TWI504091B - Electrostatic discharge protection device - Google Patents

Description

Electrostatic discharge protection device

The present invention relates to an electrostatic discharge protection device, and more particularly to an electrostatic discharge protection device having a low pass filter.

Electrostatic discharge (ESD) is the main factor affecting the reliability of the integrated circuit. Therefore, the design of the electrostatic discharge protection device is added to the integrated circuit. In addition, as semiconductor process technology advances to deep sub-micron size, existing integrated circuit electronic products must pass component-level and system-level prior to mass production. ESD test. Among them, when the integrated circuit completes the package, the ESD test of the component level is performed first. In addition, system-level ESD testing will be performed further after the integrated circuit is installed in the electronic product.

Electrostatic discharge energy is even more powerful at system level ESD testing. Therefore, most of the existing electrostatic discharge protection devices cannot cause the integrated circuit to pass the system level ESD test, thereby reducing the reliability of the integrated circuit.

The present invention provides an electrostatic discharge protection device that uses a low pass filter to direct an electrostatic signal such that the integrated circuit passes the system level ESD test.

The electrostatic discharge protection device of the present invention comprises a protection circuit, a first resistor and a low pass filter. The protection circuit includes a first component and a second component. The first component and the second component are connected in series between the power supply wiring and the ground wiring, and the first component and the second component have a connection node. The low pass filter, the protection circuit and the first resistor are connected in series between the input pad and the internal circuit.

Based on the above, the electrostatic discharge protection device of the present invention is provided with a low-pass filter and can guide the electrostatic signal to the ground wiring through the low-pass filter. Thereby, the electrostatic discharge protection device can cause the integrated circuit to pass the system level ESD test, thereby improving the reliability of the integrated circuit.

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

1 is a circuit diagram of an electrostatic discharge protection device in accordance with an embodiment of the present invention. Referring to FIG. 1, the electrostatic discharge protection device 100 is applied to an integrated circuit, and the integrated circuit includes an input pad 101 and an internal circuit 102. The internal circuit 102 can receive an input signal through the input pad 101, and the internal circuit 102 includes an input buffer composed of a PMOS transistor M11 and an NMOS transistor M12. In addition, the electrostatic discharge protection device 100 is used to prevent damage to the internal circuit 102 caused by electrostatic signals from the input pad 101.

The electrostatic discharge protection device 100 includes a protection circuit 110, a resistor 120, and a low pass filter 130. The low pass filter 130, the protection circuit 110 and the resistor 120 are connected in series between the input pad 101 and the internal circuit 102. Further, the protection circuit 110 includes a first element 111 and a second element 112. The first element 111 and the second element 112 are connected in series between the power supply line L11 and the ground line L12, and the first element 111 and the second element 112 have a connection node N1.

In an embodiment, as shown in FIG. 1, the first element 111 can be, for example, a diode D1, and the second element 112 can be, for example, an NMOS transistor M1. In addition, the cathode of the diode D1 is electrically connected to the power supply wiring L11, and the anode of the diode D1 is electrically connected to the connection node N1. The gate of the NMOS transistor M1 is electrically connected to the ground connection L1, and the gate of the NMOS transistor M1 is electrically connected to the ground line L12, and the source of the NMOS transistor M1 is electrically connected to the ground line L12.

The low pass filter 130 has an input terminal IN1 and an output terminal OUT1. In addition, the input terminal IN1 of the low-pass filter 130 is electrically connected to the input pad 101, and the output terminal OUT1 of the low-pass filter 130 is electrically connected to the drain of the NMOS transistor M1 and the first end of the resistor 120. Furthermore, the second end of the resistor 120 is electrically connected to the internal circuit 102. In an embodiment, as shown in FIG. 1, the low pass filter 130 includes a resistor R12 and a capacitor C1. The resistor R12 is electrically connected between the input terminal IN1 and the output terminal OUT1 of the low-pass filter 130. The first end of the capacitor C1 is electrically connected to the output terminal OUT1 of the low-pass filter 130, and the second end of the capacitor C1 is electrically connected to the ground line L12.

When the internal circuit 102 operates normally, the power supply wiring L11 and the ground wiring L12 are respectively used to transmit the power supply voltage VDD and the ground voltage GND, and the internal circuit 102 can receive the input signal through the input pad 101. On the other hand, when an electrostatic event occurs, that is, when an electrostatic signal is applied to the input pad 101, the electrostatic signal is equivalent to a high frequency signal, so the low pass filter 130 can be used to filter out the electrostatic signal. In addition to this, the first element 111 in the protection circuit 110 can provide a discharge path that is conducted to the power supply wiring L11, and the second element 112 in the protection circuit 110 can provide a discharge path that is conducted to the ground wiring L12. Therefore, when an electrostatic event occurs, a large amount of electrostatic signals can be guided to the ground wiring L12 through the low-pass filter 130, and the remaining electrostatic signals can be guided to the power wiring L11 or the ground wiring L12 through the protection circuit 110. In addition, the resistor 120 can be used to block electrostatic signals from flowing into the internal circuit 102.

As a result, the electrostatic discharge protection device 100 can prevent the internal circuit 102 from being damaged by the electrostatic signal from the input pad 101. It is worth noting that when an electrostatic event occurs, the low pass filter 130 can direct a large amount of electrostatic signals to the ground wiring L12. Therefore, the ESD protection device 100 can withstand electrostatic signals that meet the ESD test standards of the system level. In other words, in application, the ESD protection device 100 will cause the integrated circuit to pass the system level ESD test, thereby improving the reliability of the integrated circuit.

For example, FIG. 2 is a schematic diagram of simulation of an ESD protection device under system-level ESD testing according to an embodiment of the invention. In FIG. 2, the integrated circuit to which the electrostatic discharge protection device 100 is applied further includes a pad 210. The input pads 101 and the pads 210 are respectively used to receive the input voltages VD21 and VD22, and the inductors L21-L22 and R21-R22 are used to represent the equivalent circuits of the input voltages VD21 and VD22. In addition, the ESD generator 220 is used to generate an electrostatic signal that meets the system level ESD test standard. For example, the ESD generator 220 can, for example, generate an electrostatic signal in accordance with the IEC61000-4-2 standard.

It is worth mentioning that the integrated circuit is installed in the electronic product before the system level ESD test. In addition, during the actual test, the ESD gun can be used to test the discharge of any gap or opening in the electronic product, and the reliability of the electronic product can be evaluated according to the degree of influence of the electronic product. In contrast, in circuit simulation, the FIG. 2 embodiment utilizes the coupling effect between the ESD generator 220 and the two pads 101 and 210 to simulate the actual test environment.

Specifically, a parasitic capacitance C2 can be generated between the input pad 101 and the pad 210. When the ESD generator 220 generates an electrostatic signal, the pad 210 will receive an electrostatic signal, and the electrostatic signal from the pad 210 can be coupled to the input pad 101 via the parasitic capacitance C2. Further, when an electrostatic signal appears on the input pad 101, the capacitance C1 in the low pass filter 130 corresponds to a short circuit. Thereby, a large amount of electrostatic signals can be guided to the ground wiring L12 through the low-pass filter 130, and the remaining electrostatic signals can be guided to the power wiring L11 or the ground wiring L12 through the protection circuit 110. Thereby, the electrostatic discharge protection device 100 can cause the integrated circuit to pass the ESD test of the system level, thereby improving the reliability of the integrated circuit.

It should be noted that although the embodiment of FIG. 1 cites the connection patterns of the protection circuit 110, the resistor 120 and the low-pass filter 130, it is not intended to limit the present invention. A person skilled in the art can serially connect the protection circuit 110, the resistor 120 and the low-pass filter 130 between the input pad 101 and the internal circuit 102 in an arbitrary arrangement according to the design requirements.

For example, FIG. 3 is a circuit diagram of an electrostatic discharge protection device according to another embodiment of the present invention. The electrostatic discharge protection device 300 illustrated in FIG. 3 is similar to the electrostatic discharge protection device 100 illustrated in FIG. The main difference from FIG. 1 is that the low pass filter 330 in FIG. 3 is electrically connected between the protection circuit 110 and the resistor 120.

Specifically, the input terminal IN1 of the low-pass filter 330 is electrically connected to the drain of the NMOS transistor M1 and the input pad 101, and the output terminal OUT1 of the low-pass filter 330 is electrically connected to the first end of the resistor 120. In addition, the second end of the resistor 120 is electrically connected to the internal circuit 102. Similar to the embodiment of FIG. 1, when an electrostatic signal is generated on the input pad 101, the low-pass filter 330 can guide a large amount of electrostatic signals to the ground wiring L12, and the remaining electrostatic signals can be guided to the power supply through the protection circuit 110. Wiring L11 or ground wiring L12. Thereby, the electrostatic discharge protection device 300 can cause the integrated circuit to pass the ESD test of the system level, thereby improving the reliability of the integrated circuit.

4 is a circuit diagram of an electrostatic discharge protection device according to still another embodiment of the present invention. The electrostatic discharge protection device 400 illustrated in FIG. 4 is similar to the electrostatic discharge protection device 100 illustrated in FIG. The main difference from FIG. 1 is that the resistor 420 in FIG. 4 is electrically connected between the input pad 101 and the protection circuit 110, and the low-pass filter 430 in FIG. 4 is electrically connected to the protection circuit 110. Between internal circuits 102.

Specifically, the first end of the resistor 420 is electrically connected to the input pad 101. The input terminal IN1 of the low-pass filter 430 is electrically connected to the second end of the resistor 420 and the drain of the NMOS transistor M1, and the output terminal OUT1 of the low-pass filter 430 is electrically connected to the internal circuit 102. Similar to the embodiment of FIG. 1, when an electrostatic signal is generated on the input pad 101, the low-pass filter 430 can guide a large amount of electrostatic signals to the ground wiring L12, and the remaining electrostatic signals can be guided to the power supply through the protection circuit 110. Wiring L11 or ground wiring L12. Thereby, the electrostatic discharge protection device 400 can cause the integrated circuit to pass the ESD test of the system level, thereby improving the reliability of the integrated circuit.

Moreover, although the embodiment of FIG. 1 exemplifies the implementation of the low pass filter 130, it is not intended to limit the invention. For example, in an embodiment, the low-pass filter 130 includes a capacitor, and the first end of the capacitor is electrically connected to the input terminal IN1 and the output terminal OUT1 of the low-pass filter 130, and the capacitor is The two ends are electrically connected to the ground wiring L12. In other words, with respect to the embodiments of Figures 1, 3, and 4, those skilled in the art can remove the resistor R12 in the low pass filters 130, 330, and 430 according to the design requirements, and only use the capacitor C1. Low pass filters 130, 330 and 430.

Furthermore, FIG. 5 is a circuit diagram of an electrostatic discharge protection device according to still another embodiment of the present invention. The electrostatic discharge protection device 500 illustrated in FIG. 5 is similar to the electrostatic discharge protection device 100 illustrated in FIG. The main difference from FIG. 1 is that the low pass filter 530 in FIG. 5 further includes a Zener diode ZD5.

Specifically, the cathode of the Zener diode ZD5 is electrically connected to the first end of the resistor R12, and the anode of the Zener diode ZD5 is electrically connected to the ground wiring L12. Therefore, when the input pad 101 has an electrostatic signal, the low-pass filter 530 can guide the electrostatic signal to the grounding line L12 by using the capacitor C1, and can also guide the electrostatic signal to the ground by using the Zener diode ZD5. Wiring L12. In other words, the low pass filter 530 can use the Zener diode ZD5 to increase the discharge path for guiding the electrostatic signals, thereby filtering out more electrostatic signals. In addition to this, the Zener diode ZD5 has a low breakdown voltage, so that the reaction speed of the electrostatic discharge protection device 500 can be accelerated.

It is worth mentioning that in another embodiment, the cathode and the anode of the Zener diode ZD5 can also be electrically connected to the second end of the resistor R12 and the ground wiring L12, respectively, and the Zener diode at this time. ZD5 can also be used to guide electrostatic signals. In addition, in the teachings of the embodiment of FIG. 5, a person skilled in the art can separately set a Zener diode ZD5 in the low pass filters 330 and 430 according to the design requirements to enhance the electrostatic discharge protection devices 300 and 400. The speed of the reaction.

FIG. 6 is a circuit diagram of an electrostatic discharge protection device according to another embodiment of the present invention. The electrostatic discharge protection device 600 illustrated in FIG. 6 is similar to the electrostatic discharge protection device 100 illustrated in FIG. The main difference from FIG. 1 is that the electrostatic discharge protection device 600 in FIG. 6 further includes a Zener diode ZD6.

Specifically, the integrated circuit to which the electrostatic discharge protection device 600 is applied further includes a pad 610. In addition, the cathode of the Zener diode ZD6 is electrically connected to the pad 610, and the anode of the Zener diode ZD6 is electrically connected to the ground wiring L12. Therefore, when the solder pad 610 has an electrostatic signal, the Zener diode ZD6 can first guide the electrostatic signal to the ground wiring L12. As a result, the electrostatic signal coupled to the input pad 101 through the parasitic capacitance C6 can be greatly reduced, and the protection capability of the ESD protection device 600 can be further improved. In other words, in the teachings of the embodiment of FIG. 6, those skilled in the art can set corresponding Zener diodes for the pads in the integrated circuit according to the design requirements, so as to further improve the protection of the electrostatic discharge protection device. ability.

In summary, the electrostatic discharge protection device of the present invention is provided with a low pass filter. Thereby, the electrostatic discharge protection device can guide a large amount of electrostatic signals to the ground wiring through the low-pass filter. Therefore, the ESD protection device can withstand electrostatic signals that meet the system-level ESD test standards. In other words, in application, the ESD protection device can cause the integrated circuit to pass the system level ESD test, thereby improving the reliability of the integrated circuit.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the present invention, and any one of ordinary skill in the art can make some changes and refinements without departing from the spirit and scope of the present invention. The scope of the invention is defined by the scope of the appended claims.

100, 300, 400, 500, 600‧‧‧ Electrostatic discharge protection devices
110‧‧‧Protection circuit
111‧‧‧ first component
112‧‧‧second component
120, R11, R12, R21, R22, 420‧‧‧ resistance
130, 330, 430, 530‧‧‧ low pass filter
Input of the IN1‧‧‧ low-pass filter
Output of OUT1‧‧‧ low-pass filter
D1‧‧‧ diode
C1‧‧‧ capacitor
M1, M12‧‧‧ NMOS transistor
M11‧‧‧ PMOS transistor
101‧‧‧Input pad
102‧‧‧Internal circuits
N1‧‧‧ connection node
L11‧‧‧Power Wiring
L12‧‧‧ Grounding Wiring
VDD‧‧‧Power supply voltage
GND‧‧‧ Grounding voltage
210, 610‧‧‧ solder pads
220‧‧‧ESD Generator
VD21, VD22‧‧‧ input voltage
L21, L22‧‧‧ inductance
C2, C6‧‧‧ parasitic capacitance
ZD5, ZD6‧‧‧ Zener diode

1 is a circuit diagram of an electrostatic discharge protection device in accordance with an embodiment of the present invention. 2 is a schematic diagram of simulation of an electrostatic discharge protection device under system ESD test according to an embodiment of the invention. 3 is a circuit diagram of an electrostatic discharge protection device according to another embodiment of the present invention. 4 is a circuit diagram of an electrostatic discharge protection device according to still another embodiment of the present invention. FIG. 5 is a circuit diagram of an electrostatic discharge protection device according to still another embodiment of the present invention. FIG. 6 is a circuit diagram of an electrostatic discharge protection device according to another embodiment of the present invention.

100‧‧‧Electrostatic discharge protection device

110‧‧‧Protection circuit

111‧‧‧ first component

112‧‧‧second component

120, R11, R12‧‧‧ resistance

130‧‧‧Low-pass filter

Input of the IN1‧‧‧ low-pass filter

Output of OUT1‧‧‧ low-pass filter

D1‧‧‧ diode

C1‧‧‧ capacitor

M1, M12‧‧‧ NMOS transistor

M11‧‧‧ PMOS transistor

101‧‧‧Input pad

102‧‧‧Internal circuits

N1‧‧‧ connection node

L11‧‧‧Power Wiring

L12‧‧‧ Grounding Wiring

VDD‧‧‧Power supply voltage

GND‧‧‧ Grounding voltage

Claims (10)

An ESD protection device includes: a protection circuit comprising a first component and a second component, wherein the first component and the second component are connected in series between a power supply wiring and a ground wiring, the first Between the device and the second component, the first component is a diode, the diode is electrically connected between the power wiring and the connection node, and the second component is an NMOS transistor. The gate of the NMOS transistor is electrically connected to the connection node, and the gate of the NMOS transistor is electrically connected to the ground wiring through a second resistor, and the source of the NMOS transistor is electrically connected to the ground wiring; a first resistor; and a low pass filter, wherein the low pass filter, the protection circuit and the first resistor are connected in series between an input pad and an internal circuit. The electrostatic discharge protection device of claim 1, wherein the input end of the low pass filter is electrically connected to the input pad, and the output end of the low pass filter is electrically connected to the drain of the NMOS transistor. And the first end of the first resistor, the second end of the first resistor is electrically connected to the internal circuit. The electrostatic discharge protection device of claim 1, wherein the input end of the low pass filter is electrically connected to the drain of the NMOS transistor and the input pad, and the output end of the low pass filter is electrically Connecting the first end of the first resistor, the second end of the first resistor is electrically connected to the internal circuit. The electrostatic discharge protection device of claim 1, wherein the first end of the first resistor is electrically connected to the input pad, and the input end of the low pass filter The second end of the first resistor is electrically connected to the drain of the NMOS transistor, and the output end of the low pass filter is electrically connected to the internal circuit. The ESD protection device of claim 1, wherein the low pass filter has an input end and an output end, and the low pass filter comprises: a second resistor electrically connected to the low pass filter The input end and the output end of the capacitor; and a capacitor, the first end of which is electrically connected to the output end of the low pass filter, and the second end of the capacitor is electrically connected to the ground wiring. The electrostatic discharge protection device of claim 5, wherein the low-pass filter further comprises: a Zener diode, the cathode of which is electrically connected to the first end or the second end of the second resistor, The anode of the Zener diode is electrically connected to the ground wiring. The ESD protection device of claim 1, wherein the low pass filter has an input end and an output end, and the low pass filter comprises: a capacitor, the first end of which is electrically connected to the low pass An input end and an output end of the filter, and the second end of the capacitor is electrically connected to the ground wiring. The electrostatic discharge protection device of claim 1, wherein the electrostatic discharge protection device is suitable for an integrated circuit, the integrated circuit includes the input pad, the internal circuit and a pad, and the electrostatic discharge The protection device further includes a Zener diode, wherein a cathode of the Zener diode is electrically connected to the pad, and an anode of the Zener diode is electrically connected to the ground wiring. An electrostatic discharge protection device comprising: A protection circuit includes a first component and a second component, wherein the first component and the second component are connected in series with each other between a power supply wiring and a ground wiring, and the first component and the second component are a connection node; a first resistor; and a low pass filter, wherein the low pass filter, the protection circuit and the first resistor are connected in series between an input pad and an internal circuit, the low The pass filter has an input end and an output end, and the low pass filter comprises: a second resistor electrically connected between the input end and the output end of the low pass filter; and a capacitor, the first end thereof The output end of the low pass filter is electrically connected, and the second end of the capacitor is electrically connected to the ground wiring. An ESD protection device includes: a protection circuit comprising a first component and a second component, wherein the first component and the second component are connected in series between a power supply wiring and a ground wiring, and the a connection node between the component and the second component; a first resistor; and a low pass filter, wherein the low pass filter, the protection circuit and the first resistor are connected in series with each other on an input pad Between an internal circuit, the low-pass filter has an input end and an output end, and the low-pass filter includes: a capacitor, the first end of which is electrically connected to the input end and the output end of the low pass filter, The second end of the capacitor is electrically connected to the ground wiring.