Electrostatic discharge protection system

Abstract

The electrostatic discharge protection system includes an antenna, an electronic device, and an electrostatic discharge protection circuit. The antenna is used for receiving a wireless signal. The electronic device is coupled to the antenna and is used for receiving a wireless signal through the antenna. The electrostatic discharge protection circuit is coupled to the electronic device and is used for releasing electrostatic energy. The electrostatic discharge protection circuit includes a forward electrostatic discharge circuit and a reverse electrostatic discharge circuit. The forward electrostatic discharge circuit comprises at least one first electrostatic discharge unit formed by connecting at least one first diode and a first capacitor in parallel. The reverse electrostatic discharge circuit comprises at least one second electrostatic discharge unit formed by connecting at least one second diode and a second capacitor in parallel. The forward electrostatic discharge circuit and the reverse electrostatic discharge circuit are coupled to a ground terminal.

Description

Technical Field

[0001] This invention discloses an electrostatic discharge protection system, and more particularly relates to an electrostatic discharge protection system with high operational linearity. Background Technology

[0002] With the rapid advancement of technology and the increasing sophistication of electronic products, modern electronic components are becoming smaller and smaller, resulting in lower tolerance to static electricity. Static charge can be released rapidly in a short time. This sudden voltage spike can damage electronic components and even cause equipment malfunction. For example, during the manufacturing or testing of electronic components, electrostatic discharge energy can cause component damage, short circuits, or even open circuits. The impact of electrostatic discharge is particularly significant for the miniature chips within electronic products, ranging from minor performance degradation to complete chip breakage.

[0003] Electrostatic discharge (ESD) poses a significant challenge to electronic product manufacturing and testing, but it is not insurmountable. By employing effective ESD control measures and protection circuits, combined with process optimization and inspection / repair, the impact of ESD on electronic products can be effectively reduced, improving product yield and reliability. However, ESD protection circuits are additional circuitry; therefore, the components within them may affect the operational linearity of the electronic product. For example, when the operational linearity of an electronic product is reduced due to the influence of the ESD protection circuit, it will lead to decreased output performance.

[0004] Therefore, developing an electrostatic discharge protection circuit that does not affect the operational linearity of electronic products is an important design issue. Summary of the Invention

[0005] An embodiment of the present invention provides an electrostatic discharge (ESD) protection system. The ESD protection system includes an antenna, an electronic device, and an ESD protection circuit. The antenna is used to receive wireless signals. The electronic device is coupled to the antenna and used to receive wireless signals through the antenna. The ESD protection circuit, coupled to the electronic device, is used to release electrostatic energy. The ESD protection circuit includes a forward ESD circuit and a reverse ESD circuit. The forward ESD circuit includes at least one first ESD unit composed of at least one first diode and a first capacitor connected in parallel. The reverse ESD circuit includes at least one second ESD unit composed of at least one second diode and a second capacitor connected in parallel. The forward and reverse ESD circuits are coupled to a ground terminal. Attached Figure Description

[0006] Figure 1 This is a block diagram of an embodiment of the electrostatic discharge protection system of the present invention.

[0007] Figure 2for Figure 1 The first embodiment of the electrostatic discharge protection circuit in the electrostatic discharge protection system is shown in the diagram.

[0008] Figure 3 for Figure 1 The diagram shows the architecture of the first electrostatic discharge unit within the electrostatic discharge protection circuit of the electrostatic discharge protection system.

[0009] Figure 4 for Figure 1 The diagram shows the architecture of the second electrostatic discharge unit within the electrostatic discharge protection circuit of the electrostatic discharge protection system.

[0010] Figure 5 for Figure 1 The diagram shows the architecture of the second embodiment of the electrostatic discharge protection circuit in the electrostatic discharge protection system.

[0011] Figure 6 for Figure 1 The diagram shows the architecture of the third embodiment of the electrostatic discharge protection circuit in the electrostatic discharge protection system.

[0012] Figure 7 for Figure 1 The diagram shows the architecture of the fourth embodiment of the electrostatic discharge protection circuit in the electrostatic discharge protection system.

[0013] Figure 8 for Figure 1 A schematic diagram of the power gain function corresponding to different capacitors in an electrostatic discharge protection system.

[0014] Figure 9 for Figure 1 A schematic diagram of the power gain function corresponding to different numbers of electrostatic discharge units in an electrostatic discharge protection system.

[0015] [Symbol Explanation]

[0016] 100: Electrostatic Discharge Protection System

[0017] 10: Antenna

[0018] 11, 11a, 11b, 11c: Electrostatic discharge protection circuit

[0019] 12: Electronic devices

[0020] L1 and L2: Current paths

[0021] GND: Ground terminal

[0022] F_D1_1 to FD1_M, FD1 to FDN: First transistor

[0023] FC1', FC1 to FCN: First capacitor

[0024] F_U1a', F_U1', FU_1 to FU_N: First electrostatic discharge unit

[0025] B_D1_1 to BD1_M, BD1 to BDN: Second transistor

[0026] BC1', BC1 to BCN: Second capacitor

[0027] B_U1a', B_U1', B_U2', BU_1 to BU_N: Second electrostatic discharge unit

[0028] FP: Forward electrostatic discharge current

[0029] BP: Reverse electrostatic discharge current

[0030] R1 to R4, P1 to P4: Basic power gain function

[0031] R11 to R14, P11 to P14: Harmonic power gain function Detailed Implementation

[0032] Figure 1This is a block diagram of an embodiment of the electrostatic discharge protection system 100 of the present invention. The electrostatic discharge protection system includes an antenna 10, an electrostatic discharge protection circuit 11, and an electronic device 12. The antenna 10 is used to receive wireless signals. The electronic device 12 is coupled to the antenna 10 and is used to receive wireless signals through the antenna 10. The electronic device 12 can be any electronic product capable of receiving external energy, or a device under test (DUT). The electrostatic discharge protection circuit 11 is coupled to the electronic device 12 and is used to release electrostatic energy. It should be understood that electrostatic discharge (ESD) refers to the phenomenon of static charge being suddenly released through an insulator or air medium in a very short time. Because static charge can be released rapidly in a short time, this sudden voltage spike may damage the electronic device 10 or even cause equipment failure. Therefore, the electrostatic discharge protection circuit 11 of the electrostatic discharge protection system 100 can conduct most of the electrostatic energy. In other words, when electrostatic energy is absent, the electrostatic discharge protection circuit 11 will not activate, and the wireless signal received by the antenna 10 will be transmitted to the electronic device through the current path L1. However, when electrostatic discharge results in extremely high electrostatic energy, the electrostatic energy can be discharged to the ground terminal GND through the current path L2 to protect the electronic device from damage. Since electrostatic discharge can occur in the form of positive or negative voltage, the electrostatic discharge protection circuit 11 may include forward electrostatic discharge circuits and reverse electrostatic discharge circuits to simultaneously prevent either positive or negative electrostatic energy from damaging the electronic device 10.

[0033] In the electrostatic discharge (ESD) protection system 100, the forward ESD circuit of the ESD protection circuit 11 includes at least one first ESD unit consisting of at least one first diode and a first capacitor connected in parallel. Similarly, the reverse ESD circuit includes at least one second ESD unit consisting of at least one second diode and a second capacitor connected in parallel. The forward and reverse ESD circuits are coupled to the ground terminal GND. Since the ESD unit in the ESD protection system 100 is composed of "at least one diode" and "capacitor" connected in parallel, the capacitance value of the ESD unit is equal to the sum of the capacitance value of the capacitor and the equivalent capacitance value of at least one diode. In other words, when the capacitance value of the capacitor is much larger than the equivalent capacitance value of at least one diode, the capacitance value of the ESD unit is hardly affected by changes in the equivalent capacitance of the diode. Therefore, in the ESD protection system 100, the ESD protection circuit 11 hardly affects the operational linearity of the electronic device 12. The circuit details of the ESD protection circuit 11 are described in detail below.

[0034] Figure 2This is an architectural diagram of the first embodiment of the electrostatic discharge protection circuit 11 in the electrostatic discharge protection system 100. Figure 2 In the electrostatic discharge protection circuit 11, the forward electrostatic discharge circuit may include N first electrostatic discharge units F_U1 to F_UN connected in series. The reverse electrostatic discharge circuit includes N second electrostatic discharge units B_U1 to B_UN connected in series, where N is a positive integer. In other words, in Figure 2 In the electrostatic discharge protection circuit 11, the N first electrostatic discharge units F_U1 to F_UN have identical structures and are coupled in series. The N second electrostatic discharge units B_U1 to B_UN of the electrostatic discharge protection circuit 11 also have identical structures and are coupled in series. Furthermore, in each of the N series-connected first electrostatic discharge units F_U1 to F_UN, each first electrostatic discharge unit includes a first diode and a first capacitor connected in parallel with it. For example, the first diode FD1 of the first electrostatic discharge unit F_U1 includes an anode coupled to a first terminal of the first capacitor FC1 and a cathode coupled to a second terminal of the first capacitor FC1. Similarly, in each of the N series-connected second electrostatic discharge units B_U1 to B_UN, each second electrostatic discharge unit includes a second diode and a second capacitor connected in parallel with it. For example, the second diode BD1 of the second electrostatic discharge unit B_U1 includes an anode coupled to a second terminal of the second capacitor BC1 and a cathode coupled to a first terminal of the second capacitor BC1. Figure 2 In the circuit structure, the first capacitance value of the first capacitor is much larger than the first equivalent capacitance value of the first diode. Similarly, the second capacitance value of the second capacitor is much larger than the second equivalent capacitance value of the second diode. For example, the first capacitance value C... CAP With the first equivalent capacitance value C ESD It can be the following relationships:

[0035]

[0036] From the above equation, in the first electrostatic discharge unit, the total capacitance is equal to C. CAP +C ESD If C CAP >>C ESD The total capacitance will be reduced by the first capacitance value C. CAP The first equivalent capacitance value C of the first diode is determined by the dominant factor. ESD The change in capacitance C can be ignored. Furthermore, since the total capacitance C... CAP +C ESD It is less affected by voltage fluctuations, so its partial derivative with respect to voltage is close to zero. Therefore, the circuit structure of the first electrostatic discharge unit has almost no impact on the operational linearity of the electronic device 12. Similarly, the circuit structure of the second electrostatic discharge unit has almost no impact on the operational linearity of the electronic device 12. Furthermore, when the first capacitance value C... CAP With the first equivalent capacitance value CESD When the ratio of the first capacitance value to the second equivalent capacitance value increases (for forward electrostatic discharge), or when the ratio of the second capacitance value to the second equivalent capacitance value increases (for reverse electrostatic discharge), the electrostatic discharge protection circuit 11 will generate a small amount of harmonic power gain interference. In one embodiment, the first capacitance value C CAP With the first equivalent capacitance value C ESD The ratio can be within the following range:

[0037]

[0038] Furthermore, the frequency range of the wireless signal can be from 0 to 100 gigahertz (GHz), and the first capacitance value C CAP With the first equivalent capacitance value C ESD The operating bias voltage is 0V (volts). Based on the above ratio range, the total capacitance value C in the first electrostatic discharge unit is... TOTAL This is equivalent to setting the first capacitance value C CAP With the first equivalent capacitance value C ESD Adding them together, the total capacitance value C of the first electrostatic discharge unit is... TOTAL The range can be represented as:

[0039] 11×C ESD <C TOTAL ≤10001×C ESD

[0040] In one embodiment, the first capacitance value C CAP It is the first equivalent capacitance value C ESD One hundred times. Similarly, the second capacitance value is one hundred times the second equivalent capacitance value. However, the ratio of the "capacitance value (first capacitance value or second capacitance value)" to the "equivalent capacitance value (first equivalent capacitance value or second equivalent capacitance value)" in this invention is not limited to the above embodiments. Any reasonable design of the capacitance value and the equivalent capacitance value is within the scope of this invention. Furthermore, when static electricity occurs in the form of a positive voltage, the forward electrostatic discharge circuit can utilize the path of the forward electrostatic discharge current FP to conduct the positive voltage static energy to the ground terminal GND. Similarly, when static electricity occurs in the form of a negative voltage, the reverse electrostatic discharge circuit can utilize the path of the reverse electrostatic discharge current BP to compensate for the negative voltage static energy at the ground terminal GND. Therefore, the electronic device 12 can be protected.

[0041] Figure 3This is a schematic diagram of the architecture of the first electrostatic discharge unit within the electrostatic discharge protection circuit 11 of the electrostatic discharge protection system 100. As mentioned above, the architecture of the first electrostatic discharge unit within the electrostatic discharge protection circuit 11 can be composed of a first diode and a first capacitor connected in parallel with it. However, the architecture of the first electrostatic discharge unit within the electrostatic discharge protection circuit 11 can also be... Figure 3 The circuit architecture. In Figure 3 In the first electrostatic discharge unit F_U1', a first diode string (composed of M series-connected first diodes FD1_1 to FD1_M) and a first capacitor FC1' are included. The input terminal of the first diode string is coupled to the first terminal of the first capacitor FC1'. The output terminal of the first diode string is coupled to the second terminal of the first capacitor FC1'. M is a positive integer. Figure 3 In this circuit, the first diode string consists of M series-connected first diodes FD1_1 to FD1_M. Therefore, the first equivalent capacitance value of the first diode string is equivalent to the equivalent capacitance value of the M series-connected first diodes FD1_1 to FD1_M. Similarly, the first capacitance value of the first capacitor is much larger than the first equivalent capacitance value of the first diode string. When the ratio of the first capacitance value to the first equivalent capacitance value increases, the electrostatic discharge protection circuit 11 will generate a smaller harmonic power gain interference. Furthermore, when static electricity appears in the form of a positive voltage, the forward electrostatic discharge circuit can utilize the path of the forward electrostatic discharge current FP to conduct the positive voltage static energy to the ground terminal GND. Therefore, the electronic device 12 can be protected.

[0042] Figure 4 This is a schematic diagram of the architecture of the second electrostatic discharge unit B_U1' within the electrostatic discharge protection circuit of the electrostatic discharge protection system 100. As mentioned above, the architecture of the second electrostatic discharge unit within the electrostatic discharge protection circuit 11 can be composed of a second diode and a second capacitor connected in parallel with it. However, the architecture of the second electrostatic discharge unit within the electrostatic discharge protection circuit 11 can also be... Figure 4 The circuit architecture. In Figure 4 In the second electrostatic discharge unit B_U1', a second diode string (consisting of M series-connected second diodes BD1_1 to BD1_M) and a second capacitor BC1' are included. The input terminal of the second diode string is coupled to the second terminal of the second capacitor BC1'. The output terminal of the second diode string is coupled to the first terminal of the second capacitor BC1'. M is a positive integer. Figure 4In this circuit, the second diode string consists of M second diodes BD1_1 to BD1_M connected in series. Therefore, the second equivalent capacitance value of the second diode string is equivalent to the equivalent capacitance value of the M second diodes BD1_1 to BD1_M connected in series. Similarly, the second capacitance value of the second capacitor is much larger than the second equivalent capacitance value of the second diode string. When the ratio of the second capacitance value to the second equivalent capacitance value increases, the electrostatic discharge protection circuit 11 will generate a smaller harmonic power gain interference. Furthermore, when static electricity appears in the form of a negative voltage, the reverse electrostatic discharge circuit can utilize the path of the reverse electrostatic discharge current BP to compensate for the static energy of the negative voltage at the ground terminal GND. Therefore, the electronic device 12 can be protected.

[0043] Figure 5 This is a schematic diagram of a second embodiment of the electrostatic discharge protection circuit 11a in the electrostatic discharge protection system 100. To avoid confusion, Figure 5 The electrostatic discharge protection circuit is called electrostatic discharge protection circuit 11a. Figure 5 In the context of forward electrostatic discharge circuits, it may include: Figure 2 The structure of the first electrostatic discharge unit shown and Figure 3 The structure of the first electrostatic discharge unit is shown. Furthermore, there are no limitations on its number or specifications. For example, Figure 5 A forward electrostatic discharge circuit may include a first electrostatic discharge unit F_U1', a first electrostatic discharge unit F_UN-1, a first electrostatic discharge unit F_UN, etc. Similarly, a reverse electrostatic discharge circuit may include... Figure 2 The structure of the second electrostatic discharge unit shown and Figure 4 The structure of the second electrostatic discharge unit is shown. Furthermore, there are no limitations on its number or specifications. For example, Figure 5 The reverse electrostatic discharge circuit may include a second electrostatic discharge unit B_U1', a second electrostatic discharge unit B_UN-1, a second electrostatic discharge unit B_UN, etc. Furthermore, the electrostatic discharge protection circuit 11a can be varied in various embodiments. For example, the electrostatic discharge protection circuit 11a can use multiple such... Figure 3 The structure of the first electrostatic discharge unit shown is connected in series to form a forward electrostatic discharge circuit, and multiple such... Figure 4 The structure of the second electrostatic discharge unit shown is connected in series to form a reverse electrostatic discharge circuit. Multiple electrostatic discharge protection circuits 11a can also be used, such as... Figure 3 The structure of the first electrostatic discharge unit shown is connected in series to form a forward electrostatic discharge circuit, and multiple such... Figure 2 The structure of the second electrostatic discharge unit shown is connected in series to form a reverse electrostatic discharge circuit. Various reasonable hardware combinations of the electrostatic discharge protection circuit 11a are within the scope of this invention.

[0044] Figure 6This is an architectural diagram of a third embodiment of the electrostatic discharge protection circuit 11b in the electrostatic discharge protection system 100. To avoid confusion, Figure 6 The electrostatic discharge protection circuit is called electrostatic discharge protection circuit 11b. Figure 6 In the forward electrostatic discharge (ESD) circuit, N first transistors are connected in series. A portion of these N series-connected first transistors are connected in parallel to their respective first capacitors. For example, the forward ESD circuit may include N first transistors FD1 to FDN connected in series. First transistor FD1 is connected in parallel to first capacitor FC1. First transistor FD3 is connected in parallel to first capacitor FC3. Furthermore, when static electricity occurs in the form of a positive voltage, the forward ESD circuit can utilize the path of the forward ESD current FP to conduct the positive voltage static energy to the ground terminal GND. In other words, the forward ESD circuit can reduce its impact on the operational linearity of the electronic device 12 by using only the first ESD units F_U1 and F_U3. Furthermore, in Figure 6 In this reverse electrostatic discharge (ESD) circuit, N second transistors are connected in series. A portion of these N series-connected second transistors are connected in parallel to their respective second capacitors. For example, the reverse ESD circuit may include N series-connected second transistors BD1 to BDN. Second transistor BD3 is connected in parallel to second capacitor BC3. Second transistor BDN is connected in parallel to second capacitor BCN. Furthermore, when static electricity occurs in the form of a negative voltage, the reverse ESD circuit can utilize the path of the reverse ESD current BP to compensate for the negative voltage static energy via the ground terminal GND. In other words, the reverse ESD circuit can reduce its impact on the operational linearity of the electronic device 12 by using only second ESD units B_U3 and B_UN. Moreover, this invention is not subject to... Figure 6 The number and configuration of electrostatic discharge units in the electrostatic discharge protection circuit 11b shown are limited.

[0045] Figure 7 This is a schematic diagram of the fourth embodiment of the electrostatic discharge protection circuit 11c in the electrostatic discharge protection system 100. To avoid confusion, Figure 7 The electrostatic discharge protection circuit is called electrostatic discharge protection circuit 11c. Figure 7 In this circuit, the forward electrostatic discharge circuit includes multiple first transistors connected in series. These multiple first transistors form a first transistor string. At least a portion of the first transistor string is connected in parallel to at least one first capacitor. For example, in... Figure 7In the first transistor string, the first transistors FD1_1 to FD1_4, connected in series, are connected in parallel to the first capacitor FC1' to form the first electrostatic discharge unit F_U1a'. Furthermore, the first transistor FDN is connected in parallel to the first capacitor FCN to form the first electrostatic discharge unit F_UN. When static electricity appears in the form of a positive voltage, the forward electrostatic discharge circuit can utilize the path of the forward electrostatic discharge current FP to conduct the positive voltage static energy to the ground terminal GND. In other words, the forward electrostatic discharge circuit can reduce its impact on the operational linearity of the electronic device 12 by using only the first electrostatic discharge units F_U1a' and F_UN. Furthermore, in Figure 7 In this reverse electrostatic discharge circuit, multiple second transistors connected in series are included. These multiple series-connected second transistors form a second transistor string. At least a portion of the second transistor string is connected in parallel to at least one second capacitor. For example, in... Figure 7 In the second transistor string, the second transistors BC1_2 to BC1_3, connected in series, are connected in parallel to the second capacitor BC2' to form the second electrostatic discharge unit B_U2a'. Furthermore, the second transistor B_UN is connected in parallel to the second capacitor BCN to form the second electrostatic discharge unit B_UN. Moreover, when static electricity appears in the form of a negative voltage, the reverse electrostatic discharge circuit can utilize the path of the reverse electrostatic discharge current BP to compensate for the negative voltage static energy via the ground terminal GND. In other words, the reverse electrostatic discharge circuit can reduce its impact on the operational linearity of the electronic device 12 by using only the second electrostatic discharge units B_U2a' and B_UN. It should be understood that this invention is not intended to be... Figure 7 The electrostatic discharge unit (partial electrostatic discharge unit) in the electrostatic discharge protection circuit 11c shown is... Figure 2 The structure, some of the electrostatic discharge units are Figure 3 or Figure 4 The number and configuration of the structure are limited.

[0046] Figure 8 This is a schematic diagram showing the power gain function corresponding to different capacitors within the electrostatic discharge unit of the electrostatic discharge protection system 100. As mentioned earlier, in Figure 2 In the circuit structure, the first capacitance value of the first capacitor is much larger than the first equivalent capacitance value of the first diode. The second capacitance value of the second capacitor is much larger than the second equivalent capacitance value of the second diode. For simplicity, the example first capacitance value C will be used here. CAP With the first equivalent capacitance value C ESD The power gain function results corresponding to various different ratios. For example... Figure 8As shown, the X-axis represents input power, such as the power input from antenna 10, calculated on a logarithmic scale. The Y-axis represents output power, such as the power output from electrostatic discharge protection circuit 11 to electronic device 12, calculated on a logarithmic scale. The first capacitance value C is used as an example. CAP With the first equivalent capacitance value C ESD Taking various ratios as examples, the power gain functions R1 to R4 are different (C CAP / C ESD The fundamental power gain function. Power gain functions R11 to R14 are different (C CAP / C ESD The harmonic power gain function of ). Figure 8 In the diagram, the power gain function R1 corresponds to C. CAP / C ESD = 0, 1.33, or 10. The power gain function R2 corresponds to C. CAP / C ESD =100. The power gain function R3 corresponds to C. CAP / C ESD =1000. The power gain function R4 corresponds to C. CAP / C ESD =1920. In C CAP / C ESD In a test environment with a capacitance of 1.33, the first capacitance value C CAP A 40fF (femto-Farad) first equivalent capacitance value C can be used. ESD 30fF can be used. In C CAP / C ESD In a test environment with a capacitance of 10, the first capacitance value C CAP A 300fF first equivalent capacitance value C can be used. ESD 30fF can be used. In C CAP / C ESD In a test environment with a capacitance of 100, the first capacitance value C CAP A 3000fF first equivalent capacitance value C can be used. ESD 30fF can be used. In C CAP / C ESD In a test environment with a capacitance of 1000, the first capacitance value C CAP A first equivalent capacitance value of 30000fF can be used, C. ESD 30fF can be used. In C CAP / C ESD In a test environment of 1920, the first capacitance value C CAP A 57600fF capacitor can be used, with a first equivalent capacitance value C. ESDA capacitance of 30fF can be used. Furthermore, the capacitance value setting conditions in the second electrostatic discharge unit of the reverse electrostatic discharge circuit can be the same as those in the first electrostatic discharge unit of the forward electrostatic discharge circuit. Considering both the reverse and forward electrostatic discharge circuits simultaneously, [the following is a possible interpretation based on context:] Figure 8 From this perspective, the fundamental power gain function in C CAP / C ESD =0, 1.33, 10, and 100 show little change. However, in C... CAP / C ESD =1000 and 1920 show attenuation. Furthermore, the power gain function R11 corresponds to C CAP / C ESD = 0, 1.33, or 10. The power gain function R12 corresponds to C. CAP / C ESD =100. The power gain function R13 corresponds to C. CAP / C ESD =1000. The power gain function R14 corresponds to C. CAP / C ESD =1920. By Figure 8 From this perspective, the harmonic power gain function in C CAP / C ESD A significant attenuation occurs when the value is 100. CAP / C ESD When the value is too large, its marginal effect will actually decrease. Therefore, in the electrostatic discharge protection system 100, considering the optimization of the fundamental power gain function and the harmonic power gain function, C can be selected. CAP / C ESD =100 is used as the standard for designing electrostatic discharge protection circuit 11.

[0047] Figure 9 This is a schematic diagram showing the power gain function corresponding to different numbers of electrostatic discharge (ESD) units in the ESD protection system 100. As mentioned earlier, in Figure 2 In the circuit structure, the forward electrostatic discharge circuit of the electrostatic discharge protection circuit 11 may include N first electrostatic discharge units F_U1 to F_UN connected in series. The reverse electrostatic discharge circuit includes N second electrostatic discharge units B_U1 to B_UN connected in series, where N is a positive integer. As N increases, the electrostatic discharge protection circuit 11 can generate smaller harmonic interference, thereby reducing the impact on the operational linearity of the electronic device 12. For example... Figure 9 As shown, the X-axis represents the input power, such as the power input by antenna 10, calculated on a logarithmic scale. The Y-axis represents the output power, such as the power output by electrostatic discharge protection circuit 11 to electronic device 12, calculated on a logarithmic scale. Figure 9 C CAP / CESD =100. In a reverse electrostatic discharge circuit, the number of second electrostatic discharge units connected in series can be set to the same number as the number of first electrostatic discharge units connected in series in a forward electrostatic discharge circuit. When considering both reverse and forward electrostatic discharge circuits simultaneously, such as... Figure 9 As shown, power gain functions P1 to P4 are the fundamental power gain functions for different values ​​of N. Power gain functions P11 to P14 are the harmonic power gain functions for different values ​​of N. Figure 9 In the diagram, power gain functions P1, P2, P3, and P4 almost overlap, corresponding to N=1, N=3, N=5, and N=10 respectively. In other words, changes in N have little impact on the basic power gain function. Furthermore, power gain function P11 corresponds to N=1. Power gain function P12 corresponds to N=3. Power gain function P13 corresponds to N=5. Power gain function P14 corresponds to N=10. Figure 9 As N increases, the harmonic power gain function decreases. Therefore, in the electrostatic discharge protection system 100, a higher number of electrostatic discharge units can more effectively reduce the impact of the electrostatic discharge protection circuit 11 on the operational linearity of the electronic device 12.

[0048] In summary, this invention describes an electrostatic discharge (ESD) protection system, particularly an ESD protection system with high operational linearity. The design concept of the ESD protection system is to minimize the impact of the ESD protection circuit on the operational linearity of electronic devices. The principle is that one or more portions of the diode string in the ESD protection circuit are connected in parallel with at least one or more capacitors. Due to the introduction of at least one or more capacitors, when the capacitance value of these capacitors is significantly larger than the equivalent capacitance of the diode string, the total capacitance of the ESD protection circuit is dominated by them. Therefore, the total capacitance of the ESD protection circuit is almost unaffected by changes in the equivalent capacitance of the diode string. With this design, the ESD protection circuit has virtually no impact on the operational linearity of the electronic device; thus, the ESD protection system of this invention provides high operational linearity.

[0049] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made in accordance with the claims of the present invention shall be within the scope of the present invention.

Claims

1. An electrostatic discharge protection system, comprising: Antenna, used to receive wireless signals; An electronic device, coupled to the antenna, is used to receive the wireless signal through the antenna; and An electrostatic discharge protection circuit, coupled to the electronic device, is used to release electrostatic energy. The electrostatic discharge protection circuit includes a forward electrostatic discharge circuit and a reverse electrostatic discharge circuit. The forward electrostatic discharge circuit includes at least one first electrostatic discharge unit consisting of at least one first diode and a first capacitor connected in parallel, and the reverse electrostatic discharge circuit includes at least one second electrostatic discharge unit consisting of at least one second diode and a second capacitor connected in parallel. The forward electrostatic discharge circuit and the reverse electrostatic discharge circuit are coupled to a ground terminal.

2. The electrostatic discharge protection system as claimed in claim 1, wherein the forward electrostatic discharge circuit comprises N first electrostatic discharge units connected in series, and the reverse electrostatic discharge circuit comprises N second electrostatic discharge units connected in series, and N is a positive integer.

3. The electrostatic discharge protection system as described in claim 2, wherein: In the N series-connected first electrostatic discharge units, the first diode of each first electrostatic discharge unit includes an anode coupled to a first terminal of the first capacitor and a cathode coupled to a second terminal of the first capacitor.

4. The electrostatic discharge protection system as described in claim 2, wherein: In the N series-connected second electrostatic discharge units, the second diode of each second electrostatic discharge unit includes a cathode coupled to a first end of the second capacitor and an anode coupled to a second end of the second capacitor.

5. The electrostatic discharge protection system as described in claim 2, wherein the first capacitance value of the first capacitor is much larger than the first equivalent capacitance value of the first diode, the second capacitance value of the second capacitor is much larger than the second equivalent capacitance value of the second diode, and when N increases, the electrostatic discharge protection circuit generates smaller harmonic interference to reduce the impact on the operational linearity of the electronic device.

6. The electrostatic discharge protection system as described in claim 5, wherein the ratio of the first capacitance value to the first equivalent capacitance value is: C CAP This is the value of the first capacitance, C. ESD The first equivalent capacitance value is the first equivalent capacitance value, the frequency range of the wireless signal is 0 to 100 gigahertz (GHz), and the operating bias voltage of the first capacitance value and the first equivalent capacitance value is 0 volts.

7. The electrostatic discharge protection system as described in claim 1, wherein: The first electrostatic discharge unit includes a first diode string and a first capacitor. The input terminal of the first diode string is coupled to the first terminal of the first capacitor, and the output terminal of the first diode string is coupled to the second terminal of the first capacitor. The first diode string includes M first diodes connected in series, where M is a positive integer.

8. The electrostatic discharge protection system as described in claim 7, wherein the first capacitance value of the first capacitor is much larger than the first equivalent capacitance value of the first diode string, and when the ratio of the first capacitance value to the first equivalent capacitance value increases, the electrostatic discharge protection circuit generates a small harmonic power gain interference.

9. The electrostatic discharge protection system as described in claim 1, wherein: The second electrostatic discharge unit includes a second diode string and a second capacitor. The input terminal of the second diode string is coupled to the second terminal of the second capacitor, and the output terminal of the second diode string is coupled to the first terminal of the second capacitor. The second diode string includes M first diodes connected in series, where M is a positive integer.

10. The electrostatic discharge protection system as claimed in claim 9, wherein the second capacitance value of the second capacitor is much larger than the second equivalent capacitance value of the second diode string, and when the ratio of the second capacitance value to the second equivalent capacitance value increases, the electrostatic discharge protection circuit generates a small harmonic power gain interference.

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