CN203151433U - Double-frequency synchronous power amplifier based on T-type network and coupling line - Google Patents

Abstract

The utility model discloses a double-frequency synchronous power amplifier based on T-type network and a coupling line, which belongs to power amplifier design field of wireless communication technology. The double-frequency synchronous power amplifier based on the T-type network and the coupling line is provided with a double-path or multi-path double-frequency Doherty power amplifier. A double-frequency main power amplifier and a double-frequency auxiliary power amplifier are connected with a double-frequency double-path power amplifier+90 DEG phase difference output power divider module. A double-frequency directional coupler or double-frequency double-path powder divider+90 DEG phase difference output power divider module is connected with the input end. The double-frequency main power amplifier and the double-frequency auxiliary power amplifier are respectively connected with a main double-frequency delay line and an auxiliary double-frequency delay line. The double-frequency synchronous power amplifier can operate on two random frequency bands in a double-frequency synchronous mode, and efficiency increase can be realized on different frequency bands. The performance of the double-frequency Doherty on single frequency band is same with that of the traditional Doherty power amplifier. The efficiency of the small power area can be improved, and high efficiency is kept in a large power area.

Description

A dual-frequency synchronous power amplifier based on T-shaped network and coupled lines

technical field

The utility model belongs to the field of power amplifier design of wireless communication technology. In particular, it relates to a dual-frequency synchronous power amplifier based on a T-shaped network and a coupling line. In particular, it is a dual-band synchronous power amplifier used in the final radio frequency output of a multi-band, high-efficiency mobile communication base station. the

Background technique

In order to realize the new concept of "green" communication, high-efficiency power amplifiers are receiving more and more attention and attention. Several techniques are currently available to achieve high efficiency. Some working modes such as Class E and Class F power amplifiers can achieve very high drain efficiency, and ideally reach 100% drain efficiency, but the disadvantage of this type of power amplifier is that its linearity is relatively poor. The Doherty (Doherty) structure power amplifier has both higher efficiency (compared to class AB amplifier) and better linearity (compared to class C amplifier), and has been widely used in wireless communication base stations. However, due to its structural characteristics, the bandwidth is limited and cannot meet the requirements of broadband systems. The basic principle of the Doherty circuit is to separately amplify the average part and the peak part of the input signal, and then synthesize them to obtain high efficiency. Due to the active load-pulling characteristics of the Doherty structure, the power amplifier can guarantee higher efficiency within a certain power back-off range, and meet the amplification requirements of modulation signals with different peak-to-average ratios. The combination of digital pre-distortion technology and Doherty power amplifier can realize high efficiency and high linearity power amplifier. the

With the development of technology, the future mobile communication system needs to support different standards at the same time, which requires the base station transmitter terminal to be able to process signals of different frequencies at the same time, so power amplifiers working in multiple frequency bands will be widely used. In order to realize multi-band work, some methods of designing power amplifiers have been proposed. Among them, there is a type of power amplifier that uses parallel power amplifiers to achieve multi-frequency work. Each power amplifier is adjusted to the best working state of a single frequency. When necessary, use a switch to select a suitable power amplifier to process signals of different frequencies. The design method of this type of power amplifier is simple, but the cost is very high, and it cannot process multi-frequency signals at the same time. Another type of power amplifier uses a reconfigurable load network to achieve multi-frequency operation. The load network of this type of power amplifier contains some adjustable components, such as micro-electromechanical systems, variable capacitance diodes, etc., and these components are controlled by voltage to change the parameters of the load network. , so that it can achieve the best working condition at a certain frequency. The voltage control of this type of power amplifier is more difficult, and it cannot handle multi-frequency signals at the same time. The third type of power amplifier uses a multi-frequency band-pass network to achieve multi-frequency work. The design of this type of power amplifier is relatively complicated, and the advantage is that it can process multi-frequency signals at the same time. the

The traditional Doherty power amplifier consists of a power divider plus a quarter-wavelength transmission line, a main power amplifier, an auxiliary power amplifier, two delay lines, and a quarter-wavelength transmission line, because these components can only work at one frequency Therefore, the traditional Doherty power amplifier can only work in a single frequency band. the

At present, based on some dual-frequency structures, some passive devices can realize dual-frequency synchronous operation. In some articles, a T-type network is used to implement a dual-band directional coupler. This directional coupler has the same structure as a traditional directional coupler. The difference is that each quarter-wavelength transmission line is T-network instead. This T-network consists of two series transmission lines and a branch line placed in the middle. The branch line can be shorted to ground or open. This directional coupler can divide the input power equally to two output ports and add a 90° phase difference at any two different frequencies. In some articles, coupled lines are used to realize dual-frequency Wilkinson (Wilkinson) power dividers, and the coupled lines can be single-section or double-section. The function of the coupled line is to replace the quarter-wavelength transmission line in the traditional Wilkinson power splitter, and it shows a quarter-wavelength phase delay characteristic at two different frequencies. The characteristic of using a T-shaped network is that its frequency ratio can be made very large. The disadvantage is that its size is relatively large. When the frequency ratio is relatively large, the branch line may be very thin (open end) or thick (short circuit at the end). The characteristic of the coupled line is that the size is relatively small, and the disadvantage is that its frequency ratio range is small. When the parameters are set correctly, the T-type network or the coupled line can be equivalent to a dual-frequency transmission line.

Utility model content

The purpose of this utility model is to provide a kind of dual-frequency synchronous power amplifier based on T-type network and coupling line for the deficiencies in the prior art, it is characterized in that, the dual-frequency synchronous power amplifier based on T-type network and coupling line has Dual-channel or multi-channel dual-frequency Doherty power amplifier, including two structures: one is a dual-frequency main power amplifier and a dual-frequency auxiliary power amplifier connected to the dual-frequency dual-channel power splitter plus 90° phase difference output power splitter module ;Dual-frequency directional coupler or dual-frequency dual-channel power divider plus 90° phase difference output power divider module is connected to the input terminal, and the dual-frequency main power amplifier and dual-frequency auxiliary power amplifier are respectively connected to the main dual-frequency delay line and auxiliary dual-frequency Delay line connection, the main dual-frequency delay line is connected to the first dual-frequency quarter-wavelength transmission line, and the first dual-frequency quarter-wavelength transmission line is connected to the auxiliary dual-frequency delay line and the second dual-frequency quarter-wavelength transmission line The transmission lines are connected together, and the second section of the dual-frequency quarter-wavelength transmission line is connected to the output end; the other is a dual-frequency main power amplifier and the first dual-frequency auxiliary power amplifier to the Nth dual-frequency auxiliary power amplifier. The splitter plus 90° phase difference output power splitter module is connected; the dual-frequency main power amplifier is connected to the main dual-frequency delay line, the main dual-frequency delay line is connected to the first dual-frequency quarter-wavelength transmission line, and the first dual-frequency The auxiliary power amplifier to the Nth dual-frequency auxiliary power amplifier are correspondingly connected to the first dual-frequency delay line to the Nth dual-frequency delay line, and the common node of the first dual-frequency delay line to the Nth dual-frequency delay line is connected to the first dual-frequency four The quarter-wavelength transmission line is connected to the common node of the second section of the dual-frequency quarter-wavelength transmission line, and the second section of the dual-frequency quarter-wavelength transmission line is connected to the output end. the

The N is 1-20. the

The characteristic impedance of the first dual-frequency quarter-wavelength transmission line is 50Ω, and the characteristic impedance of the second dual-frequency quarter-wavelength transmission line is 35Ω. the

的特性阻抗，左右两段双频四分之一波长传输线具有50Ω的特性阻抗；上段双频四分之一波长传输线两端连接输入、输出端口；左右两段分别与上下两段连接，四段双频四分之一波长传输线组成一个回路； 双频Wilkinson功分器由三段双频四分之一波长传输线组成，其中，由两个双频四分之一波长传输线和一个100Ω电阻构成，两个双频四分之一波长传输线具有等效

的特性阻抗和一个50Ω的特性阻抗的四分之一波长传输线等效电长度。  The T-based network and coupling line include a quarter-wavelength transmission line for dual-frequency operation and a delay line for dual-frequency operation; the T-type network is composed of a dual-frequency quarter-wavelength transmission line, and is connected in series on the signal transmission path; wherein , the dual-frequency directional coupler consists of four dual-frequency quarter-wavelength transmission lines, in which the upper and lower dual-frequency quarter-wavelength transmission lines have

The characteristic impedance of the two-section dual-frequency quarter-wavelength transmission line on the left and right has a characteristic impedance of 50Ω; the two ends of the dual-frequency quarter-wavelength transmission line on the upper section are connected to the input and output ports; the left and right sections are respectively connected to the upper and lower sections, and the four sections The dual-frequency quarter-wavelength transmission lines form a loop; the dual-frequency Wilkinson power splitter is composed of three dual-frequency quarter-wavelength transmission lines, among which, it consists of two dual-frequency quarter-wavelength transmission lines and a 100Ω resistor. Two dual-frequency quarter-wavelength transmission lines with equivalent

The characteristic impedance and the equivalent electrical length of a quarter-wavelength transmission line with a characteristic impedance of 50Ω.

The coupled line is a single-section coupled line or a two-section coupled line. the

的特性阻抗，左右两个T型网络具有50Ω的特性阻抗，四个T型网络在两个频率上的等效电长度均为四分之一波长，双频Wilkinson功分器由两个耦合线和一个100Ω电阻构成，两个耦合线具有等效的特性阻抗和四分之一波长的等效电长度；双频主功放和辅助功放具有相同的拓扑结构，其负载网络由一个T型网络和一段并联开路线组成，能够在两个频率将标准负载变换到所需阻抗，输入网络是一个pi型网络，能够实现两个频率上的共轭匹配；双频四分之一波长传输线或延迟线可以用T型网络或者耦合线等效，其中T型网络中的分支线可以是短路或者开路线，耦合线可以使用单节或者双节的耦合线。  The dual-frequency Doherty power amplifier includes a dual-frequency directional coupler or a dual-frequency directional coupler or a dual-frequency dual-way power divider plus a 90° phase difference output power divider module, a dual-frequency main power amplifier, and a dual-frequency auxiliary power amplifier , Two sections of dual-frequency delay lines, two sections of dual-frequency quarter-wavelength impedance transformation lines with characteristic impedances of 50Ω and 35Ω respectively; among them, the dual-frequency directional coupler is composed of 4 T-shaped networks, of which the upper and lower two T-shaped network has the equivalent of

The characteristic impedance of the two T-type networks on the left and right has a characteristic impedance of 50Ω, and the equivalent electrical length of the four T-type networks at two frequencies is a quarter of a wavelength. The dual-frequency Wilkinson power splitter consists of two coupling lines and a 100Ω resistor, the two coupled lines have equivalent The characteristic impedance and the equivalent electrical length of a quarter wavelength; the dual-frequency main power amplifier and auxiliary power amplifier have the same topology, and its load network consists of a T-type network and a parallel open line, which can connect the standard at two frequencies The load is converted to the required impedance, and the input network is a pi-type network, which can realize conjugate matching on two frequencies; the dual-frequency quarter-wavelength transmission line or delay line can be equivalent to a T-type network or a coupled line, where T The branch line in the type network can be a short circuit or an open line, and the coupled line can use a single-section or double-section coupling line.

The dual-frequency quarter-wavelength transmission line or the dual-frequency delay line is a single-section coupled line, a double-section coupled line, a T-type network with a short-circuit branch line, or a T-type network with an open-circuit branch line. the

The dual-frequency power divider plus a 90° phase difference output module is realized by a dual-frequency directional coupler, or a dual-frequency Wilkinson power divider plus a dual-frequency quarter-wavelength transmission line; the dual-frequency directional coupler and the dual-frequency Wei The Wilkinson power divider is composed of a dual-frequency quarter-wavelength transmission line. the

The beneficial effect of the utility model is that the power amplifier can work on any two frequency bands at the same time, and the dual-frequency Doherty power amplifier of the present invention can process signals of two different frequencies at the same time, and the efficiency can be improved in different frequency bands. The performance of dual-band Doherty in a single frequency band is the same as that of traditional Doherty power amplifiers. It can improve the efficiency in low-power areas and maintain high efficiency in high-power areas. When amplifying signals with a relatively large peak-to-average ratio, the efficiency of the power amplifier is much higher than that of ordinary power amplifiers. . When the dual-band Doherty power amplifier works in two frequency bands at the same time, the linearity of the power amplifier will decrease due to the influence of intermodulation, and the linearity of the power amplifier can be improved by pre-distortion technology. the

Description of drawings

Figure 1 is the design model of the dual-frequency dual-channel Doherty power amplifier. the

Figure 2 is the design model of the dual-frequency multi-channel Doherty power amplifier. the

Figure 3(a) is the equivalent model of a dual-frequency transmission line, Figure 3(b) is a single-section coupled line, Figure 3(c) is a double-section coupled line, and Figure 3(d) is a T-shaped network with a short-circuit branch line , Figure 3(e) is a T-shaped network with an open branch line. the

Figure 4(a) is a dual-frequency directional coupler, and Figure 4(b) is a dual-frequency Wilkinson power divider plus a quarter-wavelength delay line module. the

Figure 5 is a dual-frequency single-channel power amplifier

Detailed ways

A kind of dual-frequency synchronous type power amplifier based on T-type network and coupling line first needs to determine the structural model of dual-frequency Doherty power amplifier, traditional Doherty power amplifier is a dual-channel model, develops a multi-channel model later, the dual-frequency Doherty power amplifier proposed by the present invention The power amplifier model is also divided into two-way and multi-way models. Figure 1 shows a dual-frequency dual-channel Doherty power amplifier model. Its structure is the same as that of the traditional single-frequency dual-channel Doherty power amplifier. The specific structure is that a dual-frequency main power amplifier and a dual-frequency auxiliary power amplifier are respectively connected to the dual-frequency dual-channel power distribution Power splitter module with 90° phase difference output; dual-frequency directional coupler or dual-frequency dual-way power splitter plus 90° phase difference output power splitter module is connected to the input terminal, dual-frequency main power amplifier and dual-frequency auxiliary The power amplifier is connected to the main dual-frequency delay line and the auxiliary dual-frequency delay line respectively, the main dual-frequency delay line is connected to the first dual-frequency quarter-wavelength transmission line, and the first dual-frequency quarter-wavelength transmission line is connected to the auxiliary dual-frequency The delay line and the second dual-frequency quarter-wavelength transmission line are connected together, and the second dual-frequency quarter-wavelength transmission line is connected to the output end; each component in it is a dual-frequency model, and the dual-frequency transmission line (delay line and quarter wavelength transmission line). The dual-frequency dual-channel power distribution and 90° phase difference output module can be implemented with a directional coupler, or with a Wilkinson power divider plus a 90° delay line. Figure 2 shows a multi-channel dual-frequency Doherty power amplifier model, which is different from the dual-channel model in that it contains multiple auxiliary power amplifiers, so a multi-channel power divider is required to distribute power to each power amplifier in its front stage. Three-way power splitters can be realized independently, and more than three-way power splitters can be realized by multiple power stages. The specific structure is that a dual-frequency main power amplifier and the first dual-frequency auxiliary power amplifier to the Nth dual-frequency auxiliary power amplifier are respectively connected to the power splitter module of the dual-frequency dual-way power divider plus 90° phase difference output; the dual-frequency main power amplifier is connected to the main Dual-frequency delay line connection, the main dual-frequency delay line is connected to the first dual-frequency quarter-wavelength transmission line, and the first dual-frequency auxiliary power amplifier to the Nth dual-frequency auxiliary power amplifier are correspondingly connected to the first dual-frequency delay line to the Nth Dual-frequency delay line connection, the common node of the first dual-frequency delay line to the Nth dual-frequency delay line is connected to the common node of the first dual-frequency quarter-wavelength transmission line and the second dual-frequency quarter-wavelength transmission line , the second section of the dual-frequency quarter-wavelength transmission line is connected to the output end. the

Designing the equivalent model of the dual-frequency transmission line in the dual-frequency Doherty power amplifier shown in Figure 3(a), the design requires the transmission line to achieve synchronous operation at frequencies f ₁ and f _2. The conditions are: this transmission line can wait It is effectively a section of ordinary transmission line, which has an equivalent characteristic impedance of Z _c1 and an equivalent electrical length of θ ₁ at the first frequency, and an equivalent characteristic impedance of Z _c2 and an equivalent electrical length of θ ₂ at the second frequency. Both coupled lines and T-networks have this property. Figure 3(b) is a single-section coupled line structure, Figure 3(c) is a double-section coupled line structure, Figure 3(d) is a T-shaped network with a short-circuit branch line, and Figure 3(e) is a T-shaped network with an open-circuit branch line T-network.

的 特性阻抗，左右两段（分别为第六段双频四分之一波长传输线和第四段双频四分之一波长传输线）传输线具有50Ω的特性阻抗。双频Wilkinson功分器包含三段双频四分之一波长传输线和一个100Ω的电阻，其中两段（分别为第三段双频四分之一波长传输线和第五段双频四分之一波长传输线）传输线具有

的特性阻抗；另一段为具有50Ω的特性阻抗的第四段双频四分之一波长传输线；这些结构中的双频四分之一波长传输线可以用耦合线或者T型网络，根据给定参数可以求出耦合线或者T型网络中各个参量的值。  In the dual-frequency Doherty power amplifier model, the front stage requires a dual-frequency power divider and a 90° phase difference output module. This module can be implemented with a dual-frequency directional coupler, as shown in Figure 4(a); it can also be implemented with a dual-frequency Wilkinson power divider plus a dual-frequency quarter-wavelength transmission line, as shown in Figure 4(b). The dual-frequency directional coupler consists of four sections of dual-frequency quarter-wavelength transmission lines, of which the upper and lower sections (respectively the third section of dual-frequency quarter-wavelength transmission line and the fifth section of dual-frequency quarter-wavelength transmission line) transmission lines have

The characteristic impedance of the left and right sections (respectively the sixth section of dual-frequency quarter-wavelength transmission line and the fourth section of dual-frequency quarter-wavelength transmission line) transmission line has a characteristic impedance of 50Ω. The dual-band Wilkinson power splitter consists of three dual-band quarter-wavelength transmission lines and a 100Ω resistor, two of which (the third dual-frequency quarter-wavelength transmission line and the fifth dual-frequency quarter-wavelength wavelength transmission line) The transmission line has

characteristic impedance; the other section is the fourth dual-frequency quarter-wavelength transmission line with a characteristic impedance of 50Ω; the dual-frequency quarter-wavelength transmission line in these structures can use a coupled line or a T-type network, according to given parameters The value of each parameter in the coupled line or T-shaped network can be obtained.

In a dual-band Doherty power amplifier, both the main power amplifier and the auxiliary power amplifier are single-channel dual-band power amplifiers. The present invention uses a single-channel dual-frequency power amplifier as shown in Figure 5. The input matching network is a п-type structure, and the conjugate matching at two frequencies can be obtained through optimization; the load network includes a section of parallel open-circuit transmission line, a short-circuit branch line T-shaped network, which can transform the standard load to the best impedance required at two frequency points. The DC bias voltage sets the power amplifier to a Class AB working mode (main power amplifier) or a Class C working mode (auxiliary power amplifier), and the DC supply voltage is directly connected to the drain of the transistor through a short-circuited branch line. the

With the dual-frequency transmission line, dual-frequency power splitter and dual-frequency single-channel power amplifier, a dual-frequency dual-channel Doherty power amplifier as shown in Figure 1 or a dual-frequency multi-channel Doherty power amplifier as shown in Figure 2 can be realized. In the simulation, by adjusting the equivalent electrical length of the dual-frequency delay line, the best working performance of the Doherty power amplifier can be optimized. the

To verify the feasibility of the dual-band Doherty power amplifier, the dual-frequency 900MHz and 2GHz dual-frequency Doherty power amplifier based on the T-shaped network designed with the SiC MESFET24010 device, the drain efficiency comparison results measured in the high frequency band show that the maximum output power retreats 9dB , The drain efficiency of the dual-frequency three-way Doherty power amplifier is 20% higher than that of the balanced amplifier. the

Claims (7)

1. double frequency synchronous mode power amplifier based on T type network and coupling line, it is characterized in that, described double frequency synchronous mode power amplifier based on T type network and coupling line has two-way or multichannel double frequency Doherty power amplifier, comprises two kinds of structures: a kind of is that a double frequency master power amplifier and a double frequency auxiliary power amplifier are connected to the power splitter module that double frequency two-way power splitter adds 90 ° of phase difference outputs respectively; The power splitter module that double-frequency directional coupler or double frequency two-way power splitter add 90 ° of phase difference outputs is connected with input, double frequency master power amplifier is connected with auxilliary double frequency delay line with main double frequency delay line respectively with the double frequency auxiliary power amplifier, main double frequency delay line is connected with first section double frequency quarter-wave transmission line, first section double frequency quarter-wave transmission line and auxilliary double frequency delay line and the second double frequency quarter-wave transmission line link together, and second section double frequency quarter-wave transmission line connects output; To be a double frequency master power amplifier be connected with the power splitter module that double frequency two-way power splitter adds 90 ° of phase differences outputs respectively with first double frequency auxiliary power amplifier to the N double frequency auxiliary power amplifier another kind; Double frequency master power amplifier is connected with main double frequency delay line, main double frequency delay line is connected with first section double frequency quarter-wave transmission line, first double frequency auxiliary power amplifier to the N double frequency auxiliary power amplifier is connected with first double frequency delay line to the N double frequency delay line accordingly, first double frequency delay line to the N double frequency delay line common node is connected with the common node of first section double frequency quarter-wave transmission line and second section double frequency quarter-wave transmission line again, and second section double frequency quarter-wave transmission line connects output.

2. according to the described double frequency synchronous mode power amplifier based on T type network and coupling line of claim 1, it is characterized in that described N is 1-20.

3. according to the described double frequency synchronous mode power amplifier based on T type network and coupling line of claim 1, it is characterized in that, the characteristic impedance of described first section double frequency quarter-wave transmission line is 50 Ω, and the characteristic impedance of second section double frequency quarter-wave transmission line is 35 Ω.

4. according to the described double frequency synchronous mode power amplifier based on T type network and coupling line of claim 1, it is characterized in that, describedly comprise the quarter-wave transmission line of two-frequency operation and the delay line of two-frequency operation based on T type network and coupling line; T type network is made up of the double frequency quarter-wave transmission line, and is connected on the signal transmission road; Wherein, double-frequency directional coupler is made up of four sections double frequency quarter-wave transmission lines, and wherein two sections double frequency quarter-wave transmission line has

Characteristic impedance, about epimere two ends with characteristic impedance of 50 Ω of two sections double frequency quarter-wave transmission lines connect input, output port; About two sections be connected with two sections respectively, four sections double frequency quarter-wave transmission lines are formed a loop; Double frequency Wilkinson power splitter is made up of three sections double frequency quarter-wave transmission lines, wherein, is made of two double frequency quarter-wave transmission lines and 100 Ω resistance, and two double frequency quarter-wave transmission lines have equivalence Characteristic impedance and the quarter-wave transmission line equivalent electric length of the characteristic impedance of 50 Ω; Described coupling line is single-unit coupling line or two joint coupling lines.

5. according to the described double frequency synchronous mode power amplifier based on T type network and coupling line of claim 1, it is characterized in that described double frequency quarter-wave transmission line or double frequency delay line are the T type network of single-unit coupling line, binodal coupling line, band short circuit branch line or the T type network of band open circuit branch line.

6. according to the described double frequency synchronous mode power amplifier based on T type network and coupling line of claim 1, it is characterized in that, described dual-frequency power divider adds 90 ° of phase difference output modules by double-frequency directional coupler, and perhaps double frequency Wilkinson power splitter adds the realization of double frequency quarter-wave transmission line; Double-frequency directional coupler and double frequency Wilkinson power splitter are to be made of the double frequency quarter-wave transmission line.

7. according to the described double frequency synchronous mode power amplifier based on T type network and coupling line of claim 1, it is characterized in that, described double frequency Doherty power amplifier contains one section double-frequency directional coupler or double frequency two-way power splitter adds power splitter module, a double frequency master power amplifier, a double frequency auxiliary power amplifier, two sections double frequency delay lines that 90 ° of phase differences are exported, and two sections characteristic impedances are respectively the double frequency quarter-wave impedance transformation line of 50 Ω and 35 Ω; Wherein, double-frequency directional coupler is made up of 4 T type networks, and wherein two T type networks have equivalence up and down

Characteristic impedance, about two T type networks have the characteristic impedance of 50 Ω, the equivalent electric length of four T type networks on two frequencies is quarter-wave; Double frequency Wilkinson power splitter is made of two coupling lines and 100 Ω resistance, and two coupling lines have equivalence

Characteristic impedance and quarter-wave equivalent electric length, double frequency master power amplifier has identical topological structure with auxiliary power amplifier, its laod network is made up of a T type network and one section open-circuit line in parallel, can standard termination be transformed to required impedance two frequencies, fan-in network is a pi type network, can realize two conjugate impedance match on the frequency; Double frequency quarter-wave transmission line or delay line can be used T type network or coupling line equivalence, and wherein the branch line in the T type network can be short circuit or open-circuit line, and coupling line can use the coupling line of single-unit or binodal.

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