Radio frequency switch circuit and radio frequency front-end module

Abstract

The invention relates to the technical field of radio frequency, in particular to a radio frequency switch circuit and a radio frequency front-end module. The radio frequency switch circuit and the radio frequency front-end module comprise a first input end, a first output end and a first switch unit, the first switch unit comprises a first series switch and a first parallel switch, and the width of a first transistor in the first series switch is smaller than that of a second transistor in the first parallel switch; through the above mode, when the first switch unit is turned off, the first series switch is turned off and the first parallel switch is turned on, and the reduction of the size of the first series switch is beneficial to reducing the parasitic capacitance when the first series switch is turned off and improving the impedance to a radio frequency signal when the first series switch is turned off, so that the leakage of the radio frequency signal is reduced, and the signal isolation is improved; the insertion loss of the radio frequency switch circuit is reduced; the size of the first parallel switch is increased, so that larger discharge current can be allowed to pass through, and the electrostatic discharge protection capability of the first switch unit is improved.

Description

Technical Field

[0001] The present application relates to the field of radio frequency technology, and in particular to a radio frequency switching circuit and a radio frequency front-end module. Background Art

[0002] In mobile communication systems, RF front-end modules are used to implement functions such as combining, filtering, eliminating interference, and amplifying communication signals. As the number of communication frequency bands continues to increase, the number of frequency bands that mobile terminals need to support also increases. During signal reception, one or more specific frequency signals are usually selected from the RF signal, filtered, amplified, and then transmitted to the receiver to obtain a sufficient signal-to-noise ratio to ensure communication quality.

[0003] The RF switch in the RF front-end module is composed of multiple groups of switch units that transmit signals of different frequencies. When some switch units are turned off, the turned-off switch units will generate parasitic capacitance, and the RF signal will easily leak through the parasitic capacitance, which will increase the insertion loss of the RF switch on the one hand and reduce the signal isolation between different switches on the other hand. Summary of the invention

[0004] In view of the above problems, the embodiments of the present application provide a radio frequency switching circuit and a radio frequency front-end module to solve the above technical problems of being unfavorable to reducing the insertion loss of the switching unit and being unfavorable to improving the signal isolation.

[0005] In a first aspect, an embodiment of the present application provides a radio frequency switch circuit, including a first input terminal, a first output terminal, and further including:

[0006] A first switch unit, the first switch unit comprises a first series switch and a first parallel switch, a first end of the first series switch is connected to the first input end, a second end of the first series switch is connected to the first output end, a first end of the first parallel switch is connected to the first input end or the first output end, and a second end of the first parallel switch is grounded;

[0007] The first series switch includes at least one first transistor, the first parallel switch includes at least one second transistor, and a width of the first transistor is smaller than a width of the second transistor.

[0008] Optionally, the first transistor and the second transistor are field effect transistors respectively, and a gate width of the first transistor is smaller than a gate width of the second transistor.

[0009] Optionally, the RF switch circuit includes a plurality of the first output terminals and a plurality of the first switch units, each of the first switch units is connected to the same first input terminal, and the plurality of the first switch units are connected to the plurality of the first output terminals in a one-to-one correspondence.

[0010] Optionally, the RF switching circuit is arranged in an RF receiving link, and the RF receiving link also includes an antenna port and multiple filters of different frequency bands, the first input end is used to connect to the antenna port and receive the RF signal input from the antenna port, and the multiple first output ends are connected to the filters of different frequency bands one by one.

[0011] Optionally, the radio frequency switch circuit further includes a second input terminal, a second output terminal and a second switch unit:

[0012] The second switch unit includes a second series switch and a second parallel switch, wherein a first end of the second series switch is connected to the second input end, a second end of the second series switch is connected to the second output end, a first end of the second parallel switch is connected to the second input end or the second output end, and a second end of the second parallel switch is grounded;

[0013] The second series switch includes at least one third transistor, the second parallel switch includes at least one fourth transistor, and a width of the third transistor is greater than a width of the fourth transistor.

[0014] Optionally, the frequency of the radio frequency signal transmitted by the first switch unit is higher than the frequency of the radio frequency signal transmitted by the second switch unit.

[0015] Optionally, the RF switch circuit includes a plurality of second output terminals and a plurality of second switch units, each of the second switch units is connected to the same second input terminal, and the plurality of second switch units are connected to the plurality of second output terminals in a one-to-one correspondence.

[0016] Optionally, the third transistor and the fourth transistor are field effect transistors respectively, and a gate width of the third transistor is greater than a gate width of the fourth transistor.

[0017] Optionally, a width of the second transistor is the same as a width of the fourth transistor.

[0018] Optionally, the width of the first transistor is 0.3 mm to 1.2 mm, and the width of the second transistor is 0.6 mm to 1.6 mm.

[0019] Optionally, the width of the first transistor is 0.4 mm to 1 mm, and the width of the second transistor is 0.8 mm to 1.2 mm.

[0020] Optionally, the width of the third transistor is 1.2 mm to 3.2 mm, and the width of the fourth transistor is 0.6 mm to 1.6 mm.

[0021] Optionally, the width of the third transistor is 1.6 mm to 2.4 mm, and the width of the fourth transistor is 0.8 mm to 1.2 mm.

[0022] Optionally, the number of the first switch units is greater than the number of the second switch units.

[0023] Optionally, the first transistor, the second transistor, the third transistor and the fourth transistor are transistors based on CMOS process, SOI process or GaAs pHEMT process respectively.

[0024] Optionally, the number of the first transistors included in the first series switch and the number of the second transistors included in the first parallel switch are 3 to 5 respectively.

[0025] Optionally, the number of the third transistors included in the second series switch and the number of the fourth transistors included in the second parallel switch are 3 to 5 respectively.

[0026] In a second aspect, an embodiment of the present application provides a radio frequency switch circuit, including:

[0027] a first switch unit, the first switch unit comprising a first series switch and a first parallel switch, the first series switch comprising at least one first transistor, the first parallel switch comprising at least one second transistor, and a width of the first transistor being smaller than a width of the second transistor;

[0028] a second switch unit, the second switch unit comprising a second series switch and a second parallel switch, the second series switch comprising at least one third transistor, the second parallel switch comprising at least one fourth transistor, and a width of the third transistor being greater than a width of the fourth transistor;

[0029] The frequency of the radio frequency signal transmitted by the first switch unit is higher than the frequency of the radio frequency signal transmitted by the second switch unit.

[0030] In a third aspect, an embodiment of the present application provides a radio frequency front-end module, comprising the above-mentioned radio frequency switching circuit.

[0031] Optionally, the RF front-end module further includes a plurality of filters of different frequency bands, and the first switch unit and the second switch unit are respectively used to select and output a RF signal of at least one frequency band to the filter of the corresponding frequency band.

[0032] Optionally, the RF front-end module also includes a first antenna port, and the first switch unit is used to select and output a RF signal of at least one frequency band received by the first antenna port.

[0033] Optionally, the RF front-end module further includes a second antenna port, and the second switch unit is used to selectively output a RF signal of at least one frequency band received by the second antenna port.

[0034] The RF switch circuit and RF front-end module provided in the embodiments of the present application include a first input terminal, a first output terminal and a first switch unit, wherein the first switch unit includes a first series switch and a first parallel switch, wherein the first series switch is connected between the first input terminal and the first output terminal, wherein the first terminal of the first parallel switch is connected to the first input terminal or the first output terminal, and the second terminal is grounded; wherein the width of the first transistor in the first series switch is smaller than the width of the second transistor in the first parallel switch; wherein in the above manner, the size of the first series switch is smaller than the size of the first parallel switch, and when the first switch unit is turned off, the first series switch is turned off and the first parallel switch is turned on, and the reduction in the size of the first series switch is beneficial to reducing the parasitic capacitance when the first series switch is turned off, and increasing the impedance to the RF signal when the first series switch is turned off, thereby reducing the leakage of the RF signal, improving the signal isolation, and reducing the insertion loss of the RF switch circuit; and, the increase in the size of the first parallel switch can allow a larger discharge current to pass through, thereby improving the electrostatic discharge protection capability of the first switch unit.

[0035] These and other aspects of the present application will become more clearly understood in the description of the following embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a schematic structural diagram of a radio frequency switch circuit according to an embodiment of the present application.

[0037] Figure 2 for Figure 1 A schematic structural diagram of an implementation of a first transistor in a radio frequency switch circuit is shown.

[0038] Figure 3 for Figure 1 A schematic structural diagram of another implementation of the first transistor in the radio frequency switch circuit is shown.

[0039] Figure 4 It is a schematic structural diagram of a radio frequency switch circuit according to an embodiment of the present application.

[0040] Figure 5 This is an application scenario diagram of a radio frequency switch circuit according to an embodiment of the present application.

[0041] Figure 6 It is a schematic structural diagram of a radio frequency switch circuit according to an embodiment of the present application.

[0042] Figure 7 It is a schematic structural diagram of a radio frequency switch circuit according to an embodiment of the present application.

[0043] Figure 8 It is a schematic structural diagram of a radio frequency switch circuit according to an embodiment of the present application.

[0044] Fig. 9 This is a schematic diagram of the structure of a radio frequency front-end module according to an embodiment of the present application.

[0045] Fig.10 This is a schematic diagram of the structure of a radio frequency front-end module according to an embodiment of the present application. DETAILED DESCRIPTION

[0046] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be understood as limiting the present application.

[0047] In order to enable those skilled in the art to better understand the solutions of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present application.

[0048] In the embodiments of the present application, it should be noted that, in this article, relational terms such as first and second, etc. are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations.

[0049] Moreover, the terms "comprises," "comprising," or any other variation thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus that includes the element.

[0050] In the description of the embodiments of the present application, words such as "example" or "for example" are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "example" or "for example" in the embodiments of the present application is not to be interpreted as being more preferred or having more advantages than another embodiment or design. The use of words such as "example" or "for example" is intended to present relative concepts in a clear manner.

[0051] In addition, the "plurality" in the embodiments of the present application refers to two or more than two. In view of this, in the embodiments of the present application, "plurality" can also be understood as "at least two". "At least one" can be understood as one or more, for example, one, two or more. For example, including at least one means including one, two or more, and there is no limit on which ones are included. For example, including at least one of A, B and C, then A, B, C, A and B, A and C, B and C, or A, B and C can be included.

[0052] It should be noted that, in the embodiments of the present application, "and / or" describes the association relationship of the associated objects, indicating that three relationships may exist. For example, A and / or B may represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / ", unless otherwise specified, generally indicates that the associated objects before and after are in an "or" relationship.

[0053] It should be noted that in the embodiments of the present application, "connection" can be understood as electrical connection, and the connection between two electrical components can be a direct or indirect connection between the two electrical components. For example, the connection between A and B can be either a direct connection between A and B or an indirect connection between A and B through one or more other electrical components.

[0054] An embodiment of the present application provides a radio frequency switch circuit 100, see Figure 1 As shown, the RF switch circuit 100 includes a first input terminal 11 , a first output terminal 12 and a first switch unit 13 .

[0055] The first switch unit 13 includes a first series switch 131 and a first parallel switch 132, wherein the first end of the first series switch 131 is connected to the first input end 11, the second end of the first series switch 131 is connected to the first output end 12, the first end of the first parallel switch 131 is connected to the first input end 11 or the first output end 12, and the second end of the first parallel switch 132 is grounded.

[0056] The first switch unit 13 can correspond to the RF signal of at least one frequency band; when the RF signal of at least one frequency band needs to be transmitted, the first switch unit 13 is turned on, that is, the first series switch 131 in the first switch unit 13 is turned on and the first parallel switch 132 is turned off, so that the corresponding RF signal is transmitted through the first series switch 131. When the RF signal of at least one frequency band does not need to be transmitted, the first switch unit 13 is turned off, that is, the first series switch 131 in the first switch unit 13 is turned off and the first parallel switch 132 is turned on. On the one hand, the RF signal leaked from the turned-off first series switch 131 can be short-circuited to the ground through the first parallel switch 132. On the other hand, when electrostatic discharge (ESD) occurs at the port, the electrostatic signal can be discharged through the first parallel switch 132.

[0057] Specifically, the first series switch 131 includes at least one first transistor Q1, and the first parallel switch 132 includes at least one second transistor Q2. In the embodiment of the application, the width of the first transistor Q1 is smaller than the width of the second transistor Q2, that is, the width of the transistor in the first parallel switch 132 is larger than the width of the transistor in the first series switch 131. The increase in the width of the transistor means that more charges can be accumulated on its surface, thereby increasing the parasitic capacitance of the transistor. In the embodiment of the present application, the reduction in the size of the first transistor Q1 in the first series switch 131 can reduce the parasitic capacitance of the first series switch 131. In this way, when the RF signal is transmitted through other paths and the first series switch 131 is turned off, the RF signal leakage caused by the parasitic capacitance of the first series switch 131 is reduced, the insertion loss of the RF switch circuit is reduced, and the isolation between the path where the first series switch 131 is located and other RF signal transmission paths is higher.

[0058] For example, see Figure 2 As shown, the first transistor Q1 includes a control terminal 131a, a first terminal 131b and a second terminal 131c; the length of the first transistor Q1 is the distance L between the first terminal 131b and the second terminal 131c, that is, the distance between the first terminal 131b and the second terminal 131c in the length direction; the width of the first transistor Q1 is the distance W of the control terminal 131a in the width direction.

[0059] For example, see Figure 3 As shown, the first transistor Q1 may include at least two first transistors Q10 connected in parallel, the first transistor Q10 includes a control terminal 10a, a first terminal 10b, and a second terminal 10c, and the width of the first transistor Q10 is a distance W from the control terminal 10a in the width direction. 10 , then the width of the first transistor Q1 is W 10 ×N1, N1 is the number of first transistors Q10 included in the first transistor Q1. It should be noted that the width direction is a direction perpendicular to the length direction, and the length direction is the arrangement direction of the source, gate, and drain of the transistor, which can also be called the channel length direction.

[0060] Exemplarily, the structure of the second transistor Q2 is similar to that of the first transistor Q1 , and the width definition of the second transistor Q2 is similar to that of the first transistor Q1 , which will not be described in detail herein.

[0061] Exemplarily, the width of the first transistor Q1 is smaller than the width of the second transistor Q2, which may be that the number of parallel first crystal tubes included in the first transistor Q1 is the same as the number of parallel second crystal tubes included in the second transistor Q2, and the width of the control end of the first crystal tube is smaller than the width of the control end of the second crystal tube; or the width of the control end of the first crystal tube in the first transistor Q1 is the same as the width of the control end of the second crystal tube in the second transistor Q2, and the number of first crystal tubes is smaller than the number of second crystal tubes; or the width of the control end of the first crystal tube in the first transistor Q1 is smaller than the width of the control end of the second crystal tube in the second transistor Q2, and the number of first crystal tubes is smaller than the number of second crystal tubes. This application does not limit how to achieve that the width of the first transistor Q1 is smaller than the width of the second transistor Q2.

[0062] In this embodiment, since the width of the first transistor Q1 is smaller than the width of the second transistor Q2, that is, the size of the first series switch 131 is smaller than the size of the first parallel switch 132. When the first switch unit is turned off, the first series switch 131 is turned off and the first parallel switch 132 is turned on. The reduction in the size of the first series switch 131 is conducive to reducing the parasitic capacitance when the first series switch 131 is turned off, and improving the impedance to the RF signal when the first series switch 131 is turned off, thereby reducing the leakage of the RF signal, improving the signal isolation, and reducing the insertion loss of the RF switch circuit; in addition, the increase in the size of the first parallel switch 132 can allow a larger discharge current to pass through, thereby improving the electrostatic discharge protection capability of the first switch unit.

[0063] As an implementation, the first transistor Q1 and the second transistor Q2 are field effect transistors, respectively, and their control terminals are gates, then the width of the first transistor Q1 is its gate width, and the width of the second transistor Q2 is its gate width, so the gate width of the first transistor Q1 is smaller than the gate width of the second transistor Q2. Exemplarily, for a field effect transistor, its control terminal may be a gate, its first terminal may be a source or a drain, and its second terminal may be a drain or a source.

[0064] Optionally, the first transistor Q1 and the second transistor Q2 may be metal oxide semiconductor field effect transistors (metal oxide semiconductor field effect transistor, MOSFET), referred to as MOS transistors or MOS tubes. Alternatively, the first transistor Q1 and the second transistor Q2 may be metal semiconductor field effect transistors (Metal semiconductor field effect transistor, MESFET), referred to as MS transistors. Alternatively, the first transistor Q1 and the second transistor Q2 may be high electron mobility transistors (High electron mobility transistor, HEMT), referred to as HEMT transistors. Alternatively, the first transistor Q1 and the second transistor Q2 may be pseudomorphic high electron mobility transistors (Pseudomorphic High Electron Mobility Transistor, pHEMT), referred to as pHEMT transistors.

[0065] Optionally, the first transistor Q1 and the second transistor Q2 may be fabricated on any one of a silicon substrate, a silicon-on-insulator (SOI) substrate, a gallium arsenide (GaAs) substrate, and a silicon carbide (SiC) substrate.

[0066] By way of example, the first transistor Q1 and the second transistor Q2 may be MOS transistors fabricated on a silicon substrate, an SOI substrate, or a SiC substrate.

[0067] By way of example, the first transistor Q1 and the second transistor Q2 may be MS transistors or HEMT transistors or pHEMT transistors fabricated on a GaAs substrate.

[0068] As an implementation, see Figure 4 As shown, the RF switching circuit 100 includes a plurality of first output terminals 12 and a plurality of first switch units 13, the number of the first output terminals 12 is the same as the number of the first switch units 13, the plurality of first switch units 13 are connected to the plurality of first output terminals 12 in a one-to-one correspondence, and each first switch unit 13 is connected to the same first input terminal 11.

[0069] When multiple first series switches 131 are turned off at the same time, the parasitic capacitance generated by the multiple first series switches 131 is connected in parallel between the first input terminal 11 and the first output terminal 12 corresponding to the turned-on first series switch 131, resulting in an increase in the parasitic capacitance between the first input terminal 11 and the corresponding first output terminal 12, an increase in the RF signal leaking through the parasitic capacitance, and an increase in the loss of the RF signal, which in turn leads to a higher insertion loss and worse signal isolation of the RF switch circuit. In the embodiment of the present application, the size of each first series switch 131 is reduced respectively, and the parasitic capacitance of each first series switch 131 is reduced accordingly. The parallel parasitic capacitance generated when multiple first series switches 131 are turned off at the same time is greatly reduced, the RF signal leaking through the parasitic capacitance is reduced, the loss of the RF signal is reduced, the insertion loss of the RF switch circuit is reduced, and the signal isolation is better.

[0070] In this embodiment, each first switch unit corresponds to a radio frequency signal of at least one frequency band. When a radio frequency signal of a specific frequency band is output, the first series switch in the first switch unit corresponding to the specific frequency band is turned on and the first parallel switch is turned off, and the first parallel switches in other first switch units are turned on and the first series switches are turned off. Through the above method, it is compatible with the transmission of radio frequency signals of different frequency bands. At the same time, due to the reduction in the size of the first series switch, the parasitic capacitance generated when the first series switch in each turned-off first switch unit is turned off is reduced, the parallel parasitic capacitance formed when the first series switch of each turned-off first switch unit is turned off is reduced, and the impedance of the first series switch in each turned-off first switch unit to the radio frequency signal is increased when it is turned off, thereby reducing the leakage of the radio frequency signal, improving the signal isolation, and reducing the insertion loss of the radio frequency switch circuit.

[0071] As an implementation method, the number of first switch units 13 is at least 3, and at the same time, the number of turned-off first switch units 13 is greater than the number of turned-on first switch units. It can be understood that in most application scenarios of RF switches that support multi-band signal transmission, in order to reduce crosstalk between different frequency bands, except for individual frequency bands that require carrier aggregation, signals of most frequency bands will not be transmitted simultaneously. Therefore, under normal circumstances, at the same time, the number of turned-off first switch units 13 will be greater than the number of turned-on first switch units 13, which results in the parasitic capacitance of multiple turned-off first switch units 13 being connected in parallel, thereby increasing the total capacitance between the first input terminal 11 and the first output terminal 12, thereby aggravating signal leakage and increasing the insertion loss of the RF switch circuit. In this case, the embodiment of the present application reduces the parasitic capacitance of each first switch unit 13 by reducing the width of each first transistor Q1. Even if multiple parasitic capacitances are connected in parallel due to the shutdown of multiple first switch units 13, the total capacitance can be controlled within a smaller range, thereby significantly improving the isolation between different paths and reducing the insertion loss of the RF switch circuit.

[0072] In some embodiments, see Figure 5 As shown, the RF switch circuit 100 is arranged in a RF receiving chain 200, and the RF receiving chain 200 also includes an antenna port 201 and multiple filters 202 of different frequency bands. The first input terminal 11 is used to connect to the antenna port 201 and receive the RF signal input from the antenna port 201. The number of first output terminals 12, the number of first switch units 13 and the number of filters 202 are respectively the same, and the multiple first output terminals 12 are connected to the filters 202 of different frequency bands one by one.

[0073] In this embodiment, during the signal reception process, a frequency signal of a specific frequency corresponding to the first switch unit that is turned on can be selected for transmission, filtered and amplified before being transmitted to the receiver to obtain a sufficient signal-to-noise ratio and ensure communication quality. At the same time, during the signal reception process, the power of the RF signal received by the antenna port is relatively weak, and the power tolerance requirement of the first series switch in the first switch unit is relatively low. Therefore, the number of the first series switch and the first parallel switch can be reduced to further reduce the insertion loss of the RF switch circuit.

[0074] In some embodiments, the first series switch 131 includes a plurality of first transistors Q1 connected in series, and the number of the first transistors Q1 may be 3-5.

[0075] During the signal reception process, the RF signal strength received by the antenna port is relatively weak, usually less than 30dBm, so the number of first transistors in the first series switch is relatively small. Compared with the parasitic capacitance when a single first transistor Q1 is turned off, the series parasitic capacitance generated by multiple first transistors Q1 connected in series is reduced, but since the number of first transistors included in the first series switch in the receiving link is small, the degree of reduction in the series parasitic capacitance is limited, so it is more necessary to reduce the parasitic capacitance of each first transistor. In the embodiment of the present application, the size of each first transistor Q1 is reduced, and the parasitic capacitance of each first transistor Q1 is reduced accordingly. The parasitic capacitance generated when multiple first series switches 131 are turned off at the same time is greatly reduced, the RF signal leaked through the parasitic capacitance is reduced, the loss of the RF signal is reduced, the insertion loss of the RF switch circuit is reduced, and the signal isolation is better.

[0076] As an embodiment, the first switch unit 13 is used to transmit a radio frequency signal having a frequency higher than a specific threshold, such as a medium frequency or high frequency radio frequency signal. It is understandable that the impedance of a parasitic capacitor of the same size to a medium frequency or high frequency radio frequency signal is smaller than that to a low frequency radio frequency signal. In other words, compared with a low frequency signal, a medium frequency or high frequency radio frequency signal is more likely to leak through the capacitor. Therefore, for the first switch unit 13 used to transmit medium and high frequency band radio frequency signals, reducing the parasitic capacitance when the first transistor Q1 is turned off can significantly improve the isolation between different paths and significantly reduce the insertion loss of the radio frequency switch circuit.

[0077] As an implementation method, the number of first switch units 13 is at least 3, each of which is used to transmit a radio frequency signal having a frequency higher than a specific threshold, and at the same time, the number of turned-off first switch units 13 is greater than the number of turned-on first switch units 13. In this scenario, compared with the related art that does not reduce the width of the first transistor, this implementation method significantly reduces the insertion loss of the radio frequency switch circuit and improves the isolation.

[0078] As an implementation, see Figure 6 As shown, the RF switch circuit 100 further includes a second input terminal 21 , a second output terminal 22 and a second switch unit 23 .

[0079] The second switch unit 23 includes a second series switch 231 and a second parallel switch 232, wherein a first end of the second series switch 231 is connected to the second input end 21, a second end of the second series switch 231 is connected to the second output end 22, a first end of the second parallel switch 232 is connected to the second input end 21 or the second output end 22, and a second end of the second parallel switch 232 is grounded.

[0080] The second switch unit 23 can correspond to the RF signal of at least one frequency band; when the RF signal of at least one frequency band needs to be transmitted, the second switch unit 23 is turned on, that is, the second series switch 231 in the second switch unit 23 is turned on and the second parallel switch 232 is turned off, so that the corresponding RF signal is transmitted through the second series switch 231. When the RF signal of at least one frequency band does not need to be transmitted, the second switch unit 23 is turned off, that is, the second series switch 231 in the second switch unit 23 is turned off and the second parallel switch 232 is turned on. On the one hand, the RF signal leaked from the turned-off second series switch 231 can be short-circuited to the ground through the second parallel switch 232. On the other hand, when electrostatic discharge (ESD) occurs at the port, the electrostatic signal can be discharged through the second parallel switch 232.

[0081] Specifically, the second series switch 231 includes at least one third transistor Q3, and the second parallel switch 232 includes at least one fourth transistor Q4. Exemplarily, the structures of the third transistor Q3 and the fourth transistor Q4 can be similar to the first transistor Q1, and the width of the third transistor Q3 and the width of the fourth transistor Q4 can be defined as Figure 2 or Figure 3 The definition of the width of the first transistor Q1 is similar and will not be repeated here.

[0082] The width of the third transistor Q3 is greater than the width of the fourth transistor Q4, that is, the width of the transistor in the second series switch 231 is greater than the width of the transistor in the second parallel switch 232. The increase in the width of the transistor means that the width of the current channel increases, more electrons can flow quickly through the current channel, and the on-resistance decreases accordingly.

[0083] Wherein, if the number of third crystal single tubes connected in parallel included in the third transistor Q3 is the same as the number of fourth crystal single tubes connected in parallel included in the fourth transistor Q4, then when the width of the control end of the third crystal single tube is greater than the width of the control end of the fourth crystal single tube, the width of the third transistor Q3 is greater than the width of the fourth transistor Q4. If the width of the control end of the third crystal single tube in the third transistor Q3 is the same as the width of the control end of the fourth crystal single tube in the fourth transistor Q4, then when the number of the third crystal single tubes is greater than the number of the fourth crystal single tubes, the width of the third transistor Q3 is greater than the width of the fourth transistor Q4. When the width of the control end of the third crystal single tube in the third transistor Q3 is greater than the width of the control end of the fourth crystal single tube in the fourth transistor Q4 and the number of the third crystal single tubes is greater than the number of the fourth crystal single tubes, the width of the third transistor Q3 is greater than the width of the fourth transistor Q4.

[0084] In this embodiment, when the second switch unit is turned on, the size of the second series switch increases, and the resistance of the second series switch when turned on decreases, which is beneficial to reducing the insertion loss of the RF switch circuit.

[0085] The third transistor Q3 and the fourth transistor Q4 are field effect transistors, respectively. The width of the third transistor Q3 is its gate width, and the width of the fourth transistor Q4 is its gate width. Therefore, the gate width of the third transistor Q3 is greater than the gate width of the fourth transistor Q4. Exemplarily, for a field effect transistor, its control terminal may be a gate, its first terminal may be a source or a drain, and its second terminal may be a drain or a source.

[0086] Optionally, the third transistor Q3 and the fourth transistor Q4 can be metal oxide semiconductor field effect transistors (metal oxide semiconductor field effect transistor, MOSFET), referred to as MOS transistors or MOS tubes. Alternatively, the third transistor Q3 and the fourth transistor Q4 can be metal semiconductor field effect transistors (Metal semiconductor field effect transistor, MESFET), referred to as MS transistors. Alternatively, the third transistor Q3 and the fourth transistor Q4 can be high electron mobility transistors (High electron mobility transistor, HEMT), referred to as HEMT transistors. Alternatively, the third transistor Q3 and the fourth transistor Q4 can be pseudomorphic high electron mobility transistors (Pseudomorphic High Electron Mobility Transistor, pHEMT), referred to as pHEMT transistors.

[0087] Optionally, the third transistor Q3 and the fourth transistor Q4 may be fabricated on any one of a silicon substrate, a silicon-on-insulator (SOI) substrate, a gallium arsenide (GaAs) substrate, and a silicon carbide (SiC) substrate.

[0088] By way of example, the third transistor Q3 and the fourth transistor Q4 may be MOS transistors fabricated on a silicon substrate, an SOI substrate, or a SiC substrate.

[0089] Exemplarily, the third transistor Q3 and the fourth transistor Q4 may be MS transistors or HEMT transistors or pHEMT transistors fabricated on a GaAs substrate.

[0090] In some embodiments, the frequency of the radio frequency signal transmitted by the first switch unit 13 is higher than the frequency of the radio frequency signal transmitted by the second switch unit 23 .

[0091] The first switch unit 13 is used to transmit a relatively high frequency RF signal, such as a medium-high frequency RF signal, and the second switch unit 23 is used to transmit a relatively low frequency RF signal, such as a low frequency RF signal.

[0092] It should be noted that the insertion loss generated by the RF switching circuit 100 mainly includes the insertion loss formed by the following three parts: first, the insertion loss formed by the on-resistance of the series switch in the turned-on switch unit; second, the insertion loss formed by the off-parasitic capacitance when the series switch in the non-conducting switch unit is turned off; third, the insertion loss formed by the off-parasitic capacitance when the parallel switch in the turned-on switch unit is turned off.

[0093] For the first switch unit, since the corresponding operating frequency band is relatively high, the turn-off parasitic capacitance of the series switch in the non-conducting first switch unit when it is turned off has a greater impact on the insertion loss; for the second switch unit, since the corresponding operating frequency band is relatively low, the on-resistance of the series switch in the conducting second switch unit has the greatest impact on the insertion loss.

[0094] When the second switch unit 23 partially transmitting low-frequency signals is turned on, the insertion loss caused by the on-resistance of the second series switch 231 in the turned-on second switch unit 23 is much greater than the insertion loss caused by the off-parasitic capacitance when the second series switch 231 in the non-turned-on second switch unit 23 is turned off. When the first switch unit 13 partially transmitting medium- and high-frequency signals is turned on, the insertion loss caused by the off-parasitic capacitance when the first series switch 131 in the non-turned-on first switch unit 13 is turned off is much greater than the insertion loss caused by the on-resistance of the first series switch 131 in the turned-on first switch unit 13. Therefore, reducing the size of the first series switch 131 in the first switch unit and increasing the size of the second series switch 231 in the second switch unit 23 is beneficial to simultaneously reduce the insertion loss formed by the on-resistance of the second series switch 231 in the conductive second switch unit 23 and the insertion loss formed by the off-parasitic capacitance when the first series switch 131 in the non-conductive first switch unit 13 is turned off, so as to simultaneously reduce the insertion loss when the second switch unit 23 is turned on and the insertion loss when the first switch unit 13 is turned off, which is beneficial to reduce the insertion loss during medium and high frequency signal transmission and the insertion loss during low frequency signal transmission.

[0095] In some embodiments, see Figure 7 As shown, the RF switch circuit 100 includes a plurality of second output terminals 22 and a plurality of second switch units 23, each second switch unit 23 is connected to the same second input terminal 21, the number of the second output terminals 22 is the same as the number of the second switch units 23, and the plurality of second switch units 23 are connected to the plurality of second output terminals 22 in a one-to-one correspondence.

[0096] In this embodiment, each first switch unit corresponds to an RF signal of at least one frequency band within the low-frequency range. When an RF signal of a specific frequency band is output, the second series switch in the second switch unit corresponding to the specific frequency band is turned on and the second parallel switch is turned off, and the second parallel switches in other second switch units are turned on and the second series switches are turned off. Through the above method, RF signal transmission in different frequency bands within the low-frequency range can be compatible.

[0097] In some embodiments, the width of the second transistor Q2 is the same as the width of the fourth transistor Q4.

[0098] Thus, the size of the first series switch is smaller than the sizes of the first parallel switch and the second parallel switch, and the size of the second series switch is larger than the sizes of the first parallel switch and the second parallel switch.

[0099] In this embodiment, by reducing the size of the first series switch and increasing the size of the second series switch, the insertion loss influence of the first switch unit and the insertion loss influence of the second switch unit are reduced at the same time, which is beneficial to reducing the insertion loss of the RF switch circuit.

[0100] In some embodiments, the width of the first transistor Q1 is 0.3 mm to 1.2 mm, and the width of the second transistor Q2 is 0.6 mm to 1.6 mm.

[0101] In this embodiment, the width of the first transistor and the width of the second transistor are respectively set within the above corresponding ranges, which can reduce the parasitic capacitance when the first series switch is turned off and adapt to the application scenarios of medium and high frequency radio frequency signals.

[0102] In some embodiments, the width of the first transistor Q1 is 0.4 mm to 1 mm, and the width of the second transistor Q2 is 0.8 mm to 1.2 mm.

[0103] In this embodiment, the width of the first transistor and the width of the second transistor are respectively set within the above corresponding ranges, which can further reduce the parasitic capacitance when the first series switch is turned off, so as to further reduce the insertion loss of the RF switch circuit.

[0104] Exemplarily, the width of the first transistor Q1 is 1 mm, and the width of the second transistor Q2 is 1.2 mm.

[0105] In some embodiments, the width of the third transistor Q3 is 1.2 mm to 3.2 mm, and the width of the fourth transistor Q4 is 0.6 mm to 1.6 mm.

[0106] In this embodiment, the width of the third transistor and the width of the fourth transistor are respectively set within the above corresponding ranges, which reduces the resistance of the second series switch when it is turned on and can adapt to the application scenario of low-frequency radio frequency signals.

[0107] In some embodiments, the width of the third transistor Q3 is 1.6 mm to 2.4 mm, and the width of the fourth transistor Q4 is 0.8 mm to 1.2 mm.

[0108] In this embodiment, the width of the third transistor and the width of the fourth transistor are respectively set within the above corresponding ranges to further reduce the resistance when the second series switch is turned on, so as to further reduce the insertion loss of the RF switch circuit.

[0109] Exemplarily, the width of the third transistor Q3 is 1.6 mm, and the width of the fourth transistor Q4 is 1.2 mm.

[0110] In some embodiments, the number of the first switch units 13 is greater than the number of the second switch units 23. For example, the number of the first switch units 13 is 5 to 7, and the number of the second switch units 23 is 2 to 4.

[0111] In this embodiment, each first switch unit can adapt to at least one frequency band in the medium and high frequency range, and each second switch unit can adapt to at least one frequency band in the low frequency range, which can fully adapt to the needs of RF signals in different frequency bands.

[0112] In some embodiments, the first transistor, the second transistor, the third transistor, and the fourth transistor are transistors based on CMOS (Complementary Metal Oxide Semiconductor) process, SOI (Silicon-On-Insulator) process, or GaAs pHEMT (gallium arsenide pseudomorphic high-electron-mobility transistor) process, respectively.

[0113] In some embodiments, the first series switch 131 includes a plurality of first transistors Q1 connected in series, and the number of the first transistors Q1 may be 3 to 5.

[0114] During the signal reception process, the RF signal strength received by the antenna port is relatively weak, usually less than 30dBm. The number of first transistors in the first series switch is relatively small. Reducing the width of the first transistor is conducive to reducing the parasitic capacitance when the first series switch is turned off, thereby reducing the insertion loss when the first switch unit is turned off.

[0115] In some implementations, the first parallel switch 132 includes a plurality of second transistors Q2 connected in series, and the number of the second transistors Q2 may be 3 to 5. Under the premise of meeting the ESD capability, the layout area and the cost can be reduced.

[0116] In some embodiments, the second series switch 231 includes a plurality of third transistors Q3 connected in series, and the number of the third transistors Q3 may be 3 to 5.

[0117] In this embodiment, during the signal reception process, the RF signal strength received by the antenna port is relatively weak, and the number of third transistors in the second series switch is relatively small, which can reduce the layout area and reduce the cost while meeting the power tolerance requirements.

[0118] In some implementations, the second parallel switch 232 includes a plurality of fourth transistors Q4 connected in series, and the number of the fourth transistors Q4 may be 3 to 5. This can reduce the layout area and the cost while meeting the ESD capability.

[0119] An embodiment of the present application provides a radio frequency switch circuit 100', see Figure 8 As shown, the radio frequency switch circuit 100 ′ includes a first switch unit 13 and a second switch unit 23 .

[0120] The first switch unit 13 includes a first series switch 131 and a first parallel switch 132 . The first series switch 131 includes at least one first transistor Q1 . The first parallel switch 132 includes at least one second transistor Q2 . The width of the first transistor Q1 is smaller than that of the second transistor Q2 .

[0121] The second switch unit 23 includes a second series switch 231 and a second parallel switch 232. The second series switch 231 includes at least one third transistor Q3. The second parallel switch 232 includes at least one fourth transistor Q4. The width of the third transistor Q3 is greater than that of the fourth transistor Q4.

[0122] The frequency of the radio frequency signal transmitted by the first switch unit 13 is higher than the frequency of the radio frequency signal transmitted by the second switch unit 23 .

[0123] For the description of the first switch unit 13 and the second switch unit 23 , reference may be made to the previous embodiment, and they will not be described one by one here.

[0124] In the embodiment of the present application, the insertion loss generated by the RF switch circuit 100' mainly includes the insertion loss formed by the following three parts: first, the insertion loss formed by the on-resistance of the series switch in the turned-on switch unit; second, the insertion loss formed by the off-parasitic capacitance when the series switch in the non-conducting switch unit is turned off; third, the insertion loss formed by the off-parasitic capacitance when the parallel switch in the turned-on switch unit is turned off.

[0125] For transistors, the larger the width of the transistor, the smaller its on-resistance and the larger its off-parasitic capacitance. Among them, for medium and high frequency signals, the off-parasitic capacitance of the series transistor on the unselected path has a much greater impact on the insertion loss than the on-resistance of the series transistor on the selected path. On the contrary, for low frequency signals, the on-resistance of the series transistor on the selected path has a much greater impact on the insertion loss than the off-parasitic capacitance of the series transistor on the unselected path.

[0126] Therefore, for the first switch unit with a higher operating frequency band, the insertion loss formed by the turn-off parasitic capacitance when the series switch in the non-conducting first switch unit is turned off has the greatest impact; for the second switch unit with a lower operating frequency band, the insertion loss formed by the on-resistance of the series switch in the conducting second switch unit has the greatest impact.

[0127] In this embodiment, by reducing the size of the first series switch and increasing the size of the second series switch, the insertion loss influence of the first switch unit and the insertion loss influence of the second switch unit are reduced at the same time, which is beneficial to reducing the insertion loss of the RF switch circuit.

[0128] An embodiment of the present application provides a radio frequency front-end module 300, see Fig. 9 As shown, the RF front-end module 300 includes the RF switch circuit 100 or the RF switch circuit 100 ′.

[0129] In this embodiment, the size of the first series switch is smaller than that of the first parallel switch. When the first switch unit is turned off, the first series switch is turned off and the first parallel switch is turned on. The reduction in the size of the first series switch is beneficial to reducing the parasitic capacitance when the first series switch is turned off and increasing the impedance to the RF signal when the first series switch is turned off, thereby reducing the leakage of the RF signal, improving signal isolation, and reducing the insertion loss of the RF switch circuit; the increase in the size of the first parallel switch can allow a larger discharge current to pass through, thereby improving the electrostatic release protection capability of the first switch unit.

[0130] As an implementation, see Fig.10 As shown, the RF front-end module 300 also includes a plurality of filters 301 of different frequency bands, and the first switch unit 13 or the second switch unit 23 is used to selectively output a RF signal of at least one frequency band to the filter 301 of the corresponding frequency band.

[0131] In some embodiments, the RF front-end module 300 further includes a first antenna port 302 , and the first switch unit 13 is used to select and output a RF signal of at least one frequency band received by the first antenna port 302 to a corresponding filter 301 .

[0132] In some implementations, the RF front-end module 300 further includes a second antenna port 303 , and the second switch unit 23 is used to select and output a RF signal of at least one frequency band received by the second antenna port 303 to a corresponding filter 301 .

[0133] The above is only an implementation method of the present application. It should be pointed out that a person skilled in the art can make improvements without departing from the inventive concept of the present application, but these improvements are within the scope of protection of the present application.

Claims

1. A radio frequency switching circuit, characterized in that: The device comprises a first input terminal, a first output terminal, and further comprises: A first switch unit, the first switch unit comprises a first series switch and a first parallel switch, a first end of the first series switch is connected to the first input end, a second end of the first series switch is connected to the first output end, a first end of the first parallel switch is connected to the first input end or the first output end, and a second end of the first parallel switch is grounded; The first series switch includes at least one first transistor, the first parallel switch includes at least one second transistor, and a width of the first transistor is smaller than a width of the second transistor.

2. The radio frequency switch circuit according to claim 1, characterized in that: The first transistor and the second transistor are field effect transistors respectively, and a gate width of the first transistor is smaller than a gate width of the second transistor.

3. The radio frequency switch circuit according to claim 1, characterized in that: The radio frequency switch circuit includes a plurality of the first output terminals and a plurality of the first switch units, each of the first switch units is connected to the same first input terminal, and the plurality of the first switch units are connected to the plurality of the first output terminals in a one-to-one correspondence.

4. The radio frequency switch circuit according to claim 3, characterized in that: The RF switching circuit is arranged in an RF receiving link, and the RF receiving link also includes an antenna port and multiple filters of different frequency bands. The first input end is used to connect to the antenna port and receive the RF signal input from the antenna port, and the multiple first output ends are connected to the filters of different frequency bands one by one.

5. The radio frequency switch circuit according to claim 1 or 2, characterized in that: The radio frequency switch circuit further includes a second input terminal, a second output terminal and a second switch unit: The second switch unit includes a second series switch and a second parallel switch, wherein a first end of the second series switch is connected to the second input end, a second end of the second series switch is connected to the second output end, a first end of the second parallel switch is connected to the second input end or the second output end, and a second end of the second parallel switch is grounded; The second series switch includes at least one third transistor, the second parallel switch includes at least one fourth transistor, and a width of the third transistor is greater than a width of the fourth transistor.

6. The radio frequency switch circuit according to claim 5, characterized in that: The frequency of the radio frequency signal transmitted by the first switch unit is higher than the frequency of the radio frequency signal transmitted by the second switch unit.

7. The radio frequency switch circuit according to claim 5, characterized in that: The radio frequency switch circuit includes a plurality of second output terminals and a plurality of second switch units, each of the second switch units is connected to the same second input terminal, and the plurality of second switch units are connected to the plurality of second output terminals in a one-to-one correspondence.

8. The radio frequency switch circuit according to claim 5, characterized in that: The third transistor and the fourth transistor are field effect transistors respectively, and a gate width of the third transistor is greater than a gate width of the fourth transistor.

9. The radio frequency switch circuit according to claim 5, characterized in that: The width of the second transistor is the same as the width of the fourth transistor.

10. The radio frequency switch circuit according to claim 5, characterized in that: The width of the first transistor is 0.3 mm to 1.2 mm, and the width of the second transistor is 0.6 mm to 1.6 mm.

11. The radio frequency switch circuit according to claim 10, characterized in that: The width of the first transistor is 0.4 mm to 1 mm, and the width of the second transistor is 0.8 mm to 1.2 mm.

12. The radio frequency switch circuit according to claim 5, characterized in that: The width of the third transistor is 1.2 mm to 3.2 mm, and the width of the fourth transistor is 0.6 mm to 1.6 mm.

13. The radio frequency switch circuit according to claim 12, characterized in that: The width of the third transistor is 1.6 mm to 2.4 mm, and the width of the fourth transistor is 0.8 mm to 1.2 mm.

14. The radio frequency switch circuit according to claim 5, characterized in that: The number of the first switch units is greater than the number of the second switch units.

15. The radio frequency switch circuit according to claim 5, characterized in that: The first transistor, the second transistor, the third transistor and the fourth transistor are transistors based on CMOS process, SOI process or GaAs pHEMT process respectively.

16. The radio frequency switch circuit according to claim 5, characterized in that: The number of the first transistors included in the first series switch and the number of the second transistors included in the first parallel switch are 3 to 5 respectively.

17. The radio frequency switch circuit according to claim 5, characterized in that: The number of the third transistors included in the second series switch and the number of the fourth transistors included in the second parallel switch are 3 to 5 respectively.

18. A radio frequency switching circuit, characterized in that: include: a first switch unit, the first switch unit comprising a first series switch and a first parallel switch, the first series switch comprising at least one first transistor, the first parallel switch comprising at least one second transistor, and a width of the first transistor being smaller than a width of the second transistor; a second switch unit, the second switch unit comprising a second series switch and a second parallel switch, the second series switch comprising at least one third transistor, the second parallel switch comprising at least one fourth transistor, and a width of the third transistor being greater than a width of the fourth transistor; The frequency of the radio frequency signal transmitted by the first switch unit is higher than the frequency of the radio frequency signal transmitted by the second switch unit.

19. A radio frequency front-end module, characterized in that: It comprises the radio frequency switch circuit as claimed in any one of claims 1 to 18.

20. The radio frequency front-end module according to claim 19, characterized in that: The RF front-end module also includes multiple filters of different frequency bands, and the first switch unit and the second switch unit are respectively used to select and output the RF signal of at least one frequency band to the filter of the corresponding frequency band.

21. The radio frequency front-end module according to claim 19, characterized in that: The RF front-end module also includes a first antenna port, and the first switch unit is used to select and output a RF signal of at least one frequency band received by the first antenna port.

22. The radio frequency front-end module according to claim 21, characterized in that: The RF front-end module also includes a second antenna port, and the second switch unit is used to select and output a RF signal of at least one frequency band received by the second antenna port.

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