sudden SCR turn-off or rapid current transfer are effectively avoided, significantly improving the stability and reliability of the system after an ESD event.

[0067] This invention is now complete.

[0068] In summary, in this embodiment of the invention, the current signal under SCR conduction state is acquired, and a trend term signal and a periodic term signal are decomposed from the current signal. Based on the magnitude of the current amplitude at each moment in the trend term signal and the difference in current amplitude at adjacent moments, the corrected main energy attenuation factor at the current moment is determined. Based on the magnitude of the current amplitude at each moment in the periodic term signal, the ringing attenuation factor at the current moment is determined. Based on the magnitudes of the corrected main energy attenuation factor and the ringing attenuation factor at the current moment, the ESD termination probability at the current moment is determined. Based on the magnitude of the ESD termination probability at the current moment, the MOS is controlled to turn on and off. This invention can significantly reduce the risks of voltage bounce, current surge, and secondary stress, and improve the reliability, stability, and engineering applicability of ESD protection circuits.

[0069] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An SCR structure ESD active protection diode, characterized in that, The diode includes the following steps: Acquire the current signal when the SCR is on; The trend term signal and the periodic term signal are decomposed from the current signal; based on the magnitude of the current amplitude at each moment in the trend term signal and the difference in the current amplitude at adjacent moments, the corrected main energy decay factor at the current moment is determined. The ringing attenuation factor at the current moment is determined based on the magnitude of the current amplitude at each moment in the periodic signal. Based on the magnitudes of the modified main energy decay factor and the ringing decay factor at the current moment, the ESD termination probability at the current moment is determined; based on the magnitude of the ESD termination probability at the current moment, the MOS is controlled to turn off and on.

2. The SCR structure ESD active protection diode according to claim 1, characterized in that, The specific steps for determining the corrected principal energy decay factor at the current moment are as follows: In the trend term signal, obtain the inverse proportional normalized value of the current amplitude at the current moment, and denot it as the main energy decay factor at the current moment; The target time period corresponding to the current moment is determined based on the preset number of adjacent moments before the current moment and the time period formed by the current moment; Based on the difference in current amplitude between adjacent times within the target time period corresponding to the current time of the trend term signal, and combined with the main energy attenuation factor at the current time, the corrected main energy attenuation factor at the current time is determined.

3. The SCR structure ESD active protection diode according to claim 2, characterized in that, The specific steps for determining the corrected main energy attenuation factor at the current moment, based on the difference in current amplitude between adjacent moments within the target time period corresponding to the current moment and in conjunction with the main energy attenuation factor at the current moment, are as follows: The time interval between any two adjacent moments is denoted as the standard duration. For trend signal, within the target time period corresponding to the current moment, the absolute value of the difference between the current amplitude at each moment and the current amplitude at the previous moment is recorded as the current difference value at each moment. The ratio of the current difference value at each moment to the standard duration is recorded as the current change per unit time at each moment. The product of the inversely proportional normalized value of the current change per unit time at each moment and the main energy decay factor is recorded as the first product at each moment. The mean of the first products at all moments is recorded as the corrected main energy decay factor at the current moment.

4. The SCR structure ESD active protection diode according to claim 2, characterized in that, The specific steps for determining the ringing attenuation factor at the current moment are as follows: For periodic signals, within the target time period corresponding to the current moment, at least two effective peak values ​​are obtained using a peak detection algorithm based on the current amplitude at all times. In chronological order, all effective peak values ​​are used to form an effective peak sequence. WMA prediction is performed on the effective peak sequence to obtain a predicted peak value. The inversely proportional normalized value of the predicted peak value at the current moment is denoted as the ringing safety level at the current moment. Based on the effective peak value of the periodic signal within the target time period corresponding to the current moment, determine the ringing attenuation stability coefficient at the current moment; The ringing attenuation factor at the current moment is determined based on the ringing safety factor and the ringing attenuation stability coefficient at the current moment.

5. The SCR structure ESD active protection diode according to claim 4, characterized in that, The specific steps for determining the ringing attenuation stability coefficient at the current moment are as follows: For a periodic signal, within the target time period corresponding to the current moment, the inversely proportional normalized value of the standard deviation of all effective peak values ​​is recorded as the ringing attenuation stability coefficient at the current moment.

6. The SCR structure ESD active protection diode according to claim 4, characterized in that, The specific steps for determining the ringing attenuation factor at the current moment based on the ringing safety factor and the ringing attenuation stability coefficient at the current moment are as follows: The product of the ringing safety factor and the ringing attenuation stability factor at the current moment is denoted as the ringing attenuation factor at the current moment.

7. The SCR structure ESD active protection diode according to claim 1, characterized in that, The specific steps for determining the ESD termination probability at the current moment are as follows: The main energy decay weight at the current moment is determined based on the magnitude of the corrected main energy decay factor at the current moment. The ESD termination probability at the current moment is determined based on the magnitude of the modified main energy decay factor, the main energy decay weight, and the ringing decay factor at the current moment.

8. The SCR structure ESD active protection diode according to claim 7, characterized in that, The specific steps for determining the primary energy decay weight at the current moment are as follows: The product of the corrected primary energy decay factor at the current moment and the preset constant is denoted as the second product. The sum of the second product and the preset constant is denoted as the primary energy decay weight at the current moment.

9. The SCR structure ESD active protection diode according to claim 7, characterized in that, The specific steps for determining the ESD termination probability at the current moment based on the magnitudes of the corrected main energy attenuation factor, main energy attenuation weight, and ringing attenuation factor are as follows: At the current moment, the product of the modified main energy decay factor and the main energy decay weight is denoted as the third product, and the product of the inverse proportional value of the main energy decay weight and the ringing decay factor is denoted as the fourth product. The sum of the third product and the fourth product is denoted as the ESD termination probability at the current moment.

10. The SCR structure ESD active protection diode according to claim 1, characterized in that, The specific steps for controlling the MOS to turn on and off based on the probability of ESD termination at the current moment are as follows: If the probability of ESD termination at the current moment is less than or equal to the preset shutdown threshold, then MOS is turned off; If the probability of ESD ending at the current moment is greater than the preset shutdown threshold and less than the preset enable threshold, then MOS is allowed to enter the gradual enable region. If the probability of ESD termination at the current moment is greater than or equal to the preset activation threshold, then MOS is allowed to enter the fully activated region.

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