Amplitude-phase imbalance correction method for multi-port amplifier

Abstract

The invention discloses a multi-port amplifier amplitude-phase imbalance correction method, and belongs to the technical field of satellite communication. According to the method, a signal source is adopted to add a dot frequency signal to a first input port, the power of each output port is measured, the last output port is taken as a benchmark, the actually measured isolation of the other output ports is calculated, the minimum deviation between the theoretical isolation and the actually measured isolation is taken as a target, ergodic search is carried out on the amplitude-phase imbalance value, and the amplitude-phase imbalance value is obtained. The amplitude-phase imbalance value corresponding to the minimum absolute error value is the amplitude-phase imbalance amount actually needing to be corrected, and the gain and the phase shift value of the high-power amplifier are adjusted according to the amplitude and phase imbalance amount to carry out amplitude-phase compensation. The method is higher in applicability and efficiency, is suitable for MPA subsystem-level and whole-satellite-level tests, is not affected by whole-satellite-level channel multi-level frequency conversion, can obtain the amplitude-phase imbalance value only through simple power measurement and calculation, and greatly reduces the MPA amplitude-phase correction efficiency.

Description

Technical Field

[0001] The invention relates to a method for correcting amplitude and phase imbalance of a multi-port amplifier, belonging to the technical field of satellite communications. Background Art

[0002] In the operation of high-throughput communication satellite systems, there are often many problems such as uneven geographical distribution of users, tidal effects in the distribution of users' network access time throughout the day, and dynamic changes in available resources due to rainfall affecting satellite links. Traditional satellite communication systems use fixed allocations for frequency and power, and different user resources are allocated within spot beams. They cannot be dynamically adjusted according to system operation conditions and user resource requirements, resulting in suboptimal utilization of satellite resources.

[0003] In order to achieve dynamic and flexible power allocation on board, effectively alleviate the problem of uneven business workload in various dimensions such as time, season, and region during satellite operation, avoid waste of onboard resources, and better meet users' dynamic, flexible, and efficient usage needs, a multi-port amplifier (MPA) is designed at the output power amplifier, and a highly integrated, miniaturized TWTA or SSPA is used to form an HPA power pool, which can provide higher RF power for congested business areas to increase the rate, provide appropriate power for different rate services, and avoid power waste.

[0004] The MPA consists of an input butler, an output butler and a power amplifier. The amplitude and phase inconsistency of the MPA will lead to poor port isolation and power concentration capabilities. Therefore, when integrating the ground system, the amplitude and phase of the HPA need to be adjusted to reduce the impact of the amplitude and phase inconsistency on the system.

[0005] The conventional method is to independently test the amplitude and phase of the input and output channels of each HPA of the MPA, use a vector network analyzer to test the amplitude and phase values ​​of each power superposition link, and then use one of them as the amplitude and phase reference to adjust the gain or phase shifter of the HPA for normalization correction. The principle and process of this method are clear, but it is limited to the MPA subsystem test. It is very inconvenient to use a vector network analyzer to measure the entire star channel after multi-stage frequency conversion. At the same time, multiple TWTAs or SSPAs need to be frequently turned on and off during the test, which will cause interruptions to existing services during on-orbit correction. Summary of the invention

[0006] The technical problem solved by the present invention is: to overcome the shortcomings of the prior art, and to propose a method for correcting amplitude and phase imbalance of a multi-port amplifier. The method aims to minimize the deviation between theoretical isolation and measured isolation, and performs an ergodic search for amplitude and phase imbalance values, so as to solve the problem that the port isolation and power concentration capability of the multi-port amplifier are deteriorated due to the inconsistent amplitude and phase during ground testing and on-orbit application.

[0007] The technical solution of the present invention is:

[0008] A method for correcting amplitude and phase imbalance of a multi-port amplifier, comprising:

[0009] S1: Integrate the input Butler, high power amplifier, and output Butler into a multi-port amplifier MPA subsystem, number the input ports and output ports; power on all high power amplifiers;

[0010] S2: Use a signal source to add a frequency signal to the first input port, the frequency signal is within the operating frequency band of the high power amplifier, and measure the power of each output port; take the last output port as the reference, and calculate the measured isolation of the remaining output ports;

[0011] S3: Establish the transmission matrix of the multi-port amplifier MPA subsystem with amplitude and phase imbalance, take the reference port set in S2 as the reference, calculate the theoretical isolation when there is amplitude and phase imbalance, and obtain the deviation f1 between the theoretical isolation and the measured isolation;

[0012] S4: Randomly change the phase shift value of the high power amplifier, execute S2 and S3 again, and obtain the deviation f2 between the theoretical isolation and the measured isolation in the new state;

[0013] S5: with f min =min(f1+f2) is the objective function, traverse the amplitude and phase imbalance values, and find the minimum absolute error f min The corresponding amplitude-phase imbalance value is the actual amplitude-phase imbalance amount that needs to be corrected;

[0014] S6: According to the obtained amplitude-phase imbalance amount that actually needs to be corrected, amplitude-phase compensation is performed by adjusting the gain and phase shift value of the high power amplifier.

[0015] Furthermore, the transmission matrix H of the multi-port amplifier MPA subsystem with amplitude and phase imbalance is established. MPA , specifically:

[0016] H MPA =H·A n ·H

[0017] Wherein, the number of input ports and output ports of the multi-port amplifier MPA subsystem are both n; n is the high power amplifier matrix, H is the multi-port amplifier MPA subsystem mixing matrix;

[0018] The first high power amplifier in the multi-port amplifier MPA subsystem is used as the reference amplifier, and the high power amplifier matrix A n for:

[0019]

[0020] In the formula, Λ and φ are the gain and phase constants of the reference amplifier, respectively. i and δ i are respectively the imbalance values ​​of the amplitude and phase of the ith high power amplifier relative to the amplitude and phase of the reference amplifier, where E1=1, δ1=0.

[0021] Furthermore, for the 4-port amplifier MPA subsystem, the mixing matrix H is:

[0022]

[0023] Furthermore, for the 8-port amplifier MPA subsystem, the mixing matrix H is:

[0024]

[0025] Furthermore, based on the transmission matrix of the multi-port amplifier MPA subsystem with amplitude and phase imbalance, the theoretical isolation in the presence of amplitude and phase imbalance is obtained, including:

[0026] According to the transmission matrix H of the multi-port amplifier MPA subsystem with amplitude and phase imbalance MPA , use V in =[v i1 ,v i2 ,v i3 ,...,v in ]′ represents the input signal of the multi-port amplifier MPA subsystem, V out =[v o 1,v o2 ,v o3 ,...,v on ]′ represents the output signal of the multi-port amplifier MPA subsystem, then the output signal is:

[0027] V out =H MPA ·V in

[0028] Taking the last output port n as the reference port, calculate the theoretical isolation I' of other output ports i i,n :

[0029]

[0030] Furthermore, a mathematical model of the influence of amplitude and phase imbalance on the isolation of the MPA port is established, and the deviation f1 between the theoretical isolation and the measured isolation is obtained; the mathematical model of the influence of amplitude and phase imbalance on the isolation of the MPA port is:

[0031]

[0032] In the formula, 1 i,n Indicates the measured isolation of the ith output port relative to the nth output port.

[0033] Further, the measured isolation I of the remaining output ports is calculated and outputted. i,n :

[0034]

[0035] Where P 1,i P represents the power of the i-th output port after the frequency signal is input from the first input port; 1,n It indicates the power of the last output port, i.e. the nth output port, after the dot frequency signal is input from the first input port.

[0036] Further, the amplitude and phase imbalance values ​​are traversed, and the first high power amplifier is taken as the reference. The amplitude imbalance of the other n-1 high power amplifiers is the amplitude of the n-1th high power amplifier divided by the amplitude of the first high power amplifier, and the phase imbalance is the phase of the n-1th high power amplifier minus the phase of the first high power amplifier. The amplitude and phase imbalance values ​​of the first high power amplifier are 1 and 0, respectively.

[0037] Furthermore, according to the imbalance values ​​of the amplitude and phase, the gain and phase shift value of the high power amplifier are adjusted for compensation, with the goal of compensating the amplitude and phase to be close to the same as the reference channel.

[0038] The advantages of the present invention compared with the prior art are:

[0039] The method of the present invention establishes a mathematical model for the influence of amplitude-phase imbalance on the isolation of the MPA port, and takes the minimum deviation between the theoretical isolation and the measured isolation as the goal, and performs an ergodic search for the amplitude-phase imbalance value. The proposed method is more applicable and efficient, and is applicable to both MPA subsystem-level and whole-star-level tests. It is not affected by the multi-level frequency conversion of the whole-star-level channel, and the amplitude-phase imbalance value can be obtained only through simple power measurement and calculation, which greatly reduces the efficiency of MPA amplitude-phase correction. At the same time, there is no need to turn the HPA on and off multiple times during the operation, and it supports real-time correction on orbit without affecting normal communication services, which has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Moreover, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

[0041] Figure 1This is a schematic diagram of an 8×8 port MPA;

[0042] Figure 2 It is a schematic diagram of a 4×4 port MPA;

[0043] Figure 3 This is a flow chart of a novel method for correcting amplitude and phase imbalance of a multi-port amplifier according to an embodiment of the present invention. DETAILED DESCRIPTION

[0044] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0045] The present invention proposes a method for correcting amplitude and phase imbalance of a multi-port amplifier, which solves the problem that the amplitude and phase inconsistency of the multi-port amplifier during ground testing and on-orbit application leads to poor port isolation and power concentration capability. Figure 3 As shown, the specific steps include:

[0046] Step 1: Integrate the input Butler, high power amplifier (HPA), and output Butler into a multi-port amplifier subsystem, and power on all HPAs normally. Define the input Butler input port number as 1,2,3....n, the output Butler output port number as 1,2,3....n, and define P (x,y) is the output power of the link from the MPA input Butler port x to the output Butler port y.

[0047] Step 2: Use a signal source to output a point frequency signal within the working frequency band of the MPA to the Butler input port 1, and then use a spectrum analyzer to measure the power of the MPA output Butler output port 1, recorded as P (1,1) , the input remains unchanged, and the output power of Butler output port 2 is measured with a spectrum analyzer, recorded as P (1,2) , and so on, measure the power P of other output ports in turn (1,3) ...P (1,n) .

[0048] Step 3: Use the power values ​​P of different output ports measured in step 2 (1,1) ...P (1,n) , using the output Butler output port n output power P (1,n) Normalize the power and find the isolation of n-1 ports.

[0049]

[0050] Step 4: Express the HPA matrix as:

[0051]

[0052] Λ and φ are the gain and phase constants of the first HPA, respectively. i and δ i are the unbalanced values ​​of the amplitude and phase relative to the first HPA, respectively, where E1 = 1, δ1 = 0, so the transmission matrix of the MPA with amplitude and phase imbalance is:

[0053] H MPA =H·A n ·H

[0054] The commonly used 4-port mixing matrix is:

[0055]

[0056] The 8-port mixing matrix is:

[0057]

[0058] Use V in =[v i1 ,v i2 ,...,v in ]′ represents the input signal of MPA, V out =[v o1 ,v o2 ,...,v on ]′ represents the output signal of MPA, then the output signal is:

[0059] V out =H MPA ·V in

[0060] The isolation of each n-1 port can also be calculated:

[0061]

[0062] In the above formula, i ' ,n Only with the amplitude and phase imbalance E i and δ i Changes, that is, port isolation is only related to amplitude-phase imbalance. Establishing the influence model of amplitude-phase imbalance on isolation, we can get the value of E when there is amplitude-phase imbalance. i and δ i Theoretical isolation under the condition of i ' ,n And the measured isolation Ι i,n Deviation f1, that is, the mathematical model of the impact of amplitude and phase imbalance on MPA port isolation:

[0063] f1=abs(Ι 1,n -1′ 1,n )+abs(Ι 2,n -1′ 2,n )+...abs(Ι n-1,n -1′ n-1,n )

[0064] Step 5 randomly changes the phase shift values ​​of the 2nd, 3rd, ..., nth HPA, and then calculates f2 under the new state according to steps 2, 3, and 4, and finally calculates f min =min(f1+f2) is the objective function, and the ergodic error E i and δ i , (i=2,…,n), the amplitude-phase imbalance value corresponding to the minimum absolute error is found, which is the actual amplitude-phase imbalance that needs to be corrected.

[0065] The present invention will be described in detail below with reference to examples and drawings. An MPA is generally composed of an input Butler, an HPA and an output Butler. Commonly used MPAs generally have 8×8 ports and 4×4 ports, such as Figure 1 and Figure 2 As shown. The HPA has the functions of phase shifting and attenuation. The amplitude and phase inconsistency of the channel can be corrected by adjusting the phase and gain of the HPA. The following will take the 4×4 port MPA as an example. The implementation scheme is as follows:

[0066] Step 1: Integrate the input Butler, high power amplifier (HPA), and output Butler into a multi-port amplifier subsystem and power on all HPAs normally. Define the input Butler input port numbers as 1, 2, 3, 4, the output Butler output port numbers as 1, 2, 3, 4, and define P (x,y) is the output power of the link from the MPA input Butler port x to the output Butler port y.

[0067] Step 2: Use a signal source to output a point frequency signal within the working frequency band of the MPA to the Butler input port 1, and then use a spectrum analyzer to measure the power of the MPA output Butler output port 1, recorded as P (1,1) , the input remains unchanged, and the output power of Butler output port 2 is measured with a spectrum analyzer, recorded as P (1,2) , and so on, measure the power P of other output ports in turn (1,3) ...P (1,4) .

[0068] Step 3: Use the power values ​​P of different output ports measured in step 2 (1,1) ...P (1,4), the output power P of the Butler output port n (1,n) Normalize the power and find the isolation of n-1 ports.

[0069]

[0070] Step 4: Express the HPA matrix as:

[0071]

[0072] Λ and φ are the gain and phase constants of the first HPA, respectively. i and δ i are the unbalanced values ​​of the amplitude and phase relative to the first HPA, respectively, where E1 = 1, δ1 = 0, so the transmission matrix of the MPA with amplitude and phase imbalance is:

[0073] H MPA =H·A4·H

[0074] The 4-port mixing matrix is:

[0075]

[0076] Use V i4 =[v i1 ,v i2 ,v i3 ,v i4 ]′ represents the input signal of MPA, V out =[v o1 ,v o2 ,v o3 ,v o4 ]′ represents the output signal of MPA, then the output signal is:

[0077] V out =H MPA ·V in

[0078] The isolation of the three ports can also be calculated.

[0079]

[0080] In the above formula, i ' ,4 Only with the amplitude and phase imbalance E i and δ i Changes, that is, port isolation is only related to amplitude-phase imbalance. Establishing the influence model of amplitude-phase imbalance on isolation, we can get the value of E when there is amplitude-phase imbalance. i and δ i Theoretical isolation under the condition of i ' ,4 And the measured isolation Ιi,4 The deviation f1.

[0081] f1=abs(Ι 1,4 -1′ 1,4 )+abs(Ι 2,4 -1′ 2,4 )+abs(Ι 3,4 -1′ 3,4 )

[0082] Step 5: Randomly change the phase shift values ​​of the 2nd, 3rd, ..., nth HPA, and then calculate f2 under the new state according to steps 2, 3, and 4, and finally use f min =min(f1+f2) is the objective function, and the ergodic error E i and δ i , (i=2,…,n), the amplitude-phase imbalance value corresponding to the minimum absolute error is found, which is the actual amplitude-phase imbalance that needs to be corrected.

[0083] Considering that the isolation requirement is no less than 24dB (power inconsistency is less than ±0.5dB, phase inconsistency is less than ±6°), the use requirements of MPA can be met, and the amplitude and phase search steps are set to 0.03 and 3° to meet the requirements (the search step will affect the calculation time. Under the same computing resource configuration, the smaller the search step, the longer the calculation time). Since HPA has power telemetry, the gain of HPA can be adjusted according to the power telemetry value to keep the output power basically consistent and reduce the amplitude search range.

[0084] The following is an example of amplitude and phase imbalance of a 4×4 port MPA. Taking the first input port as the reference, the amplitude error E=[1 0.97 1.2 1.15] and the phase error δ=[0 -11 20 -7] of the four ports are respectively E i =-0.8:0.03:1.19,δ i =-21:3:21, i=2,3,4 for traversal search, a total of 9261000 combinations, according to step 4 first calculate the I of each combination i ' ,4 , and then the measured isolation Ι calculated in step 3 i ' ,4 Calculate the absolute error and get S 1j ,(j=1,2,...,9261000), Similarly, change the HPA phase value. Here, take the first HPA as the reference, adjust the phase shift values ​​of the second to fourth HPA by 45°, 90° and 135° respectively, and then calculate S according to the above steps 2 to 4 2j ,(j=1,2,...,9261000), find the minimum absolute error Smin =min(S 1j +S 2j ), (j=1,2,...,9261000) the corresponding amplitude-phase imbalance value is the required amplitude-phase correction value. According to the calculation, when E min =[1 0.98 1.191.13], δ min =[1 -12 21 -6] corresponds to the theoretical isolation Ι i ' ,4 And the measured isolation Ι i,4 The deviation is the smallest. The isolation of the three ports before compensation is 21dB, 17dB, and 15dB, and the isolation after compensation is 40dB, 38dB, and 41dB, which meets the use requirement of no less than 24dB after compensation, verifying the effectiveness of this method.

[0085] The above-described embodiments are only preferred specific implementations of the present invention. Common changes and substitutions made by those skilled in the art within the scope of the technical solution of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for correcting amplitude and phase imbalance of a multi-port amplifier, characterized in that: include: S1: Integrate the input Butler, high power amplifier, and output Butler into a multi-port amplifier MPA subsystem, and number the input ports and output ports; Power up all high power amplifiers; S2: Use a signal source to add a frequency signal to the first input port, the frequency signal is within the operating frequency band of the high power amplifier, and measure the power of each output port; take the last output port as the reference, and calculate the measured isolation of the remaining output ports; S3: Establish the transmission matrix of the multi-port amplifier MPA subsystem with amplitude and phase imbalance, take the reference port set in S2 as the reference, calculate the theoretical isolation when there is amplitude and phase imbalance, and obtain the deviation f1 between the theoretical isolation and the measured isolation; S4: Randomly change the phase shift value of the high power amplifier, execute S2 and S3 again, and obtain the deviation f2 between the theoretical isolation and the measured isolation in the new state; S5: with f min =min(f1+f2) is the objective function, traverse the amplitude and phase imbalance values, and find the minimum absolute error f min The corresponding amplitude-phase imbalance value is the actual amplitude-phase imbalance amount that needs to be corrected; S6: According to the obtained amplitude-phase imbalance amount that actually needs to be corrected, amplitude-phase compensation is performed by adjusting the gain and phase shift value of the high power amplifier.

2. A method for correcting amplitude and phase imbalance of a multi-port amplifier according to claim 1, characterized in that: Establish the transmission matrix H of the multi-port amplifier MPA subsystem with amplitude and phase imbalance MPA , specifically: H MPA =H·A n ·H Wherein, the number of input ports and output ports of the multi-port amplifier MPA subsystem are both n; n is the high power amplifier matrix, H is the multi-port amplifier MPA subsystem mixing matrix; The first high power amplifier in the multi-port amplifier MPA subsystem is used as the reference amplifier, and the high power amplifier matrix A n for: In the formula, Λ and φ are the gain and phase constants of the reference amplifier, respectively. i and δ i are respectively the imbalance values ​​of the amplitude and phase of the ith high power amplifier relative to the amplitude and phase of the reference amplifier, where E1=1, δ1=0.

3. A method for correcting amplitude and phase imbalance of a multi-port amplifier according to claim 1, characterized in that: For the 4-port amplifier MPA subsystem, the mixing matrix H is:

4. A method for correcting amplitude and phase imbalance of a multi-port amplifier according to claim 1, characterized in that: For the 8-port amplifier MPA subsystem mixing matrix H is:

5. A method for correcting amplitude and phase imbalance of a multi-port amplifier according to claim 1, characterized in that: Based on the transmission matrix of the multi-port amplifier MPA subsystem with amplitude and phase imbalance, the theoretical isolation in the presence of amplitude and phase imbalance is obtained, including: According to the transmission matrix H of the multi-port amplifier MPA subsystem with amplitude and phase imbalance MPA , use V in =[v i1 ,v i2 ,v i3 ,...,v in ]′ represents the input signal of the multi-port amplifier MPA subsystem, V out =[v o1 ,v o2 ,v o3 ,...,v on ]′ represents the output signal of the multi-port amplifier MPA subsystem, then the output signal is: V out =H MPA ·V in Taking the last output port n as the reference port, calculate the theoretical isolation I' of other output ports i i,n :

6. A method for correcting amplitude and phase imbalance of a multi-port amplifier according to claim 5, characterized in that: A mathematical model of the influence of amplitude and phase imbalance on the isolation of MPA ports is established, and the deviation f1 between the theoretical isolation and the measured isolation is obtained; the mathematical model of the influence of amplitude and phase imbalance on the isolation of MPA ports is: In the formula, 1 i,n Indicates the measured isolation of the ith output port relative to the nth output port.

7. A method for correcting amplitude and phase imbalance of a multi-port amplifier according to claim 1 or 6, characterized in that: Calculate the measured isolation of the remaining output ports. i,n : Where P 1,i P represents the power of the i-th output port after the frequency signal is input from the first input port; 1,n It indicates the power of the last output port, i.e. the nth output port, after the dot frequency signal is input from the first input port.

8. A method for correcting amplitude and phase imbalance of a multi-port amplifier according to claim 1, characterized in that: Traversing the amplitude and phase imbalance values, taking the first high power amplifier as the reference, the amplitude imbalance of the other n-1 high power amplifiers is the amplitude of the n-1th high power amplifier divided by the amplitude of the first high power amplifier, and the phase imbalance is the phase of the n-1th high power amplifier minus the phase of the first high power amplifier. The amplitude and phase imbalance values ​​of the first high power amplifier are 1 and 0 respectively.

9. A method for correcting amplitude and phase imbalance of a multi-port amplifier according to claim 1, characterized in that: According to the imbalance values ​​of amplitude and phase, the gain and phase shift value of the high power amplifier are adjusted for compensation, with the goal of compensating the amplitude and phase to be close to the reference channel.

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