RF switches and RF terminals

Abstract

A radio frequency (RF) switch and RF terminal are disclosed. The RF switch includes: an RF port; an antenna port; an antenna circuit; and a signal transmission branch located between the RF port and the RF ground port or between the RF port and the antenna port, for controlling the transmission of RF signals. The signal transmission branch includes two or more cascaded switching transistor units and a common bias resistor. At least one stage of the switching transistor unit adjacent to at least one end of the input or output port of the signal transmission branch is connected to the second end of the common bias resistor, while other switching transistor units are connected to the first end of the common bias resistor. The second end of the common bias resistor is the end of the common bias resistor furthest from the RF port. This design improves the ESD window effect of the RF switch.

Description

Technical Field

[0001] This invention relates to the field of electronic circuit technology, and more specifically to a radio frequency switch and a radio frequency terminal. Background Technology

[0002] Radio frequency (RF) switches are control devices used to control the transmission path of radio frequency signals. They are widely used in many fields such as wireless communication, electronic countermeasures, radar systems, and electronic measuring instruments.

[0003] In radio frequency (RF) switches, the RF port and antenna port are typically connected via series and parallel switch branches to control the RF signal transmission path. Parallel switch branches generally have a larger size and stronger electrostatic discharge (ESD) capability. Therefore, RF switches typically utilize their parallel switch branches as ESD self-discharge paths without introducing an additional ESD module. This minimizes the introduction of RF parasitic effects, thus avoiding impact on RF performance and reducing additional chip area costs.

[0004] However, RF switches exhibit an ESD window effect during ESD scan testing. Summary of the Invention

[0005] The problem this invention aims to solve is: how to improve the ESD window effect of radio frequency switches.

[0006] To address the above problems, embodiments of the present invention provide a radio frequency switch, the radio frequency switch comprising:

[0007] RF port;

[0008] Antenna port;

[0009] Antenna circuit;

[0010] A signal transmission branch, located between the radio frequency port and the radio frequency ground port or between the radio frequency port and the antenna port, is used to control the transmission of radio frequency signals;

[0011] The signal transmission branch includes two or more cascaded switching transistor units and a common bias resistor. At least one of the switching transistor units adjacent to at least one of the input port or output port of the signal transmission branch is connected to the second end of the common bias resistor, and the other switching transistor units are connected to the first end of the common bias resistor.

[0012] The second end of the common bias resistor is the end of the common bias resistor that is furthest from the RF port.

[0013] In one possible embodiment, the switching transistor unit connected to the second terminal of the common bias resistor is a series of k switching transistor units adjacent to the input port or output port of the signal transmission branch, wherein k is a positive integer and less than half of the switching transistor units in the signal transmission branch.

[0014] In one possible embodiment, k = 1.

[0015] In one possible embodiment, the signal transmission branch is a first signal transmission branch located between the radio frequency port and the radio frequency ground port, and the first signal transmission branch is connected in parallel with the radio frequency port.

[0016] In one possible embodiment, the signal transmission branch is a second signal transmission branch located between the radio frequency port and the antenna port, and the second signal transmission branch is connected in series with the radio frequency port and the antenna circuit.

[0017] In one possible embodiment, the radio frequency switch includes two signal transmission branches, namely a first signal transmission branch and a second signal transmission branch, wherein the first signal transmission branch is connected in parallel with the radio frequency port; and the second signal transmission branch is connected in series with the radio frequency port and the antenna circuit.

[0018] In one possible embodiment, the switching transistor unit includes: an NMOS transistor, a gate bias resistor, a path resistor, and a body bias diode; wherein, the gate bias resistor is located at the gate of the NMOS transistor; one end of the path resistor is connected to the drain of the NMOS transistor, and the other end is connected to the source of the NMOS transistor; the body bias diode is connected to the substrate of the NMOS transistor.

[0019] In one possible embodiment, the radio frequency switch further includes: analog and digital control circuitry connected to a second terminal of the common bias resistor, adapted to control the on / off state of the signal transmission branch.

[0020] In one possible embodiment, there are two or more radio frequency ports, and a signal transmission branch is provided between any radio frequency port and the antenna port.

[0021] In one possible embodiment, there is a signal transmission branch between any radio frequency port and the radio frequency ground port.

[0022] An embodiment of the present invention also provides a radio frequency terminal, the radio frequency terminal including any of the radio frequency switches described above.

[0023] Compared with the prior art, the technical solution of the embodiments of the present invention has the following advantages:

[0024] By applying the solution of the present invention, along the electrostatic discharge direction, by connecting at least one stage of the switching transistor unit adjacent to at least one end of the input port or output port of the signal transmission branch to the second end of the common bias resistor, the gate coupling voltage of at least one stage of the switching transistor unit in the signal transmission branch can be reduced, so that at least one stage of the switching transistor unit in the signal transmission branch remains in the off state during electrostatic discharge. This prevents other switching transistor units in the signal transmission branch from switching failure due to insufficient channel current, and ultimately improves the ESD window effect of the RF switch. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the circuit structure of a single-pole multi-throw radio frequency switch;

[0026] Figure 2 This is a schematic diagram of the circuit structure of a single-pole multi-throw radio frequency switch in an embodiment of the present invention;

[0027] Figure 3 This is a schematic diagram of the circuit structure of another single-pole multi-throw radio frequency switch in an embodiment of the present invention;

[0028] Figure 4 This is a schematic diagram of the circuit structure of another single-pole multi-throw radio frequency switch in an embodiment of the present invention;

[0029] Figure 5 This is a schematic diagram of the circuit structure of another single-pole multi-throw radio frequency switch in an embodiment of the present invention;

[0030] Figure 6 This is a comparative diagram of the simulation results of an electrostatic discharge window. Detailed Implementation

[0031] Figure 1 This is a schematic diagram of the circuit structure of a single-pole multi-throw radio frequency switch. (Refer to...) Figure 1 The single-pole multi-throw RF switch includes M RF ports (RF1, RF2, ..., RFM) and one antenna port ANT. Each RF port and the antenna port ANT are connected by a series switch branch and a parallel switch branch, which are used to select the transmission path of the RF signal between the RF port and the antenna port ANT.

[0032] To simplify the illustration, Figure 1Only the series switch branch 11 and the parallel switch branch 12 between the first RF port RF1 and the antenna port ANT are shown. The series switch branch 11 is connected in series with the antenna circuit 100, and the parallel switch branch 12 is connected in parallel with the antenna circuit 100. The control terminals of both the series switch branch 11 and the parallel switch branch 12 are connected to the analog and digital control circuit 200, which controls the on / off state of the series switch branch 11 and the parallel switch branch 12.

[0033] The parallel switch branch 12 includes n cascaded multi-switch transistor units 121 and a common bias resistor Rcom. The n cascaded switch transistor units 121 are connected to the same end of the common bias resistor Rcom, and the other end of the common bias resistor Rcom is connected to the analog and digital control circuit 200.

[0034] Specifically, when the analog and digital control circuit 200 controls the series switch branch 11 to be turned on and the parallel switch branch 12 to be turned off, the radio frequency signal is transmitted between the first radio frequency port RF1 and the antenna port ANT via the series switch branch 11. When the analog and digital control circuit 200 controls the parallel switch branch 12 to be turned on and the series switch branch 11 to be turned off, the radio frequency signal is transmitted between the first radio frequency port RF1 and the antenna port ANT via the parallel switch branch 12.

[0035] Since one end of the parallel switch branch 12 is connected to the first RF port RF1 and the other end is grounded, when the parallel switch branch 12 is not used to transmit RF signals, it can serve as an ESD self-discharge path for the RF switch, thereby avoiding the impact on RF performance due to the introduction of RF parasitic effects.

[0036] When performing single or multiple repeated ESD scans on RF switches, an ESD window effect sometimes occurs. Specifically, when starting the scan test directly from a higher ESD capability (i.e., a larger input signal voltage), the RF switch's ESD capability meets the ESD design expectations. However, when starting the scan from an extremely low ESD capability (i.e., an extremely low input signal voltage), ESD failure (i.e., inability to release static electricity) occurs before reaching the designed lower ESD capability (i.e., a lower input signal voltage). This exhibits a low ESD capability failure window effect under high ESD capability. The ESD window (i.e., the input signal voltage range) of an RF switch is typically 100V to 600V.

[0037] The inventors discovered that the ESD window effect causes ESD failure in RF switches because, taking the forward electrostatic discharge (discharging static electricity from the RF port to ground) of parallel switch branch 12 as an example, during the forward electrostatic discharge, positive charges couple to the common node Node-G of parallel switch branch 12, causing the switches in each stage of the switching transistor unit 121 to turn on and discharge positive charges to ground in channel conduction mode. As the ESD energy further increases, the switches in each stage of the switching transistor unit 121 will switch from channel conduction to parasitic bipolar junction transistor (BJT) mode to further reduce the on-resistance. For ease of description, this switching is referred to as "onbreakdown". Tests revealed that once onbreakdown occurs in the mode where the gate is on and there is channel current, the switches in each stage of the switching transistor unit 121 are very prone to thermal burnout, resulting in ESD failure.

[0038] The ESD energy corresponding to a failure switching event is typically around 0.1KV to 0.6KV. In other words, the probability of an ESD failure is higher when the ESD energy is in the range of 0.1KV to 0.6KV.

[0039] To address this problem, the present invention provides a radio frequency switch in which at least one switching transistor unit along the electrostatic discharge direction in the signal transmission branch is connected to the second end of a common bias resistor. This reduces the gate coupling voltage of the switching transistor unit connected to the second end of the common bias resistor, thereby enabling the switching transistor unit connected to the second end of the common bias resistor to remain in the off state during electrostatic discharge, thus avoiding switching failure and ultimately improving the ESD window effect.

[0040] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0041] This invention provides a radio frequency switch, the radio frequency switch comprising:

[0042] RF port;

[0043] Antenna port;

[0044] Antenna circuit;

[0045] A signal transmission branch, located between the radio frequency port and the radio frequency ground port or between the radio frequency port and the antenna port, is used to control the transmission of radio frequency signals;

[0046] The signal transmission branch includes two or more cascaded switching transistor units and a common bias resistor. At least one stage of the switching transistor unit adjacent to at least one of the input port or output port of the signal transmission branch is connected to the second end of the common bias resistor, and the other switching transistor units are connected to the first end of the common bias resistor. The second end of the common bias resistor is the end of the common bias resistor that is furthest from the RF port.

[0047] Specifically, at least one stage of the switching transistor unit adjacent to the input port of the signal transmission branch can be connected to the second terminal of the common bias resistor; alternatively, at least one stage of the switching transistor unit adjacent to the output port of the signal transmission branch can be connected to the second terminal of the common bias resistor; and alternatively, at least one stage of the switching transistor unit adjacent to both the input and output ports of the signal transmission branch can be connected to the second terminal of the common bias resistor. Here, the input and output ports refer to the input and output ports of the signal transmission branch.

[0048] By connecting at least one stage of the switching transistor unit adjacent to at least one end of the input port or output port of the signal transmission branch to the second end of the common bias resistor, the switching transistor unit connected to the second end of the common bias resistor can be prevented from turning on due to excessive voltage at the first end of the common bias resistor during electrostatic discharge, and can thus remain in the off state. This ensures that the switching transistor units at each stage in the signal transmission branch do not have sufficient channel current to avoid switching failure, thereby improving the ESD window effect.

[0049] In specific implementation, at least one stage of the switching transistor unit adjacent to at least one end of the signal transmission branch, either the input port or the output port, is connected to the second end of a common bias resistor. The switching transistor unit connected to the second end of the common bias resistor can be at least one stage in the middle of the signal transmission branch (i.e., excluding the first stage and the last stage). The multi-stage switching transistor units connected to the second end of the common bias resistor can be consecutive or discontinuous; no restriction is imposed here.

[0050] In one embodiment of the present invention, in order to balance the radio frequency performance of the signal transmission branch and avoid affecting signal transmission, a series of k-stage switching transistor units adjacent to the input or output port of the signal transmission branch can be selected and connected to the second terminal of the common bias resistor. Here, k is a positive integer and less than half the total number of switching transistor units in the signal transmission branch. In this case, the last k-stage switching transistor unit is the last series of k-stage switching transistor units.

[0051] In one embodiment, k=1. In this case, only the first-stage switching transistor unit of the signal transmission branch adjacent to the input port or output port can be connected to the second terminal of the common bias resistor. This can improve the ESD window effect while maximizing the RF performance.

[0052] In another embodiment, k≥2, at this time, only at least two stages of switching transistors adjacent to the input port or output port of the signal transmission branch can be connected to the second end of the common bias resistor, thereby improving the ESD window effect while taking into account the RF performance.

[0053] In one embodiment, each switching transistor unit in the signal transmission branch has the same structure and may include: an NMOS transistor, a gate bias resistor, a path resistor, and a body bias diode; wherein, the gate bias resistor is located at the gate of the NMOS transistor; one end of the path resistor is connected to the drain of the NMOS transistor, and the other end is connected to the source of the NMOS transistor; the body bias diode is connected to the substrate of the NMOS transistor.

[0054] In one embodiment, the radio frequency switch may further include analog and digital control circuitry. The analog and digital control circuitry may be connected to the second terminal of the common bias resistor and is adapted to control the on / off state of the signal transmission branch. Connecting at least one stage of a switching transistor unit adjacent to at least one end of the signal transmission branch, either at the input port or the output port, to the second terminal of the common bias resistor means connecting at least one stage of a switching transistor unit near the electrostatic discharge outlet to the analog and digital control circuitry, bypassing the common bias resistor.

[0055] In practical implementation, analog and digital control circuits can provide control voltage to the signal transmission branch, thereby controlling the switching transistors in the signal transmission branch to turn on or off. When all switching transistors in the signal transmission branch are off, the signal transmission branch can be used to transmit signals, and of course, it can also be used to discharge static electricity.

[0056] In specific implementations, the RF switch can be a single-pole double-throw RF switch, a single-pole multi-throw RF switch, a double-pole double-throw RF switch, a double-pole double-throw RF switch, or a multi-pole multi-throw RF switch; no limitation is imposed here. Any type of RF switch may include an RF port, an antenna port, an antenna circuit, and a signal transmission branch.

[0057] Understandably, different types of RF switches result in different numbers of RF ports, antenna ports, and antenna circuits, and the location of signal transmission branches may also change.

[0058] In one embodiment, there are two or more radio frequency (RF) ports, and a signal transmission branch is provided between any RF port and the antenna port. For example, in a single-pole multi-throw (SPMD) RF switch, there is only one antenna port, but there can be multiple RF ports, and at least one signal transmission branch can be provided between each RF port and the single antenna port.

[0059] In another embodiment, there are two or more radio frequency ports and two or more radio frequency grounding ports; a signal transmission branch is provided between any radio frequency port and any radio frequency grounding port. For example, in a double-pole multi-throw radio frequency switch, there may be two antenna ports and multiple radio frequency ports, and each radio frequency port has a signal transmission branch with at least one of the radio frequency grounding ports.

[0060] It should be noted that, regardless of the type of RF switch, a signal transmission branch is provided in the RF switch. Through this signal transmission branch, the RF signal can be transmitted from the connected RF port to the connected antenna port, or from the connected antenna port to the connected RF port.

[0061] In embodiments of the present invention, for any signal transmission branch in a radio frequency switch, at least one switching transistor unit adjacent to the input port or output port can be connected to the second end of a common bias resistor, while other switching transistor units are kept connected to the first end of the common bias resistor. In this way, the switching transistor unit connected to the second end of the common bias resistor will not turn on due to excessive voltage at the first end of the common bias resistor, thereby avoiding the signal transmission branch from failing to switch and thus being unable to perform ESD release.

[0062] In practical implementation, when designing the RF switch, the signal transmission branch serving as the ESD discharge path can be adjusted according to the scheme of this invention. Specifically, at least one switching transistor unit adjacent to the input or output port in the signal transmission branch serving as the ESD discharge path is connected to the second terminal of a common bias resistor. Each signal transmission branch in the RF switch can be used as an ESD discharge path, or only a portion of the signal transmission branches can be selected; there is no limitation here. For all signal transmission branches serving as ESD discharge paths, some can be adjusted using the scheme of this invention, or all can be adjusted using the scheme of this invention.

[0063] The following uses a single-pole multi-throw radio frequency switch as an example to describe the solution of the present invention in detail:

[0064] Figure 2 This is a schematic diagram of the circuit structure of a single-pole multi-throw radio frequency switch according to an embodiment of the present invention. For the sake of simplicity, [the diagram is omitted here]. Figure 2 Only the signal transmission branch between the first RF port RF1 and the RF ground port RFGND, and the first RF port RF1 and the antenna port ANT are shown. The signal transmission branch between the first RF port RF1 and the antenna port ANT is not shown. The signal transmission branches between other RF ports (including the second RF port RF2, ..., the Mth RF port RFM) and the antenna port ANT or the RF ground port RFGND are not shown.

[0065] In some embodiments, the signal transmission branch can be a first signal transmission branch. The first signal transmission branch is located between the RF port and the RF ground port, and is connected in parallel with the RF port. That is, at least one stage of the switching transistor unit in the signal transmission branch connected in parallel with the RF port, adjacent to at least one end of the input port or output port, can be connected to the second end of the common bias resistor.

[0066] Specifically, refer to Figure 2 Taking the first signal transmission branch 21 as an example, one end of the first signal transmission branch 21 can be connected to the first radio frequency port RF1, and the other end is grounded to RFGND. One end of the antenna circuit 10 is connected to the first radio frequency port RF1 through the second signal transmission branch 22, and the other end is grounded to RFGND. In this way, the first signal transmission branch 21 and the first radio frequency port RF1 are connected in parallel.

[0067] The first signal transmission branch 21 may include n cascaded switching transistor units, namely the first switching transistor unit to the nth switching transistor unit, where n ≥ 2 and is a positive integer. Each switching transistor unit may include: an NMOS transistor, a gate bias resistor, a path resistor, and a body bias diode. Taking the first diode as an example, the gate bias resistor Rg1 is located at the gate of the NMOS transistor M1; one end of the path resistor Rds1 is connected to the drain of the NMOS transistor M1, and the other end is connected to the source of the NMOS transistor M1; the body bias diode D1 is connected to the substrate of the NMOS transistor M1. When the NMOS transistor M1 is turned on, the path resistor Rds1 is connected.

[0068] In one embodiment, reference is made to Figure 2 For the first signal transmission branch 21, only the first-level switch unit adjacent to the first RF port RF1 or the RF ground port RFGND can be connected to the second terminal of the common bias resistor Rcom, while the other (n-1) switch units are connected to the first terminal of the common bias resistor Rcom. For example, when the electrostatic discharge direction is forward electrostatic discharge, only the nth switch unit can be connected to the second terminal of the common bias resistor Rcom, while the first to (n-1)th switch units are connected to the first terminal of the common bias resistor Rcom. When the electrostatic discharge direction is reverse electrostatic discharge, only the first switch unit can be connected to the second terminal of the common bias resistor Rcom, while the second to nth switch units are connected to the first terminal of the common bias resistor Rcom.

[0069] In one embodiment, for the first signal transmission branch 21, only two or more switching transistor units adjacent to the first RF port RF1 or the RF ground port RFGND can be connected to the second terminal of the common bias resistor Rcom, while the other switching transistor units are connected to the first terminal of the common bias resistor Rcom. For example, when the electrostatic discharge direction is reverse electrostatic discharge, the first and second switching transistor units can both be connected to the second terminal of the common bias resistor Rcom, while the third to nth switching transistor units are connected to the first terminal of the common bias resistor Rcom. When the electrostatic discharge direction is forward electrostatic discharge, the (n-1)th and nth switching transistor units can both be connected to the second terminal of the common bias resistor Rcom, while the first to (n-2)th switching transistor units are connected to the first terminal of the common bias resistor Rcom.

[0070] In other embodiments, the signal transmission branch can be a second signal transmission branch located between the RF port and the antenna port, and the second signal transmission branch is connected in series with the RF port and the antenna circuit. That is, only at least one stage of the switching transistor unit along the electrostatic discharge direction in the signal transmission branch connected in series with the RF port and the antenna circuit can be connected to the second terminal of the common bias resistor.

[0071] Specifically, refer to Figure 3 Taking the second signal transmission branch 22 as an example, one end of the second signal transmission branch 22 can be connected to the first radio frequency port RF1, and the other end can be connected in series with the antenna circuit 10.

[0072] The second signal transmission branch 22 may include h cascaded switching transistor units, namely the first switching transistor unit to the h-th switching transistor unit, where h ≥ 2 and is positive. Each switching transistor unit may include: an NMOS transistor, a gate bias resistor, a path resistor, and a body bias diode. Taking the h-th diode as an example, the gate bias resistor Rgh is located at the gate of the NMOS transistor Mh; one end of the path resistor Rdsh is connected to the drain of the NMOS transistor Mh, and the other end is connected to the source of the NMOS transistor Mh; the body bias diode Dh is connected to the substrate of the NMOS transistor Mh. When the NMOS transistor Mh is turned on, the path resistor Rdsh is connected.

[0073] In one embodiment, reference is made to Figure 4For the second signal transmission branch 22, only the last stage switching transistor unit immediately adjacent to the input or output port can be connected to the second terminal of the common bias resistor Rcom, while the other (h-1) switching transistor units can be connected to the first terminal of the common bias resistor Rcom. For example, when the electrostatic discharge direction is reverse electrostatic discharge, only the first switching transistor unit can be connected to the second terminal of the common bias resistor Rcom, while the second to h-th switching transistor units can be connected to the first terminal of the common bias resistor Rcom.

[0074] In one embodiment, for the second signal transmission branch 22, only the last two stages of switching transistors immediately adjacent to the input or output port can be connected to the second terminal of the common bias resistor Rcom, while the other switching transistors are connected to the first terminal of the common bias resistor Rcom. For example, refer to... Figure 5 When the electrostatic discharge direction is positive, the first and second switch units can be connected to the second terminal of the common bias resistor Rcom, while the third to nth switch units can be connected to the first terminal of the common bias resistor Rcom.

[0075] In other embodiments, at least one discontinuous switching transistor unit may also be connected to the second terminal of a common bias resistor Rcom. For example, refer to... Figure 5 The second, fourth, and h-th switching transistor units can be connected to the second terminal of the common bias resistor Rcom. The specific number of switching transistor units connected to the second terminal of the common bias resistor Rcom can be set according to actual RF performance requirements.

[0076] In some embodiments, the radio frequency switch may include two signal transmission branches, namely a first signal transmission branch 21 (e.g., Figure 2 (as shown) and the second signal transmission branch 22 (as shown) Figure 4 As shown in the figure, the first signal transmission branch 21 is connected in parallel with the radio frequency port RF1; the second signal transmission branch 22 is connected in series with the radio frequency port and the antenna circuit.

[0077] In other words, at least one switching transistor unit in the series switching branch (i.e., the second signal transmission branch 22) and the parallel switching branch (the first signal transmission branch 21) of the RF switch can be connected to the second terminal of the common bias resistor. In this case, both the series switching branch and the parallel switching branch can serve as electrostatic discharge paths.

[0078] Regarding how the first signal branch 21 and the second signal branch 22 are connected to the second terminal of the common bias resistor, please refer to the above-mentioned... Figure 2 and Figure 4 The implementation will be carried out as described above, and will not be repeated here.

[0079] Will Figure 2 The electrostatic discharge window of the RF switch and Figure 1 By comparing the electrostatic discharge windows of the RF switches, we can obtain... Figure 6 The diagram shows a comparison of the simulation results for the electrostatic discharge window. Curve 61 represents... Figure 1 The curve of the gate coupling voltage of MOS transistor Mn in the last stage of the RF switch unit versus time is shown in curve 62. Figure 2 The curve showing the change of the gate coupling voltage of MOS transistor Mn in the last stage of the RF switch unit over time.

[0080] As can be seen from curves 61 and 62, after the improvement, the gate coupling voltage of the switching transistor Mn in the last stage of the RF switch is effectively reduced, so that it can remain in the off state during the electrostatic discharge process. This ensures that each stage of the switching transistor unit does not have enough channel current before switching to the parasitic BJT mode, thus preventing switching failure. The test shows that the ESD window effect is improved.

[0081] By employing the solution of this invention, at least one stage of the switching transistor unit adjacent to at least one end of the input port or output port in the signal transmission branch is connected to the second end of the common bias resistor, while other switching transistor units remain connected to the first end of the common bias resistor. This reduces the gate coupling voltage of the MOS transistor in the switching transistor unit connected to the second end of the common bias resistor, thereby enabling it to remain in the off state during electrostatic discharge and reducing the occurrence of switching failures.

[0082] This invention also provides a radio frequency (RF) terminal, which includes any of the RF switches described in the above embodiments. The RF switch allows control of the RF signal transmission path and possesses good ESD protection.

[0083] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A radio frequency switch, characterized in that, include: RF port; Antenna port; Antenna circuit; A signal transmission branch is located between the radio frequency port and the radio frequency ground port or between the radio frequency port and the antenna port, and is used to control the transmission of radio frequency signals and as a static discharge path. The signal transmission branch includes two or more cascaded switching transistor units and a common bias resistor. At least one stage of the switching transistor unit adjacent to at least one of the input port or output port of the signal transmission branch is connected to the second end of the common bias resistor, and the other switching transistor units are connected to the first end of the common bias resistor. The input port is a radio frequency port, and the output port is a radio frequency ground port or an antenna port. The second end of the common bias resistor is the end of the common bias resistor that is furthest from the RF port; The switching transistor unit includes: an NMOS transistor, a gate bias resistor, a path resistor, and a body bias diode; wherein, one end of the gate bias resistor is connected to the gate of the NMOS transistor; one end of the path resistor is connected to the drain of the NMOS transistor, and the other end is connected to the source of the NMOS transistor; the body bias diode is connected to the substrate of the NMOS transistor; and the other end of the gate bias resistor is connected to the common bias resistor.

2. The radio frequency switch as described in claim 1, characterized in that, The switching transistor unit connected to the second terminal of the common bias resistor is a continuous k-stage switching transistor unit adjacent to the input port or output port of the signal transmission branch, where k is a positive integer and less than half of the total number of switching transistor units in the signal transmission branch.

3. The radio frequency switch as described in claim 2, characterized in that, k=1。 4. The radio frequency switch as described in claim 1, characterized in that, The signal transmission branch is a first signal transmission branch, located between the radio frequency port and the radio frequency ground port, and the first signal transmission branch is connected in parallel with the radio frequency port.

5. The radio frequency switch as described in claim 1, characterized in that, The signal transmission branch is a second signal transmission branch, located between the radio frequency port and the antenna port, and the second signal transmission branch is connected in series with the radio frequency port and the antenna circuit.

6. The radio frequency switch as described in claim 1, characterized in that, The radio frequency switch includes two signal transmission branches, namely a first signal transmission branch and a second signal transmission branch, wherein the first signal transmission branch is connected in parallel with the radio frequency port; and the second signal transmission branch is connected in series with the radio frequency port and the antenna circuit.

7. The radio frequency switch as described in claim 1, characterized in that, Also includes: An analog and digital control circuit, connected to the second terminal of the common bias resistor, is adapted to control the on / off state of the signal transmission branch.

8. The radio frequency switch according to any one of claims 1 to 7, characterized in that, There are two or more radio frequency ports, and a signal transmission branch is provided between any radio frequency port and the antenna port.

9. The radio frequency switch according to any one of claims 1 to 7, characterized in that, There is a signal transmission branch between any radio frequency port and the radio frequency ground port.

10. A radio frequency terminal, characterized in that, Includes the radio frequency switch as described in any one of claims 1 to 9.

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