Radio frequency switch and radio frequency terminal

Abstract

A radio frequency switch and a radio frequency terminal. The radio frequency switch comprises: a radio frequency port; an antenna port; an antenna circuit; and a signal transmission branch, which is located between the radio frequency port and a radio frequency grounding port or located between the radio frequency port and the antenna port and is used for controlling the transmission of a radio frequency signal, wherein the signal transmission branch comprises two or more cascaded switch transistor units and a common bias resistor; at least one switch transistor unit of the signal transmission branch closely adjacent to at least one of an input port or an output port is connected to a second end of the common bias resistor, and the other switch transistor units are connected to a first end of the common bias resistor; and the second end of the common bias resistor is the end of the common bias resistor away from the radio frequency port. By means of the above-described solution, the ESD window effect of the radio frequency switch can be improved.

Description

Radio frequency switch and radio frequency terminal

[0001] The present application claims priority to the Chinese patent application No. 202410855748.3, filed on June 27, 2024, and entitled "Radio frequency switch and radio frequency terminal", the whole content of which is incorporated herein by reference. TECHNICAL FIELD

[0002] The present application relates to the technical field of electronic circuit, in particular to a radio frequency switch and a radio frequency terminal. BACKGROUND

[0003] The radio frequency switch is one of the control devices for controlling the radio frequency signal transmission path, and has a wide range of applications in many fields such as wireless communication, electronic countermeasures, radar systems and electronic measuring instruments.

[0004] Generally, series switch branches and parallel switch branches are used to control the radio frequency signal transmission path between the radio frequency port and the antenna port of the radio frequency switch. Among them, the parallel switch branch generally has a large size and strong electro-static discharge (ESD) capability, so the radio frequency switch usually uses its parallel switch branch as an ESD self-discharge path, without introducing an additional ESD module, thereby maximizing the degree of not introducing radio frequency parasitic effects without affecting the radio frequency performance, and without increasing the additional chip area cost.

[0005] However, the radio frequency switch will have an ESD window effect when performing ESD scan test.

[0006] SUMMARY

[0007] The problem to be solved by the present application is how to improve the ESD window effect of the radio frequency switch.

[0008] To solve the above problems, the present application provides a radio frequency switch, which comprises:

[0009] a radio frequency port;

[0010] an antenna port;

[0011] an antenna circuit;

[0012] 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, for controlling the transmission of radio frequency signals;

[0013] The signal transmission branch includes two or more cascaded switch tube units and a common bias resistor, at least one switch tube unit adjacent to at least one of the input port or the output port is connected to the second end of the common bias resistor, and the other switch tube units are connected to the first end of the common bias resistor.

[0014] The second end of the common bias resistor is an end of the common bias resistor away from the radio frequency port.

[0015] In a possible embodiment, the switch tube unit connected to the second end of the common bias resistor is a continuous k-level switch tube unit adjacent to the input port or the output port of the signal transmission branch, wherein k is a positive integer and less than half of the switch tube units in the signal transmission branch.

[0016] In a possible embodiment, k = 1.

[0017] In a 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 to the radio frequency port.

[0018] In a 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 to the radio frequency port and the antenna circuit.

[0019] In a possible embodiment, the radio frequency switch includes two signal transmission branches, which are a first signal transmission branch and a second signal transmission branch, wherein the first signal transmission branch is connected in parallel to the radio frequency port, and the second signal transmission branch is connected in series to the radio frequency port and the antenna circuit.

[0020] In a possible embodiment, the switch tube unit includes an NMOS tube, a gate bias resistor, a pass resistor, and a body bias diode, wherein the gate bias resistor is located at the gate of the NMOS tube, one end of the pass resistor is connected to the drain of the NMOS tube, and the other end of the pass resistor is connected to the source of the NMOS tube, and the body bias diode is connected to the substrate of the NMOS tube.

[0021] In a possible embodiment, the radio frequency switch further includes an analog and digital control circuit connected to the second end of the common bias resistor and adapted to control the on-off of the signal transmission branch.

[0022] In a possible embodiment, the radio frequency port is two or more, and the signal transmission branch is provided between any radio frequency port and the antenna port.

[0023] In one possible embodiment, the signal transmission branch is provided between any radio frequency port and a radio frequency ground port.

[0024] Embodiments of the present application also provide a radio frequency terminal comprising any of the above radio frequency switches.

[0025] Compared with the prior art, the technical scheme of the embodiments of the present application has the following advantages:

[0026] By connecting the at least one stage of switch tube unit of the signal transmission branch adjacent to at least one of the input port or the output port to the second end of the common bias resistor in the electrostatic discharge direction, the gate coupling voltage of the at least one stage of switch tube unit in the signal transmission branch can be reduced, so that the at least one stage of switch tube unit in the signal transmission branch can remain in the closed state during the electrostatic discharge, thereby preventing the other switch tube units in the signal transmission branch from failing to switch due to insufficient channel current, and finally improving the ESD window effect of the radio frequency switch. BRIEF DESCRIPTION OF DRAWINGS

[0027] Fig. 1 is a schematic diagram of a circuit structure of a single-pole multi-throw radio frequency switch;

[0028] Fig. 2 is a schematic diagram of a circuit structure of a single-pole multi-throw radio frequency switch in an embodiment of the present application;

[0029] Fig. 3 is a schematic diagram of a circuit structure of another single-pole multi-throw radio frequency switch in an embodiment of the present application;

[0030] Fig. 4 is a schematic diagram of a circuit structure of still another single-pole multi-throw radio frequency switch in an embodiment of the present application;

[0031] Fig. 5 is a schematic diagram of a circuit structure of yet another single-pole multi-throw radio frequency switch in an embodiment of the present application;

[0032] Fig. 6 is a comparative schematic diagram of simulation results of an electrostatic discharge window. DETAILED DESCRIPTION

[0033] Fig. 1 is a schematic diagram of a circuit structure of a single-pole multi-throw radio frequency switch. Referring to Fig. 1, the single-pole multi-throw radio frequency switch comprises M radio frequency ports (RF1, RF2, …, RFM) and an antenna port ANT. A series switch branch and a parallel switch branch are provided between each radio frequency port and the antenna port ANT, and the series switch branch and the parallel switch branch are used to select a transmission path of a radio frequency signal between the radio frequency port and the antenna port ANT.

[0034] For simplifying the illustration, only the series switch branch 11 and the parallel switch branch 12 between the first radio frequency port RF1 and the antenna port ANT are shown in FIG. 1. 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 the series switch branch 11 and the parallel switch branch 12 are connected with the analog and digital control circuit 200, and the analog and digital control circuit 200 controls the on-off of the series switch branch 11 and the parallel switch branch 12.

[0035] In the parallel switch branch 12, n cascaded multi-switch tube units 121 and a common bias resistor Rcom are included. The n cascaded multi-switch tube 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 with the analog and digital control circuit 200.

[0036] Specifically, when the analog and digital control circuit 200 controls the series switch branch 11 to be on and the parallel switch branch 12 to be off, the radio frequency signal is transmitted between the first radio frequency port RF1 and the antenna port ANT through the series switch branch 11. When the analog and digital control circuit 200 controls the parallel switch branch 12 to be on and the series switch branch 11 to be off, the radio frequency signal is transmitted between the first radio frequency port RF1 and the antenna port ANT through the parallel switch branch 12.

[0037] Since one end of the parallel switch branch 12 is connected with the first radio frequency port RF1 and the other end is grounded, when the parallel switch branch 12 is not used for transmitting the radio frequency signal, it can be used as an ESD self-discharge path of the radio frequency switch, thereby avoiding the influence on the radio frequency performance due to the introduction of the radio frequency parasitic effect.

[0038] When the radio frequency switch is actually used for ESD single or multiple repeated scan test, sometimes the ESD window effect occurs. Specifically, when the scan test is directly started from a higher ESD capability (i.e. a larger input signal voltage), the ESD capability of the radio frequency switch meets the ESD design expectation, but when the scan is started from an extremely low ESD capability (i.e. an extremely small input signal voltage), the ESD failure (i.e. unable to discharge static electricity) occurs when the design lower ESD capability (i.e. a lower input signal voltage) is far from being reached, thereby presenting the low ESD capability failure window effect under the high ESD capability. The ESD window (i.e. the input signal voltage range) of the radio frequency switch is generally 100V-600V.

[0039] The inventor has found that the reason for the ESD failure of the radio frequency switch caused by the ESD window effect is that: taking the positive static electricity release of the parallel switch branch 12 (discharging static electricity from the radio frequency port to the ground) as an example, during the positive static electricity release process, the positive charge is coupled to the common node Node-G of the parallel switch branch 12, and then causes the switch tube in each stage of switch tube unit 121 to be turned on, and the positive charge is discharged to the ground in the channel conduction mode. With the further increase of the ESD energy, the switch tube in each stage of switch tube unit 121 will switch from the channel conduction to the parasitic bipolar junction transistor (BJT) mode to further reduce the conduction resistance. For the convenience of description, the switching is called "on breakdown". Tests have found that once the switching of the switch tube in each stage of switch tube unit 121 occurs in the mode of the gate being turned on and having channel current, the switch tube is very easy to be burned out, and thus the ESD failure occurs.

[0040] The corresponding ESD energy when the failure switching occurs is usually about 0.1KV-0.6KV. That is to say, when the ESD energy is in the interval of 0.1KV-0.6KV, the probability of ESD failure is greater.

[0041] In view of the problem, the present application provides a radio frequency switch, wherein at least one stage of switch tube unit in the signal transmission branch is connected with the second end of the common bias resistor in the direction of static electricity release, so as to reduce the gate coupling voltage of the switch tube unit connected with the second end of the common bias resistor, and thus the switch tube unit connected with the second end of the common bias resistor can be kept in the closed state during the static electricity release process, so as to avoid the switching failure, and finally improve the ESD window effect.

[0042] In order to make the above-mentioned purpose, characteristics and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application will be described in detail below with reference to the drawings.

[0043] The present application provides a radio frequency switch, which comprises:

[0044] A radio frequency port;

[0045] An antenna port;

[0046] An antenna circuit;

[0047] A signal transmission branch, which 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 for controlling the transmission of radio frequency signals;

[0048] The signal transmission branch includes two or more cascaded switch tube units and a common bias resistor, at least one switch tube unit adjacent to at least one of the input port or the output port is connected to the second end of the common bias resistor, and the other switch tube units are connected to the first end of the common bias resistor; and the second end of the common bias resistor is an end of the common bias resistor away from the radio frequency port.

[0049] Specifically, the second end of the common bias resistor can be connected to at least one switch tube unit adjacent to the input port, or connected to at least one switch tube unit adjacent to the output port, or connected to at least one switch tube unit adjacent to both the input port and the output port. Here, the input port and the output port refer to the input port and the output port of the signal transmission branch.

[0050] By connecting the second end of the common bias resistor to at least one switch tube unit adjacent to at least one of the input port or the output port, the switch tube unit connected to the second end of the common bias resistor can be prevented from being turned on due to the excessively high voltage at the first end of the common bias resistor during electrostatic discharge, thereby maintaining the closed state, and ensuring that the switch tube units in the signal transmission branch do not have sufficient channel current to cause switching failure, thereby improving the ESD window effect.

[0051] In a specific implementation, the second end of the common bias resistor can be connected to at least one switch tube unit adjacent to at least one of the input port or the output port, and the switch tube unit connected to the second end of the common bias resistor can be at least one switch tube unit in the middle of the signal transmission branch (i.e., not including the first stage unit and the last stage switch tube unit). The multiple switch tube units connected to the second end of the common bias resistor can be consecutive multiple switch tube units or discontinuous switch tube units, which is not limited here.

[0052] In an embodiment of the present application, in order to consider the radio frequency performance of the signal transmission branch and avoid affecting signal transmission, the second end of the common bias resistor can be connected to consecutive k-stage switch tube units adjacent to the input port or the output port of the signal transmission branch. Here, k is a positive integer and less than half of the total number of switch tube units in the signal transmission branch. At this time, the last k-stage switch tube unit is the last consecutive k-stage switch tube unit.

[0053] In an embodiment, k = 1, at this time, only one switch tube unit adjacent to the input port or the 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 maximizing the consideration of the radio frequency performance.

[0054] In another embodiment, k≥2, at this time, only the signal transmission branch can be connected to the second end of the common bias resistor through at least two-stage switch tube units adjacent to the input port or the output port, so that the ESD window effect can be improved while the RF performance is considered.

[0055] In an embodiment, each switch tube unit in the signal transmission branch has the same structure, and can include an NMOS tube, a gate bias resistor, a pass resistor and a body bias diode; the gate bias resistor is located at the gate of the NMOS tube; one end of the pass resistor is connected to the drain of the NMOS tube, and the other end is connected to the source of the NMOS tube; the body bias diode is connected to the substrate of the NMOS tube.

[0056] In an embodiment, the RF switch can further include an analog and digital control circuit. The analog and digital control circuit can be connected to the second end of the common bias resistor, and is adapted to control the on-off of the signal transmission branch. At least one-stage switch tube unit adjacent to at least one end of the input port or the output port in the signal transmission branch is connected to the second end of the common bias resistor, that is, at least one-stage switch tube unit adjacent to the ESD outlet is connected to the analog and digital control circuit without bypassing the common bias resistor.

[0057] In a specific implementation, the analog and digital control circuit can provide a control voltage for the signal transmission branch, so as to control the on or off of the switch tube in the signal transmission branch. When all the switch tubes in the signal transmission branch are off, the signal transmission branch can be used for signal transmission, and of course, can also be used for ESD.

[0058] In a specific implementation, 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, which is not limited here. For any type of RF switch, it can include an RF port, an antenna port, an antenna circuit and a signal transmission branch.

[0059] It can be understood that the type of RF switch is different, and the number of corresponding RF ports, antenna ports and antenna circuits is also different, and the position of the signal transmission branch can change.

[0060] In an embodiment, the RF port is more than two, and the signal transmission branch is arranged between any RF port and the antenna port. For example, in a single-pole multi-throw RF switch, there is only one antenna port, but there can be multiple RF ports, and at least one signal transmission branch can be arranged between each RF port and the unique antenna port.

[0061] In another embodiment, the radio frequency ports are more than two, and the radio frequency ground ports are more than two; the signal transmission branch is arranged between any radio frequency port and any radio frequency ground port. For example, in a double-pole multi-throw radio frequency switch, there can be two antenna ports and multiple radio frequency ports, and a signal transmission branch is arranged between each radio frequency port and at least one radio frequency ground port.

[0062] It should be noted that, regardless of the type of radio frequency switch, a signal transmission branch is arranged in the radio frequency switch, and through the signal transmission branch, the radio frequency signal can be transmitted from the connected radio frequency port to the connected antenna port, or from the connected antenna port to the connected radio frequency port.

[0063] In the embodiments of the present application, for any signal transmission branch in the radio frequency switch, at least one level of switch tube unit adjacent to the input port or the output port can be connected to the second end of the common bias resistor, while the other switch tube units are kept connected to the first end of the common bias resistor, so that the switch tube unit connected to the second end of the common bias resistor will not be turned on due to the excessively high voltage at the first end of the common bias resistor, thereby avoiding the switching failure of the signal transmission branch and the failure of ESD release.

[0064] In the specific implementation, when designing the radio frequency switch, the signal transmission branch as the ESD discharge path can be adjusted according to the scheme of the present application, that is, at least one level of switch tube unit adjacent to the input port or the output port in the signal transmission branch as the ESD discharge path is connected to the second end of the common bias resistor. Among them, each signal transmission branch in the radio frequency switch can be selected as the ESD discharge path, or part of the signal transmission branches can be selected as the ESD discharge path, which is not limited here. For all the signal transmission branches as the ESD discharge path, part of them can be adjusted according to the scheme of the present application, or all of them can be adjusted according to the scheme of the present application.

[0065] The scheme of the present application will be described in detail below taking a single-pole multi-throw radio frequency switch as an example:

[0066] FIG. 2 is a schematic diagram of the circuit structure of a single-pole multi-throw radio frequency switch in an embodiment of the present application. In order to simplify the diagram, only the signal transmission branch between the first radio frequency port RF1 and the radio frequency ground port RFGND, and the first radio frequency port RF1 and the antenna port ANT are shown in FIG. 2. For the signal transmission branch between the first radio frequency port RF1 and the antenna port ANT, the signal transmission branches between the other radio frequency ports (including the second radio frequency port RF2, …, the Mth radio frequency port RFM) and the antenna port ANT or the radio frequency ground port RFGND are not shown.

[0067] In some embodiments, the signal transmission branch can be a first signal transmission branch. The first signal transmission branch is located between the radio frequency port and the radio frequency ground port, and is connected in parallel with the radio frequency port. That is, only the at least one level of switch tube unit closest to at least one of the input port or the output port and the second end of the common bias resistor in the signal transmission branch connected in parallel with the radio frequency port can be connected.

[0068] Specifically, referring to FIG. 2, taking the first signal transmission branch 21 as an example, one end of the first signal transmission branch 21 can be connected with the first radio frequency port RF1, and the other end is grounded RFGND. One end of the antenna circuit 10 is connected with the first radio frequency port RF1 through the second signal transmission branch 22, and the other end is grounded RFGND, so that the first signal transmission branch 21 is connected in parallel with the first radio frequency port RF1.

[0069] In the first signal transmission branch 21, n cascaded switch tube units can be included, which are the first switch tube unit to the nth switch tube unit, n≥2 and is a positive integer. Each switch tube unit can include an NMOS tube, a gate bias resistor, a pass-through resistor, and a body bias diode. Taking the first diode unit as an example, the gate bias resistor Rg1 is located at the gate of the NMOS tube M1; one end of the pass-through resistor Rds1 is connected with the drain of the NMOS tube M1, and the other end is connected with the source of the NMOS tube M1; the body bias diode D1 is connected with the substrate of the NMOS tube M1. When the NMOS tube M1 is turned on, the pass-through resistor Rds1 is connected.

[0070] In an embodiment, referring to FIG. 2, for the first signal transmission branch 21, only the level of switch tube unit closest to the first radio frequency port RF1 or the radio frequency ground port RFGND can be connected with the second end of the common bias resistor Rcom, and the other (n-1) switch tube units are connected with the first end of the common bias resistor Rcom. For example, when the electrostatic discharge direction is forward electrostatic discharge, only the nth switch tube unit can be connected with the second end of the common bias resistor Rcom, and the first switch tube unit to the (n-1)th switch tube unit are connected with the first end of the common bias resistor Rcom. When the electrostatic discharge direction is reverse electrostatic discharge, only the first switch tube unit can be connected with the second end of the common bias resistor Rcom, and the second switch tube unit to the nth switch tube unit are connected with the first end of the common bias resistor Rcom.

[0071] In an embodiment, for the first signal transmission branch 21, only the two or more switch tube units adjacent to the first radio frequency port RF1 or the radio frequency ground port RFGND can be connected to the second end of the common bias resistor Rcom, and the other switch tube units are connected to the first end of the common bias resistor Rcom. For example, when the electrostatic discharge direction is reverse electrostatic discharge, the first switch tube unit and the second switch tube unit are connected to the second end of the common bias resistor Rcom, and the third switch tube unit to the nth switch tube unit are connected to the first end of the common bias resistor Rcom. When the electrostatic discharge direction is forward electrostatic discharge, the (n-1)th switch tube unit and the nth switch tube unit are connected to the second end of the common bias resistor Rcom, and the first switch tube unit to the (n-2)th switch tube unit are connected to the first end of the common bias resistor Rcom.

[0072] In other embodiments, the signal transmission branch can be a second signal transmission branch 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. That is, only the switch tube unit at least one level in the signal transmission branch connected in series with the radio frequency port and the antenna circuit in the electrostatic discharge direction can be connected to the second end of the common bias resistor.

[0073] Specifically, referring to FIG. 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 is connected in series with the antenna circuit 10.

[0074] In the second signal transmission branch 22, h cascaded switch tube units can be included, which are the first switch tube unit to the hth switch tube unit, h≥2 and is a positive integer. Each switch tube unit can include an NMOS tube, a gate bias resistor, a pass-through resistor, and a body bias diode. Taking the hth diode unit as an example, the gate bias resistor Rgh is located at the gate of the NMOS tube Mh; one end of the pass-through resistor Rdsh is connected to the drain of the NMOS tube Mh, and the other end is connected to the source of the NMOS tube Mh; the body bias diode Dh is connected to the substrate of the NMOS tube Mh. When the NMOS tube Mh is turned on, the pass-through resistor Rdsh is connected.

[0075] In an embodiment, referring to FIG. 4, for the second signal transmission branch 22, only the last stage switch unit next to the input port or the output port can be connected to the second end of the common bias resistor Rcom, and the other (h-1) switch units can be connected to the first end of the common bias resistor Rcom. For example, when the electrostatic discharge direction is reverse electrostatic discharge, only the first switch unit can be connected to the second end of the common bias resistor Rcom, and the second switch unit to the hth switch unit can be connected to the first end of the common bias resistor Rcom.

[0076] In an embodiment, for the second signal transmission branch 22, only the last two stage switch units next to the input port or the output port can be connected to the second end of the common bias resistor Rcom, and the other switch units can be connected to the first end of the common bias resistor Rcom. For example, referring to FIG. 5, when the electrostatic discharge direction is forward electrostatic discharge, the first switch unit and the second switch unit can be connected to the second end of the common bias resistor Rcom, and the third switch unit to the nth switch unit can be connected to the first end of the common bias resistor Rcom.

[0077] In other embodiments, at least one discontinuous switch unit can also be connected to the second end of the common bias resistor Rcom. For example, referring to FIG. 5, the second switch unit, the fourth switch unit, and the hth switch unit can be connected to the second end of the common bias resistor Rcom. The number of switch units connected to the second end of the common bias resistor Rcom can be set according to actual radio frequency performance requirements.

[0078] In some embodiments, the radio frequency switch can include two signal transmission branches, i.e., a first signal transmission branch 21 (as shown in FIG. 2) and a second signal transmission branch 22 (as shown in FIG. 4), wherein the first signal transmission branch 21 is connected in parallel with the radio frequency port RF1; and the second signal transmission branch 22 is connected in series with the radio frequency port and the antenna circuit.

[0079] That is, at least one switch unit in the series switch branch (i.e., the second signal transmission branch 22) and the parallel switch branch (the first signal transmission branch 21) in the radio frequency switch can be connected to the second end of the common bias resistor. At this time, the series switch branch and the parallel switch branch can both serve as an electrostatic discharge path.

[0080] The connection of the first signal branch 21 and the second signal branch 22 to the second end of the common bias resistor can be implemented according to the above description of FIG. 2 and FIG. 4, and will not be described here.

[0081] Comparing the electrostatic discharge window of the radio frequency switch in figure 2 with the electrostatic discharge window of the radio frequency switch in figure 1, a comparison diagram of the electrostatic discharge window simulation results shown in figure 6 can be obtained. Wherein, the curve 61 is a curve of the gate coupling voltage of the MOS transistor Mn in the last stage switch tube unit of the radio frequency switch in figure 1 varying with time, and the curve 62 is a curve of the gate coupling voltage of the MOS transistor Mn in the last stage switch tube unit of the radio frequency switch in figure 2 varying with time.

[0082] From the curve 61 and the curve 62, it can be known that after the improvement, the gate coupling voltage of the switch tube Mn in the last stage switch tube unit of the radio frequency switch is effectively reduced, so that the closing state can be maintained during the electrostatic discharge process, so that each stage switch tube unit does not have enough channel current before switching to the parasitic BJT mode and does not occur switching failure, and the ESD window effect is improved.

[0083] By adopting the scheme of the present application, at least one stage of switch tube units adjacent to at least one end of the input port or the output port in the signal transmission branch are connected with the second end of the common bias resistor, and other switch tube units remain connected with the first end of the common bias resistor, so that the gate coupling voltage of the MOS transistor in the switch tube unit connected with the second end of the common bias resistor can be reduced, so that the closing state can be maintained during the electrostatic discharge process, and the switching failure is reduced.

[0084] The present application further provides a radio frequency terminal, which comprises the radio frequency switch of any one of the above-mentioned embodiments. By means of the radio frequency switch, the transmission path of the radio frequency signal can be controlled, and the radio frequency switch has good ESD capability.

[0085] Although the present application is disclosed as above, the present application is not limited thereto. Any person skilled in the art, without departing from the spirit and scope of the present application, can make various changes and modifications, and therefore the protection scope of the present application should be subject to the scope defined by the claims.

Claims

1. A radio frequency switch, characterized in that, include: RF port; Antenna port; Antenna circuit; 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; 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. The second end of the common bias resistor is the end of the common bias resistor that is furthest from the RF port.

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, 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.

8. 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.

9. The radio frequency switch according to any one of claims 1 to 8, 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.

10. The radio frequency switch according to any one of claims 1 to 8, characterized in that, There is a signal transmission branch between any radio frequency port and the radio frequency ground port.

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

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