Radio frequency switch and radio frequency chip
Optimized RF switches through four switch branch structures and MOS tube capacitance connections, solving the problems of adjacent channel signal leakage and ESD capability reduction in 5G communication, achieving high isolation and good ESD protection RF switch and chip performance.
Patent Information
- Application Number
- CN202422147894.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-02
- Publication Date
- 2025-06-27
- Estimated Expiration
- 2034-09-02
AI Technical Summary
The existing RF switches have adjacent channel signal leakage problems in 5G communication, which affects isolation, and the increase in the size of the shunt tube leads to a decrease in ESD capability.
Four switching branch structures are adopted, including the first, second, third and fourth switching branches. By setting MOS tubes at the output ends of the third and fourth switching branches, and connecting them with the gate of the MOS tube using capacitors, adjusting the values of inductors and capacitors to optimize the frequency and quality factor, and achieving good ESD capability and isolation.
While ensuring ESD capabilities, the isolation and performance of RF switches and RF chips are improved, the adjacent channel signal leakage is reduced, and the overall performance of RF switches is enhanced.
Smart Images
Figure CN223040004U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of radio frequency switches, and particularly relates to a radio frequency switch and a radio frequency chip. Background Art
[0002] With the development of communication technology, the communication mode has entered from 4G communication to 5G communication. In 5G communication, the communication speed has been greatly improved. However, correspondingly, the resources of the channel frequency bands used for communication are becoming increasingly tense, and the adjacent frequency bands are relatively close to each other. As a result, the specific radio frequency switch circuit has the problem of adjacent channel signal leakage, which affects the performance of the entire radio frequency system.
[0003] For a radio frequency switch, as a front-end component of a radio frequency system, it has the functions of selective conduction and isolation. The commonly used semiconductor process for manufacturing the existing radio frequency switch circuit is the silicon-on-insulator process, i.e., the SOI process. Integrating the entire circuit on a single die has a cost advantage. In addition, the existing radio frequency switch topology generally adopts a series-shunt structure, where series refers to a series transistor and shunt refers to a parallel transistor. The specific radio frequency switch structure is as Figure 1 shown. In Figure 1 , when the series transistor is conducting, it is equivalent to a resistor Rsc, and when it is turned off, it is equivalent to a parasitic capacitor Cse. When the shunt transistor is conducting, it is equivalent to a resistor Rsh, and when it is turned off, it is equivalent to a parasitic capacitor Csh. For the structure shown in Figure 1 , during the actual packaging process, when the RFC terminal is conducting to the RF1 terminal, due to the existence of the packaging parasitic inductance Lc, the radio frequency signal can also leak to the RF2 terminal through the capacitor Csh -> inductor La -> inductor Lb -> inductor La -> resistor Rsh, thus deteriorating the isolation degree.
[0004] In addition, since the shunt transistor is sized larger to improve the ESD ability, this will increase the capacitance Csh, which will further deteriorate the isolation degree of the radio frequency switch. Summary of the Utility Model
[0005] In view of the deficiencies in the background art, the utility model provides a radio frequency switch and a radio frequency chip, and the technical problem to be solved is that the existing radio frequency switch cannot simultaneously ensure high isolation and good ESD protection ability.
[0006] To solve the above technical problems, in the first aspect, the utility model provides the following technical solution: A radio frequency switch includes a first switch branch, a second switch branch, a third switch branch, and a fourth switch branch;
[0007] The input ends of the first switch branch and the second switch branch are electrically connected to form the input end of the radio frequency switch;
[0008] The output terminal of the first switch branch is the first output terminal of the RF switch and is electrically connected to the output terminal of the third switch branch. The output terminal of the second switch branch is the second output terminal of the RF switch and is electrically connected to the input terminal of the fourth switch branch;
[0009] The output terminal of the third switch branch is electrically connected to the drain of MOS transistor N5. The source of MOS transistor N5 is electrically connected to one end of inductor L1, and one end of inductor Lc through the other end of inductor L1. The gate of MOS transistor N5 is electrically connected to its own drain and source through capacitor C1 and capacitor C2 respectively;
[0010] The output terminal of the fourth switch branch is electrically connected to the drain of MOS transistor N6. The source of MOS transistor N6 is electrically connected to one end of inductor L2, and one end of inductor Lc through the other end of inductor L2. The gate of MOS transistor N6 is electrically connected to its own drain and source through capacitor C3 and capacitor C4 respectively. The other end of inductor Lc is grounded.
[0011] In a certain embodiment of the first aspect, when the first switch branch is turned on, the second switch branch is turned off; when the first switch branch is turned off, the second switch branch is turned on; the first switch branch and the fourth switch branch are turned on and off simultaneously, and the second switch branch and the third switch branch are turned on and off simultaneously.
[0012] In a certain embodiment of the first aspect, the first switch branch includes a plurality of MOS transistors N1 connected in series in sequence. The gate of each MOS transistor N1 is electrically connected to a resistor R1 respectively, and the end of resistor R1 far away from the gate of MOS transistor N1 is used for inputting a driving voltage V1.
[0013] In a certain embodiment of the first aspect, the fourth switch branch includes a plurality of MOS transistors N4 connected in series in sequence. The gate of each MOS transistor N4 is electrically connected to a resistor R4 respectively, and the end of resistor R4 far away from the gate of MOS transistor N4 is used for inputting a driving voltage V1.
[0014] In a certain embodiment of the first aspect, the second switch branch includes a plurality of MOS transistors N2 connected in series in sequence. The gate of each MOS transistor N2 is electrically connected to a resistor R2 respectively, and the end of resistor R2 far away from the gate of MOS transistor N2 is used for inputting a driving voltage V2.
[0015] In a certain embodiment of the first aspect, the third switch branch includes a plurality of MOS transistors N3 connected in series in sequence. The gate of each MOS transistor N3 is electrically connected to a resistor R3 respectively, and the end of resistor R3 far away from the gate of MOS transistor N3 is used for inputting a driving voltage V2.
[0016] In a certain implementation manner of the first aspect, when the driving voltage V1 is at a high level, the first switch branch and the fourth switch branch are turned on; when the driving voltage V1 is at a low level, the first switch branch and the fourth switch branch are turned off.
[0017] When the driving voltage V2 is at a high level, the second switch branch and the third switch branch are turned on; when the driving voltage V2 is at a low level, the second switch branch and the third switch branch are turned off.
[0018] In a certain implementation manner of the first aspect, the gates of the MOS transistors N5 and N6 are respectively used to input the negative voltage Vneg.
[0019] In a certain implementation manner of the first aspect, the negative voltage Vneg is respectively input to the gates of the MOS transistors N5 and N6 through the resistors R5.
[0020] In the second aspect, the present utility model provides a radio frequency chip, and the above-mentioned radio frequency switch is provided on the radio frequency chip.
[0021] The beneficial effects of the present utility model compared with the prior art are as follows: by respectively arranging the MOS transistors N5 and N6 at the output ends of the third switch branch and the fourth switch branch, and electrically connecting the gate of the MOS transistor N5 to its own drain and source through the capacitors C1 and C2 respectively, and electrically connecting the gate of the MOS transistor N6 to its own drain and source through the capacitors C3 and C4 respectively, the ESD capability of the radio frequency switch can be ensured while providing the isolation degree of the radio frequency switch, thereby improving the performance of the radio frequency switch and the radio frequency chip. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] Figure 1 It is a schematic diagram of the circuit structure on the chip body in the embodiment;
[0023] Figure 2 It is a circuit diagram of the signal output unit in the embodiment;
[0024] Figure 3 For Figure 2 It is an equivalent schematic diagram of the circuit when the first switch branch and the fourth switch branch are turned on and the second switch branch and the third switch branch are turned off. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0025] Now, the present utility model will be further described in detail with reference to the accompanying drawings. These drawings are all simplified schematic diagrams, only illustrating the basic structure of the present utility model in a schematic manner, so they only show the components related to the present utility model.
[0026] Embodiment 1
[0027] AsFigure 2 As shown in the figure, a radio frequency switch includes a first switch branch 1, a second switch branch 2, a third switch branch 3, and a fourth switch branch 4;
[0028] The input ends of the first switch branch 1 and the second switch branch 2 are electrically connected, serving as the input end RFC of the radio frequency switch;
[0029] The output end of the first switch branch 1 is the first output end RF1 of the radio frequency switch and is electrically connected to the output end of the third switch branch 3. The output end of the second switch branch 2 is the second output end RF2 of the radio frequency switch and is electrically connected to the input end of the fourth switch branch 4;
[0030] The output end of the third switch branch 3 is electrically connected to the drain of the MOS transistor N5. The source of the MOS transistor N5 is electrically connected to one end of the inductor Lc through one end of the inductor L1. The gate of the MOS transistor N5 is electrically connected to its own drain and source through the capacitors C1 and C2 respectively;
[0031] The output end of the fourth switch branch 4 is electrically connected to the drain of the MOS transistor N6. The source of the MOS transistor N6 is electrically connected to one end of the inductor Lc through one end of the inductor L2. The gate of the MOS transistor N6 is electrically connected to its own drain and source through the capacitors C3 and C4 respectively, and the other end of the inductor Lc is grounded.
[0032] In actual use, in the present utility model, by respectively arranging the MOS transistors N5 and N6 at the output ends of the third switch branch 3 and the fourth switch branch 4, and making the gate of the MOS transistor N5 be electrically connected to its own drain and source through the capacitors C1 and C2 respectively, and making the gate of the MOS transistor N6 be electrically connected to its own drain and source through the capacitors C3 and C4 respectively, in this way, while ensuring that the radio frequency switch has good ESD ability, the isolation degree of the radio frequency switch can also be provided, improving the performance of the radio frequency switch and the radio frequency chip.
[0033] Specifically, in this embodiment, the capacitance values of the capacitors C1 and C2 are the same, and the capacitance values of the capacitors C3 and C4 are the same.
[0034] Specifically, in this embodiment, the conduction relationships of the first switch branch 1, the second switch branch 2, the third switch branch 3, and the fourth switch branch 4 are as follows:
[0035] When the first switch branch 1 is conducting, the second switch branch 2 is turned off; when the first switch branch 1 is turned off, the second switch branch 2 is conducting; the first switch branch 1 and the fourth switch branch 4 are conducting and turned off simultaneously, and the second switch branch 2 and the third switch branch 3 are conducting and turned off simultaneously, thereby realizing the channel selection function of the radio frequency switch.
[0036] Specifically, in this implementation, as Figure 1As shown, the first switch branch 1 includes multiple MOS transistors N1 connected in series in sequence. The gate of each MOS transistor N1 is electrically connected to a resistor R1, and one end of the resistor R1 far from the gate of the MOS transistor N1 is used to input the driving voltage V1. The number of MOS transistors N1 is selected according to actual requirements, and the MOS transistor N1 is an NMOS transistor.
[0037] Specifically, in this embodiment, as Figure 1 shown, the fourth switch branch 4 includes multiple MOS transistors N4 connected in series in sequence. The gate of each MOS transistor N4 is electrically connected to a resistor R4, and one end of the resistor R4 far from the gate of the MOS transistor N4 is used to input the driving voltage V1. The number of MOS transistors N4 is selected according to actual requirements, and the MOS transistor N4 is an NMOS transistor.
[0038] Specifically, in this embodiment, as Figure 1 shown, the second switch branch 2 includes multiple MOS transistors N2 connected in series in sequence. The gate of each MOS transistor N2 is electrically connected to a resistor R2, and one end of the resistor R2 far from the gate of the MOS transistor N2 is used to input the driving voltage V2. The number of MOS transistors N2 is selected according to actual requirements, and the MOS transistor N2 is an NMOS transistor.
[0039] Specifically, in this embodiment, as Figure 1 shown, the third switch branch includes multiple MOS transistors N3 connected in series in sequence. The gate of each MOS transistor N3 is electrically connected to a resistor R3, and one end of the resistor R3 far from the gate of the MOS transistor N3 is used to input the driving voltage V2. The number of MOS transistors N3 is selected according to actual requirements, and the MOS transistor N3 is an NMOS transistor.
[0040] Specifically, in this embodiment, when the driving voltage V1 is at a high level, the first switch branch 1 and the fourth switch branch 4 are turned on, that is, all the MOS transistors N1 and all the MOS transistors N4 are turned on; when the driving voltage V1 is at a low level, the first switch branch 1 and the fourth switch branch 4 are turned off, that is, all the MOS transistors N1 and all the MOS transistors N4 are turned off;
[0041] When the driving voltage V2 is at a high level, the second switch branch 2 and the third switch branch 3 are turned on, that is, all the MOS transistors N2 and all the MOS transistors N3 are turned on; when the driving voltage V2 is at a low level, the second switch branch 2 and the third switch branch 3 are turned off, that is, all the MOS transistors N2 and all the MOS transistors N3 are turned off.
[0042] Specifically, in this embodiment, the gates of MOS transistor N5 and MOS transistor N6 are respectively used to input the negative voltage Vneg. In actual use, when ESD protection is not required and radio frequency channel selection is performed, the negative voltage Vneg turns off MOS transistor N5 and MOS transistor N6, where both MOS transistor N5 and MOS transistor N6 are NMOS transistors.
[0043] More specifically, in this embodiment, the negative voltage Vneg is respectively input to the gates of MOS transistor N5 and MOS transistor N6 through resistor R5.
[0044] For Figure 2 the circuit shown, when the first switch branch 1 is turned on and the second switch branch 2 is turned off, Figure 2 the equivalent circuit of the circuit shown is as Figure 3 shown. At this time, the first switch branch 1 is equivalent to resistor Rse, the second switch branch 2 is equivalent to capacitor Cse, the third switch branch 3 is equivalent to capacitor Csh, the fourth switch branch 4 is equivalent to resistor Rsh, and the series value of capacitor C1 and capacitor C2 and the series value of capacitor C3 and capacitor C4 are both denoted as Cr;
[0045] First, for Figure 2 and Figure 3 the circuit shown, the series resonance branch composed of inductor Lc and capacitor Cr can be approximately short-circuited at the frequency center. Therefore, the inductance value of inductor Lc can be adjusted by adjusting the metal property of inductor Lc or the length, number or width of the metal column, so as to adjust the size of the center frequency value; where the frequency center is the harmonic frequency of inductor Lc, inductor L1, capacitor C1 and capacitor C2, or the harmonic frequency of inductor Lc, inductor L2, capacitor C3 and capacitor C4, and inductor L1 and inductor L2 are the same. The calculation formula of the harmonic frequency is as follows: It can be understood that the larger the inductor Lc, the smaller the center frequency value. In this way, when the first switch branch 1 is turned on and the second switch branch 2 is turned off, the low-frequency radio frequency signal flowing into the RF2 end can flow into the ground end through capacitor Cse and resistor Rsh as much as possible, thereby reducing the influence of the parasitic inductance on the performance of the radio frequency switch, and thus improving the isolation of the radio frequency switch;
[0046] In addition, for the series resonance branch, Q is the quality factor, Rx is the frequency-selective resistor, Lc is the parasitic inductance, and Cr is the resonant capacitor. When the value of Lc is adjusted, the size of Rx can also be adjusted, so as to adjust the size of the quality factor. Among them, the larger Rx and Lc are, the smaller Q is; in addition, according to the formula B = f / Q, when the center frequency f is known, the smaller Q is, the larger the bandwidth value B of the radio frequency switch is. Therefore, the frequency band range of the radio frequency signal flowing into the RF2 port channel can be determined by combining the center frequency f and the bandwidth value B; specifically, in Figure 3Among them, Rx is the resistor Rsh, so the size of Rsh can be adjusted by adjusting the size of MOS transistor N4.
[0047] Finally, in the case of ESD, for the current discharge path, the smaller the resistance on the path, the more conducive it is to current discharge. When ESD occurs, through the voltage division of capacitor C1 and capacitor C2, and the voltage division of capacitor C3 and capacitor C4, MOS transistor N5 or MOS transistor N6 can be turned on, thereby reducing the resistance value on the current discharge path, facilitating the discharge of ESD charges, and further providing the isolation degree of the RF switch while ensuring that the RF switch has good ESD capabilities, improving the performance of the RF switch and the RF chip. When MOS transistor N5 and MOS transistor N6 are turned off, the resistance values of their corresponding channel resistances Rds1 and Rds2 are above several tens of kiloohms.
[0048] Embodiment 2
[0049] This embodiment provides an RF chip, and an RF switch in Embodiment 1 is provided on the RF chip.
[0050] Based on the inspiration of the present invention, through the above description, relevant staff can completely make various changes and modifications without departing from the technical idea of this invention. The technical scope of this invention is not limited to the content in the specification, and its technical scope must be determined according to the scope of the claims.
Claims
1. A radio frequency switch, characterized in that: comprising a first switch branch, a second switch branch, a third switch branch and a fourth switch branch; The input end of the first switch branch is electrically connected to the input end of the second switch branch and is the input end of the radio frequency switch; The output end of the first switch branch is the first output end of the RF switch and is electrically connected to the output end of the third switch branch; the output end of the second switch branch is the second output end of the RF switch and is electrically connected to the input end of the fourth switch branch; The output end of the third switch branch is electrically connected to the drain of the MOS transistor N5, the source of the MOS transistor N5 is electrically connected to one end of the inductor Lc through one end of the inductor L1, and the gate of the MOS transistor N5 is electrically connected to its own drain and source through the capacitor C1 and the capacitor C2 respectively; The output end of the fourth switch branch is electrically connected to the drain of the MOS transistor N6, the source of the MOS transistor N6 is electrically connected to one end of the inductor Lc through one end of the inductor L2, the gate of the MOS transistor N6 is electrically connected to its own drain and source through the capacitor C3 and the capacitor C4 respectively, and the other end of the inductor Lc is grounded.
2. A radio frequency switch according to claim 1, characterized in that: When the first switch branch is turned on, the second switch branch is turned off; when the first switch branch is turned off, the second switch branch is turned on; the first switch branch and the fourth switch branch are turned on and off at the same time, and the second switch branch and the third switch branch are turned on and off at the same time.
3. The radio frequency switch according to claim 1, characterized in that: The first switch branch includes a plurality of MOS transistors N1 connected in series in sequence. The gate of each MOS transistor N1 is electrically connected to a resistor R1. One end of the resistor R1 away from the gate of the MOS transistor N1 is used to input a driving voltage V1.
4. The radio frequency switch according to claim 3, characterized in that: The fourth switch branch includes a plurality of MOS transistors N4 connected in series in sequence. The gate of each MOS transistor N4 is electrically connected to a resistor R4. One end of the resistor R4 away from the gate of the MOS transistor N4 is used to input a driving voltage V1.
5. The radio frequency switch according to claim 4, characterized in that: The second switch branch includes a plurality of MOS transistors N2 connected in series in sequence. The gate of each MOS transistor N2 is electrically connected to a resistor R2. One end of the resistor R2 away from the gate of the MOS transistor N2 is used to input a driving voltage V2.
6. The radio frequency switch according to claim 5, characterized in that: The third switch branch includes a plurality of MOS transistors N3 connected in series in sequence, the gate of each MOS transistor N3 is electrically connected to a resistor R3, and one end of the resistor R3 away from the gate of the MOS transistor N3 is used to input a driving voltage V2.
7. The radio frequency switch according to claim 5, characterized in that: When the driving voltage V1 is at a high level, the first switch branch and the fourth switch branch are turned on, and when the driving voltage V1 is at a low level, the first switch branch and the fourth switch branch are turned off; When the driving voltage V2 is at a high level, the second switch branch and the third switch branch are turned on, and when the driving voltage V2 is at a low level, the second switch branch and the third switch branch are turned off.
8. The radio frequency switch according to claim 1, characterized in that: The gate of the MOS transistor N5 and the gate of the MOS transistor N6 are respectively used to input a negative voltage Vneg.
9. The radio frequency switch according to claim 8, characterized in that: The negative voltage Vneg is input to the gates of the MOS transistor N5 and the MOS transistor N6 through the resistor R5 .
10. A radio frequency chip, characterized in that: The radio frequency chip is provided with a radio frequency switch according to any one of claims 1 to 9.