Amplifier circuit

Abstract

This invention provides an amplification circuit for amplifying radio frequency signals. [Solution] The amplification circuit includes a first signal terminal N1, a second signal terminal N2, and a pass circuit 110. The first signal terminal can receive radio frequency signals. The second signal terminal outputs an output signal corresponding to the radio frequency signal. The pass circuit includes a radio frequency switch 112, an electrical overstress circuit 114, a low-pass filter 116, a high-pass filter 118, and an amplifier circuit 119. The radio frequency switch can selectively receive radio frequency signals. The first terminal of the radio frequency switch is coupled to the first signal terminal. The low-pass filter and the electrical overstress circuit are coupled in series between the second terminal of the radio frequency switch and a reference voltage terminal to form a conduction path for discharging charge when an electrical overstress event occurs. The high-pass filter is coupled in parallel with the electrical overstress circuit.

Description

Technical Field

[0001] The present disclosure relates to an amplifier circuit, and more particularly to an amplifier circuit capable of reducing the impact of electrical overstress events and improving reliability.

Background Art

[0002] In the field of circuit design, reliability is an important technical parameter. In operation in an actual application environment, a circuit is susceptible to the effects of instantaneous high-current events resulting from an electrical overstress (EOS) phenomenon that can cause permanent circuit damage. Therefore, reliability considerations are of utmost importance and must be integrated at the initial circuit design stage. Existing technical approaches for improving reliability mainly require the placement of larger-sized transistors, thereby substantially increasing the complexity of the design. Also, alternative solutions that require external protection circuits always result in the consumption of excessive layout space. Given the inherent limitations of these conventional methods, the art requires more advanced approaches to address these fundamental reliability issues.

Summary of the Invention

[0003] One embodiment provides an amplifier circuit having a first signal terminal, a second signal terminal, and a first pass circuit. The first signal terminal is used to receive a radio frequency signal. The second signal terminal is used to output an output signal corresponding to the radio frequency signal. The first pass circuit includes a first radio frequency switch, an electrical overstress circuit, a low-pass filter, a high-pass filter, and an amplifier circuit. The first radio frequency switch is used to selectively receive the radio frequency signal and has a first terminal and a second terminal. The first terminal of the first radio frequency switch is coupled to the first signal terminal. The low-pass filter is connected in series with the electrical overstress circuit between the second terminal of the first radio frequency switch and a first reference voltage terminal and is used to form a low-frequency conduction path and discharge charge through the low-frequency conduction path when an electrical overstress event occurs. The high-pass filter is connected in parallel with the electrical overstress circuit. The amplifier circuit is used to amplify the above-mentioned radio frequency signal and has a first terminal connected to the second terminal of the first radio frequency switch and a second terminal connected to the second signal terminal. [Brief explanation of the drawing]

[0004] [Figure 1] An amplifier circuit according to one embodiment is shown. [Figure 2] Figures 2-5 show amplification circuits according to various embodiments. [Figure 3] Figures 2-5 show amplification circuits according to various embodiments. [Figure 4] Figures 2-5 show amplification circuits according to various embodiments. [Figure 5] Figures 2-5 show amplification circuits according to various embodiments. [Figure 6] Figures 6-12 show protection circuits coupled to a first radio frequency switch and amplifier circuit according to various embodiments. [Figure 7]Figures 6-12 show protection circuits coupled to a first radio frequency switch and amplifier circuit according to various embodiments. [Figure 8] Figures 6-12 show protection circuits coupled to a first radio frequency switch and amplifier circuit according to various embodiments. [Figure 9] Figures 6-12 show protection circuits coupled to a first radio frequency switch and amplifier circuit according to various embodiments. [Figure 10] Figures 6-12 show protection circuits coupled to a first radio frequency switch and amplifier circuit according to various embodiments. [Figure 11] Figures 6-12 show protection circuits coupled to a first radio frequency switch and amplifier circuit according to various embodiments. [Figure 12] Figures 6-12 show protection circuits coupled to a first radio frequency switch and amplifier circuit according to various embodiments. [Figure 13] An amplifier circuit according to another embodiment is shown. [Figure 14] A radio frequency discharge switch according to one embodiment is shown. [Figure 15] A protection circuit according to one embodiment is shown. [Modes for carrying out the invention]

[0005] Hereinafter, exemplary embodiments will be described in detail with reference to the attached drawings, so as to be easily implemented by those skilled in the art. The concepts of the present invention can be embodied in various forms, but are not limited to the exemplary embodiments described herein. For clarity, descriptions of well-known parts have been omitted, and similar elements are referred to by similar reference numerals throughout.

[0006] In this disclosure, the term “having” is to be interpreted as an unrestrictive term. For example, when a circuit is described as having certain electronic components, such description is to be interpreted as meaning that the circuit may have not only the enumerated electronic components but also additional elements not expressly described herein. In this disclosure, when it is mentioned that one element is coupled to another, such coupling may constitute a direct coupling or, instead, be achieved through an indirect coupling via one or more intervening elements. In this disclosure, the term “and / or” is used to specify the inclusion of one or more items from a plurality of items. For example, when “A, B, and / or C” is mentioned, such mention is to be interpreted as including A, B, C, or any combination thereof. This formulation includes all possible permutations, including, but not limited to, selections of a single item (i.e., A, B, or C), selections of items in any pair (i.e., A and B, B and C, or A and C), and collective selections of all items (i.e., A, B, and C). Within this disclosure, the terms “multiple” or “plural” may be used to mean any integer quantity greater than one, including, but not limited to, two, three, or any larger quantity.

[0007] Figure 1 shows an amplifier circuit 100 according to one embodiment. The amplifier circuit 100 may include a first signal terminal N1, a second signal terminal N2, and a first pass circuit 110. The first signal terminal N1 is used to receive a radio frequency signal SI. The second signal terminal N2 is used to output an output signal SO corresponding to the radio frequency signal SI. The first pass circuit 110 may include a first radio frequency switch 112, an electrical overstress circuit 114, a low-pass filter 116, a high-pass filter 118, and an amplifier circuit 119. The first pass circuit 110 can be coupled to the first signal terminal N1 to receive and process the radio frequency signal SI.

[0008] A first radio frequency switch 112 may be used to selectively receive a radio frequency signal SI. The first radio frequency switch 112 may include a first terminal and a second terminal, the first terminal of which may be coupled to a first signal terminal N1. A low-pass filter 116 and an electrical overstress circuit 114 may be coupled in series between the second terminal of the first radio frequency switch 112 and a first reference voltage terminal REF1, and may be used to form a low-frequency conduction path P1 through which charge can be discharged when an electrical overstress event occurs. Thus, protection can be effectively provided when an electrical overstress event occurs, thereby improving reliability. A high-pass filter 118 may be coupled in parallel with the electrical overstress circuit 114, i.e., the high-pass filter 118 may also be coupled in series with the low-pass filter 116 between the second terminal of the first radio frequency switch 112 and the first reference voltage terminal REF1. An amplifier circuit 119 may be used to amplify the radio frequency signal SI to produce an output signal SO. The amplifier circuit 119 may include a first terminal and a second terminal, the first terminal of which may be coupled to the second terminal of the first radio frequency switch 112, and the second terminal of which may be coupled to the second signal terminal N2. The first radio frequency switch 112 may include at least one transistor 1120, or it may include a switch string formed by a plurality of stacked transistors.

[0009] Figure 2 shows an amplifier circuit 200 according to another embodiment. The amplifier circuit 200 may be similar to the amplifier circuit 100, and similar aspects may not be repeated here. The amplifier circuit 200 may further include an antenna ANT. The antenna ANT may be coupled to a first signal terminal N1. The antenna ANT may receive an external radio signal SRX and thereby generate a radio frequency signal SI. In yet another embodiment, the antenna ANT may also generate a radio signal STX based on the radio frequency signal SI and radio transmit the radio signal STX externally, in which embodiment the transmission direction of the radio frequency signal SI may be opposite to that shown in Figure 2. The transmission direction of the output signal SO may also be opposite to that shown in Figure 2 (i.e., the input / output relationship of the radio frequency signal SI and the output signal SO to the amplifier circuit 119 may be reversed). The antenna ANT may include, but is not limited to, a patch antenna, a monopole antenna, a dipole antenna, a phased array antenna, a loop antenna, a slot antenna, a microstrip antenna, and / or a reflector antenna. The type of antenna (ANT) can be selected based on factors such as system specifications, operating frequency, spatial limitations, gain requirements, and radiation characteristics.

[0010] Figures 1 and 2 show that the amplifier circuit 119 can be a low-noise amplifier (LNA). Low-noise amplifiers can be used to amplify weak radio frequency signals and can have an extremely low noise figure while maintaining appropriate signal gain. In wireless communication systems, a low-noise amplifier can be located at the front end of the receiver to amplify the weak radio frequency signal received by the antenna ANT while minimizing the introduction of additional noise, so that subsequent circuits can process the signal correctly.

[0011] As shown in Figures 1 and 2, the electrical overstress circuit 114, the low-pass filter 116, and the high-pass filter 118 may form a protection circuit 117 to protect other circuits (e.g., the amplifier circuit 119). When an electrical overstress event occurs, the protection circuit 117 can be used to discharge the current to prevent the current from damaging the circuit, thereby improving reliability. The electrical overstress events described herein may include, but are not limited to, electrostatic discharge (ESD) events, surges caused by power instability, transient surge currents generated by hot-plugging, transient induced currents generated by lightning strikes, transient currents caused by incorrect wiring procedures, and other unexpected events that may damage the circuit.

[0012] As shown in Figures 1 and 2, when an electrical overstress event occurs, such as an electrostatic discharge event, the large current generated by charge transfer flowing into or out of the first signal terminal N1 may be led to the first reference voltage terminal REF1 (e.g., ground) through the low-frequency conduction path P1 of the protection circuit 117. Similarly, when an electrical overstress event occurs, such as an electrostatic discharge event, the large current generated by charge transfer originating from the first reference voltage terminal REF1 may be led to the first signal terminal N1 through the low-frequency conduction path P1 of the protection circuit 117. Therefore, the protection circuit 117 can provide a bidirectional discharge path to reduce damage caused by the large current generated when an electrical overstress event flows through the amplifier circuit 119.

[0013] FIG. 3 shows an amplifier circuit 300 according to another embodiment. Similar aspects among FIG. 3, FIG. 1, and FIG. 2 may not be repeated here. The amplifier circuit 300 can further include a second path circuit 120. The second path circuit 120 may include a second radio frequency switch 122. During normal operation, either the first radio frequency switch 112 or the second radio frequency switch 122 can be turned on while the other remains off. For example, the first path circuit 110 can correspond to an amplification mode, and the second path circuit 120 can correspond to a transmission mode or a bypass mode.

[0014] FIG. 3 shows that when the second path circuit 120 corresponds to the transmission mode, the second path circuit 120 can further include a power amplifier 129 used to amplify a signal for transmission to the first signal terminal N1. The amplified signal can further be transmitted to an antenna via the first signal terminal N1 for wireless transmission.

[0015] FIG. 4 shows an amplifier circuit 400 according to another embodiment. Similar aspects between FIG. 4 and FIG. 3 may not be repeated here. Compared with the amplifier circuit 300, the amplifier circuit 400 further includes a third path circuit 130. The third path circuit 130 may include a third radio frequency switch 132. During normal operation of the amplifier circuit 400, one of the first radio frequency switch 112, the second radio frequency switch 122, and the third radio frequency switch 132 can be turned on while the other two remain off.

[0016] FIG. 4 shows various operating modes of the amplifier circuit of the present disclosure as described below. The amplifier circuit 400 in FIG. 4 is provided as an example for illustration. The switching between the various modes described below can be performed according to requirements, thereby operating the amplifier circuit in one of the various modes described below.

[0017] (Mode - 1) Amplification mode: When operating in the amplification mode, a signal can be transmitted through the first path circuit 110, and the radio frequency signal SI received at the first signal terminal N1 can be amplified using an amplifier circuit 119 (e.g., a low-noise amplifier). Therefore, the amplification mode can be considered as the reception mode (RX mode). The radio frequency signal SI can be received by an antenna and transmitted to the first signal terminal N1. In the amplification mode, the first radio frequency switch 112 can be turned on, and the second radio frequency switch 122 and the third radio frequency switch 132 can be turned off.

[0018] (Mode-2) Transmission mode (TX mode): When operating in the transmission mode, a signal can be transmitted through the second path circuit 120, and the radio frequency signal SI can be transmitted to an antenna for transmission. The signal is amplified by an amplifier (e.g., a power amplifier 129) before being transmitted to the first signal terminal N1. The amplified signal can be further transmitted to the antenna via the first signal terminal N1 for transmission. In the transmission mode, the second radio frequency switch 122 can be turned on, and the first radio frequency switch 112 and the third radio frequency switch 132 can be turned off.

[0019] (Mode-3) Bypass mode: When operating in the bypass mode, a signal can be transmitted through the third path circuit 130. In the bypass mode, the signal can be directly transmitted from the first signal terminal N1 to the transceiver circuit. The radio frequency signal SI can be received by an antenna and transmitted to the first signal terminal N1. In the bypass mode, the third radio frequency switch 132 can be turned on, and the first radio frequency switch 112 and the second radio frequency switch 122 can be turned off.

[0020] According to one embodiment, the first pass circuit 110 and the third pass circuit 130 can be arranged in parallel and connected between the first signal terminal N1 and the transceiver circuit, which means that after the radio frequency signal SI is received by the antenna and transmitted to the first signal terminal N1, the radio frequency signal SI can be selectively transmitted to the transceiver circuit via either the first pass circuit 110 or the third pass circuit 130.

[0021] In the embodiment, the first radio frequency switch 112, the second radio frequency switch 122, and the third radio frequency switch 132 may each include a transistor. The first radio frequency switch 112, the second radio frequency switch 122, and the third radio frequency switch 132 may each be a switch formed by a plurality of switches connected in series. The series-connected switches may be formed by stacked transistors. Forming switches using stacked transistors can achieve higher voltage tolerance, better isolation effect, improved linearity, better control of parasitic capacitance, improved high-frequency performance, increased reliability, and easier sizing. For example, any of the first radio frequency switch 112, the second radio frequency switch 122, and the third radio frequency switch 132 may include a series of switches formed by stacking at least one transistor 1120.

[0022] Figure 5 shows an amplifier circuit 500 according to another embodiment. Similar aspects between Figure 5 and Figure 4 are not repeated here. As shown in Figure 5, the first terminals of the first path circuit 110, the second path circuit 120, and the third path circuit 130 do not necessarily have to be connected to the same node. In Figure 5, the third path circuit 130 may be connected to node N51. Thus, the switch 150, as a shared element, may be located in both the first path circuit 110 and the third path circuit 130. In other words, the third path circuit 130 may extend from node N51 in the first radio frequency switch 112 and form a branch that constitutes a different path from the first path circuit 110. In other words, the radio frequency switch of the first pass can consist of a series of switches formed by stacking at least one transistor 1120 and at least one switch 150 (as shown by the first radio frequency switch 112 in Figure 5), and the radio frequency switch of the third pass can consist of a third radio frequency switch 132 and switch 150.

[0023] In the embodiment, the low-pass filter 116 may include a low-pass filter circuit formed of active and / or passive components. The low-pass filter 116 may include an inductor. The inductor of the low-pass filter 116 may have a notch inductance value of less than 20 nanohenries (nH). The inductor of the low-pass filter 116 may be the inductance of a bonding wire.

[0024] In some embodiments, the high-pass filter 118 may include a high-pass filter circuit formed of active and / or passive components. From the viewpoint of frequency response characteristics, the passband frequency range of the high-pass filter 118 may be higher than that of the low-pass filter 116. The high-pass filter 118 may include a capacitor.

[0025] At a specific frequency, the high-pass filter 118 and the low-pass filter 116 can form a specific frequency notch path P2 between the second terminal of the first radio frequency switch 112 and the first reference voltage terminal REF1, thereby inducing signals of the specific frequency to the first reference voltage terminal REF1 and achieving the objective of filtering out signals of the specific frequency. This specific frequency can be higher than the frequency range of the low-frequency conduction path, and can be between 2 GHz and 3 GHz (2 GHz - 3 GHz), for example, approximately 2.45 GHz. In other words, the low-frequency conduction path P1 and the specific frequency notch path P2 can share the low-pass filter 116, thereby simplifying the design and reducing the area of ​​the amplification circuit.

[0026] Signals processed in amplification mode, transmission mode, and bypass mode can have frequencies in the range of 5 gigahertz to 7 gigahertz (5 GHz - 7 GHz).

[0027] Compared to signals processed in amplification, transmission, and bypass modes, the frequency of signals in electrical overstress events (e.g., electrostatic discharge events) may be lower frequency signals. For example, the instantaneous frequency of an electrical overstress event may not be a fixed value but could be between 6 megahertz and 0.1 gigahertz (0.6 MHz - 0.1 GHz).

[0028] The frequency values ​​above are merely examples. By adjusting the structure and component characteristics (e.g., capacitance values, inductance values, etc.) of the high-pass filter 118 and the low-pass filter 116, the protection circuit 117 can provide conduction paths for discharging large currents in other frequency bands, thereby providing protection.

[0029] Various types of protection circuits 117 are further described below with reference to Figures 6-10. Figure 6 shows a protection circuit 117 coupled to a first radio frequency switch 112 and an amplifier circuit 119 according to one embodiment. The electrical overstress circuit 114 may include a first diode D1 and a second diode D2. The first diode D1 can be configured in the forward bias direction, and the second diode D2 can be configured in the reverse bias direction. The first diode D1 and the second diode D2 can be connected in parallel (as shown in Figure 6) between the second terminal of the first radio frequency switch 112 and the low-pass filter 116. If a large current generated by an electrical overstress event comes from the first signal terminal N1, the large current can be discharged through the first diode D1 to the first reference voltage terminal REF1 (e.g., ground). If a large current generated by an electrical overstress event comes from the first reference voltage terminal REF1, this large current can be discharged to the first signal terminal N1 via the second diode D2.

[0030] The first diode D1 and the second diode D2 can form a clamp circuit structure. This clamp circuit can provide bidirectional protection, allowing the diodes to conduct when the input terminal is subjected to low-frequency noise or transient interference exceeding the normal operating voltage range. Specifically, the forward conduction voltage of the diodes can prevent damage to the circuit elements. This protection structure is applicable to input / output interface circuits in analog signal processing circuits. Its structure is simple, fast response speed, and highly reliable. Since the protection circuit 117 already provides protection, the architecture disclosed herein can handle large currents from electrical overstress events without requiring any other clamp circuits besides the protection circuit 117.

[0031] In the protection circuit 117 described in this document, the electrical overstress circuit 114 and the low-pass filter 116 (e.g., an inductor, but not limited to one) may form a clamping circuit in the low-frequency domain to handle unexpected current changes and provide protection, thereby suppressing damage from electrical overstress events.

[0032] Figure 7 shows a protection circuit 117 coupled to a first radio frequency switch 112 and an amplifier circuit 119, according to another embodiment. The electrical overstress circuit 114 may include a transistor T1 and a first resistor R1. Transistor T1 may include a first terminal, a second terminal, and a control terminal. The first terminal of transistor T1 may be coupled to the second terminal of the first radio frequency switch 112, the second terminal of transistor T1 may be coupled to the first terminal of the low-pass filter 116, and the control terminal of transistor T1 may be coupled to one terminal of the first resistor R1. The other terminal of the first resistor R1 may receive a voltage V11. The voltage V11 may be a predetermined voltage to keep transistor T1 in the off state when an electrical overstress event occurs. Taking transistor T1 as an N-type transistor as an example, the voltage V11 may be a negative voltage or a zero voltage. The control terminal of transistor T1 may be the gate terminal. In this document, if transistor T1 is a metal-oxide-semiconductor transistor, it may be a grounded-gate N-type metal-oxide-semiconductor transistor (grounded-gate NMOS, GGNMOS) or a grounded-gate N-type metal-oxide-semiconductor transistor with resistor (grounded-gate NMOS with resistor, GRNMOS).

[0033] Figure 8 shows a protection circuit 117 coupled to a first radio frequency switch 112 and an amplifier circuit 119, according to another embodiment. In Figure 8, one terminal of the first resistor R1 can be coupled to the control terminal of transistor T1. Similar embodiments are not repeated between Figure 8 and Figure 7. Unlike Figure 7, in Figure 8, the other terminal of the first resistor R1 is coupled to the second terminal of transistor T1. Transistor T1 can be a bipolar junction transistor (BJT), and its first terminal, second terminal, and control terminal can be the collector terminal, emitter terminal, and base terminal, respectively.

[0034] Figure 9 shows a protection circuit 117 coupled to a first radio frequency switch 112 and an amplifier circuit 119, according to another embodiment. In Figure 9, one terminal of the first resistor R1 is coupled to the control terminal of transistor T1. The same configuration is not repeated between Figure 9 and Figure 7, the difference being that the other terminal of the first resistor R1 is coupled to the second terminal of transistor T1. Transistor T1 can be a field-effect transistor, and its first terminal, second terminal, and control terminal can be the drain terminal, source terminal, and gate terminal, respectively.

[0035] In Figures 7-9, transistor T1 can establish a low-frequency conduction path P1 through a coupling effect or breakdown effect. The low-frequency conduction path P1 is used to bypass abnormally large currents, thereby enabling a protection mechanism.

[0036] Figure 10 shows a protection circuit 117 coupled to a first radio frequency switch 112 and an amplifier circuit 119, according to another embodiment. Similar embodiments are not repeated between Figure 10 and Figure 7. As shown in Figure 10, the electrical overstress circuit 114 may further include a second resistor R2. One terminal of the second resistor R2 may be connected to the body terminal of transistor T1, and the other terminal of the second resistor R2 may receive a voltage V12. The voltage V12 may be a predetermined voltage to keep transistor T1 in an off state when an electrical overstress event occurs. Taking transistor T1 as an N-type transistor as an example, the voltage V12 can be a negative voltage or zero voltage. The second resistor R2 may be omitted as required. In Figure 10, the coupling effect causes transistor T1 to conduct, establishing a low-frequency conduction path P1 to bypass abnormally large currents, thereby realizing a protection mechanism.

[0037] In Figures 7 and 10, the first resistor R1 and / or the second resistor R2 may be coupled to a bias circuit 1010. The bias circuit 1010 may provide a control bias to provide a voltage V11 to the first resistor R1. The bias circuit 1010 may also provide a substrate bias to provide a voltage V12 to the second resistor R2. The bias circuit 1010 may include a ground terminal, a negative voltage generator (e.g., a charge pump), a transformer, a node with an appropriate voltage, a suitable conductive layer, or other suitable circuitry so that when an electrical overstress event occurs, the transistor T1 may conduct through a coupling effect or break down through a breakdown effect to establish a low-frequency conduction path P1. Voltages V11 and V12 in Figure 10 may be the same or different.

[0038] Figure 11 shows a protection circuit 117 coupled to a first radio frequency switch 112 and an amplifier circuit 119, according to another embodiment. The protection circuit 117 in Figure 11 may be as shown in any of the figures above. The amplifier circuit 119 in Figure 11 may include an amplifying transistor TA. The control terminal of the amplifying transistor TA may be coupled to a second terminal of the first radio frequency switch 112, the second terminal of the amplifying transistor TA may be coupled to a first reference voltage terminal REF1, and the first terminal of the amplifying transistor TA may be coupled to a second signal terminal N2.

[0039] In Figure 11, the amplifier circuit 119 may further include an amplifying transistor TA1, and the amplifying transistors TA1 and TA may be coupled in a stacked manner, with the first terminal of the amplifying transistor TA being coupled to the second signal terminal N2 via the amplifying transistor TA1. However, Figure 11 is merely an example. The amplifying transistor TA1 may optionally be omitted, and the first terminal of the amplifying transistor TA may be directly coupled to the second signal terminal N2, which is also within the scope of the embodiment.

[0040] In Figure 11, the amplifier circuit 119 may further include an input capacitor C1. The control terminal of the amplification transistor TA may be coupled to the second terminal of the first radio frequency switch 112 via the input capacitor C1. The amplifier circuit 119 may further include a clamp circuit 1192, which may be connected between the control terminal of the amplification transistor TA and the first reference voltage terminal REF1. When the input signal or noise exceeds a predetermined range, the clamp circuit 1192 can limit the voltage swing to prevent the amplifier circuit 119 from being damaged by excessive stress. This protection mechanism ensures the operation of the amplifier circuit 119 and can extend its lifespan.

[0041] Figure 12 shows the first path circuit 110 in another embodiment. Similarities between Figure 12 and the embodiments described above will not be repeated. As shown in Figure 12, the first path circuit 110 may further include a radio frequency discharge switch 115. The radio frequency discharge switch 115 may be connected between the second terminal of the first radio frequency switch 112 and the first reference voltage terminal REF1. The radio frequency discharge switch 115 can operate as a shunt switch used to discharge unintended radio frequency signals to a predetermined terminal, such as the ground terminal, thereby improving isolation between multiple paths. When the first radio frequency switch 112 is turned on, the radio frequency discharge switch 115 can be turned off. When the first radio frequency switch 112 is turned off, the radio frequency discharge switch 115 can be turned on.

[0042] Figure 13 shows an amplifier circuit 1300 according to another embodiment. Similarities between amplifier circuit 1300 and amplifier circuit 400 will not be repeated. In amplifier circuit 1300, the first pass circuit 110 may include a radio frequency discharge switch 115 connected between the second terminal of the first radio frequency switch 112 and the first reference voltage terminal REF1. The second pass circuit 120 may include a radio frequency discharge switch 125 connected between the second terminal of the second radio frequency switch 122 and the first reference voltage terminal REF1. The third pass circuit 130 may include a radio frequency discharge switch 135 connected between the second terminal of the third radio frequency switch 132 and the first reference voltage terminal REF1. The radio frequency discharge switches 115, 125, and 135 shown in Figure 13 may be optionally arranged, and for example, one or two of them may be omitted as needed.

[0043] When operating in amplification mode, the signal can be transmitted through the first pass circuit 110. The first radio frequency switch 112 can be turned on, the radio frequency discharge switch 115 can be turned off, the second radio frequency switch 122 and the third radio frequency switch 132 can be turned off, and the radio frequency discharge switches 125 and 135 can be turned on.

[0044] When operating in transmit mode, signals can be transmitted through the second pass circuit 120. The second radio frequency switch 122 can be turned on, the radio frequency discharge switch 125 can be turned off, the first radio frequency switch 112 and the third radio frequency switch 132 can be turned off, and the radio frequency discharge switches 115 and 135 can be turned on.

[0045] When operating in bypass mode, signals can be transmitted through the third pass circuit 130. The third radio frequency switch 132 can be turned on, the radio frequency discharge switch 135 can be turned off, the first radio frequency switch 112 and the second radio frequency switch 122 can be turned off, and the radio frequency discharge switches 115 and 125 can be turned on.

[0046] Figure 14 shows a radio frequency discharge switch 145 according to one embodiment. The radio frequency discharge switch 145 may represent the circuit architecture of radio frequency discharge switches 115, 125, and 135. As shown in Figure 14, the radio frequency discharge switch 145 may include a discharge transistor TS. The first terminal of the discharge transistor TS may be coupled to a second terminal of a radio frequency switch (e.g., one of radio frequency switches 112, 122, or 132), and the second terminal of the discharge transistor TS may be coupled to a first reference voltage terminal REF1. As shown in Figure 14, the radio frequency discharge switch 145 may also be formed using a plurality of series-connected switches, which may include stacked transistors to improve circuit performance. The stacked transistors in the radio frequency discharge switch 145 can be turned on and turned off synchronously.

[0047] Figure 15 shows a protection circuit 117 according to another embodiment. The configuration of components in the protection circuit 117 of Figure 15 may differ from that described above. As shown in Figure 15, in the protection circuit 117, the low-pass filter 116 may be coupled to a second terminal of a radio frequency switch (e.g., one of radio frequency switches 112, 122, or 132). A high-pass filter 118 may be coupled between the low-pass filter 116 and a first reference voltage terminal REF1. An electrical overstress circuit 114 may be coupled between the low-pass filter 116 and a first reference voltage terminal REF1. The high-pass filter 118 and the electrical overstress circuit 114 may be coupled in parallel between the low-pass filter 116 and the first reference voltage terminal REF1. In other words, compared to the configurations in Figures 1-13, in Figure 15, the low-pass filter 116 can be adjusted and moved to a position between the radio frequency switch (e.g., one of radio frequency switches 112, 122, or 132) and the electrical overstress circuit 114. The electrical overstress circuit 114 in Figure 15 can be used in correspondence with one of those shown in Figures 6-10.

[0048] In summary, in the amplifier circuit provided by the embodiment, the low-frequency conduction path P1 of the protection circuit 117 can provide a bidirectional protection mechanism for discharging unintended high currents during electrical overstress events (e.g., electrostatic discharge events), thereby suppressing damage. Furthermore, since the low-frequency conduction path P1 and the specific-frequency notch path P2 can share the low-pass filter 116, the design can be simplified and the size of the amplifier circuit can be reduced. Moreover, since it is possible to discharge high currents during electrical overstress events without using radio frequency discharge switches (e.g., radio frequency discharge switches 115, 125, and 135 in Figure 13), the transistor size of the radio frequency discharge switches can be effectively reduced, thus avoiding problems such as excessive circuit size, limited design space, and insufficient parasitic capacitance characteristics. In addition, by utilizing the protection circuit 117, the need to install external protection circuits is reduced. For example, it may not be necessary to install a protection circuit at the antenna location, thus preventing excessive layout space occupation. The response speed of the protection circuit 117 is sufficiently fast, enabling rapid discharge of high current during electrical overstress events and minimizing damage. Thus, the solutions provided by the embodiments enhance circuit reliability, improve circuit characteristics, reduce design complexity, and optimize circuit layout.

[0049] As those skilled in the art will readily notice, numerous modifications and alterations of the device and method can be made while retaining the teachings of the present invention. Accordingly, the above disclosure should be construed as being limited only by the boundaries of the appended claims.

Claims

1. A first signal terminal configured to receive radio frequency signals, A second signal terminal configured to output an output signal corresponding to the aforementioned radio frequency signal, This is the first path circuit, A first radio frequency switch configured to selectively receive the aforementioned radio frequency signal, having a first terminal coupled to the first signal terminal and a second terminal, Electrical overstress circuits, A low-pass filter is coupled in series with the electrical overstress circuit between the second terminal and the first reference voltage terminal of the first radio frequency switch, and is configured to form a low-frequency conduction path and discharge charge through the low-frequency conduction path when an electrical overstress event occurs. A high-pass filter coupled in parallel with the aforementioned electrical overstress circuit, and An amplifier circuit configured to amplify the radio frequency signal, having a first terminal connected to the second terminal of the first radio frequency switch and a second terminal connected to the second signal terminal, A first path circuit having, An amplification circuit having [a certain feature].

2. The amplification circuit according to claim 1, further comprising an antenna coupled to the first signal terminal.

3. The amplifier circuit according to claim 1, wherein the amplifier circuit is a low-noise amplifier.

4. The amplification circuit according to claim 3, further comprising a second pass circuit, the second pass circuit comprising a second radio frequency switch, wherein during normal operation, the first radio frequency switch or the second radio frequency switch is turned on.

5. The amplification circuit according to claim 4, wherein the second pass circuit further comprises a power amplifier.

6. The amplification circuit according to claim 4, wherein the second pass circuit further includes a radio frequency discharge switch, the radio frequency discharge switch is coupled between the second terminal of the second radio frequency switch and the first reference voltage terminal.

7. The amplifier circuit according to claim 3, further comprising a second pass circuit and a third pass circuit, wherein the second pass circuit comprises a second radio frequency switch, and the third pass circuit comprises a third radio frequency switch, and during normal operation, the first radio frequency switch, the second radio frequency switch, or the third radio frequency switch is turned on.

8. The amplifier circuit according to claim 1, wherein the low-pass filter has an inductor.

9. The amplification circuit according to claim 1, wherein the high-pass filter and the low-pass filter form a conductive path between the second terminal and the first reference voltage terminal of the first radio frequency switch at a specific frequency.

10. The amplification circuit according to claim 1, wherein the high-pass filter has a capacitor.

11. The amplification circuit according to claim 1, wherein the electrical overstress circuit comprises a first diode and a second diode, the first diode being configured in the forward bias direction and the second diode being configured in the reverse bias direction, and the first diode and the second diode are coupled in parallel between the second terminal of the first radio frequency switch and the low-pass filter.

12. The amplification circuit according to claim 1, wherein the electrical overstress circuit comprises a transistor and a first resistor, the transistor having a first terminal coupled to the second terminal of the first radio frequency switch, a second terminal coupled to the first terminal of the low-pass filter, and a control terminal coupled to the first terminal of the first resistor.

13. The amplification circuit according to claim 12, wherein the second terminal of the first resistor is coupled to the second terminal of the transistor, and the transistor is a bipolar transistor or a field-effect transistor.

14. The amplification circuit according to claim 12, wherein the electrical overstress circuit has a second resistor, the transistor is a field-effect transistor, and the first terminal of the second resistor is coupled to the body of the field-effect transistor.

15. The amplification circuit according to claim 14, wherein the second terminal of the first resistor and the second terminal of the second resistor are coupled to a bias circuit, the bias circuit provides a control bias voltage to the second terminal of the first resistor, and the bias circuit provides a substrate bias voltage to the second terminal of the second resistor.

16. The amplifier circuit according to claim 1, wherein the amplifier circuit has an amplifying transistor, the control terminal of the amplifying transistor is coupled to the second terminal of the first radio frequency switch, the second terminal of the amplifying transistor is coupled to the first reference voltage terminal, and the first terminal of the amplifying transistor is coupled to the second signal terminal.

17. The amplifier circuit according to claim 16, further comprising an input capacitor, wherein the control terminal of the amplification transistor is coupled to the second terminal of the first radio frequency switch via the input capacitor.

18. The amplifier circuit according to claim 16, further comprising a clamp circuit, wherein the clamp circuit is coupled between the control terminal of the amplification transistor and the first reference voltage terminal.

19. The amplification circuit according to claim 1, wherein the electrical overstress circuit and the low-pass filter form a clamp circuit at low frequencies.

20. The amplification circuit according to claim 1, wherein the first pass circuit further includes a radio frequency discharge switch, the radio frequency discharge switch is coupled between the second terminal of the first radio frequency switch and the first reference voltage terminal.

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