Radio frequency switch circuit and radio frequency front end module
By designing series and parallel switches with transistor widths in the RF switching circuit, parasitic capacitance and insertion loss are reduced, signal isolation is improved, and the problem of RF signal leakage is solved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- RADROCK (SHENZHEN) SEMICONDUCTOR LTD
- Filing Date
- 2024-12-31
- Publication Date
- 2026-05-19
AI Technical Summary
In RF switching circuits, the parasitic capacitance of the switching unit causes RF signal leakage, increases insertion loss, and reduces signal isolation.
Design an RF switch circuit in which the transistor width of the first series switch is smaller than that of the transistor width of the parallel switch. The parasitic capacitance is reduced by decreasing the size of the series switch, and the electrostatic discharge protection capability is improved by increasing the size of the parallel switch.
It reduces RF signal leakage, improves signal isolation, and reduces insertion loss in RF switching circuits.
Smart Images
Figure CN119853715B_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of radio frequency technology, and in particular to a radio frequency switch circuit and a radio frequency front-end module. Background Technology
[0002] In mobile communication systems, the radio frequency (RF) front-end module is used to perform functions such as combining, filtering, interference cancellation, and amplification of 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 typically selected from the RF signal, filtered, and amplified before being transmitted to the receiver to obtain a sufficient signal-to-noise ratio and ensure communication quality.
[0003] The RF switch in the RF front-end module consists of multiple sets of switching units that transmit signals of different frequencies. When some switching units are turned off, the turned-off switching units will generate parasitic capacitance. The RF signal is easily leaked through the parasitic capacitance, which increases the insertion loss of the RF switch on the one hand, and reduces the signal isolation between different switches on the other. Summary of the Invention
[0004] In view of the above problems, this application provides an RF switch circuit and an RF front-end module to solve the technical problems that are not conducive to reducing the insertion loss of the switch unit and improving the signal isolation.
[0005] In a first aspect, embodiments of this application provide a radio frequency switch circuit, including a first input terminal, a first output terminal, and further comprising:
[0006] The first switching unit includes a first series switch and a first parallel switch. The first end of the first series switch is connected to the first input terminal, the second end of the first series switch is connected to the first output terminal, the first end of the first parallel switch is connected to either the first input terminal or the first output terminal, and the second end of the first parallel switch is grounded.
[0007] The first series switch includes at least one first transistor, and the first parallel switch includes at least one second transistor, wherein the width of the first transistor is smaller than the width of the second transistor.
[0008] Optionally, the first transistor and the second transistor are both field-effect transistors, and the gate width of the first transistor is smaller than the gate width of the second transistor.
[0009] Optionally, the radio frequency switch circuit includes a plurality of first output terminals and a plurality of first switch units, each of the first switch units being connected to the same first input terminal, and the plurality of first switch units being connected one-to-one to the plurality of first output terminals.
[0010] Optionally, the radio frequency switch circuit is disposed in the radio frequency receiving link, which further includes an antenna port and multiple filters of different frequency bands. The first input terminal is used to connect to the antenna port and receive the radio frequency signal input from the antenna port, and multiple first output terminals are connected one-to-one to the filters of different frequency bands.
[0011] Optionally, the radio frequency switching circuit further includes a second input terminal, a second output terminal, and a second switching unit:
[0012] The second switching unit includes a second series switch and a second parallel switch. The first end of the second series switch is connected to the second input terminal, the second end of the second series switch is connected to the second output terminal, the first end of the second parallel switch is connected to either the second input terminal or the second output terminal, and the second end of the second parallel switch is grounded.
[0013] The second series switch includes at least one third transistor, and the second parallel switch includes at least one fourth transistor, wherein the width of the third transistor is greater than the width of the fourth transistor.
[0014] Optionally, the frequency of the radio frequency signal transmitted by the first switching unit is higher than the frequency of the radio frequency signal transmitted by the second switching unit.
[0015] Optionally, 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 being connected to the same second input terminal, and the plurality of second switch units being connected one-to-one to the plurality of second output terminals.
[0016] Optionally, the third transistor and the fourth transistor are both field-effect transistors, and the gate width of the third transistor is greater than the gate width of the fourth transistor.
[0017] Optionally, the width of the second transistor is the same as the width of the fourth transistor.
[0018] Optionally, the width of the first transistor is 0.3mm to 1.2mm, and the width of the second transistor is 0.6mm to 1.6mm.
[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 1.2mm to 3.2mm, and the width of the fourth transistor is 0.6mm to 1.6mm.
[0021] Optionally, the width of the third transistor is 1.6mm to 2.4mm, and the width of the fourth transistor is 0.8mm to 1.2mm.
[0022] Optionally, the number of the first switching units is greater than the number of the second switching units.
[0023] Optionally, the first transistor, the second transistor, the third transistor, and the fourth transistor are transistors based on CMOS technology, SOI technology, or GaAs pHEMT technology, 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] Secondly, embodiments of this application provide a radio frequency switching circuit, including:
[0027] A first switching unit, comprising a first series switch and a first parallel switch, wherein the first series switch comprises at least one first transistor and the first parallel switch comprises at least one second transistor, wherein the width of the first transistor is smaller than the width of the second transistor.
[0028] The second switching unit includes a second series switch and a second parallel switch. The second series switch includes at least one third transistor, and the second parallel switch includes at least one fourth transistor. The width of the third transistor is greater than the width of the fourth transistor.
[0029] The frequency of the radio frequency signal transmitted by the first switching unit is higher than the frequency of the radio frequency signal transmitted by the second switching unit.
[0030] Thirdly, embodiments of this application provide a radio frequency front-end module, including the radio frequency switch circuit described above.
[0031] Optionally, the RF front-end module further includes multiple filters for different frequency bands, and the first switching unit and the second switching unit are respectively used to select and output RF signals of at least one frequency band to the filter of the corresponding frequency band.
[0032] Optionally, the radio frequency front-end module further includes a first antenna port, and the first switching unit is used to select and output radio frequency signals of at least one frequency band received by the first antenna port.
[0033] Optionally, the radio frequency front-end module further includes a second antenna port, and the second switching unit is used to select and output radio frequency signals of at least one frequency band received by the second antenna port.
[0034] The RF switch circuit and RF front-end module provided in this application include a first input terminal, a first output terminal, and a first switch unit. The first switch unit includes a first series switch and a first parallel switch. The first series switch is connected between the first input terminal and the first output terminal. The first end of the first parallel switch is connected to the first input terminal or the first output terminal, and the second end is grounded. 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. In this way, the size of the first series switch is smaller than the size 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 helps to reduce the parasitic capacitance when the first series switch is turned off and increase 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. Furthermore, the increase in the size of the first parallel switch allows a larger discharge current to pass through, improving the electrostatic discharge protection capability of the first switch unit.
[0035] These or other aspects of this application will become more apparent from the description of the following embodiments. Attached Figure Description
[0036] Figure 1 This is a schematic diagram of the structure of a radio frequency switch circuit according to an embodiment of this application.
[0037] Figure 2 for Figure 1 A schematic diagram of one embodiment of the first transistor in the radio frequency switch circuit shown.
[0038] Figure 3 for Figure 1 A schematic diagram of another implementation of the first transistor in the radio frequency switch circuit shown.
[0039] Figure 4 This is a schematic diagram of the structure of a radio frequency switch circuit according to an embodiment of this application.
[0040] Figure 5 This is a diagram illustrating an application scenario of a radio frequency switch circuit according to an embodiment of this application.
[0041] Figure 6 This is a schematic diagram of the structure of a radio frequency switch circuit according to an embodiment of this application.
[0042] Figure 7 This is a schematic diagram of the structure of a radio frequency switch circuit according to an embodiment of this application.
[0043] Figure 8 This is a schematic diagram of the structure of a radio frequency switch circuit according to an embodiment of this application.
[0044] Figure 9 This is a schematic diagram of the structure of a radio frequency front-end module according to an embodiment of this application.
[0045] Figure 10 This is a schematic diagram of the structure of a radio frequency front-end module according to an embodiment of this application. Detailed Implementation
[0046] The embodiments of this application are described in detail below. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.
[0047] To enable those skilled in the art to better understand the solutions of this application, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.
[0048] In the embodiments of this application, it should be noted that, in this document, relational terms such as first and second are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations.
[0049] Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.
[0050] In the description of the embodiments of this application, the words "example" or "for example" are used to indicate exemplification, illustration, or description. Any embodiment or design described as "example" or "for example" in the embodiments of this application is not to be construed as being more preferred or having more advantages than another embodiment or design. The use of the words "example" or "for example" is intended to present relative concepts in a clear manner.
[0051] Furthermore, in the embodiments of this application, "multiple" refers to two or more. Therefore, in the embodiments of this application, "multiple" can also be understood as "at least two". "At least one" can be understood as one or more, such as one, two, or more. For example, including at least one means including one, two, or more, and is not limited to which ones are included. For example, including at least one of A, B, and C, then it could include A, B, C, A and B, A and C, B and C, or A and B and C.
[0052] It should be noted that in the embodiments of this application, "and / or" describes the relationship between associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. In addition, the character " / ", unless otherwise specified, generally indicates that the associated objects before and after it are in an "or" relationship.
[0053] It should be noted that in the embodiments of this application, "connection" can be understood as electrical connection. 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 a direct connection between A and B, or an indirect connection between A and B through one or more other electrical components.
[0054] One embodiment of this application provides a radio frequency switching circuit 100, please refer to [link / reference]. Figure 1 As shown, the radio frequency switch circuit 100 includes a first input terminal 11, a first output terminal 12, and a first switch unit 13.
[0055] The first switching unit 13 includes a first series switch 131 and a first parallel switch 132. The first end of the first series switch 131 is connected to the first input terminal 11, the second end of the first series switch 131 is connected to the first output terminal 12, the first end of the first parallel switch 132 is connected to either the first input terminal 11 or the first output terminal 12, and the second end of the first parallel switch 132 is grounded.
[0056] The first switching unit 13 can correspond to at least one frequency band of radio frequency signal. When the radio frequency signal of the at least one frequency band needs to be transmitted, the first switching unit 13 is turned on, that is, the first series switch 131 in the first switching unit 13 is turned on and the first parallel switch 132 is turned off, so that the corresponding radio frequency signal is transmitted through the first series switch 131. When the radio frequency signal of the at least one frequency band does not need to be transmitted, the first switching unit 13 is turned off, that is, the first series switch 131 in the first switching unit 13 is turned off and the first parallel switch 132 is turned on. On the one hand, the radio frequency signal leaking from the turned-off first series switch 131 can be shorted to 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 embodiments 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 greater than the width of the transistor in the first series switch 131. The increased transistor width means that more charge can accumulate on its surface, thereby increasing the parasitic capacitance of the transistor. In this embodiment, reducing the size of the first transistor Q1 in the first series switch 131 can reduce the parasitic capacitance of the first series switch 131. Thus, when the radio frequency signal is transmitted through other paths and the first series switch 131 is turned off, the radio frequency signal leakage caused by the parasitic capacitance of the first series switch 131 is reduced, the insertion loss of the radio frequency switch circuit is reduced, and the isolation between the path where the first series switch 131 is located and other radio frequency signal transmission paths is higher.
[0058] For example, please refer to 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, which 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, please refer to Figure 3 As shown, the first transistor Q1 may include at least two first single-cell transistors Q10 connected in parallel. Each first single-cell transistor Q10 includes a control terminal 10a, a first terminal 10b, and a second terminal 10c. The width of the first single-cell transistor Q10 is the distance of the control terminal 10a in the width direction. Then the width of the first transistor Q1 is × , This refers to the number of first single-cell transistors Q10 contained in the first transistor Q1. It should be noted that the width direction is the 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] For example, 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 repeated here.
[0061] For example, the width of the first transistor Q1 is smaller than the width of the second transistor Q2. This can be achieved by the following methods: the number of first transistors connected in parallel in the first transistor Q1 is the same as the number of second transistors connected in parallel in the second transistor Q2, and the width of the control terminal of the first transistor is smaller than the width of the control terminal of the second transistor; or the width of the control terminal of the first transistor in the first transistor Q1 is the same as the width of the control terminal of the second transistor in the second transistor Q2, and the number of first transistors is less than the number of second transistors; or the width of the control terminal of the first transistor in the first transistor Q1 is less than the width of the control terminal of the second transistor in the second transistor Q2, and the number of first transistors is less than the number of second transistors. This application does not limit how 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, the size of the first series switch 131 is smaller than the size of the first parallel switch 132. When the first switching 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 helps to reduce the parasitic capacitance when the first series switch 131 is turned off, increase the impedance to the radio frequency signal when the first series switch 131 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 switching circuit. In addition, the increase in the size of the first parallel switch 132 allows a larger discharge current to pass through, improving the electrostatic discharge protection capability of the first switching unit.
[0063] In one implementation, the first transistor Q1 and the second transistor Q2 are both field-effect transistors (FETs), with their control terminals being gates. Therefore, the width of the first transistor Q1 is its gate width, and the width of the second transistor Q2 is its gate width. Consequently, the gate width of the first transistor Q1 is smaller than the gate width of the second transistor Q2. For example, for a field-effect transistor, its control terminal can be the gate, its first terminal can be the source or drain, and its second terminal can be the drain or source.
[0064] Optionally, the first transistor Q1 and the second transistor Q2 can be metal-oxide-semiconductor field-effect transistors (MOSFETs), abbreviated as MOS transistors or MOS tubes. Alternatively, the first transistor Q1 and the second transistor Q2 can be metal-semiconductor field-effect transistors (MESFETs), abbreviated as MS transistors. Alternatively, the first transistor Q1 and the second transistor Q2 can be high electron mobility transistors (HEMTs), abbreviated as HEMT transistors. Alternatively, the first transistor Q1 and the second transistor Q2 can be pseudomorphic high electron mobility transistors (pHEMTs), abbreviated as pHEMT transistors.
[0065] Optionally, the first transistor Q1 and the second transistor Q2 can be fabricated on any one of a silicon substrate, a silicon-on-insulator (SOI) substrate, a gallium arsenide (GaAs) substrate, or a silicon carbide (SiC) substrate.
[0066] For 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] For example, the first transistor Q1 and the second transistor Q2 can be MS transistors, HEMT transistors, or pHEMT transistors fabricated on a GaAs substrate.
[0068] As one implementation method, please refer to Figure 4 As shown, the radio frequency switch circuit 100 includes a plurality of first output terminals 12 and a plurality of first switch units 13. The number of first output terminals 12 is the same as the number of first switch units 13. The plurality of first switch units 13 are connected one-to-one to the plurality of first output terminals 12, and each first switch unit 13 is connected to the same first input terminal 11.
[0069] When multiple first series switches 131 are simultaneously turned off, the parasitic capacitance generated by these switches 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. This increases the parasitic capacitance between the first input terminal 11 and the corresponding first output terminal 12, leading to increased leakage of radio frequency (RF) signal through the parasitic capacitance, increased RF signal loss, and consequently, higher insertion loss and poorer signal isolation in the RF switch circuit. In this embodiment, the size of each first series switch 131 is reduced, and the parasitic capacitance of each switch 131 is correspondingly reduced. The parallel parasitic capacitance generated when multiple first series switches 131 are simultaneously turned off is significantly reduced, resulting in reduced RF signal leakage, lower RF signal loss, lower insertion loss in the RF switch circuit, and better signal isolation.
[0070] In this embodiment, each first switching unit corresponds to at least one frequency band of radio frequency (RF) signal. When an RF signal of a specific frequency band is output, the first series switch in the first switching unit corresponding to that specific frequency band is turned on and the first parallel switch is turned off. In other first switching units, the first parallel switch is turned on and the first series switch is turned off. Through this method, RF signal transmission of different frequency bands can be compatible. 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 switching unit is turned off is reduced, the parallel parasitic capacitance formed when the first series switch in each turned-off first switching unit is turned off is reduced, and the impedance to the RF signal when the first series switch in each turned-off first switching unit is turned off is increased. This reduces RF signal leakage, improves signal isolation, and reduces insertion loss of the RF switching circuit.
[0071] In one implementation, the number of first switching units 13 is at least three, and at any given time, the number of first switching units 13 that are turned off is greater than the number of first switching units that are turned on. It is understood that in most application scenarios of RF switches supporting multi-band signal transmission, to reduce crosstalk between different frequency bands, except for a few bands requiring carrier aggregation, signals from most frequency bands are not transmitted simultaneously. Therefore, generally, at any given time, the number of first switching units 13 that are turned off is greater than the number of first switching units 13 that are turned on. This results in the parasitic capacitances of multiple turned-off first switching units 13 being connected in parallel, increasing the total capacitance between the first input terminal 11 and the first output terminal 12, thereby exacerbating signal leakage and increasing the insertion loss of the RF switching circuit. In this case, the embodiments of this application reduce the width of each first transistor Q1, thereby reducing the parasitic capacitance of each first switching unit 13. Even if multiple parasitic capacitances are connected in parallel due to the turn-off of multiple first switching units 13, the total capacitance can be controlled within a small range, thereby significantly improving the isolation between different paths and reducing the insertion loss of the RF switching circuit.
[0072] In some implementations, please refer to Figure 5 As shown, the RF switch circuit 100 is disposed in the RF receiving link 200. The RF receiving link 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 the same. Multiple first output terminals 12 are connected one-to-one to filters 202 of different frequency bands.
[0073] In this embodiment, during signal reception, a specific frequency signal corresponding to the first activated switching unit can be selected for transmission. This signal is then filtered and amplified before being transmitted to the receiver to obtain a sufficient signal-to-noise ratio and ensure communication quality. Simultaneously, during signal reception, the RF signal power received at the antenna port is relatively weak, placing lower demands on the power tolerance of the first series switch in the first switching unit. Therefore, the number of first series switches and first parallel switches can be reduced to further decrease the insertion loss of the RF switching circuit.
[0074] In some embodiments, the first series switch 131 includes a plurality of first transistors Q1 connected in series, and the number of first transistors Q1 can be 3 to 5.
[0075] During signal reception, the RF signal strength received at the antenna port is relatively weak, typically less than 30 dBm. Therefore, the number of first transistors in the first series switch is relatively small. Compared to the parasitic capacitance when a single first transistor Q1 is turned off, the series parasitic capacitance generated by multiple interconnected first transistors Q1 is reduced. However, since the number of first transistors in the first series switch in the receiving link is small, the reduction in series parasitic capacitance is limited. Therefore, it is more necessary to reduce the parasitic capacitance of each first transistor. In the embodiment of this 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 simultaneously is greatly reduced. This reduces the RF signal leakage through the parasitic capacitance, lowers the RF signal loss, reduces the insertion loss of the RF switch circuit, and improves signal isolation.
[0076] In one implementation, the first switching unit 13 is used to transmit radio frequency signals with frequencies higher than a specific threshold, such as intermediate frequency (IF) or high frequency (HF) radio frequency signals. It is understood that the impedance of a parasitic capacitance of the same size to IF or HF radio frequency signals is less than that to low frequency radio frequency signals. In other words, IF or HF radio frequency signals are more prone to leakage through capacitance compared to low frequency signals. Therefore, for the first switching unit 13 used to transmit IF or HF 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 switching circuit.
[0077] In one implementation, there are at least three first switching units 13, each used to transmit radio frequency signals with a frequency higher than a specific threshold. At any given time, the number of first switching units 13 that are turned off exceeds the number of first switching units that are turned on. In this scenario, compared to related technologies that do not reduce the width of the first transistor, this implementation significantly reduces insertion loss and improves isolation in the radio frequency switching circuit.
[0078] As one implementation method, please refer to Figure 6 As shown, the RF switch circuit 100 also includes a second input terminal 21, a second output terminal 22, and a second switch unit 23.
[0079] The second switching unit 23 includes a second series switch 231 and a second parallel switch 232. The first end of the second series switch 231 is connected to the second input terminal 21, the second end of the second series switch 231 is connected to the second output terminal 22, the first end of the second parallel switch 232 is connected to either the second input terminal 21 or the second output terminal 22, and the second end of the second parallel switch 232 is grounded.
[0080] The second switching unit 23 can correspond to at least one frequency band of radio frequency signal. When the radio frequency signal of the at least one frequency band needs to be transmitted, the second switching unit 23 is turned on, that is, the second series switch 231 in the second switching unit 23 is turned on and the second parallel switch 232 is turned off, so that the corresponding radio frequency signal is transmitted through the second series switch 231. When the radio frequency signal of the at least one frequency band does not need to be transmitted, the second switching unit 23 is turned off, that is, the second series switch 231 in the second switching unit 23 is turned off and the second parallel switch 232 is turned on. On the one hand, the radio frequency signal leaking from the turned-off second series switch 231 can be shorted to 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 those of the first transistor Q1, and the widths of the third transistor Q3 and the fourth transistor Q4 can be defined as follows: Figure 2 or Figure 3 The width of the first transistor Q1 shown is defined similarly, and will not be repeated here.
[0082] In this circuit, the width of the third transistor Q3 is greater than the width of the fourth transistor Q4, meaning 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 increased transistor width means an increased current path width, allowing more electrons to flow rapidly through the current path, thus reducing the on-resistance.
[0083] Specifically, if the number of parallel-connected third transistors in the third transistor Q3 is the same as the number of parallel-connected fourth transistors in the fourth transistor Q4, then when the width of the control terminal of the third transistor is greater than the width of the control terminal of the fourth transistor, the width of the third transistor Q3 is greater than the width of the fourth transistor Q4. If the width of the control terminal of the third transistor in the third transistor Q3 is the same as the width of the control terminal of the fourth transistor in the fourth transistor Q4, then when the number of third transistors is greater than the number of fourth transistors, the width of the third transistor Q3 is greater than the width of the fourth transistor Q4. When the width of the control terminal of the third transistor in the third transistor Q3 is greater than the width of the control terminal of the fourth transistor in the fourth transistor Q4, and the number of third transistors is greater than the number of fourth transistors, the width of the third transistor Q3 is greater than the width of the fourth transistor Q4.
[0084] In this embodiment, when the second switching unit is turned on, the resistance of the second series switch is reduced due to the increased size of the second series switch, which helps to reduce the insertion loss of the radio frequency switching circuit.
[0085] The third transistor Q3 and the fourth transistor Q4 are both field-effect transistors (FETs). 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. For example, for a field-effect transistor, its control terminal can be the gate, its first terminal can be the source or drain, and its second terminal can be the drain or source.
[0086] Optionally, the third transistor Q3 and the fourth transistor Q4 can be metal-oxide-semiconductor field-effect transistors (MOSFETs), abbreviated as MOS transistors or MOSFETs. Alternatively, the third transistor Q3 and the fourth transistor Q4 can be metal-semiconductor field-effect transistors (MESFETs), abbreviated as MS transistors. Alternatively, the third transistor Q3 and the fourth transistor Q4 can be high electron mobility transistors (HEMTs), abbreviated as HEMT transistors. Alternatively, the third transistor Q3 and the fourth transistor Q4 can be pseudomorphic high electron mobility transistors (pHEMTs), abbreviated as pHEMT transistors.
[0087] Optionally, the third transistor Q3 and the fourth transistor Q4 can be fabricated on any one of a silicon substrate, a silicon-on-insulator (SOI) substrate, a gallium arsenide (GaAs) substrate, or a silicon carbide (SiC) substrate.
[0088] For 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] For example, the third transistor Q3 and the fourth transistor Q4 can be MS transistors, HEMT transistors, or pHEMT transistors fabricated on a GaAs substrate.
[0090] In some implementations, the frequency of the radio frequency signal transmitted by the first switching unit 13 is higher than the frequency of the radio frequency signal transmitted by the second switching unit 23.
[0091] The first switching unit 13 is used to transmit relatively high frequency radio frequency signals, such as medium-high frequency radio frequency signals, and the second switching unit 23 is used to transmit relatively low frequency radio frequency signals, such as low frequency radio frequency signals.
[0092] It should be noted that 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 conducting switch unit; Second, the insertion loss formed by the off-state parasitic capacitance of the series switch in the non-conducting switch unit when it is turned off; Third, the insertion loss formed by the off-state parasitic capacitance of the parallel switch in the conducting switch unit when it is turned off.
[0093] For the first switching unit, since the corresponding operating frequency band is relatively high, the shutdown parasitic capacitance of the series switch in the non-conducting first switching unit has a greater impact on the insertion loss when it is turned off; for the second switching unit, since the corresponding operating frequency band is relatively low, the on-resistance of the series switch in the conducting second switching unit has the greatest impact on the insertion loss.
[0094] When the second switching unit 23, which partially transmits 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 switching unit 23 is much greater than the insertion loss caused by the off-resistance parasitic capacitance when the second series switch 231 in the non-turned-on second switching unit 23 is turned off. When the first switching unit 13, which partially transmits medium- and high-frequency signals, is turned on, the insertion loss caused by the off-resistance parasitic capacitance when the first series switch 131 in the non-turned-on first switching unit 13 is much greater than the insertion loss caused by the on-resistance of the first series switch 131 in the turned-on first switching unit 13. Therefore, reducing the size of the first series switch 131 in the first switching unit and increasing the size of the second series switch 231 in the second switching unit 23 is beneficial to simultaneously reduce the insertion loss caused by the on-resistance of the second series switch 231 in the conducting second switching unit 23 and the insertion loss caused by the off-resistance parasitic capacitance of the first series switch 131 in the non-conducting first switching unit 13 when it is turned off. This reduces the insertion loss when the second switching unit 23 is conducting and the insertion loss when the first switching unit 13 is turning off, thereby reducing the insertion loss during medium- and high-frequency signal transmission and the insertion loss during low-frequency signal transmission.
[0095] In some implementations, please refer to Figure 7 As shown, the radio frequency switch circuit 100 includes multiple second output terminals 22 and multiple second switch units 23. Each second switch unit 23 is connected to the same second input terminal 21. The number of second output terminals 22 is the same as the number of second switch units 23. The multiple second switch units 23 are connected one-to-one to the multiple second output terminals 22.
[0096] In this embodiment, each first switching unit corresponds to at least one frequency band of radio frequency signal in the low frequency range. When a radio frequency signal of a specific frequency band is output, the second series switch in the second switching unit corresponding to that specific frequency band is turned on and the second parallel switch is turned off. In other second switching units, the second parallel switch is turned on and the second series switch is turned off. In this way, radio frequency signal transmission of different frequency bands in the low frequency range can be compatible.
[0097] In some implementations, the width of the second transistor Q2 is the same as the width of the fourth transistor Q4.
[0098] Therefore, the size of the first series switch is smaller than the size of the first parallel switch and the second parallel switch, and the size of the second series switch is larger than the size 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 of the first switch unit and the insertion loss of the second switch unit are reduced simultaneously, which is beneficial to reducing the insertion loss of the radio frequency switch circuit.
[0100] In some implementations, 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 widths of the first transistor and the second transistor are respectively set within the aforementioned corresponding ranges, which reduces the parasitic capacitance when the first series switch is turned off and can be adapted to application scenarios of medium and high frequency radio frequency signals.
[0102] In some implementations, 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, by setting the width of the first transistor and the width of the second transistor within the aforementioned corresponding ranges, the parasitic capacitance when the first series switch is turned off can be further reduced, thereby further reducing the insertion loss of the RF switch circuit.
[0104] For example, 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 implementations, 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 widths of the third transistor and the fourth transistor are respectively set within the aforementioned corresponding ranges, which reduces the resistance when the second series switch is turned on and can be adapted to low-frequency radio frequency signal application scenarios.
[0107] In some implementations, 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 widths of the third transistor and the fourth transistor are respectively set within the aforementioned corresponding ranges to further reduce the resistance when the second series switch is turned on, thereby further reducing the insertion loss of the RF switch circuit.
[0109] For example, 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 first switch units 13 is greater than the number of second switch units 23. For example, the number of first switch units 13 is 5 to 7, and the number of second switch units 23 is 2 to 4.
[0111] In this embodiment, each first switching unit can adapt to at least one frequency band in the mid-to-high frequency range, and each second switching unit can adapt to at least one frequency band in the low frequency range, thus fully adapting to the needs of radio frequency signals in different frequency bands.
[0112] In some implementations, the first transistor, the second transistor, the third transistor, and the fourth transistor are transistors based on CMOS (Complementary Metal Oxide Semiconductor) technology, SOI (Silicon-On-Insulator) technology, or GaAs pHEMT (gallium arsenide pseudomorphic high-electron-mobility transistor) technology.
[0113] In some embodiments, the first series switch 131 includes a plurality of first transistors Q1 connected in series, and the number of first transistors Q1 can be 3 to 5.
[0114] During signal reception, the RF signal strength received at the antenna port is relatively weak, usually less than 30dBm. The number of first transistors in the first series switch is relatively small. The reduction in the width of the first transistor helps to reduce the parasitic capacitance when the first series switch is turned off and reduces 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, wherein the number of second transistors Q2 can be 3 to 5. This allows for a reduction in layout area and cost while still meeting ESD requirements.
[0116] In some embodiments, the second series switch 231 includes a plurality of third transistors Q3 connected in series, and the number of third transistors Q3 can be 3 to 5.
[0117] In this embodiment, during signal reception, the radio frequency 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 lower the cost while meeting the power tolerance requirements.
[0118] In some implementations, the second parallel switch 232 includes multiple fourth transistors Q4 connected in series, with the number of fourth transistors Q4 being 3 to 5. This allows for a reduction in layout area and cost while still meeting ESD requirements.
[0119] One embodiment of this application provides a radio frequency switch circuit 100'. Please refer to [link / reference]. 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 switching 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, and the first parallel switch 132 includes at least one second transistor Q2. The width of the first transistor Q1 is smaller than the width of the second transistor Q2.
[0121] The second switching 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, and the second parallel switch 232 includes at least one fourth transistor Q4. The width of the third transistor Q3 is greater than the width of the fourth transistor Q4.
[0122] The frequency of the radio frequency signal transmitted by the first switching unit 13 is higher than the frequency of the radio frequency signal transmitted by the second switching unit 23.
[0123] For a description of the first switching unit 13 and the second switching unit 23, please refer to the previous embodiment, and will not be repeated here.
[0124] In the embodiments of this 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 conducting switch unit; second, the insertion loss formed by the off-state parasitic capacitance when the series switch in the non-conducting switch unit is turned off; and third, the insertion loss formed by the off-state parasitic capacitance when the parallel switch in the conducting switch unit is turned off.
[0125] For transistors, a larger transistor width results in a smaller on-resistance and a larger turn-off parasitic capacitance. Specifically, for mid-to-high frequency signals, the turn-off parasitic capacitance of a transistor in series on an unselected path has a much greater impact on insertion loss than the on-resistance of a transistor in series on a selected path. Conversely, for low-frequency signals, the on-resistance of a transistor in series on a selected path has a much greater impact on insertion loss than the turn-off parasitic capacitance of a transistor in series on an unselected path.
[0126] Therefore, for the first switching unit with a higher operating frequency, the insertion loss caused by the parasitic capacitance of the series switch when it is turned off in the unconducted first switching unit has the greatest impact; for the second switching unit with a lower operating frequency, the insertion loss caused by the on-resistance of the series switch in the conducted second switching 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 of the first switch unit and the insertion loss of the second switch unit are reduced simultaneously, which is beneficial to reducing the insertion loss of the radio frequency switch circuit.
[0128] One embodiment of this application provides a radio frequency front-end module 300. Please refer to [link to relevant documentation]. Figure 9 As shown, the RF front-end module 300 includes the aforementioned RF switch circuit 100 or the aforementioned 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 helps to reduce the parasitic capacitance when the first series switch is turned off and increase the impedance to the radio frequency signal when the first series switch 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. The increase in the size of the first parallel switch allows a larger discharge current to pass through, improving the electrostatic discharge protection capability of the first switch unit.
[0130] As one implementation method, please refer to Figure 10 As shown, the RF front-end module 300 also includes multiple filters 301 for different frequency bands. The first switching unit 13 or the second switching unit 23 is used to select and output the 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 a first switching unit 13 is used to select and output the RF signals of at least one frequency band received by the first antenna port 302 to the corresponding filter 301.
[0132] In some embodiments, the RF front-end module 300 further includes a second antenna port 303, and a second switching unit 23 is used to select and output the RF signals of at least one frequency band received by the second antenna port 303 to the corresponding filter 301.
[0133] The above description is merely an embodiment of this application. It should be noted that those skilled in the art can make improvements without departing from the inventive concept of this application, but these improvements all fall within the protection scope of this application.
Claims
1. A radio frequency switching circuit, characterized in that, Including a first input terminal, multiple first output terminals, and also including: Multiple first switching units, each first switching unit includes a first series switch and a first parallel switch, the first end of the first series switch is connected to the first input terminal, the second end of the first series switch is connected to the first output terminal, the first end of the first parallel switch is connected to either the first input terminal or the first output terminal, and the second end of the first parallel switch is grounded; The first series switch includes at least one first transistor, and the first parallel switch includes at least one second transistor; In this configuration, the first transistors in the plurality of first switching units are connected to the same first input terminal, and the first transistor and the second transistor are both field-effect transistors, with the gate width of the first transistor being smaller than the gate width of the second transistor.
2. The radio frequency switching circuit according to claim 1, characterized in that, The radio frequency switch circuit includes multiple first output terminals and multiple first switch units, each of the first switch units being connected to the same first input terminal, and the multiple first switch units being connected one-to-one to the multiple first output terminals.
3. The radio frequency switching circuit according to claim 2, characterized in that, The radio frequency switch circuit is disposed in the radio frequency receiving link, which also includes an antenna port and multiple filters of different frequency bands. The first input terminal is used to connect to the antenna port and receive the radio frequency signal input from the antenna port. The multiple first output terminals are connected one-to-one to the filters of different frequency bands.
4. The radio frequency switching circuit according to claim 1, characterized in that, The radio frequency switching circuit further includes a second input terminal, a second output terminal, and a second switching unit: The second switching unit includes a second series switch and a second parallel switch. The first end of the second series switch is connected to the second input terminal, the second end of the second series switch is connected to the second output terminal, the first end of the second parallel switch is connected to either the second input terminal or the second output terminal, and the second end of the second parallel switch is grounded. The second series switch includes at least one third transistor, and the second parallel switch includes at least one fourth transistor, wherein the width of the third transistor is greater than the width of the fourth transistor.
5. The radio frequency switching circuit according to claim 4, characterized in that, The frequency of the radio frequency signal transmitted by the first switching unit is higher than the frequency of the radio frequency signal transmitted by the second switching unit.
6. The radio frequency switching circuit according to claim 4, characterized in that, The radio frequency switch circuit includes multiple second output terminals and multiple second switch units. Each second switch unit is connected to the same second input terminal, and the multiple second switch units are connected one-to-one to the multiple second output terminals.
7. The radio frequency switching circuit according to claim 4, characterized in that, The third transistor and the fourth transistor are both field-effect transistors, and the gate width of the third transistor is greater than the gate width of the fourth transistor.
8. The radio frequency switching circuit according to claim 4, characterized in that, The width of the second transistor is the same as the width of the fourth transistor.
9. The radio frequency switching circuit according to claim 4, characterized in that, The width of the first transistor is 0.3mm to 1.2mm, and the width of the second transistor is 0.6mm to 1.6mm.
10. The radio frequency switching circuit according to claim 9, 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.
11. The radio frequency switching circuit according to claim 4, characterized in that, The width of the third transistor is 1.2mm to 3.2mm, and the width of the fourth transistor is 0.6mm to 1.6mm.
12. The radio frequency switching circuit according to claim 11, characterized in that, The width of the third transistor is 1.6mm to 2.4mm, and the width of the fourth transistor is 0.8mm to 1.2mm.
13. The radio frequency switching circuit according to claim 4, characterized in that, The number of the first switching units is greater than the number of the second switching units.
14. The radio frequency switching circuit according to claim 4, characterized in that, The first transistor, the second transistor, the third transistor, and the fourth transistor are transistors based on CMOS technology, SOI technology, or GaAs pHEMT technology, respectively.
15. The radio frequency switching circuit according to claim 4, characterized in that, The number of the first transistors in the first series switch and the number of the second transistors in the first parallel switch are 3 to 5, respectively.
16. The radio frequency switching circuit according to claim 4, 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.
17. A radio frequency switching circuit, characterized in that, include: A first switching unit, comprising a first series switch and a first parallel switch, wherein the first series switch comprises at least one first transistor and the first parallel switch comprises at least one second transistor, wherein the width of the first transistor is smaller than the width of the second transistor. The second switching unit includes a second series switch and a second parallel switch. The second series switch includes at least one third transistor, and the second parallel switch includes at least one fourth transistor. The width of the third transistor is greater than the width of the fourth transistor. The frequency of the radio frequency signal transmitted by the first switching unit is higher than the frequency of the radio frequency signal transmitted by the second switching unit.
18. A radio frequency front-end module, characterized in that, Includes the radio frequency switching circuit as described in any one of claims 1 to 17.
19. The radio frequency front-end module according to claim 18, characterized in that, The radio frequency front-end module also includes multiple filters for different frequency bands. The first switching unit and the second switching unit are respectively used to select and output radio frequency signals of at least one frequency band to the filter of the corresponding frequency band.
20. The radio frequency front-end module according to claim 18, characterized in that, The radio frequency front-end module further includes a first antenna port, and the first switching unit is used to select and output radio frequency signals of at least one frequency band received by the first antenna port.
21. The radio frequency front-end module according to claim 20, characterized in that, The radio frequency front-end module also includes a second antenna port, and the second switching unit is used to select and output radio frequency signals of at least one frequency band received by the second antenna port.