Amplification circuit

Abstract

An amplification circuit includes a first signal terminal, a second signal terminal, and a path circuit. The first signal terminal can receive a radio frequency signal. The second signal terminal can output an output signal corresponding to the radio frequency signal. The path circuit includes a radio frequency switch element, an electrical overstress circuit, a low-pass filter element, a high-pass filter element, and an amplifier circuit. The radio frequency switch element can selectively receive the radio frequency signal. A first terminal of the radio frequency switch element is coupled to the first signal terminal. The low-pass filter element and the electrical overstress circuit are coupled in series between a second terminal of the radio frequency switch element and a reference voltage terminal, forming a conduction path for discharging electrical charges when an electrical overstress event occurs. The high-pass filter element is coupled in parallel with the electrical overstress circuit. The amplifier circuit can amplify the radio frequency signal.

Description

Technical Field

[0001] This disclosure relates to an amplifier circuit, and more particularly to an amplifier circuit that can reduce the effects of electrical over-stress events to improve reliability. Prior Technology

[0002] In the field of circuit design, circuit reliability is a critical technical indicator. For example, when a circuit operates in a real-world environment, the instantaneous large current generated by an electrical overstress (EOS) event can cause permanent damage. Therefore, reliability should be considered during the circuit design phase. However, in existing technologies, circuit designs that improve reliability often require the use of larger transistors, increasing design complexity. Furthermore, adding external protection circuits consumes excessive layout space. Given the significant drawbacks of these solutions, a more optimized technical solution is urgently needed in the field. Summary of the Invention

[0003] An embodiment provides an amplifier circuit including a first signal terminal, a second signal terminal, and a first path circuit. The first signal terminal is used to receive a radio frequency (RF) signal. The second signal terminal is used to output an output signal corresponding to the RF signal. The first path circuit includes a first RF switching element, an electrical over-stress circuit, a low-pass filter element, a high-pass filter element, and an amplifier circuit. The first RF switching element, used to selectively receive the RF signal, includes a first terminal and a second terminal, the first terminal being coupled to the first signal terminal. The low-pass filter element and the electrical over-stress circuit are connected in series between the second terminal of the first RF switching element and a first reference voltage terminal to form a low-frequency conduction path, through which charge is discharged when an electrical over-stress event occurs. The high-pass filter element is connected in parallel with the electrical over-stress circuit. The amplifier circuit is used to amplify the radio frequency signal. The amplifier circuit includes a first terminal coupled to the second terminal of the first radio frequency switching element, and a second terminal coupled to the second signal terminal. Simple Explanation of the Diagram

[0004] Figure 1 is a schematic diagram of the amplifier circuit in the embodiment. Figures 2 through 5 are schematic diagrams of the amplifier circuit in different embodiments. Figures 6 to 12 are schematic diagrams of the protection circuit coupled to the first radio frequency switching element and the amplifier circuit in different embodiments. Figure 13 is a schematic diagram of the amplifier circuit in another embodiment. Figure 14 is a schematic diagram of the radio frequency venting switch element in the embodiment. Figure 15 is a schematic diagram of the protection circuit in the embodiment. Implementation

[0005] In this document, the term "comprising" should be understood as an open-ended term. For example, when describing a circuit as containing a specific electronic component, it should be interpreted as meaning that the circuit may contain not only the stated electronic component but also other components not explicitly listed. In this document, when this specification refers to a component coupled to another component, this coupling relationship can be direct coupling or indirect coupling achieved through one or more intermediate components. In this document, the term "and / or" is used to indicate the inclusion of one or more items. For example, when describing "A, B, and / or C," it means including any one of A, B, and C, any combination of any number of items, or all of the items. This expression covers all possible cases: selecting only one item (i.e., A, B, or C), selecting any two combinations (i.e., A and B, B and C, or A and C), and including all items simultaneously (i.e., A, B, and C). In this article, the terms "multiple" or "plural" refer to a quantity greater than one, including but not limited to two, three or more. This term can be used for an integer quantity of more than one.

[0006] Figure 1 is a schematic diagram of the amplifier circuit 100 in the embodiment. The amplifier circuit 100 may include a first signal terminal N1, a second signal terminal N2, and a first path circuit 110. The first signal terminal N1 can be used to receive the radio frequency signal SI. The second signal terminal N2 can be used to output an output signal SO corresponding to the radio frequency signal SI. The first path circuit 110 may include a first radio frequency switching element 112, an electrical overload circuit 114, a low-pass filter element 116, a high-pass filter element 118, and an amplifier circuit 119. The first path circuit 110 can be coupled to the first signal terminal N1 to receive and process the radio frequency signal SI.

[0007] The first RF switching element 112 can be used to selectively receive the RF signal SI. The first RF switching element 112 includes a first terminal and a second terminal, wherein the first terminal can be coupled to the first signal terminal N1. A low-pass filter element 116 and an electrical over-stress circuit 114 can be connected in series between the second terminal of the first RF switching element 112 and the first reference voltage terminal REF1 to form a low-frequency conduction path P1. In the event of an electrical over-stress event, charge is discharged through the low-frequency conduction path P1. Therefore, effective protection can be provided and reliability improved in the event of an electrical over-stress event. A high-pass filter element 118 can be connected in parallel with the electrical over-stress circuit 114, that is, the high-pass filter element 118 can be simultaneously connected in series with the low-pass filter element 116 between the second terminal of the first RF switching element 112 and the first reference voltage terminal REF1. An amplifier circuit 119 can be used to amplify the RF signal SI to generate an output signal SO. The amplifier circuit 119 may include a first terminal and a second terminal, wherein the first terminal may be coupled to the second terminal of the first radio frequency switching element 112, and the second terminal may be coupled to the second signal terminal N2. The first radio frequency switching element 112 may include at least one transistor 1120, or include a string of switching elements formed by stacking a plurality of transistors.

[0008] Figure 2 is a schematic diagram of the amplifier circuit 200 in another embodiment. The amplifier circuit 200 may be similar to the amplifier circuit 100, and the similarities will not be repeated. The amplifier circuit 200 may further include an antenna ANT. The antenna ANT may be coupled to the first signal terminal N1. The antenna ANT may receive an external wireless signal SRX and generate a radio frequency signal SI accordingly. In yet another embodiment, the antenna ANT may also generate a wireless signal STX based on the radio frequency signal SI, and wirelessly transmit the wireless signal STX to the outside. In this embodiment, the transmission direction of the radio frequency signal SI is opposite to that shown in Figure 2. Furthermore, the transmission direction of the output signal SO may also be opposite to that shown in Figure 2 (that is, the input / output relationship of the radio frequency signal SI and the output signal SO relative to the amplifier circuit 119 is opposite). Antennas (ANTs) can include, but are not limited to, patch antennas, monopole antennas, dipole antennas, phased array antennas, loop antennas, slot antennas, microstrip antennas, and / or reflector antennas. The type of ANT can be selected based on factors such as system specifications, operating frequency, space constraints, gain requirements, and radiation characteristics.

[0009] The amplifier circuit 119 shown in Figures 1 and 2 can be a low-noise amplifier (LNA). A low-noise amplifier can be used to amplify weak radio frequency signals, exhibiting extremely low noise while maintaining appropriate signal gain. In wireless communication systems, the low-noise amplifier can be placed before the receiver stage to amplify the weak radio frequency signal received by the antenna ANT while minimizing the introduction of additional noise, so that subsequent circuitry can properly process the signal.

[0010] As shown in Figures 1 and 2, the electrical overstress circuit 114, the low-pass filter element 116, and the high-pass filter element 118 can form a protection circuit 117 to protect other circuits (e.g., amplifier circuit 119). When an electrical overstress event occurs, the protection circuit 117 can be used to discharge current to prevent current damage to the circuit, thus 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 wiring errors, and other unexpected events that may damage the circuit.

[0011] When an electrical overstress event occurs, such as an electrostatic discharge event, the large current generated by charge movement flows into or out through the first signal terminal N1. This large current can be guided 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 movement originates from the first reference voltage terminal REF1 and can be guided to the first signal terminal N1 through the low-frequency conduction path P1 of the protection circuit 117. Therefore, the protection circuit 117 provides a bidirectional discharge path to reduce the damage caused by the large current generated by the electrical overstress event flowing through the amplifier circuit 119.

[0012] Figure 3 is a schematic diagram of the amplifier circuit 300 in another embodiment. The similarities between Figure 3 and Figures 1 and 2 will not be repeated. The amplifier circuit 300 may further include a second path circuit 120. The second path circuit 120 may include a second radio frequency (RF) switching element 122. During normal operation, one of the first RF switching element 112 and the second RF switching element 122 is on, and the other is off. For example, the first path circuit 110 may correspond to an amplification mode, while the second path circuit 120 may correspond to a transmit mode or a bypass mode.

[0013] As shown in Figure 3, if the second path circuit 120 corresponds to the transmission mode, the second path circuit 120 may further include a power amplifier 129 to amplify the signal for transmission to the first signal terminal N1. The amplified signal can then be further transmitted to the antenna through the first signal terminal N1 for wireless transmission.

[0014] Figure 4 is a schematic diagram of the amplifier circuit 400 in another embodiment. The similarities between Figure 4 and Figure 3 will not be repeated. Compared to Figure 3, Figure 4 further includes a third path circuit 130. The third path circuit 130 may include a third radio frequency (RF) switch element 132. During normal operation of the amplifier circuit 400, one of the first RF switch element 112, the second RF switch element 122, and the third RF switch element 132 is turned on, while the other two are turned off.

[0015] The various operating modes of the amplifier circuit described in this article are as follows. The amplifier circuit 400 in Figure 4 is used as an example for illustration. Depending on the requirements, the amplifier circuit can be switched between the following modes to operate in one of them.

[0016] (Mode-1) Amplification Mode: When operating in amplification mode, the signal can be transmitted through the first path circuit 110. The RF signal SI received by the first signal terminal N1 can be amplified using the amplifier circuit 119 (e.g., a low-noise amplifier). Therefore, the amplification mode can be a receive mode (RX mode). The RF signal SI can be received by the antenna and transmitted to the first signal terminal N1. In amplification mode, the first RF switch element 112 can be turned on, and the second RF switch element 122 and the third RF switch element 132 can be turned off.

[0017] (Mode-2) Transmit Mode (TX mode): When operating in transmit mode, the signal can be transmitted through the second path circuit 120, which can transmit the radio frequency signal SI to the antenna for transmission. The signal is amplified by an amplifier (e.g., power amplifier 129) and then transmitted to the first signal terminal N1. The amplified signal can be further transmitted to the antenna through the first signal terminal N1 for transmission. In transmit mode, the second radio frequency switch element 122 can be turned on, and the first radio frequency switch element 112 and the third radio frequency switch element 132 can be turned off.

[0018] (Mode-3) Bypass Mode: When operating in bypass mode, the signal can be transmitted through the third path circuit 130. In bypass mode, the signal can be transmitted directly from the first signal terminal N1 to the transceiver circuit (not shown). The radio frequency signal SI can be received by the antenna and transmitted to the first signal terminal N1. In bypass mode, the third radio frequency switch element 132 can be turned on, and the first radio frequency switch element 112 and the second radio frequency switch element 122 can be turned off.

[0019] In one embodiment, the first path circuit 110 and the third path circuit 130 are configured in parallel and connected in series between the first signal terminal N1 and the transceiver circuit. That is, the radio frequency signal SI can be received by the antenna and transmitted to the first signal terminal N1, and then selectively transmitted to the transceiver circuit through one of the first path circuit 110 and the third path circuit 130.

[0020] In this document, each of the first RF switching element 112, the second RF switching element 122, and the third RF switching element 132 may include a transistor. Each of the first RF switching element 112, the second RF switching element 122, and the third RF switching element 132 may be one of a plurality of series-connected switching elements. The aforementioned series-connected switching elements may be formed by stacking transistors. Using stacked transistors to form switching elements can achieve higher voltage withstand capability, better isolation, better linearity, better control of parasitic capacitance, improved high-frequency performance, increased reliability, and easier size adjustment. For example, any of the first RF switching element 112, the second RF switching element 122, and the third RF switching element 132 may be a string of switching elements formed by stacking at least one transistor 1120.

[0021] Figure 5 is a schematic diagram of the amplifier circuit 500 in another embodiment. The similarities between Figure 5 and Figure 4 will not be repeated. As shown in Figure 5, the first ends of the first path circuit 110, the second path circuit 120, and the third path circuit 130 are not necessarily coupled to the same node. In Figure 5, the third path circuit 130 may be coupled to node N51. Therefore, the switching element 150 may be located in the first path circuit 110 or the third path circuit 130, and is a shared element. In other words, the third path circuit 120 may extend from node N51 in the first RF switching element 112, forming a branched path different from the first path circuit 110. In other words, the RF switching element of the first path may consist of a string of switching elements (first RF switching element 112) formed by stacking at least one transistor 1120 and at least one switching element 150, and the RF switching element of the third path may consist of a third RF switching element 132 and the switching element 150.

[0022] In this document, the low-pass filter element 116 may comprise a low-pass filter circuit composed of active and / or passive components. The low-pass filter element 116 may include an inductor. The notch inductance value of the inductor in the low-pass filter element 116 may be less than 20 NH. The inductor in the low-pass filter element 116 may be a bonding wire inductor.

[0023] In this document, the high-pass filter element 118 may comprise a high-pass filter circuit composed of active and / or passive components. In terms of frequency response characteristics, the passband frequency range of the high-pass filter element 118 may be higher than that of the low-pass filter element 116. The high-pass filter element 118 may include a capacitor.

[0024] The high-pass filter element 118 and the low-pass filter element 116 can form a specific-frequency notch path P2 between the second terminal of the first RF switching element 112 and the first reference voltage terminal REF1 at a specific frequency, so as to guide the specific frequency signal to the first reference voltage terminal REF1 and achieve the purpose of filtering out the specific frequency signal. 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, it can be about 2.45 GHz. That is to say, the low-frequency conduction path P1 and the specific-frequency notch path P2 can share the low-pass filter element 116, thereby simplifying the design and reducing the area of ​​the amplifier circuit.

[0025] The signals processed in amplification mode, transmit mode and bypass mode can be in the frequency band of 5 GHz to 7 GHz (5 GHz ~ 7 GHz).

[0026] Compared to the signals processed in amplification, transmit, and bypass modes, the signals in electrical overstress events (e.g., electrostatic discharge events) can be of lower frequencies. For example, the instantaneous frequency of an electrical overstress event is not a fixed value and can range from 6 MHz to 0.1 GHz (0.6 MHz ~ 0.1 GHz).

[0027] The frequency values ​​mentioned above are merely examples. By adjusting the architecture and component characteristics (e.g., capacitance and inductance values) of the high-pass filter element 118 and the low-pass filter element 116, the protection circuit 117 can provide conductive paths in other frequency bands to discharge large currents and thus provide protection.

[0028] The various configurations of the protection circuit 117 will be further described in Figures 6 through 10 below. Figure 6 is a schematic diagram of the protection circuit 117 coupled to the first RF switching element 112 and the amplifier circuit 119 in an embodiment. The electrical overstress circuit 114 may include a first diode D1 and a second diode D2. The first diode D1 may be configured in a forward direction, and the second diode D2 may be configured in a reverse direction. The first diode D1 and the second diode D2 may be configured in parallel and connected in series between the second terminal of the first RF switching element 112 and the low-pass filter element 116, as shown in Figure 6. When a large current generated by an electrical overstress event originates from the first signal terminal N1, the large current can be discharged to the first reference voltage terminal REF1 (e.g., ground) through the first diode D1. When a large current generated by an electrical overstress event originates from the first reference voltage terminal REF1, the large current can be discharged to the first signal terminal N1 through the second diode D2.

[0029] The first diode D1 and the second diode D2 can form a clamping circuit architecture. This clamping circuit has a bidirectional protection function; when the input terminal is subjected to low-frequency noise or transient interference exceeding the normal operating voltage range, the diodes can conduct. Specifically, when the diodes are forward-biased, damage to circuit components can be prevented. This protection architecture is suitable for input / output interface circuits, particularly in analog signal processing circuits. It features a simple structure, fast response speed, and high reliability. Since protection circuit 117 already provides protection, the architecture disclosed herein does not require additional clamping circuits besides protection circuit 117 to handle large currents during electrical over-stress events.

[0030] In the protection circuit 117 described herein, the electrical overstress circuit 114 and the low-pass filter element 116 (e.g., but not limited to, an inductor) can form a clamping circuit in the low-frequency domain to handle unexpected current changes, thereby providing protection and reducing the damage from electrical overstress events.

[0031] Figure 7 is a schematic diagram of a protection circuit 117 coupled to a first RF switching element 112 and an amplifier circuit 119 in another embodiment. The electrical overstress circuit 114 may include a transistor T1 and a first resistor R1. The transistor T1 may include a first terminal, a second terminal, and a control terminal. The first terminal of the transistor T1 may be coupled to the second terminal of the first RF switching element 112, the second terminal of the transistor T1 may be coupled to the first terminal of the low-pass filter element 116, and the control terminal of the transistor T1 may be coupled to one end of the first resistor R1. The other end of the first resistor R1 may receive a voltage V11. The voltage V11 may be a predetermined voltage to keep the transistor T1 in an off state when an electrical overstress event occurs. Taking an N-type transistor as an example, the voltage V11 may be a negative voltage or zero voltage. The control terminal of the transistor T1 may be a gate terminal. In this article, if transistor T1 is a metal-oxide-semiconductor, it can be a grounded-gate NMOS (GGNMOS) or a grounded-gate NMOS with resistor (GRNMOS).

[0032] Figure 8 is a schematic diagram of another embodiment, showing the protection circuit 117 coupled to the first RF switching element 112 and the amplifier circuit 119. In Figure 8, one end of the first resistor R1 is coupled to the control terminal of the transistor T1. The similarities between Figure 8 and Figure 7 will not be repeated. The difference between Figure 8 and Figure 7 is that the other end of the first resistor R1 is coupled to the second terminal of the transistor T1. The 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.

[0033] Figure 9 is a schematic diagram of another embodiment, showing the protection circuit 117 coupled to the first RF switching element 112 and the amplifier circuit 119. In Figure 9, one end of the first resistor R1 is coupled to the control terminal of the transistor T1. The similarities between Figure 9 and Figure 7 will not be repeated. The difference between Figure 9 and Figure 7 is that the other end of the first resistor R1 is coupled to the second terminal of the transistor T1. The 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.

[0034] In Figures 7 to 9, transistor T1 can establish a low-frequency conduction path P1 through coupling or breakdown effects. This path can be used to conduct abnormally large currents, thereby achieving a protection mechanism.

[0035] Figure 10 is a schematic diagram of a protection circuit 117 coupled to a first RF switching element 112 and an amplifier circuit 119 in another embodiment. Similarities between Figure 10 and Figure 7 will not be repeated. As shown in Figure 10, the electrical overstress circuit 114 may further include a second resistor R2. One end of the second resistor R2 may be coupled to the body of transistor T1, and the other end of the second resistor R2 may receive a voltage V12. The voltage V12 may be a predetermined voltage to keep transistor T1 off when an electrical overstress event occurs. Taking an N-type transistor as an example, the voltage V12 may be a negative voltage or zero voltage. Depending on the requirements, the second resistor R2 may be omitted. In Figure 10, transistor T1 can be turned on through coupling to establish a low-frequency conduction path P1 to conduct abnormally large currents, thereby achieving a protection mechanism.

[0036] In Figures 7 and 10, the first resistor R1 and / or the second resistor R2 may be coupled to the bias circuit 1010. The bias circuit 1010 may provide a control bias to provide voltage V11 to the first resistor R1, and the bias circuit 1010 may provide a substrate bias to provide 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 a suitable voltage, a suitable conductive layer, or other suitable circuitry to enable transistor T1 to conduct through coupling effects or collapse through collapse effects in the event of an electrical overstress event, establishing a low-frequency conduction path P1. Voltages V11 and V12 in Figure 10 may be the same or different.

[0037] Figure 11 is a schematic diagram of a protection circuit 117 coupled to a first RF switching element 112 and an amplifier circuit 119 in another embodiment. The protection circuit 117 in Figure 11 can be as shown in any of the above figures. The amplifier circuit 119 in Figure 11 may include an amplifying transistor TA. The control terminal of the amplifying transistor TA can be coupled to the second terminal of the first RF switching element 112, the second terminal of the amplifying transistor TA can be coupled to the first reference voltage terminal REF1, and the first terminal of the amplifying transistor TA can be coupled to the second signal terminal N2.

[0038] In Figure 11, the amplifier circuit 119 may further include an amplifying transistor TA1. The amplifying transistor TA1 and the amplifying transistor TA can be coupled in a stacked manner. The first terminal of the amplifying transistor TA can be coupled to the second signal terminal N2 through the amplifying transistor TA1. However, Figure 11 is only an example, and the amplifying transistor TA1 can be selectively omitted. The first terminal of the amplifying transistor TA can be directly coupled to the second signal terminal N2, which is also within the scope of the embodiment.

[0039] As shown in Figure 11, the amplifier circuit 119 may further include an input capacitor C1. The control terminal of the amplifying transistor TA can be coupled to the second terminal of the first RF switching element 112 through the input capacitor C1. The amplifier circuit 119 may further include a clamping circuit 1192, which can be connected in series between the control terminal of the amplifying transistor TA and the first reference voltage terminal REF1. When the input signal or noise exceeds the expected range, the clamping circuit 1192 can limit the voltage swing, preventing the amplifier circuit 119 from being damaged by excessive stress. This protection mechanism can ensure the operation of the amplifier circuit 119 and extend the life of the amplifier circuit 119.

[0040] Figure 12 is a schematic diagram of the first path circuit 110 in another embodiment. The similarities between Figure 12 and the aforementioned embodiments will not be repeated. As shown in Figure 12, the first path circuit 110 may further include a radio frequency (RF) venting switch element 115. The RF venting switch element 115 may be connected in series between the second terminal of the first RF switch element 112 and the first reference voltage terminal REF1. The RF venting switch element 115 may be a shunt element to vent unintended RF signals to a predetermined endpoint, such as ground, to improve the isolation between multiple paths. When the first RF switch element 112 is turned on, the RF venting switch element 115 may be turned off. When the first RF switch element 112 is turned off, the RF venting switch element 115 may be turned on.

[0041] Figure 13 is a schematic diagram of amplifier circuit 1300 in another embodiment. The similarities between amplifier circuit 1300 and amplifier circuit 400 will not be repeated. In amplifier circuit 1300, the first path circuit 110 may include a radio frequency venting switch element 115, which is connected in series between the second terminal of the first radio frequency switch element 112 and the first reference voltage terminal REF1. The second path circuit 120 may include a radio frequency venting switch element 125, which is connected in series between the second terminal of the second radio frequency switch element 122 and the first reference voltage terminal REF1. The third path circuit 130 may include a radio frequency venting switch element 135, which is connected in series between the second terminal of the third radio frequency switch element 132 and the first reference voltage terminal REF1. The radio frequency venting switch elements 115, 125, and 135 in Figure 13 can be selectively configured; for example, one or two of them may be omitted depending on requirements.

[0042] When operating in amplification mode, the signal can be transmitted through the first path circuit 110. The first RF switch element 112 can be turned on, the RF venting switch element 115 can be turned off, the second RF switch element 122 and the third RF switch element 132 can be turned off, and the RF venting switch elements 125 and 135 can be turned on.

[0043] When operating in transmit mode, the signal can be transmitted through the second path circuit 120. The second RF switch element 122 can be turned on, the RF venting switch element 125 can be turned off, the first RF switch element 112 and the third RF switch element 132 can be turned off, and the RF venting switch elements 115 and 135 can be turned on.

[0044] When operating in bypass mode, the signal can be transmitted through the third path circuit 130. The third RF switch element 132 can be turned on, the RF venting switch element 135 can be turned off, the first RF switch element 112 and the second RF switch element 122 can be turned off, and the RF venting switch elements 115 and 125 can be turned on.

[0045] Figure 14 is a schematic diagram of the radio frequency venting switch element 145 in the embodiment. The radio frequency venting switch element 145 can be a circuit architecture diagram of radio frequency venting switch elements 115, 125, and 135. As shown in Figure 14, the radio frequency venting switch element 145 may include a venting transistor TS. The first terminal of the venting transistor TS may be coupled to the second terminal of a radio frequency switch element (e.g., one of radio frequency switch elements 112, 122, and 132), and the second terminal of the venting transistor TS may be coupled to a first reference voltage terminal REF1. As shown in Figure 14, the radio frequency venting switch element 145 can be formed using multiple series-connected switch elements, which may be multiple stacked transistors to improve circuit performance. The multiple stacked transistors of the radio frequency venting switch element 145 can be simultaneously turned on or simultaneously turned off.

[0046] Figure 15 is a schematic diagram of the protection circuit 117 in the embodiment. The component coupling method of the protection circuit 117 in Figure 15 may differ from that described above. As shown in Figure 15, in the protection circuit 117, the low-pass filter element 116 may be coupled to the second terminal of the radio frequency switching element (e.g., one of radio frequency switching elements 112, 122, and 132). The high-pass filter element 118 may be coupled between the low-pass filter element 116 and the first reference voltage terminal REF1. The electrical over-stress circuit 114 may be coupled between the low-pass filter element 116 and the first reference voltage terminal REF1. The high-pass filter element 118 and the electrical over-stress circuit 114 may be coupled in parallel between the low-pass filter element 116 and the first reference voltage terminal REF1. In other words, compared to the architecture in Figures 1 through 13, in Figure 15, the low-pass filter element 116 can be adjusted and moved between the RF switching element (e.g., one of RF switching elements 112, 122, and 132) and the electrical over-stress circuit 114. The electrical over-stress circuit 114 in Figure 15 can be as shown in one of Figures 6 through 10.

[0047] In summary, in the amplifier circuit provided in the embodiment, by using the low-frequency conduction path P1 of the protection circuit 117, a bidirectional protection mechanism can be provided to vent unexpected large currents from electrical over-stress events (e.g., electrostatic discharge events), thereby reducing damage. Furthermore, since the low-frequency conduction path P1 and the specific frequency notch path P2 can share the low-pass filter element 116, the design can be simplified and the area of ​​the amplifier circuit can be reduced. Moreover, since the large currents from electrical over-stress events do not need to be vented through radio frequency venting switching elements (e.g., radio frequency venting switching elements 115, 125, and 135 in Figure 13), the size of the transistors in the radio frequency venting switching elements can be effectively reduced, avoiding problems such as excessive circuit size, limited design space, and poor parasitic capacitance characteristics. Additionally, by using the protection circuit 117, it is not necessary to set up an external protection circuit; for example, it is not necessary to set up a protection circuit at the antenna location, thus avoiding the problem of excessive layout space occupation. The protection circuit 117 has a sufficiently fast response speed to quickly discharge large currents to reduce damage in the event of an electrical overstress event. Therefore, it is beneficial for improving circuit reliability, enhancing circuit characteristics, reducing design complexity, and improving circuit layout. The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made in accordance with the scope of the patent application of the present invention shall be covered by the present invention.

[0048] 100: Amplifier Circuit

[0049] 1010: Bias circuit

[0050] 110, 120, 130: Path circuit

[0051] 112, 122, 132: Radio frequency switching elements

[0052] 1120: Transistor

[0053] 114: Electrically Excessive Stress Circuit

[0054] 115, 125, 135, 145: Radio frequency venting switching elements

[0055] 116: Low-pass filter element

[0056] 117: Protection Circuit

[0057] 118: High-pass filter element

[0058] 119: Amplifier Circuit

[0059] 1192: Clamping Circuit

[0060] 129: Power Amplifier

[0061] 150: Switching element

[0062] ANT: Antenna

[0063] C1: Input capacitor

[0064] D1, D2: Diodes

[0065] N1, N2: Signal terminals

[0066] N51: Node

[0067] P1: Low-frequency conduction path

[0068] P2: Notch Filter Path at Specific Frequency

[0069] R1, R2: Resistors

[0070] REF1: Reference voltage terminal

[0071] SI: Radio Frequency Signal

[0072] SO: Output signal

[0073] STX, SRX: Wireless signal

[0074] T1: Transistor

[0075] TA,TA1: Amplifying transistors

[0076] TS: Discharge Transistor

[0077] V11, V12: Voltage

Claims

1. An amplifier circuit, comprising: a first signal terminal for receiving a radio frequency (RF) signal; a second signal terminal for outputting an output signal corresponding to the RF signal; and a first path circuit, comprising: a first RF switching element for selectively receiving the RF signal, including a first terminal and a second terminal, the first terminal being coupled to the first signal terminal; an electrical over-stress circuit; and a low-pass filter element connected in series with the electrical over-stress circuit between the second terminal of the first RF switching element and a first reference voltage terminal to form a low-frequency conduction path for discharging charge through the low-frequency conduction path when an electrical over-stress event occurs, the low-pass filter element including a first terminal coupled to the electrical over-stress circuit and a second terminal coupled to the first reference voltage terminal; A high-pass filter element is connected in parallel with the electrical over-stress circuit. The high-pass filter element includes a first terminal coupled to the second terminal of the first RF switching element and a second terminal coupled to the first terminal of the low-pass filter element. An amplifier circuit is also included for amplifying the RF signal. The amplifier circuit includes a first terminal coupled to the second terminal of the first RF switching element and a second terminal coupled to the second signal terminal. The high-pass filter element and the low-pass filter element form a specific frequency notch path between the second terminal of the first RF switch element and the first reference voltage terminal at a specific frequency.

2. The amplifier circuit as described in claim 1, further comprising an antenna coupled to the first signal terminal.

3. The amplifier circuit as claimed in claim 1, wherein the amplifier circuit is a low-noise amplifier.

4. The amplifier circuit as claimed in claim 3 further includes a second path circuit, wherein the second path circuit includes a second radio frequency switching element, wherein, during normal operation, one of the first radio frequency switching element and the second radio frequency switching element is turned on.

5. The amplifier circuit as claimed in claim 4, wherein the second path circuit further includes a power amplifier.

6. The amplifier circuit as claimed in claim 5, further comprising a third path circuit, wherein the third path circuit includes a third radio frequency switching element, wherein, during normal operation, one of the first radio frequency switching element, the second radio frequency switching element, and the third radio frequency switching element is turned on.

7. The amplifier circuit as claimed in claim 1, wherein the low-pass filter element includes an inductor.

8. The amplifier circuit as claimed in claim 1 or 7, wherein the high-pass filter element includes a capacitor.

9. The amplifier circuit of claim 1, wherein the electrical over-stress circuit includes a first diode and a second diode, the first diode being configured in a forward orientation and the second diode being configured in a reverse orientation, the first diode and the second diode being configured in parallel and connected in series between the second terminal of the first RF switching element and the low-pass filter element.

10. An amplifier circuit comprising: a first signal terminal for receiving a radio frequency (RF) signal; a second signal terminal for outputting an output signal corresponding to the RF signal; and a first path circuit comprising: a first RF switching element for selectively receiving the RF signal, including a first terminal and a second terminal, the first terminal being coupled to the first signal terminal; an electrical over-stress circuit including a transistor and a first resistor, wherein the transistor includes a first terminal, a second terminal and a control terminal, the first terminal being coupled to the second terminal of the first RF switching element, the second terminal being coupled to a first terminal of a low-pass filter element, and the control terminal being coupled to one terminal of the first resistor; a low-pass filter element connected in series with the electrical over-stress circuit between the second terminal of the first RF switching element and a first reference voltage terminal to form a low-frequency conduction path for dissipating charge through the low-frequency conduction path when an electrical over-stress event occurs; A high-pass filter element connected in parallel with the electrical over-stress circuit; and an amplifier circuit for amplifying the radio frequency signal, the amplifier circuit including a first terminal coupled to the second terminal of the first radio frequency switching element, and a second terminal coupled to the second signal terminal.

11. The amplifier circuit of claim 10, wherein the other end of the first resistor is coupled to the second end of the transistor, and the transistor is a bipolar transistor or a field-effect transistor.

12. The amplifier circuit of claim 10, wherein the electrical over-stress circuit includes a second resistor and the transistor is a field-effect transistor, wherein one end of the second resistor is coupled to one end of the field-effect transistor.

13. The amplifier circuit of claim 12, wherein the other end of the first resistor and the other end of the second resistor are respectively coupled to a bias circuit, the bias circuit providing a control bias to the other end of the first resistor and a substrate bias to the other end of the second resistor.

14. The amplifier circuit of claim 1, wherein the amplifier circuit includes an amplifying transistor, the control terminal of the amplifying transistor being coupled to the second terminal of the first radio frequency switching element, the second terminal of the amplifying transistor being coupled to the first reference voltage terminal, and the first terminal of the amplifying transistor being coupled to the second signal terminal.

15. The amplifier circuit as claimed in claim 14, wherein the amplifier circuit further includes an input capacitor, and the control terminal of the amplifying transistor is coupled to the second terminal of the first radio frequency switching element through the input capacitor.

16. An amplifier circuit comprising: a first signal terminal for receiving a radio frequency (RF) signal; a second signal terminal for outputting an output signal corresponding to the RF signal; and a first path circuit comprising: a first RF switching element for selectively receiving the RF signal, including a first terminal and a second terminal, the first terminal being coupled to the first signal terminal; an electrical over-stress circuit; and a low-pass filter element connected in series with the electrical over-stress circuit between the second terminal of the first RF switching element and a first reference voltage terminal to form a low-frequency conduction path for dissipating charge through the low-frequency conduction path when an electrical over-stress event occurs. A high-pass filter element is connected in parallel with the electrical over-stress circuit; and an amplifier circuit for amplifying the radio frequency signal, the amplifier circuit including a first terminal coupled to the second terminal of the first radio frequency switching element, a second terminal coupled to the second signal terminal, an amplifying transistor, and a clamping circuit, wherein the amplifying transistor includes a first terminal, a control terminal and a second terminal, the control terminal of the amplifying transistor is coupled to the second terminal of the first radio frequency switching element, the second terminal of the amplifying transistor is coupled to the first reference voltage terminal, the first terminal of the amplifying transistor is coupled to the second signal terminal, and the clamping circuit is connected in series between the control terminal and the first reference voltage terminal of the amplifying transistor.

17. The amplifier circuit as claimed in claim 1, wherein the electrical over-stress circuit and the low-pass filter element can form a clamping circuit at low frequencies.

18. The amplifier circuit of claim 1, wherein the first path circuit further includes a radio frequency venting switch element connected in series between the second terminal of the first radio frequency switch element and the first reference voltage terminal.

19. The amplifier circuit as claimed in claim 4, wherein the second path circuit further includes a radio frequency venting switch element connected in series between the second terminal of the second radio frequency switch element and the first reference voltage terminal.

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