Electrostatic protection circuit
By connecting a Zener diode and a resistor in parallel in the electrostatic discharge (ESD) protection circuit, the gate voltage of the transistor is stabilized, solving the problem of damage to the main bleeder transistor under high voltage and achieving effective ESD protection under high voltage.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-06
- Publication Date
- 2026-03-13
AI Technical Summary
In existing electrostatic discharge protection circuits, the main bleeder transistor is easily damaged at high voltage levels, and the unreasonable design of the trigger signal leads to voltage overshoot or overshoot, which cannot effectively protect the main transistor.
A Zener diode is connected in parallel with the gate of the main bleeder transistor and the main transistor. Combined with auxiliary circuitry and resistors, the gate voltage of the transistor is stabilized by the clamping characteristics of the Zener diode and the current limiting effect of the resistor, preventing damage from excessive voltage.
The electrostatic withstand voltage rating of the electrostatic protection circuit has been improved to ensure that the transistor gate voltage is within a safe range, thus avoiding damage and achieving effective electrostatic protection under high voltage.
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Figure CN121663436A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of power electronic devices and circuit technology, and specifically to an electrostatic discharge protection circuit. Background Technology
[0002] The essence of an ESD event is the instantaneous release of static charge. Its physical characteristics determine that high voltage levels are inevitably accompanied by short-duration and high-energy impacts. The response speed and energy handling capacity of the main bleeder transistor have natural upper limits. The main bleeder transistor needs to rely on the trigger signal of the protection circuit to achieve precise conduction. If the trigger mechanism is not designed properly, it will lead to premature or delayed triggering. Premature triggering increases the loss of normal circuits, while delayed triggering will cause voltage overshoot under high-level ESD.
[0003] In electrostatic discharge (ESD) protection circuits, the main transistor is a key component that assists the main bleeder transistor in operation or controls the start / stop of the protection circuit. Given the problem that the main bleeder transistor is easily damaged by voltage overshoot under high electrostatic voltage levels, there is an urgent need for an ESD protection circuit with high voltage level electrostatic discharge protection capability to protect the main transistor. Summary of the Invention
[0004] Therefore, the present invention provides an electrostatic discharge protection circuit to solve the problems mentioned in the background art.
[0005] To achieve the above objectives, the present invention provides the following technical solution: an electrostatic discharge protection circuit, comprising: Main bleeder transistor S5; Zener diode D1 is connected in parallel between the gate and source of the main bleeder transistor S5. The clamping characteristic of Zener diode D1 is used to stabilize the gate voltage VG2 of the main bleeder transistor. Zener diode D2 has one end connected to the gate VG1 of the main transistor M and the other end grounded. It is used to clamp the voltage between the gate VG1 and the source VS of the main transistor M to prevent excessive voltage from damaging the gate of the main transistor M.
[0006] Preferably, the electrostatic discharge protection circuit further includes an auxiliary circuit S consisting of at least two transistors connected in parallel; The auxiliary circuit S consists of multiple transistors connected in a diode configuration, with the source and drain of two adjacent transistors connected together. The gates of the multiple transistors receive external control signals. One end of the auxiliary circuit S is the gate VG1 of the main transistor M, and the other end is grounded through a resistor R, which is equivalent to being connected in series with VG1 and ground in the branch.
[0007] Preferably, the transistors S1, S2, S3, S4, main bleeder transistor S5, and main transistor M in the auxiliary circuit S are made of GaN material.
[0008] Preferably, the source VS of the main transistor M is grounded, the drain VD is connected to an external load or power supply, and the gate VG1 receives a control signal to control the main transistor M to turn on and off, thereby realizing functions such as power control.
[0009] Preferably, the source of the main bleeder transistor S5 is grounded, the drain is connected to the connection line between the gate VG1 and the main transistor M, and the gate VG2 receives the control voltage.
[0010] Preferably, the Zener diode D1 is connected in parallel with the resistor R, with one end connected to the connection node of the auxiliary circuit S and the resistor R, and the other end grounded. This parallel structure mainly serves to clamp and limit current. When the voltage at the connection node does not reach the breakdown voltage of the Zener diode D1, D1 is reverse cut off, and the resistor R limits the current of this branch. When the voltage reaches the Zener breakdown voltage of D1, D1 conducts, clamping the voltage at the node at the Zener voltage value. At the same time, the resistor R can also prevent the current from being too large.
[0011] Preferably, the gate width and current rating of the main bleeder transistor S5 are both higher than those of the transistors in the auxiliary circuit S.
[0012] Preferably, when the gate voltage VG1 of the main transistor M is less than the trigger voltage, the entire electrostatic discharge (ESD) protection circuit will not be activated. When the voltage exceeds the trigger voltage of the ESD protection circuit (the trigger voltage is equal to the sum of the threshold voltages of transistors S1, S2, S3, and S4, where the threshold voltages of transistors S1, S2, S3, and S4 are Vth1, Vth2, Vth3, and Vth4 respectively, and the sum of the threshold voltages Vths = Vth1 + Vth2 + Vth3 + Vth4), the auxiliary circuit S is activated, and the electrostatic charge is released through the auxiliary circuit S and the resistor R. Then, the voltage VG2 = VG1 - Vths will be applied to the main bleeder transistor S5. At the gate, the main bleeder transistor S5 is turned on, and the accumulated electrostatic charge is discharged through the main bleeder transistor S5. When the gate VG1 of the main transistor M is subjected to a low-voltage electrostatic discharge voltage of less than 2kV, the auxiliary circuit S is turned on. Under the adjustment of the resistor R, the gate voltage VG2 of the main bleeder transistor is turned on, thus turning on the main bleeder transistor. The electrostatic discharge current is discharged sequentially or simultaneously from two paths: the main bleeder transistor S5 and the branch formed by the auxiliary circuit S and R. Usually, the leakage current of the main bleeder transistor is greater than the leakage current of other branches. At this time, the gate voltage VG2 of the main bleeder transistor is subjected to a spike of less than 7V, and the transistor works normally.
[0013] Preferably, when the gate VG1 of the main transistor M is subjected to a high-voltage electrostatic discharge voltage greater than 2kV, Zener diode D1 clamps the gate voltage VG2 of the main bleeder transistor S5 below the safe voltage, which is less than the gate breakdown voltage of the main bleeder transistor S5. Zener diode D2 clamps the main transistor M below the safe voltage, thereby improving the electrostatic protection voltage level. The auxiliary circuit S turns on, and under the adjustment of resistor R, the gate voltage VG2 of the main bleeder transistor is turned on, thus turning on the main bleeder transistor. The electrostatic discharge current is discharged sequentially or simultaneously from two paths: the branch formed by the main bleeder transistor, the auxiliary circuit S, and R. Typically, the discharge current of the main bleeder transistor is greater than the leakage current of other branches. At this time, Zener diode D1 is reverse-biased and clamped at 6V, so that the gate voltage VG2 of the main bleeder transistor is clamped within the safe operating voltage range, preventing damage. This allows the electrostatic protection circuit to perform its electrostatic protection function normally.
[0014] The present invention has the following advantages: This invention, by connecting a Zener diode in parallel with the gate of the main bleeder transistor and the main transistor, enables the gate voltage clamping of the transistor to be within a safe operating voltage range. Even when subjected to high-voltage electrostatic discharge, it can still effectively provide electrostatic protection and improve the electrostatic withstand voltage level of the electrostatic protection circuit. Attached Figure Description
[0015] Figure 1 This is a schematic diagram of the structure of Embodiment 1 provided by the present invention; Figure 2 The gate voltage of the bleeder transistor S5 in a conventional electrostatic discharge circuit when the electrostatic discharge voltage is 4kV, as provided by this invention. Figure 3 The gate voltage of the bleeder transistor S5 of the present invention when the electrostatic discharge voltage is 4kV; Figure 4 This is a schematic diagram of the structure of Embodiment 2 provided by the present invention; Figure 5 This is a schematic diagram of the structure of Embodiment 3 provided by the present invention; Figure 6 This is a schematic diagram of the structure of Embodiment 4 provided by the present invention; Figure 7 This is a schematic diagram of the structure of Embodiment 5 provided by the present invention. Detailed Implementation
[0016] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0017] Ordinary electrostatic discharge (ESD) protection circuits have limited capacity to withstand ESD voltage levels (typically <2kV). When the main transistor experiences a higher ESD voltage level (>2kV), the gate of the main bleeder transistor S5 is prone to voltage spikes. For example... Figure 2 The diagram shows that when the electrostatic discharge voltage is 4kV, the gate voltage of the bleeder transistor S5 in a typical electrostatic discharge protection circuit experiences an 11V voltage spike. However, the safe gate voltage of GaN is typically less than 7V, therefore this electrostatic discharge protection circuit cannot withstand high-voltage electrostatic discharges.
[0018] Example 1: This example proposes an electrostatic discharge (ESD) protection circuit, such as... Figure 1 As shown, it includes: Main bleeder transistor S5; Zener diode D1 is connected in parallel between the gate and source of main bleeder transistor S5. The clamping characteristic of Zener diode D1 is used to stabilize the gate voltage VG2 of main bleeder transistor S5. Zener diode D2 has one end connected to the gate VG1 of the main transistor M and the other end grounded. It is used to clamp the voltage between the gate VG1 and the source VS of the main transistor M to prevent excessive voltage from damaging the gate of the main transistor M.
[0019] The electrostatic discharge protection circuit also includes an auxiliary circuit S consisting of at least two transistors connected in parallel. Specifically, the auxiliary circuit S consists of multiple transistors connected in a diode configuration, with the source and drain of two adjacent transistors connected together. The drain of S1 is connected to the source of S2, the drain of S2 is connected to the source of S3, and the drain of S3 is connected to the source of S4. The gates of transistors S1, S2, S3, and S4 receive external control signals. One end of the auxiliary circuit S is connected to the gate VG1 of the main transistor M, and the other end is grounded through a resistor R, which is equivalent to being connected in series in the branch between VG1 and ground.
[0020] The transistors S1, S2, S3, S4, main bleeder transistor S5, and main transistor M in the auxiliary circuit S are made of GaN material.
[0021] Specifically, the source VS of the main transistor M is grounded, the drain VD is connected to an external load or power supply, and the gate VG1 receives a control signal to control the main transistor M to turn on and off, thereby realizing functions such as power control.
[0022] Specifically, the source of the main bleeder transistor S5 is grounded, the drain is connected to the connection line between VG1 and the main transistor M, and the gate VG2 receives the control voltage.
[0023] Specifically, Zener diode D1 is connected in parallel with resistor R. One end is connected to the connection node of auxiliary circuit S and resistor R, and the other end is grounded. This parallel structure mainly serves to clamp and limit current. When the voltage at the connection node does not reach the breakdown voltage of Zener diode D1, D1 is reverse cut off, and resistor R limits the current of this branch. When the voltage reaches the Zener breakdown voltage of D1, D1 conducts, clamping the voltage at the node at the Zener voltage value. At the same time, resistor R can also prevent excessive current.
[0024] The gate width and current rating of the main bleeder transistor S5 are both higher than those of the transistors in the auxiliary circuit S.
[0025] When the gate VG1 of the main transistor M is subjected to a low-voltage electrostatic discharge voltage of less than 2kV, the auxiliary circuit S turns on. Under the adjustment of the resistor R, the gate voltage VG2 of the main bleeder transistor S5 is turned on, thus turning on the main bleeder transistor S5. The electrostatic discharge current is discharged through two paths: the branch formed by the main bleeder transistor S5 and the auxiliary circuit S and R. Normally, the leakage current of the main bleeder transistor S5 is greater than the leakage current of other branches (auxiliary circuit S and Zener diode D2). At this time, the gate voltage VG2 of the main bleeder transistor S5 is subjected to a spike of less than 7V, and the transistor works normally.
[0026] When the gate VG1 of the main transistor M is subjected to a high-voltage electrostatic discharge voltage greater than 2kV, the auxiliary circuit S turns on. Under the adjustment of the resistor R, the gate voltage VG2 of the main bleeder transistor S5 is turned on, thus turning on the main bleeder transistor S5. The electrostatic discharge current is discharged through two paths: the main bleeder transistor S5 and the branch formed by the auxiliary circuit S and R. Normally, the leakage current of the main bleeder transistor S5 is greater than the leakage current of other branches. At this time, the Zener diode D1 is reverse-biased and clamped at 6V. Figure 3 As shown, this clamps the gate voltage VG2 of the main bleeder transistor S5 within a safe operating voltage range, preventing damage. This ensures the electrostatic discharge (ESD) protection circuit can properly perform its ESD protection function.
[0027] Zener diode D2 functions similarly to D1. When the main transistor M experiences an excessively high gate voltage, Zener diode D2 conducts in reverse, clamping the gate voltage of the main transistor M within a safe operating voltage range.
[0028] Example 2: As Figure 4As shown, in Example 1, the Zener diode D1 is equivalently derived by connecting at least two transistors S6 and S7 (it can be derived by connecting more transistors in series). The gates of the GaN transistors S6 and S7 are connected to the drains of S6 and S7, respectively, and are connected in series to obtain the equivalent Zener diode D1. The Zener diode D2 is equivalently derived by connecting in series in the same way.
[0029] Example 3: As Figure 5 As shown, unlike Example 1, this example does not include Zener diode D2.
[0030] Example 4: Figure 6 As shown, unlike Example 3, this example does not include Zener diode D1. A capacitor C is added to the gate of S5. The function of capacitor C is to buffer the gate voltage spike of the main bleeder transistor S5, which also helps to improve the electrostatic withstand voltage level.
[0031] Example 5: Figure 7 As shown, unlike Example 1, this example does not include Zener diode D1.
[0032] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.
Claims
1. An electrostatic discharge protection circuit, characterized in that: include: Main bleeder transistor S5; Zener diode D1 is connected in parallel between the gate and source of the main bleeder transistor S5. The clamping characteristic of Zener diode D1 is used to stabilize the gate voltage VG2 of the main bleeder transistor. Zener diode D2 is connected at one end to the gate VG1 of the main transistor M and at the other end to ground. It is used to clamp the voltage between the gate VG1 and the source VS of the main transistor M.
2. The electrostatic discharge protection circuit according to claim 1, characterized in that: The electrostatic discharge protection circuit also includes an auxiliary circuit S consisting of at least two transistors connected in parallel. The auxiliary circuit S consists of multiple transistors connected in a diode configuration, with the source and drain of two adjacent transistors connected together. One end of the auxiliary circuit S is connected to the gate VG1 of the main transistor M, and the other end is grounded through a resistor R.
3. The electrostatic discharge protection circuit according to claim 2, characterized in that: The transistors S1, S2, S3, S4, main bleeder transistor S5, and main transistor M in the auxiliary circuit S are made of GaN material.
4. The electrostatic discharge protection circuit according to claim 1, characterized in that: The source VS of the main transistor M is grounded, the drain VD is connected to an external load or power supply, and the gate VG1 receives a control signal to control the main transistor M to turn on and off.
5. The electrostatic discharge protection circuit according to claim 1, characterized in that: The source of the main bleeder transistor S5 is grounded, and its drain is connected to the connection line between the gate VG1 and the main transistor M. The gate VG2 receives the control voltage.
6. The electrostatic discharge protection circuit according to claim 2, characterized in that: Zener diode D1 is connected in parallel with resistor R, with one end connected to the connection node between auxiliary circuit S and resistor R, and the other end grounded.
7. The electrostatic discharge protection circuit according to claim 2, characterized in that: The gate width and current rating of the main bleeder transistor S5 are both higher than those of the transistors in the auxiliary circuit S.
8. The electrostatic discharge protection circuit according to claim 2, characterized in that: When the gate voltage VG1 of the main transistor M is less than the trigger voltage, the entire electrostatic discharge (ESD) protection circuit will not be activated. When the voltage exceeds the trigger voltage of the ESD protection circuit (the trigger voltage is equal to the sum of the threshold voltages of transistors S1, S2, S3, and S4, where the threshold voltages of transistors S1, S2, S3, and S4 are Vth1, Vth2, Vth3, and Vth4 respectively, and the sum of the threshold voltages Vths = Vth1 + Vth2 + Vth3 + Vth4), the auxiliary circuit S is activated, and the electrostatic charge is released through the auxiliary circuit S and resistor R. The voltage VG2 = VG1 - Vths will be applied to the gate of the main discharge transistor S5, causing the main discharge transistor S5 to turn on, and the accumulated electrostatic charge will be discharged through the main discharge transistor S5; when the gate VG1 of the main transistor M is subjected to a low-voltage electrostatic discharge voltage of less than 2kV, the auxiliary circuit S turns on, and under the adjustment of the resistor R, the gate voltage VG2 of the main discharge transistor is turned on, causing the main discharge transistor to turn on; the electrostatic discharge current is discharged sequentially or simultaneously from two paths: the main discharge transistor S5 and the branch formed by the auxiliary circuit S and R.
9. The electrostatic discharge protection circuit according to claim 1, characterized in that: When the gate VG1 of the main transistor M is subjected to a high-voltage electrostatic discharge voltage greater than 2kV, the Zener diode D1 clamps the gate voltage VG2 of the main bleeder transistor S5 below the safe voltage, which is less than the gate breakdown voltage of the main bleeder transistor S5. The Zener diode D2 clamps the main transistor M below the safe voltage to improve the electrostatic protection voltage level. The auxiliary circuit S turns on, and under the adjustment of the resistor R, the gate voltage VG2 of the main bleeder transistor is turned on, thus turning on the main bleeder transistor. The electrostatic discharge current is discharged sequentially or simultaneously from two paths: the branch formed by the main bleeder transistor, the auxiliary circuit S, and R.