Radio frequency switch protection circuit, radio frequency front-end circuit and electronic device

Abstract

The application discloses a radio frequency switch protection circuit, a radio frequency front-end circuit and electronic equipment. The radio frequency switch protection circuit is applied to the radio frequency front-end circuit; the radio frequency front-end circuit comprises a radio frequency switch module which is arranged on a radio frequency signal transmission path and has a gate control node; the radio frequency switch protection circuit comprises an induction module which is coupled with the gate control node and is used for sensing voltage change of the gate control node; a current leakage module which has a control end coupled with the induction module, a first end coupled with the gate control node and a second end grounded; and a voltage division module which is coupled between the control end of the current leakage module and the ground; when the voltage of the gate control node changes overloading, the induction module forms a control voltage on the voltage division module according to the sensed voltage change, the control voltage makes the current leakage module conduct, and thus overloading current at the gate control node is discharged to the ground through the current leakage module.

Description

Technical Field

[0001] This application relates to the field of semiconductor technology, specifically to a radio frequency switch protection circuit, a radio frequency front-end circuit, and an electronic device. Background Technology

[0002] With the development of wireless communication technology, radio frequency (RF) switches play a crucial role in wireless communication systems. They are used to switch signals between different circuit paths (e.g., switching between receive and transmit modes) or to distribute signals between different antenna and receiver circuits. Currently, the performance requirements for RF switches are becoming increasingly stringent, and their rapid switching capabilities are essential for improving communication efficiency, reducing power consumption, and enhancing user experience.

[0003] Currently, the industry standard practice is to incorporate gate protection diodes in RF switches (such as RF FET stacks) to prevent damage from overvoltage. However, in complex applications involving high frequency, high power, and rapid switching, gate protection diodes are prone to performance degradation, leading to decreased reliability of the RF switch. Furthermore, gate protection diodes are highly sensitive to static voltage. During normal operation of the RF switch, even small voltage fluctuations (such as substrate ripple voltage caused by RF signals) can easily cause the gate protection diode to mis-conduct, introducing additional parasitic leakage paths into the RF main circuit and thus affecting the overall linearity performance of the RF switch.

[0004] Therefore, a solution is needed to address the above issues. Summary of the Invention

[0005] The purpose of this application is to provide a radio frequency switch protection circuit, a radio frequency front-end circuit, and an electronic device to solve the problems that existing radio frequency switches are prone to performance degradation of the gate protection diode during high voltage protection, resulting in reduced reliability, and are also prone to parasitic effects caused by accidental conduction, leading to poor linearity of the radio frequency switch.

[0006] According to a first aspect of this application, an embodiment of this application provides a radio frequency switch protection circuit applied to a radio frequency front-end circuit, the radio frequency front-end circuit including: a radio frequency switch module disposed on a radio frequency signal transmission path, the radio frequency switch module having a gate control node; The radio frequency switch protection circuit includes: A sensing module, coupled to the gate control node, is used to sense voltage changes in the gate control node; A current-discharging module, wherein the control terminal of the current-discharging module is coupled to the sensing module, the first terminal of the current-discharging module is coupled to the gate control node, and the second terminal of the current-discharging module is grounded; A voltage divider module is coupled between the control terminal of the bleeder module and ground. When the voltage of the gate control node undergoes an overload change, the sensing module generates a control voltage on the voltage divider module based on the sensed voltage change. The control voltage causes the current-discharging module to conduct, so that the overload current at the gate control node is discharged to ground through the current-discharging module.

[0007] In some possible implementations, the sensing module includes a PMOS transistor, the bleeder module includes a first NMOS transistor, and the voltage divider module includes a voltage divider resistor.

[0008] In some possible implementations, the drain and source of the PMOS transistor are coupled to the gate control node of the RF switch module; the drain of the first NMOS transistor is coupled to the gate control node, and the source of the first NMOS transistor is grounded; the voltage divider resistor is coupled between the coupling node of the gate of the PMOS transistor and the gate of the first NMOS transistor and ground.

[0009] In some possible implementations, the trigger threshold voltage of the PMOS transistor is greater than the first turn-on voltage of the first NMOS transistor.

[0010] According to a second aspect of this application, an embodiment of this application provides a radio frequency front-end circuit, the radio frequency front-end circuit comprising: the radio frequency switch protection circuit described in the embodiment of this application; at least one second NMOS transistor, wherein the gate control node is coupled to the gate of the second NMOS transistor.

[0011] In some possible implementations, the first turn-on voltage of the first NMOS transistor is less than the gate oxide breakdown voltage of the second NMOS transistor.

[0012] In some possible implementations, the RF switch module includes a transmit path and a receive path, the transmit path and the receive path each including multiple series-connected second NMOS transistors; wherein the gate of at least one second NMOS transistor in the transmit path and the gate of at least one second NMOS transistor in the receive path are respectively coupled to the corresponding RF switch protection circuit.

[0013] In some possible implementations, the RF front-end circuit further includes a bias control module, which is coupled to the gate of the corresponding second NMOS transistor through a series of resistors to provide a DC bias voltage.

[0014] In some possible implementations, the RF front-end circuit further includes multiple feedforward capacitors, a first bleeder resistor, and a second bleeder resistor; each feedforward capacitor is connected in parallel with a corresponding second NMOS transistor; the RF signal transmission path includes an RF input terminal and an RF output terminal, the first bleeder resistor is coupled between the RF input terminal and ground, and the second bleeder resistor is coupled between the RF output terminal and ground.

[0015] According to a third aspect of this application, an embodiment of this application provides an electronic device, the electronic device comprising: an antenna, a radio frequency processing circuit, and a radio frequency front-end circuit as described in the embodiment of this application; the radio frequency front-end circuit is coupled to the radio frequency signal transmission path between the antenna and the radio frequency processing circuit.

[0016] This application provides an RF switch protection circuit, an RF front-end circuit, and an electronic device. The RF switch protection circuit, by coupling a corresponding sensing module and a bleeder module at the gate control node of the RF switch module, can maintain a high-impedance cutoff state when the RF switch module is in normal operation or experiencing small static voltage fluctuations, effectively isolating the interference of substrate ripple voltage on the RF signal transmission path. When a transient overload occurs at the gate control node, the sensing module senses the voltage change and, in conjunction with the voltage divider module, generates a control voltage to turn on the bleeder module, discharging the overload current to ground, thereby reducing the risk of thermal breakdown of the transistors in the RF switch module.

[0017] Furthermore, this application employs a drain-source coupled PMOS transistor as a variable capacitor in the sensing module, working in conjunction with the first NMOS transistor and the voltage divider resistor. Compared to existing technologies, this application enhances the circuit's isolation capability against substrate ripple voltage, eliminating parasitic leakage paths introduced into the main circuit due to mis-conduction, thereby improving overall linearity. In addition, by configuring the circuit components, the turn-on voltage of the first NMOS transistor is made lower than the gate oxide breakdown voltage of the second NMOS transistor, ensuring that the protection branch conducts and discharges current before the main circuit transistor experiences thermal breakdown. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of a radio frequency front-end circuit provided in an embodiment of this application, and shows the structure of a radio frequency switch protection circuit.

[0020] Figure 2 This is an architectural diagram of an electronic device provided in one embodiment of this application. Detailed Implementation

[0021] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0022] Radio frequency (RF) switches play a crucial role in wireless communication systems, primarily used to switch signals between different circuit paths (e.g., switching between receive and transmit modes) or to distribute signals between different antenna and receiver circuits. Currently, industry-standard RF field-effect transistor (RF FET) switch stacks typically consist of multiple N-type silicon-on-insulator (NMOS SOI) transistors connected in series, along with corresponding gate resistors, drain-source resistors, and gate protection diodes. In this stack topology, the sources and drains of multiple NMOS SOI transistors are connected in series, forming the main path for RF signal transmission. Gate resistors are coupled to the gates of each transistor; source-drain resistors are connected in parallel between the source and drain of each transistor; and gate protection diodes are coupled between the gate and source (or drain) of the transistor, providing a protection path against overvoltage breakdown.

[0023] However, the researchers in this application discovered the following problems with the gate protection diode scheme in practical applications. In high-frequency, fast-switching applications of RF switches, charge accumulation within the RF field-effect transistor (RF FET) causes performance degradation of the gate protection diode. Especially under high-power conditions, after the gate protection diode undergoes multiple reverse breakdowns (non-thermal breakdowns), its protection performance significantly decreases, leading to a decline in the overall reliability of the RF switch and making it difficult to effectively prevent thermal breakdown of the aforementioned N-type silicon-on-insulator (SiI) transistors. Furthermore, the RF switch suffers from linearity degradation. Because the thickness of the top silicon (TOP Si) in the RF SiI process is typically less than 1000 angstroms, the forward breakdown voltage of the gate protection diode is excessively low, usually only around 0.2V. Therefore, during normal operation of the RF switch, the substrate ripple voltage caused by the RF signal can easily exceed this extremely low conduction threshold, allowing even a weak substrate ripple voltage to penetrate the gate protection diode and unexpectedly turn on the N-type SiI transistor in the RF main circuit. Therefore, the parasitic leakage current path caused by substrate ripple voltage affects the overall linearity performance of the RF switch.

[0024] In view of the above situation, this application provides a radio frequency front-end circuit 10 (such as...) Figure 2 (As shown). (Refer to reference). Figure 1 The radio frequency front-end circuit 10 may include: radio frequency switch module 100 and radio frequency switch protection circuit 200.

[0025] The RF switch protection circuit 200 may include a sensing module 210, a bleeder module 220, and a voltage divider module 230. The RF switch module 100 is disposed on the RF signal transmission path and has a gate control node 103. The sensing module 210 is coupled to the gate control node 103 and is used to sense voltage changes in the gate control node 103. The control terminal of the bleeder module 220 is coupled to the sensing module 210, the first terminal of the bleeder module 220 is coupled to the gate control node 103, and the second terminal of the bleeder module 220 is grounded.

[0026] When the voltage of the gate control node 103 undergoes an overload change, the sensing module 210 generates a control voltage on the voltage divider module 230 based on the sensed voltage change. The control voltage causes the current bleeder module 220 to conduct, so that the overload current at the gate control node 103 is discharged to ground through the current bleeder module 220.

[0027] To enable those skilled in the art to better understand the radio frequency front-end circuit 10 of this application, a detailed description will be provided below in conjunction with the circuit topology shown in the accompanying drawings.

[0028] refer to Figure 1 and Figure 2 In this embodiment of the application, the sensing module 210 may include a PMOS transistor, the current bleeder module 220 may include a first NMOS transistor, and the voltage divider module 230 may include a voltage divider resistor.

[0029] Specifically, the drain and source of the PMOS transistor are coupled (i.e., source-drain short-circuited) and jointly coupled to the gate control node 103 of the RF switch module 100. The source-drain short-circuited PMOS transistor can be equivalent to a variable capacitor in the circuit, not responding to static DC voltage but responding to the rate of change (dv / dt) of AC voltage. The drain of the first NMOS transistor is coupled to the gate control node 103, and the source of the first NMOS transistor is grounded. The voltage divider resistor is coupled between the coupling node of the gates of the PMOS transistor and the first NMOS transistor and ground.

[0030] Furthermore, in some exemplary embodiments, the operating frequency range of the RF switch module 100 is configured to be from 3 GHz to 70 GHz to meet high-frequency requirements. Additionally, the capacitance value of the variable capacitor equivalent to the PMOS transistor is preferably configured to be from 0.1 pF to 5 pF, so that the RF front-end circuit 10 can respond to (i.e., sense) transient voltage changes in this high-frequency band. Furthermore, the specific resistance value of the voltage divider resistor is preferably configured to be from 5 kΩ to 200 kΩ. It should be noted that the voltage divider resistor is determined by calculation based on the actual target operating frequency of the RF switch module 100, taking into account parameters such as parasitic capacitance and parasitic inductance in the circuit layout.

[0031] Based on the above configuration, when the RF switch module 100 is in normal operating condition (including off state), the RF signal transmission path contains RF signal or a small substrate ripple voltage. Due to the small voltage fluctuation amplitude, the voltage generated by the PMOS transistor is insufficient to generate a sufficient turn-on voltage across the voltage divider resistor. At this time, the first NMOS transistor is in the off state. Compared with the prior art, the PMOS transistor in the sensing module 210 of this application only generates a coupling voltage sufficient to trigger the first NMOS transistor when the gate voltage undergoes a rapid transient change. This enhances the isolation capability of the RF front-end circuit 10 against the substrate ripple voltage and cuts off the parasitic leakage current path under normal operating conditions, thereby improving the overall linearity of the RF switch. When the RF switch module 100 encounters overload conditions such as antenna mismatch (e.g., high voltage standing wave ratio) or high power input, a transient overload voltage is instantaneously generated at the gate control node 103. At this time, the PMOS transistor senses this overload change and, in conjunction with the voltage divider resistor, converts the overload change into a control voltage (V0) acting on the gate of the first NMOS transistor. gs When the control voltage exceeds the turn-on threshold of the first NMOS transistor, the first NMOS transistor quickly turns on, providing a direct grounding discharge path for the overload current at the gate control node 103, and this discharge path has extremely low impedance. By timely discharging the overload current, the risk of thermal breakdown of the transistor in the RF switch module 100 can be reduced, thereby effectively protecting the RF switch module 100.

[0032] In some embodiments, the RF switch module 100 may include at least one second NMOS transistor 101 as a transistor for the main RF signal transmission path. The aforementioned gate control node 103 is coupled to the second NMOS transistor 101. In other words, the gate of the second NMOS transistor 101 is coupled to the source and drain of the PMOS transistor and the drain of the first NMOS transistor.

[0033] In some embodiments, the trigger threshold of the PMOS transistor in the RF front-end circuit 10 is greater than the first turn-on voltage of the first NMOS transistor. Furthermore, through process adjustments or device selection, the first turn-on voltage of the first NMOS transistor is made less than the gate oxide (GOX) breakdown voltage of the second NMOS transistor. It is understood that under the aforementioned overload conditions, as long as the voltage of the gate control node 103 rises rapidly, the first NMOS transistor can turn on and discharge current before the gate oxide of the second NMOS transistor reaches the breakdown critical point, thereby preventing thermal breakdown of the transistors in the RF switching module 100.

[0034] In some embodiments, the radio frequency switch module 100 may specifically include a transmit path (TX) and a receive path (RX). The transmit path and the receive path may each include multiple series-connected second NMOS transistors 101 (e.g., Figure 1 (as shown in T1~Tn and t1~tn).

[0035] Furthermore, in some embodiments, the gate of at least one second NMOS transistor 101 in the transmission path (preferably the gate of the first stage transistor T1 of the transmission path near the antenna end A) is coupled to the corresponding radio frequency switch protection circuit 200.

[0036] Similarly, the gate of at least one second NMOS transistor 101 in the receiving path (preferably the gate of the first stage transistor t1 of the receiving path near the antenna end A) is coupled to the corresponding radio frequency switch protection circuit 200.

[0037] In this configuration, each gate control node 103 is coupled to a corresponding RF switch protection circuit 200. That is, each gate control node 103 is coupled to the source and drain of the corresponding PMOS transistor and the drain of the corresponding first NMOS transistor. This not only provides high reliability protection for the RF front-end circuit 10 but also avoids significantly increasing the chip's layout area and introducing excessive parasitic capacitance.

[0038] In some embodiments, the radio frequency front-end circuit 10 may further include a bias control module 106 and a control terminal 300 coupled to the bias control module 106.

[0039] Specifically, the control terminal 300 may include a transmission control terminal corresponding to each transmission path (e.g., Figure 1 The VT shown) and the corresponding receiving control terminal of the receiving path (such as Figure 1 The bias control module 106 uses a multi-stage resistor (i.e., VR shown). Figure 1The gate resistors R1~Rn and r1~rn in the circuit are respectively coupled to the gates of the corresponding second NMOS transistors 101. During normal signal transmission and reception, the bias control module 106 receives external control voltage through the control terminals 300 (VT and VR) and provides the required DC bias voltage to each second NMOS transistor 101 through the gate resistors to control the conduction or isolation of the transmit or receive path.

[0040] In these embodiments, the RF switch module 100 may further include a stacked resistor module 105, which includes a plurality of stacked resistors, such as... Figure 1 The resistors R11, R22, and Rnn are located in the transmit path, and r11, r22, and rnn are located in the receive path. Each stack resistor is connected in parallel with the corresponding second NMOS transistor (i.e., one end of the stack resistor is coupled to the source of the corresponding second NMOS transistor, and the other end of the stack resistor is coupled to the drain of the corresponding second NMOS transistor).

[0041] Furthermore, the RF front-end circuit 10 may also include multiple feedforward capacitors (such as...). Figure 1 The diagram shows a first feedforward capacitor C1 and a second feedforward capacitor C2), a first bleeder resistor R21, and a second bleeder resistor R21. Each feedforward capacitor is connected in parallel with its corresponding second NMOS transistor (one end of the feedforward capacitor is coupled to the source of the corresponding second NMOS transistor, and the other end is coupled to the drain of the corresponding second NMOS transistor). It is worth noting that more feedforward capacitors can be included in the receiving path, such as... Figure 1 As shown, in addition to setting the first feedforward capacitor C1, an nth feedforward capacitor Cn can also be set (which is connected in parallel with the corresponding second NMOS transistor tn) to meet the needs of more filtering. And in the transmit path, as... Figure 1 As shown, only the second feedforward capacitor C2 is set to meet the demand for more energy.

[0042] Furthermore, the RF front-end circuit 10 may also include a transmitter S2 and a receiver S3. A first bleed resistor R21 is coupled between the transmitter S2 and ground. A second bleed resistor R21 is coupled between the receiver S3 and ground. These two bleed resistors provide a high-impedance DC bleed path when the RF switch module is in a long-term non-operating state or encounters external static electricity accumulation, thereby preventing damage to the internal circuitry caused by the accumulation of static charge at the ports.

[0043] As can be seen from the above, this application, through the combined design of PMOS transistor, first NMOS transistor, and voltage divider resistor, not only overcomes the defect of gate protection diodes in the prior art being prone to false turn-on, but also ensures that the first NMOS transistor remains in the off state when the RF switch module is off or operating normally, thereby better isolating the influence of substrate ripple voltage on the RF switch and improving the overall linearity; moreover, when the gate control node voltage of the RF switch module experiences an overload change, the PMOS transistor (variable capacitor) senses the transient voltage change and converts it into a turn-on voltage acting on the control terminal of the first NMOS transistor, enabling the first NMOS transistor to quickly turn on and discharge the overload current, thereby reducing the risk of thermal breakdown of the transistors in the RF switch module and achieving high reliability protection for the RF switch module.

[0044] refer to Figure 2 This application also provides an electronic device 1. The electronic device 1 can be a smartphone, tablet computer, smart wearable device, wireless router, or other terminal product with wireless communication capabilities. The electronic device 1 may include an antenna 20, a radio frequency processing circuit 30, and a radio frequency front-end circuit 10 as described in any of the embodiments above. The radio frequency front-end circuit 10 is coupled to the radio frequency signal transmission path between the antenna 20 and the radio frequency processing circuit 30. As mentioned above, the radio frequency front-end circuit 10 has high breakdown resistance and good linearity. Therefore, the electronic device 1 using this radio frequency front-end circuit 10 can ensure high linearity and stability of the radio frequency signal in complex radio frequency communication environments (such as frequent cell handover, high-power transmission, etc.).

[0045] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The features, structures, or characteristics described above can be combined in any suitable manner in one or more embodiments.

[0046] It is understood that those skilled in the art, guided by the above embodiments, can combine various implementation methods in the above embodiments to obtain technical solutions with multiple implementation methods. The above descriptions are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A radio frequency switch protection circuit, applied to a radio frequency front-end circuit, characterized in that, The radio frequency front-end circuit includes: a radio frequency switch module disposed on the radio frequency signal transmission path, the radio frequency switch module having a gate control node; The radio frequency switch protection circuit includes: A sensing module, coupled to the gate control node, is used to sense voltage changes in the gate control node; A current-discharging module, wherein the control terminal of the current-discharging module is coupled to the sensing module, the first terminal of the current-discharging module is coupled to the gate control node, and the second terminal of the current-discharging module is grounded; A voltage divider module is coupled between the control terminal of the bleeder module and ground. When the voltage of the gate control node undergoes an overload change, the sensing module generates a control voltage on the voltage divider module based on the sensed voltage change. The control voltage causes the current-discharging module to conduct, so that the overload current at the gate control node is discharged to ground through the current-discharging module.

2. The radio frequency switch protection circuit as described in claim 1, characterized in that, The sensing module includes a PMOS transistor, the current bleeder module includes a first NMOS transistor, and the voltage divider module includes a voltage divider resistor.

3. The radio frequency switch protection circuit as described in claim 2, characterized in that, The drain and source of the PMOS transistor are coupled to the gate control node of the RF switch module; the drain of the first NMOS transistor is coupled to the gate control node, and the source of the first NMOS transistor is grounded; the voltage divider resistor is coupled between the coupling node of the gate of the PMOS transistor and the gate of the first NMOS transistor and ground.

4. The radio frequency switch protection circuit as described in claim 3, characterized in that, The trigger threshold voltage of the PMOS transistor is greater than the first turn-on voltage of the first NMOS transistor.

5. A radio frequency front-end circuit, characterized in that, include: The radio frequency switch protection circuit as described in any one of claims 2 to 4; At least one second NMOS transistor, wherein the gate control node is coupled to the gate of the second NMOS transistor.

6. The radio frequency front-end circuit as described in claim 5, characterized in that, The first turn-on voltage of the first NMOS transistor is less than the gate oxide breakdown voltage of the second NMOS transistor.

7. The radio frequency front-end circuit as described in claim 5, characterized in that, The radio frequency switch module includes a transmit path and a receive path, and the transmit path and the receive path each include multiple series-connected second NMOS transistors; wherein, the gate of at least one second NMOS transistor in the transmit path and the gate of at least one second NMOS transistor in the receive path are respectively coupled to the corresponding radio frequency switch protection circuit.

8. The radio frequency front-end circuit as described in claim 7, characterized in that, The RF front-end circuit also includes a bias control module, which is coupled to the gate of the corresponding second NMOS transistor through multiple resistors to provide a DC bias voltage.

9. The radio frequency front-end circuit as described in claim 8, characterized in that, The RF front-end circuit also includes multiple feedforward capacitors, a first bleeder resistor, and a second bleeder resistor; each feedforward capacitor is connected in parallel with the corresponding second NMOS transistor; the RF signal transmission path includes an RF input terminal and an RF output terminal, the first bleeder resistor is coupled between the RF input terminal and ground, and the second bleeder resistor is coupled between the RF output terminal and ground.

10. An electronic device, characterized in that, include: Antenna, radio frequency processing circuit, and radio frequency front-end circuit as described in any one of claims 5 to 9; The radio frequency front-end circuit is coupled to the radio frequency signal transmission path between the antenna and the radio frequency processing circuit.

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