Dual-pole multi-throw radio frequency switch, control method thereof and radio frequency chip

Abstract

The application discloses a double-pole multi-throw radio frequency switch, a control method thereof and a radio frequency chip. The double-pole multi-throw radio frequency switch comprises a first radio frequency port, a second radio frequency port and three or more antenna ports. Each radio frequency port is connected with the three or more antenna ports in one-to-one correspondence through three or more radio frequency switch channels. A switch device is connected in series on each radio frequency switch channel. A common end is connected in series with each antenna port through a first inductor. The radio frequency switch has a small chip area and improved performance.

Description

Technical Field

[0001] The present application relates to the field of radio frequency technology, and in particular to a double-pole multi-throw radio frequency switch, a control method thereof, and a radio frequency chip. Background Art

[0002] With the in-depth development of modern communication technology, communication equipment is moving towards miniaturization and low power consumption. This requires that each component in the communication equipment adopts a miniaturized design, controlling the device size and thickness as much as possible, while also minimizing the number of components and component power consumption.

[0003] RF signal input and output modules primarily perform low-noise amplification of received RF signals and power amplification of transmitted RF signals, making them an indispensable component of RF communication equipment. RF switches are used in circuits to control the flow of RF signals. For example, a double-pole, double-throw (DPDT) switch can switch the paths between two RF ports and two antennas.

[0004] With the increase in communication needs, electronic devices often have more than two antennas, which requires double-pole multi-throw switches to achieve switching of more paths.

[0005] Please refer to Figure 1 , which is a simplified structural diagram of an existing double-pole multi-throw RF switch.

[0006] The double-pole multi-throw radio frequency switch is connected between port T, port R and multiple antennas. Figure 1 In the figure, a double-pole four-throw switch is taken as an example, which is used to switch the signal paths between ports T, R and ANT1, ANT2, ANT3, and ANT4.

[0007] Among them, port T and port R are connected to each antenna ANT1~ANT4 through four switch arms respectively. On each switch arm, a switch element S and capacitors (not shown in the figure) located on both sides of the switch element are connected in series to isolate DC signals.

[0008] A switch Se: S_Ti is connected in series between port T and ANTi (i = 1, 2, 3, 4); a switch Se: S_Ri is connected in series between port R and ANTi (i = 1, 2, 3, 4), and a switch Sh: S_Ai is connected between antenna ANTi and ground; Sh: S_T is connected between port T and ground, and Sh: S_R is connected between port R and ground.

[0009] For N antennas, existing double-pole multi-throw (DPMT) RF switches have 2N series-connected RF switch elements and N+2 parallel-connected RF switch elements. These switch arms need to withstand the maximum signal output power. The greater the power tolerance, the larger the switch element area. If the RF switch chip used does not have a negative voltage bias, since capacitors are required in series on both sides of each switch, a total of 2*(2N+N+2)=6N+4 capacitors are required, occupying a large chip area and exposing ESD risks to each antenna port. Summary of the Invention

[0010] In view of this, the present application provides a double-pole multi-throw radio frequency switch and its control method, and a radio frequency chip to solve the problem of large area of ​​existing double-pole multi-throw radio frequency switches and improve the performance of the radio frequency switch.

[0011] The present application provides a double-pole multi-throw radio frequency switch, comprising: a first radio frequency port, a second radio frequency port, and three or more antenna ports, each radio frequency port being connected to the three or more antenna ports in a one-to-one correspondence through three or more radio frequency switch paths, each radio frequency switch path being connected in series with a switching device; and a common end, wherein a first inductor is connected in series between the common end and each antenna port.

[0012] Optionally, each RF switch path is sequentially connected in series with a first capacitor, the switch device, and a second capacitor.

[0013] Optionally, each RF switch path may have the same on-resistance and the same off-capacitance.

[0014] Optionally, when there are N antenna ports, N*Coff and N*L1 / (N-1) satisfy the resonance condition, where Coff is the off capacitance of the RF switch path, L1 is the inductance value of the first inductor, and N is an integer greater than or equal to 3.

[0015] Optionally, each RF switch path further includes at least one incremental switch structure connected in parallel to both ends of the switching device, each of the incremental switch structures including: an incremental switch, and two identical incremental tuning capacitors respectively connected in series on both sides of the incremental switch, the incremental switch structure satisfies |Ron'|<|1 / (jωΔC)|, where Ron' is the on-resistance of the incremental switch, ΔC is the capacitance of the incremental tuning capacitor, and ω is the operating frequency of the incremental switch structure.

[0016] Optionally, when there are n different operating frequencies, n-1 incremental switch structures are connected in parallel at both ends of each switching device, where n is a positive integer and n≤N.

[0017] Optionally, the incremental tuning capacitors in different incremental switch structures connected in parallel at both ends of the same switch device have different capacitances; and / or the two incremental tuning capacitors in the same incremental switch structure have the same capacitance.

[0018] Optionally, a second inductor is also connected in series between the common terminal and the ground terminal.

[0019] Optionally, a third capacitor is further included, which is connected in parallel to both ends of the second inductor; the third capacitor and the second inductor form a parallel resonant network.

[0020] The present application provides a radio frequency chip, comprising: a signal transmission link connected to the first radio frequency port; a signal receiving link connected to the second radio frequency port; and a double-pole multi-throw radio frequency switch as described in any one of the above items.

[0021] The present application also provides a control method for a double-pole multi-throw radio frequency switch, the double-pole multi-throw radio frequency switch being as described in any one of claims 1 to 9, wherein an radio frequency switch path L(i, j) is provided between the i-th radio frequency port and the j-th antenna port; wherein i=1, 2; j=1, 2, 3, ..., N; N is an integer greater than or equal to 3; a switching device S(i, j) is connected in series on the radio frequency switch path L(i, j), and the on and off states of the radio frequency switch path L(i, j) are controlled by controlling the on and off states of the switching device S(i, j); the control method comprises: when the radio frequency switch path between the i0-th radio frequency port and the j0-th antenna port is selected, the radio frequency switch paths L(i0, j0) and L(3-i0, j (j≠j0)) are turned on, and other radio frequency switch paths are disconnected.

[0022] Optionally, when an incremental switch structure is connected in parallel at both ends of the switching device S(i, j), when the switching device S(i, j) is disconnected, a corresponding number of incremental switches connected in parallel with the switching device S(i, j) are synchronously turned on according to the operating frequency of the corresponding antenna port, and N*Coff' and N*L1 / (N-1) satisfy the resonance condition, where Coff' refers to the total off-capacitance contributed by all incremental switch structures including the switching device S(i, j) and the switching device S(i, j) connected in parallel on the RF switching path L(i, j); the lower the operating frequency, the more incremental switches are turned on.

[0023] The DPMT switch described in this application saves circuit area and provides high isolation between ports. The parallel connection of an incremental switch structure to the main switch path allows the DPMT switch to be compatible with multiple antennas operating at different frequencies, enabling operation within a more precise frequency range, such as within a sub-channel within the WiFi operating frequency range, to avoid network congestion. A second inductor connected in series between the common terminal and ground also provides an ESD discharge path, improving the reliability of the RF chip. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0025] Figure 1 It is a structural diagram of a double-pole multi-throw radio frequency switch in the prior art;

[0026] Figure 2a 2 is a schematic structural diagram of a double-pole multi-throw radio frequency switch according to an embodiment of the present application;

[0027] Figure 2b 2 is a schematic structural diagram of a double-pole multi-throw radio frequency switch according to an embodiment of the present application;

[0028] Figure 3a 1 is a schematic structural diagram of a radio frequency switch path of a double-pole multi-throw radio frequency switch according to an embodiment of the present application;

[0029] Figure 3b 1 is a schematic structural diagram of a radio frequency switch path of a double-pole multi-throw radio frequency switch according to an embodiment of the present application;

[0030] Figure 4 1 is a schematic diagram of an equivalent circuit of a double-pole multi-throw radio frequency switch according to an embodiment of the present application when a signal is transmitted between the first radio frequency port T and the antenna port ANT1;

[0031] Figure 5 1 is a schematic structural diagram of a radio frequency switch path of a double-pole multi-throw radio frequency switch according to an embodiment of the present application;

[0032] Figure 6 1 is a structural diagram of a radio frequency switch path of a double-pole multi-throw radio frequency switch according to an embodiment of the present application. DETAILED DESCRIPTION

[0033] The following is a clear and complete description of the technical solutions in the embodiments of the present application in conjunction with the accompanying drawings. Obviously, the embodiments described are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of this application. In the absence of conflict, the following embodiments and their technical features can be combined with each other.

[0034] Please refer to Figure 2a and 2b , is a schematic structural diagram of a double-pole multi-throw radio frequency switch according to an embodiment of the present invention.

[0035] The double-pole multi-throw RF switch includes a first RF port T, a second RF port R, and more than three antenna ports, each RF port is connected to the more than three antenna ports in a one-to-one correspondence through more than three RF switch paths; a common terminal P, and a first inductor L1 is connected in series between the common terminal P and each antenna port.

[0036] Figure 2a and 2b , N antenna ports are shown, namely antenna port ANT1, antenna port ANT2, ..., antenna port ANTN, for connecting to corresponding antennas, where N is an integer greater than or equal to 3. The first RF port T is connected to each antenna port via N RF switch paths, and the second RF port R is also connected to each antenna port via N RF switch paths. Therefore, the double-pole multi-throw RF switch has a total of 2N switch paths.

[0037] For example, an RF switch path L11 is connected between the first RF port T and the antenna port ANT1, an RF switch path L12 is connected between the first RF port T and the antenna port ANT2, and an RF switch path L1N is connected between the first RF port T and the antenna port ANTN.

[0038] Similarly, an RF switch path L21 is connected between the second RF port R and the antenna port ANT1, an RF switch path L22 is connected between the second RF port R and the antenna port ANT2, and an RF switch path L2N is connected between the second RF port R and the antenna port ANTN.

[0039] In summary, there is a radio frequency switch path L(i, j) between the i-th radio frequency port and the j-th antenna port; wherein i=1, 2; j=1, 2, 3, ..., N; and N is an integer greater than or equal to 3.

[0040] Each RF switch path is connected in series with a switching device, which controls the on and off states of the RF switch path. Specifically, the RF switch path L(i, j) is connected in series with a switching device S(i, j). The switching device is a switching transistor suitable for use in RF circuits, such as PMOS, NMOS, HEMT, or LDMOS.

[0041] A common terminal P, wherein a first inductor L1 is connected in series between the common terminal P and each antenna port. The common terminal P can be a single electrical connection terminal or multiple electrically connected electrical connection terminals P. That is, in an actual circuit, the common terminal P can be a single electrical contact point on the chip or multiple interconnected contact points.

[0042] In this embodiment, a second inductor L2 is also connected in series between the common terminal P and the ground terminal to serve as an ESD current discharge path between the common terminal and the ground. The second inductor L2 is generally selected to have an inductance value significantly greater than that of the first inductor L1. This ensures that the ESD discharge path requirements are met while minimizing the impact of the second inductor L2 on the RF resonance conditions.

[0043] In other embodiments (such as Figure 2b As shown in FIG5 , when the chip size does not allow or other circumstances prevent the second inductor L2 from achieving L2>>L1, a third capacitor C3 may be connected in parallel across the second inductor L2 to form a parallel resonant network with the third capacitor C3 and the second inductor L2 for parallel resonance, thus satisfying: In this way, the common terminal P can still achieve AC isolation, no RF loss, and will not affect the resonance conditions of other parts.

[0044] In other embodiments, if the ESD problem is not significant, it is not necessary to connect the second inductor L2 in series between the common terminal and the ground terminal.

[0045] Please refer to Figure 3a , is a structural diagram of a radio frequency switch path L(i, j) according to an embodiment of the present invention.

[0046] In this embodiment, the RF switch path L(i, j) is connected in series with an NMOS transistor as the switch device S(i, j). In other embodiments, the switch device may also be a PMOS tube or other types of transistors.

[0047] Please refer to Figure 3b , is a structural diagram of a radio frequency switch path L(i, j) according to another embodiment of the present invention.

[0048] In this embodiment, the RF switch path L(i, j) is based on an NMOS transistor as a switch device S(i, j), and the source and drain sides of the NMOS transistor are respectively connected in series with a first capacitor C1 and a second capacitor C2.

[0049] The first capacitor C1 and the second capacitor C2 are DC blocking capacitors. The first capacitor C1 and the second capacitor C2 are large enough so that they can be considered as an AC short circuit (AC short) state at the operating frequency used by the RF switch.

[0050] Figure 3a and Figure 3b In the embodiment shown, the on-off state of the switching device S(i, j) is controlled by controlling the voltage difference between the gate G and the drain D and the source S of the switching device S(i, j), thereby controlling the on-off state of the RF switch path L(i, j).

[0051] In some embodiments, a control voltage can be provided for the control of the switch device S(i, j) by a charge pump or other structure, and the gate voltage can be controlled to be below the turn-off voltage. For example, when the switch device S(i, j) is an NMOS transistor, the gate voltage can be controlled to be less than 0V to ensure that the switch device S(i, j) is in the off state. Figure 3a The structure of the radio frequency switch path L(i, j) eliminates the need for connecting DC blocking capacitors in series at both ends of the switch device S(i, j), thereby reducing the chip area.

[0052] In some embodiments, the gate voltage range of the switching device is limited, preferably Figure 3b The structure shown serves as a radio frequency switch path to ensure that the on and off states of the radio frequency switch path are stable.

[0053] In some embodiments, the operating frequencies of the N antenna ports may all have the same operating frequency. At this time, the on-resistance and off-capacitance of each RF switch path L(i, j) are the same, and the resonance condition is met. Since the first capacitor C1 and the second capacitor C2 are equivalent to short circuits for AC signals, regardless of whether there is a DC blocking capacitor on the RF switch path, the on-resistance on each RF switch path can be equivalent to the on-resistance Ron of the switch device S(i, j), and the off-capacitance can also be equivalent to the off-capacitance Coff of the switch device S(i, j). When the operating frequencies of the antenna ports are the same, the parameters of the switch device S(i, j) and other devices (if any) of each RF switch path are the same to ensure that the on-resistance and off-capacitance of each RF switch path are the same.

[0054] When the double-pole multi-throw switch is working, if the RF switch path between the i0th RF port and the j0th antenna port is selected, the RF switch paths L(i0, j0) and L(3-i0, j(j≠j0)) are turned on, and other RF switch paths are disconnected, that is, the switching devices S(i0, j0) and S(3-i0, j(j≠j0)) are turned on.

[0055] If i0=1, j0=1, N=4, then the switching devices S(1,1), S(2,2), S(2,3), and S(2,4) are turned on, and S(1,2), S(1,3), S(1,4), and S(2,1) are turned off.

[0056] If i0=2, j0=3, and N=4, then the switching devices S(2,3), S(1,1), S(1,2), and S(1,4) are turned on, and S(2,1), S(2,2), S(2,4), and S(1,3) are turned off.

[0057] For specific switching logic, please refer to the table below ("1" means on; "0" means off)

[0058] model S(1,1) S(1,2) S(1,3) S(1,4) S(2,1) S(2,2) S(2,3) S(2,4) T(1)-ANT1 1 0 0 0 0 1 1 1 R(2)-ANT3 1 1 0 1 0 0 1 0

[0059] If the operating frequency of each antenna port is f, when any path is enabled, N RF switch paths are disconnected, and each disconnected RF switch path provides an off-capacitor Coff. In addition to the enabled RF path, N-1 paths are enabled and connected to the common terminal P through the first inductor L1, thus forming a resonant network. N*Coff and N*L1 / (N-1) meet the resonance condition, where Coff is the off-capacitor of the RF switch path, L1 is the inductance of the first inductor, and N is an integer greater than or equal to 3.

[0060] In the absence of the second inductor L2, or when the influence of the second inductor L2 on the resonance is negligible, the resonance condition includes:

[0061] The above structure can generate parallel resonance at the operating frequency used by the double-pole multi-throw radio frequency switch, thereby improving the isolation between the ports and reducing the insertion loss in the radio frequency switch path.

[0062] Please refer to Figure 4 , is a schematic diagram of an equivalent circuit with four antenna ports, with the first RF port T and the first antenna port ANT1 selected. The first RF port T is the transmitter, connected to the signal transmission link TX, and the second RF port R is the receiver, connected to the signal reception link RX.

[0063] The impedance of each conducting switch device in the circuit is very small, which is equivalent to a short circuit. The off-capacitor Coff of each switch forms a resonant network with the first inductor L1. The circuit meets the following resonance conditions: N = 4,

[0064] In actual circuit design, the general design is to first select the size of the switch device S, that is, first determine the parameters of the switch device S such as the off capacitance Coff and the on resistance Ron, and then select the inductance value of the first inductor L1 according to the above resonance condition.

[0065] Please refer to Figure 5 , is a structural diagram of a radio frequency switch path according to another embodiment of the present invention.

[0066] The RF switch path also includes at least one incremental switch structure connected in parallel across the switch device S(i, j). Each incremental switch structure includes an incremental switch S' and two identical incremental tuning capacitors C' connected in series on either side of the incremental switch. The incremental switch structure satisfies |Ron'|<|1 / (jωΔC)|, where Ron' is the on-resistance of the incremental switch, ΔC is the capacitance of the incremental tuning capacitor, and ω is the operating frequency of the incremental switch structure.

[0067] In this embodiment, the double-pole multi-throw RF switch has N antenna ports, and each antenna port corresponds to a different operating frequency, that is, it has N operating frequencies, and the switching device S (i, j) of each RF switch path is connected in parallel with (N-1) groups of incremental switch structures, and the (N-1) groups of incremental switch structures are connected in parallel with each other (such as Figure 5 For example, when there are three antenna ports corresponding to three operating frequencies, two sets of incremental switch structures are connected in parallel at both ends of the switch device of each RF switch path.

[0068] In other embodiments, if there are N antenna ports, but some of the antenna ports correspond to the same operating frequency, the number of incremental switch structures can be appropriately reduced. When there are n (n ≤ N) different operating frequencies, each switch device is connected in parallel with n-1 incremental switch structures, where n is a positive integer.

[0069] Each group of incremental switch structures has the same circuit structure, including an incremental tuning capacitor C', an incremental switch S', and another incremental tuning capacitor C' connected in series. The kth group of incremental switch structures includes a tuning capacitor Ck', an incremental switch Sk', and another incremental tuning capacitor Ck', where k is a positive integer less than or equal to the total number of incremental switch structures.

[0070] Preferably, the incremental switch and the switching device are the same type of switching transistors. In other embodiments, the incremental switch and the switching device may also use different types of switching transistors.

[0071] The value of the incremental tuning capacitor within each incremental switch structure can be set based on the resonance condition. In some embodiments, two incremental tuning capacitors within the same incremental switch structure have the same capacitance. In some embodiments, different incremental switch structures connected in parallel to the same switch device can have incremental tuning capacitors with different capacitances.

[0072] Figure 5 The structure shown can be applied when different antenna ports have different operating frequencies. When the switch device S(i, j) is turned off, the corresponding number of incremental switches connected in parallel with the switch device S(i, j) are synchronously turned on according to the operating frequency of the corresponding antenna port ANTj, as long as the resonance conditions N*Coff' and N*L1 / (N-1) are still met. Here, Coff' refers to the total off-capacitance contributed by S(i, j) and all incremental switch structures connected in parallel on the RF switch path L(i, j). The lower the operating frequency, the greater the number of incremental switches turned on. By fine-tuning the shutdown circuit on the switch path through the incremental switch structure, the double-pole multi-throw switch can support antennas with multiple frequencies.

[0073] Please refer to Figure 6 , which is a schematic diagram of the RF switch path of a double-pole, multi-throw RF switch structure according to another embodiment of the present invention. In this embodiment, a first capacitor C1 and a second capacitor C2 are connected in series at both ends of the switch device S(i, j). The two ends of the incremental switch structure are connected to the connection path between the switch device S(i, j) and the first capacitor C1, and the connection path between the switch device S(i, j) and the second capacitor C2, respectively.

[0074] The following describes the working principles of different antenna ports operating at different frequencies for the double-pole multi-throw RF switch structure.

[0075] For N antenna ports, there are at most N different frequencies, denoted as f1, f2, ..., fN. For the transmission between the N antenna ports ANT and the two RF ports, 2N design constraint equations can be written.

[0076] Below, N=3 is used as an example for explanation. If only the off capacitance Coff of the switching device S(i, j) on each path is considered, under different selection paths, six equations can be listed, where Coff is denoted as C and S(i, j) is abbreviated as Sij. The symbol Sij also represents the off capacitance parameter of the corresponding switching device.

[0077] (1) T is gated with ANT1 (switch devices S12, S13, S21 are off): S12 + S13 + S21 = 3C = K1(f1);

[0078] (2) T is gated with ANT2 (switch devices S11, S13, S22 are off): S11 + S13 + S22 = 3C = K2(f2);

[0079] (3) T is gated with ANT3 (switch devices S11, S12, S23 are off): S11 + S12 + S23 = 3C = K3(f3);

[0080] (4) R is gated with ANT1 (switch devices S22, S23, S11 are off): S22 + S23 + S11 = 3C = K1(f1);

[0081] (5) R is gated with ANT2 (switch devices S21, S23, S12 are off): S21 + S23 + S12 = 3C = K2(f2);

[0082] (6) R is gated with ANT3 (switch devices S21, S22, S13 are off): S21 + S22 + S13 = 3C = K3(f3).

[0083] Where, Ki is a constant that satisfies resonance at the frequency fi, ω i = 2πfi. Obviously, the same C cannot satisfy three different equations.

[0084] In the case where different antenna ports have different operating frequencies, without loss of generality, we assume that f1 < f2 < f3, then K1 > K2 > K3. At the same time, for different frequencies, the corresponding number of incremental switches is turned on. For the three antenna ports, each RF switch path has 2 groups of incremental switch structures in parallel for the switch devices. For the 3 different operating frequencies, from small to large, they correspond to turning on 2, 1, and 0 respectively. Considering the influence of the incremental tuning capacitors in the turned-on incremental switch structures on the resonance conditions, the following equations can be further constructed:

[0085] (1) T is gated with ANT1: 3(C + ΔC1 + ΔC2) = K1; corresponding to both of the two incremental switches on the paths where S12, S13, and S21 are located being turned on; obviously here ΔC1 = C1' / 2, ΔC2 = C2' / 2, and C1', C2' are the capacitance values of the corresponding capacitors as shown in Figure 5 、 Figure 6 ;

[0086] (2) T and ANT2 are selected: 3(C+ΔC1)=K2; this corresponds to one of the two incremental switches in the path where S11, S13, and S22 are located being turned on;

[0087] (3) T and ANT3 are selected: 3C = K3; the two incremental switches on the path where S11, S12, and S23 are located are all disconnected;

[0088] (4) R and ANT1 are selected: 3(C+ΔC1+ΔC2)=K1; this corresponds to the two incremental switches in the path where S22, S23, and S11 are all turned on;

[0089] (5) R and ANT2 are selected: (C + ΔC1) = K2; this corresponds to one of the two incremental switches in the path where S21, S23, and S12 are located being turned on;

[0090] (6) R and ANT3 are selected: 3(C) = K3; the two incremental switches on the path where S21, S22, and S13 are located are all disconnected.

[0091] In this way, the resonance condition parameters of each device can be obtained through the above 6 equations.

[0092] In one embodiment, the calculation is performed using f1 = 2.3 GHz, f2 = 2.5 GHz, and f3 = 2.7 GHz as an example. For example, an RF switch manufacturing process (SOI / CMOS process) can achieve Ron*Coff = 200 fs. When Ron = 1 Ω, Coff = C = 0.2 pF.

[0093] Since K3 = 3*C = 0.6pF is the smallest (corresponding to the highest frequency f3), the third equation K3 shows that L = 2 / (9C*ω3 2 ) = 3.86nH. And K2 = 0.7pF, then C1' = 2ΔC1 = 67fF. Similarly, if K1 = 0.83pF, then C2' = 2ΔC2 = 87fF. It can be seen that these incremental tuning capacitors C1' and C2' are very small.

[0094] Similarly, because the incremental tuning capacitors are small, they occupy a small chip area, and the reactance of the paths is also high. Therefore, the on-resistance of the RF switches (i.e., the incremental switches) that conduct these incremental switching paths does not need to be very low, and the size of the incremental switches can be minimized. Because the incremental tuning capacitors and the incremental switches can both be designed to be very small, even with the addition of the incremental switch structure, the impact on the overall chip area is still minimal.

[0095] In the actual design process, since the insertion loss of the path is a very important performance parameter, the size of the main switch of the RF switch path, namely the switch device S(i, j) (corresponding to the on-resistance Ron), is the primary design target. Since Ron*Coff is a fixed value in the semiconductor manufacturing process, when Ron is determined, Coff is also a fixed value. After the size of the switch device S(i, j) is designed, the value of the first inductor L1 can be adjusted according to the off-capacitance Coff of the switch device S(i, j) and the maximum operating frequency of the path to meet the resonant condition.

[0096] Since the off-capacitor Coff completely and independently determines the size of the RF switch, by appropriately adjusting the value of the first inductor L1, all parameter designs of the double-pole multi-throw RF switch described in the above embodiment can be completed: that is, the off-capacitor Coff (C) of the switching device S(i, j), the capacitance ΔCi of the incremental tuning capacitor, and the first inductor L1 are designed.

[0097] An embodiment of the present invention further provides a radio frequency chip, comprising: a double-pole multi-throw radio frequency switch as described in any of the above embodiments; a signal transmission link connected to the first radio frequency port; and a signal receiving link connected to the second radio frequency port.

[0098] An embodiment of the present invention also provides a control method for the double-pole multi-throw radio frequency switch described in the above embodiment, wherein a radio frequency switch path L(i, j) is provided between the i-th radio frequency port and the j-th antenna port of the double-pole multi-throw radio frequency switch; wherein i=1, 2; j=1, 2, 3, ..., N; N is an integer greater than or equal to 3; a switching device S(i, j) is connected in series on the radio frequency switch path L(i, j), and the on and off states of the switching device S(i, j) are controlled to control the on and off states of the radio frequency switch path L(i, j); the control method includes: when the radio frequency switch path between the i0-th radio frequency port and the j0-th antenna port is selected, the radio frequency switch paths L(i0, j0) and L(3-i0, j (j≠j0)) are turned on, and other radio frequency switch paths are disconnected.

[0099] When multiple incremental switch structures are connected in parallel at both ends of the switching device S(i, j), when the switching device S(i, j) is turned off, the corresponding number of incremental switches connected in parallel with the switching device S(i, j) are synchronously turned on according to the operating frequency of the corresponding antenna port, as long as N*Coff' and N*L1 / (N-1) still meet the resonance conditions. Here, Coff' refers to the total off-capacitance contributed by S(i, j) and all the incremental switch structures connected in parallel on the RF switch path L(i, j). The lower the operating frequency, the more incremental switches are turned on.

[0100] The above-mentioned specific control methods and principles have been specifically described in the above-mentioned embodiments and will not be repeated here.

[0101] The double-pole multi-throw switch described in the above embodiment can save circuit area, and has high isolation between the ports. In addition, an incremental switch structure is connected in parallel on the main switch path, so that the double-pole multi-throw switch can be applied to multiple antennas with different operating frequencies, and can operate within a more precise frequency range to avoid network congestion.

[0102] The above description is merely an embodiment of the present application and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the description and drawings of this application, such as the mutual combination of technical features between the embodiments, or direct or indirect application in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A double-pole multi-throw radio frequency switch, characterized in that: include: A first RF port, a second RF port, and three or more antenna ports, each RF port being connected to the three or more antenna ports in a one-to-one correspondence via three or more RF switch paths, and each RF switch path being connected in series with a switch device; A common terminal, wherein a first inductor is connected in series between the common terminal and each antenna port, and a second inductor is also connected in series between the common terminal and the ground terminal; Each RF switch path further includes at least one incremental switch structure connected in parallel to both ends of the switching device. Each incremental switch structure includes: an incremental switch, and two identical incremental tuning capacitors connected in series on both sides of the incremental switch. The incremental switch structure satisfies |Ron'| <|1 / (jωΔC)|, where Ron' is the on-resistance of the incremental switch, ΔC is the capacitance of the incremental tuning capacitor, and ω is the operating frequency of the incremental switch structure.

2. The double-pole multi-throw radio frequency switch according to claim 1, characterized in that: Each RF switch path is connected in series with a first capacitor, the switch device and a second capacitor.

3. The double-pole multi-throw radio frequency switch according to claim 1, characterized in that: It also includes the same on-resistance and off-capacitance for each RF switch path.

4. The double-pole multi-throw radio frequency switch according to claim 1, wherein: When there are N antenna ports, N*Coff and N*L1 / (N-1) satisfy the resonance condition, where Coff is the off capacitance of the RF switch path, L1 is the inductance value of the first inductor, and N is an integer greater than or equal to 3.

5. The double-pole multi-throw radio frequency switch according to claim 1, characterized in that: When there are n different operating frequencies, n-1 incremental switch structures are connected in parallel at both ends of each switching device, where n is a positive integer and n≤N.

6. The double-pole multi-throw radio frequency switch according to claim 1, characterized in that: The incremental tuning capacitors in different incremental switch structures connected in parallel at both ends of the same switch device have different capacitance values; and / or the two incremental tuning capacitors in the same incremental switch structure have the same capacitance value.

7. The double-pole multi-throw radio frequency switch according to claim 1, characterized in that: It also includes a third capacitor connected in parallel to both ends of the second inductor; the third capacitor and the second inductor form a parallel resonant network.

8. A radio frequency chip, characterized in that: include: The double-pole multi-throw radio frequency switch according to any one of claims 1 to 7; a signal transmission link connected to the first RF port; A signal receiving link is connected to the second RF port.

9. A control method for a double-pole multi-throw radio frequency switch, characterized in that: The double-pole multi-throw radio frequency switch is according to any one of claims 1 to 7, wherein a radio frequency switch path L(i, j) is provided between the i-th radio frequency port and the j-th antenna port; wherein i=1, 2; j=1, 2, 3, ..., N; and N is an integer greater than or equal to 3; a switch device S(i, j) is connected in series to the radio frequency switch path L(i, j), and the on and off states of the radio frequency switch path L(i, j) are controlled by controlling the on and off states of the switch device S(i, j); and the control method comprises: When the RF switch path between the i0th RF port and the j0th antenna port is enabled, the RF switch paths L(i0, j0) and L(3-i0, j (j≠j0)) are turned on, and the other RF switch paths are turned off.

10. The control method according to claim 9, characterized in that: When an incremental switch structure is connected in parallel at both ends of the switching device S(i, j), when the switching device S(i, j) is disconnected, the corresponding number of incremental switches connected in parallel with the switching device S(i, j) are synchronously turned on according to the operating frequency of the corresponding antenna port, and N*Coff' and N*L1 / (N-1) meet the resonance condition, where Coff' refers to the total off-capacitance contributed by all incremental switch structures including the switching device S(i, j) and the switching device S(i, j) connected in parallel on the RF switch path L(i, j); the lower the operating frequency, the more incremental switches are turned on.

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