A high power radio frequency switch for wireless communication

Abstract

The application belongs to the technical field of electronic communication, and discloses a high-power radio frequency switch for wireless communication, which is constructed based on a PIN diode, and a coupling transmission line is used instead of a traditional connection transmission line between a switch input port and a switch output port of the high-power radio frequency switch, mainly, the switch input port is connected with the switch output port, the PIN diode and a short-circuit stub through the coupling transmission line, the PIN diode is connected with an open-circuit stub, one end of one transmission line in the coupling transmission line is connected with the switch input port, the other end of the one transmission line is connected with the PIN diode, one end of the other transmission line is connected with the switch output port, the other end of the other transmission line is connected with the short-circuit stub, and the other ends of the two transmission lines are short-circuited. The radio frequency switch realizes high power, high switching speed and wide bandwidth, meets the application requirement of the radio frequency switch, and expands the application range.

Description

Technical Field

[0001] This invention belongs to the technical field of electronic communication, and specifically relates to a high-power radio frequency switch for wireless communication. Background Technology

[0002] Radio frequency (RF) switches, as core components in modern wireless communication, are widely used in various time-division multiplexing communication terminals and base stations to switch RF paths. These switches typically include uplink and downlink switching within the same communication standard (switching between transmission and reception at the communication terminal) and switching between different communication standards such as GSM, DCS, WCDMA, CDMA, TD-SCDMA, and LTE.

[0003] There are three main methods for implementing radio frequency (RF) switches: The first is relay-based switches, whose switching speed is typically in the microsecond or even millisecond range, failing to meet the short rise and fall time requirements of high-speed wireless communication. The second is electronic RF switches based on bipolar transistors (BPTZs) and field-effect transistors (FETs). Their main advantage is that the switching time is typically in the nanosecond range, meeting the short rise and fall time requirements of high-speed wireless communication. Furthermore, their relative bandwidth can typically reach over 50%. However, limited by the power handling capacity of PN junction RF switches, which is usually no more than 1 W, they are often used in communication applications with low transmission power and short communication distances. The third is PIN diode-based electronic RF switches. Because they are based on a PN junction with an intrinsic layer, the maximum power handling capacity is significantly increased. Moreover, their rise and fall times are typically in the nanometer range, meeting the requirements of high-speed wireless communication. However, PIN diodes exhibit parasitic inductance, capacitance, and resistance at radio frequency, resulting in a relatively narrow bandwidth (typically only around 10%) when using a quarter-impedance transmission line for the switching path. This makes it difficult to meet the bandwidth requirements in many communication applications.

[0004] Technical solution

[0005] This invention provides a radio frequency switch that solves the problem that existing PIN diode-based electronic radio frequency switches have narrow bandwidth and cannot meet the requirements.

[0006] This invention can be achieved through the following technical solutions:

[0007] A high-power radio frequency switch for wireless communication is constructed based on a PIN diode, wherein the connection transmission line between the switch input port and the switch output port is a coupled transmission line.

[0008] Furthermore, the switch input port is connected to the switch output port, the PIN diode, and the short-circuit stub via a coupling transmission line, and the PIN diode is connected to the open-circuit stub.

[0009] Furthermore, one end of one of the coupled transmission lines is connected to the switch input port and the other end is connected to the PIN diode; one end of the other transmission line is connected to the switch output port and the other end is connected to the short-circuit stub; and the other ends of the two transmission lines are short-circuited.

[0010] Furthermore, the coupled transmission line adopts a quarter-wavelength coupled microstrip line structure.

[0011] Furthermore, the switch input port is connected to the first switch output port, the first PIN diode, and the first short-circuit stub via a first coupling transmission line, and the first PIN diode is connected to the first open-circuit stub; the switch input port is also connected to the second switch output port, the second PIN diode, and the second short-circuit stub via a second coupling transmission line, and the second PIN diode is connected to the second open-circuit stub.

[0012] Furthermore, the first short-circuit stub, the second short-circuit stub, the first open-circuit stub, and the second open-circuit stub all adopt a coplanar waveguide structure.

[0013] The beneficial technical effects of this invention are as follows:

[0014] 1. By improving the traditional high-power RF switch based on PIN diodes, a coupled transmission line is used to replace the microstrip transmission line in the traditional high-power RF switch based on PIN diodes. By adopting the proposed circuit topology, the coupling degree of the coupled transmission line can be controlled to further improve the operating bandwidth, reaching more than 5 times the bandwidth of the traditional RF switch. This achieves high power, high switching speed and wide bandwidth, meets the application requirements of RF switches, and expands the application range.

[0015] 2. By changing the short-circuit stub in a traditional PIN diode-based high-power RF switch from a microstrip form to a coplanar waveguide structure, its characteristic impedance can be reduced, thereby further improving its operating bandwidth. At the same time, by changing the open-circuit stub in a traditional PIN diode-based high-power RF switch from a microstrip form to a coplanar waveguide structure, its characteristic impedance can be increased, thereby further improving its operating bandwidth.

[0016] 3. Based on PIN diodes, open and short stubs, and coupled transmission lines, single-pole arbitrary-throw, multi-pole multi-throw, or reconfigurable RF switches can be constructed. Attached Figure Description

[0017] Figure 1 The schematic diagram of the conventional high-power radio frequency switch for wireless communication based on PIN diode is shown in the present invention. It is based on a quarter-wavelength impedance transmission line.

[0018] Figure 2This is a schematic diagram of a high-power radio frequency switch for wireless communication based on a PIN diode, which is implemented using a coupled transmission line.

[0019] Figure 3 The equivalent circuit of the radio frequency path between the switch input port and the switch output port 1 of the present invention is shown in (a), where (b) represents the equivalent circuit of the radio frequency path between the switch input port and the switch output port 1, and (c) represents the equivalent circuit of the radio frequency path between the switch input port and the switch output port 2.

[0020] Figure 4 The equivalent circuits of the PIN diode under forward and reverse bias according to the present invention are shown in (a), which represents the even-mode equivalent circuit of the PIN diode under reverse bias, (b) represents the odd-mode equivalent circuit of the PIN diode under reverse bias, (c) represents the even-mode equivalent circuit of the PIN diode under forward bias, and (d) represents the odd-mode equivalent circuit of the PIN diode under forward bias. Detailed Implementation

[0021] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0022] This invention provides a high-power radio frequency switch for wireless communication, based on a PIN diode. Instead of a traditional connection transmission line, the transmission line connecting the switch input port and output port uses a coupled transmission line. Based on the proposed circuit topology, the switch input port is connected to the switch output port, the PIN diode, and a short-circuit stub via a coupled transmission line. The PIN diode is connected to the open-circuit stub. One end of one transmission line is connected to the switch input port, and the other end is connected to the PIN diode. The other transmission line has one end connected to the switch output port and the other end connected to the short-circuit stub. The other ends of the two transmission lines are shorted. Preferably, the coupled transmission line uses a quarter-wavelength coupled microstrip line structure.

[0023] Furthermore, the RF switch with the above structure can also be made into a single-pole double-throw switch. Specifically, the switch input port is connected to the first switch output port, the first PIN diode, and the first short-circuit stub via a first coupling transmission line. The first PIN diode is connected to the first open-circuit stub. The switch input port is also connected to the second switch output port, the second PIN diode, and the second short-circuit stub via a second coupling transmission line. The second PIN diode is connected to the second open-circuit stub. The first short-circuit stub, the second short-circuit stub, the first open-circuit stub, and the second open-circuit stub all adopt a coplanar waveguide structure. Of course, other RF switch structures can also be made, such as multi-pole multi-throw, single-pole arbitrary-throw, reconfigurable RF switches, etc., and the structure of the coupling transmission line is not limited to a uniform characteristic impedance coupling transmission line, but can also be a stepped characteristic impedance coupling transmission line.

[0024] The following uses a single-pole double-throw switch as an example to illustrate the working process of the radio frequency switch of the present invention.

[0025] To simplify the analysis, we use the attached... Figure 1 , 2 The implementation principle of a high-power single-pole double-throw (SPDF) reconfigurable RF switch is illustrated using the conventional and the present invention's single-pole double-throw (SPDF) switches as examples. In the accompanying drawings, the termination impedance Z0 represents the switch input port and switch output ports 1 and 2. The open-circuit stub with characteristic impedance Z1 and electrical length θ1 is mainly used to compensate for the parasitic inductance of the PIN diode under forward bias and as the positive terminal of the bias voltage. The short-circuit stub with characteristic impedance Z2 and electrical length θ2 is mainly used to compensate for the parasitic capacitance of the PIN diode under reverse bias and as the negative terminal of the bias voltage. The transmission line with an electrical length of 90° serves as the transmission path between the input and switch output ports. (See attached diagram.) Figure 1 and 2 The diagrams show the schematics of a conventional and the present invention, respectively, both based on a PIN diode to achieve high-power single-pole double-throw circuitry. As can be seen from the diagrams, the present invention… Figure 2 A quarter-wavelength coupling transmission line replaces the traditional RF switch. Figure 1 A quarter-wavelength transmission line. Furthermore... Figure 2 The short-circuit stub with characteristic impedance Z2 and electrical length θ2 is replaced by a coplanar waveguide structure. Figure 1 The microstrip line structure is used to achieve a larger characteristic impedance.

[0026] To more clearly illustrate the working principle of the broadband RF switch in this invention, we will analyze it as an example where the path from the RF switch input port to the switch output port 1 is open and the path to the switch output port 2 is closed. In this case, PIN diode 1 is under reverse bias, while PIN diode 2 is under forward bias. Considering that the PIN diodes contain equivalent circuits with parasitic inductance, resistance, and capacitance under both forward and reverse bias conditions, the equivalent circuits of the two RF paths are shown in the attached figures. Figure 3 Figures (a) and (b) are shown in the figure.

[0027] In the appendix Figure 3 In Figure (a), the PIN diode under reverse bias is equivalent to a capacitor C0 and a resistor Rp connected in parallel, and then an inductor L0 cascaded in series. Considering the attached... Figure 3 The equivalent circuit in Figure (a) is a symmetrical structure. We can simplify the analysis using the even / odd mode method. Its even / odd mode equivalent circuits are shown in the appendix. Figure 4 Figures (a) and (b) are shown in the figure.

[0028] Based on parity analysis, its transmission coefficient is:

[0029] (1)

[0030] Where Γ e and Γ o Let be the even-mode and odd-mode reflection coefficients, respectively, which are expressed by the input impedance of the odd and even modes:

[0031] (2)

[0032] In the formula, Z inre and Z inro These represent the even-mode and odd-mode input impedances of the PIN diode under reverse bias, respectively. In even mode, the PIN diode's input admittance Y is mainly compensated for by the characteristic impedance Z2 and the short-circuit stub of the electrical length θ2 within a narrow band. inpin The input impedance Z is close to zero after passing through a transmission line of electrical length. inre The reflection coefficient Γ of the reverse bias even mode is close to 0. e According to formula (2), it is close to -1; while in odd mode, its input impedance is transformed from 0 impedance through a 90-degree transmission line, so it is infinite, thus the odd mode reflection coefficient Γ is reverse biased. o According to formula (2), the value is 1. Therefore, according to formula (1), the transmission coefficient between the input and output ports has a modulus of 1, which means that the input port and output port 1 are connected.

[0033] exist Figure 3 In Figure (b), the PIN diode under reverse bias is equivalent to a series resistor R0 and inductor L0. Similarly, since this equivalent circuit is a symmetrical structure, we can also obtain its even-mode and odd-mode equivalent circuits as shown in the attached figure. Figure 4 As shown in Figures (c) and (d), the PIN diode primarily achieves its input impedance Z within a narrow band after compensation through the open-circuit stub of its characteristic impedance Z1 and electrical length θ1. inpin The input impedance Z is close to zero after passing through a transmission line with an electrical length of 90 degrees. infe Approaching infinity, the forward bias even-mode reflection coefficient Γ is... e The input impedance is close to 1; however, in the odd mode, the input impedance is transformed from zero impedance through a 90-degree transmission line, hence it is infinite, thus positively biasing the odd mode reflection coefficient Γ. o The value is approximately 1. Therefore, according to formula (1), the transmission coefficient between input port and output port 2 has a modulus of 0, which means that input port and output port 2 are disconnected.

[0034] For traditional high-power RF switches based on PIN diodes, the parasitic parameters of the PIN diode forward bias are compensated by a short-circuit stub with characteristic impedance Z2 and electrical length θ2. Since the input impedance at the PIN diode tends to be 0, the infinite input impedance bandwidth at the switch input port after passing through a quarter-wavelength transmission line is very narrow, resulting in a narrow isolation bandwidth and thus a narrow overall switch bandwidth. However, for high-power switches based on coupled transmission lines, although they also compensate for the parasitic parameters of the PIN diode forward bias by a short-circuit stub with characteristic impedance Z2 and electrical length θ2, their total transmission coefficient formula (1) is determined by the difference between the odd and even mode reflection coefficients. The odd and even mode impedance brought by the coupled transmission line eliminates the problem of narrow isolation bandwidth caused by the quarter-wavelength transmission line. The parasitic effects generated by the PIN diode are compensated together by the circuit topology proposed in this invention, expanding the switch bandwidth. Therefore, the high-power switch based on coupled transmission lines has a wide bandwidth. Similarly, we can analyze that the bandwidth in the "conduction" state between the input port and output port 1 is wider when reverse biased.

[0035] The situation where the path from the switch input port to output port 1 is disconnected while the path from the input port to output port 2 is connected is exactly the same as the analysis above, and will not be repeated here.

[0036] In summary, we compensate for the parasitic inductance of the PIN diode under forward bias and the parasitic capacitance under short circuit by controlling the electrical parameters Z1, θ1, Z2, and θ2 of the open-circuit and short-circuit stubs, respectively, and provide the positive and negative terminals of the bias circuit. Based on this, by controlling PIN diode 1 to be reverse biased and PIN diode 2 to be forward biased, we can also achieve conduction from the input port to output port 1 and disconnection from the input port to output port 2. Similarly, by controlling PIN diode 1 to be forward biased and PIN diode 2 to be reverse biased, we can achieve disconnection from the input port to output port 1 and conduction from the input port to output port 2. This demonstrates that replacing the uncoupled transmission line RF path in a traditional switch with a coupled transmission line can also achieve switching functionality. In particular, when the coupled transmission line is used as an RF path, it determines the "on" and "off" states of the RF path by the difference between the odd-mode and even-mode reflection coefficients, which differs from the traditional uncoupled transmission line used as a transmission RF path. This also increases the bandwidth to approximately five times that of the traditional uncoupled transmission line structure. Furthermore, it is easy to prove that by changing the structure of the short-circuited / open-circuited microstrip line to a coplanar waveguide structure, the characteristic impedance of the short-circuited transmission line can be reduced / increased, thereby further increasing the bandwidth.

[0037] While specific embodiments of the present invention have been described above, those skilled in the art should understand that these are merely illustrative examples. Various changes or modifications can be made to these embodiments without departing from the principles and essence of the present invention. Therefore, the scope of protection of the present invention is defined by the appended claims.

Claims

1. A high-power radio frequency switch for wireless communication, characterized in that: Based on PIN diodes, the connection transmission line between the switch input port and the switch output port is a coupled transmission line; The switch input port is connected to the switch output port, the PIN diode, and the short-circuit stub via a coupling transmission line, and the PIN diode is connected to the open-circuit stub. The switch input port is connected to the first switch output port, the first PIN diode, and the first short-circuit stub via a first coupling transmission line, and the first PIN diode is connected to the first open-circuit stub; the switch input port is also connected to the second switch output port, the second PIN diode, and the second short-circuit stub via a second coupling transmission line, and the second PIN diode is connected to the second open-circuit stub. The first short-circuit stub, the second short-circuit stub, the first open-circuit stub, and the second open-circuit stub all adopt a coplanar waveguide structure; One end of the coupling transmission line is connected to the switch input port and the other end is connected to the PIN diode; one end of the other transmission line is connected to the switch output port and the other end is connected to the short-circuit stub; the other ends of the two transmission lines are shorted together. The coupled transmission line adopts a quarter-wavelength coupled microstrip line structure.

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