Vector testing device and method for frequency conversion system based on dual-tone re-frequency conversion

Abstract

The invention discloses a frequency conversion system vector testing device and method based on dual-tone re-frequency conversion, belongs to the technical field of testing, and provides a frequency mixing / frequency conversion vector testing device and method for up and down frequency conversion based on dual-tone signal excitation. The inverse frequency converter is connected in series with the frequency mixer / frequency converter to be tested, and a frequency conversion link is converted into a same-frequency link for measurement, so that the vector network analyzer can complete the vector test of the frequency mixer in a standard measurement state, excitation and measurement signals of a port are dual-tone signals through an internal combiner of the vector network analyzer, and the measurement accuracy is improved. The problem that the vector test of the local oscillator embedded frequency converter cannot be realized by the traditional up-conversion and down-conversion methods is solved; the introduction of the dual-tone signal eliminates the influence of local oscillation drift and local oscillation phase noise of a local oscillation source on vector frequency conversion transmission, improves the accuracy of transmission parameter testing of the frequency converter, and is higher in phase-frequency characteristic testing result precision.

Description

Technical Field

[0001] The invention belongs to the technical field of testing, and in particular relates to a frequency conversion system vector testing device and method based on dual-tone re-frequency conversion. Background Art

[0002] Frequency conversion devices are one of the basic components of every RF or microwave transceiver system. They are widely used in the transmitting and receiving parts of communications, radar, microwave remote sensing and other fields. Their parameter performance indicators directly affect the performance of microwave transmission. Only by accurately mastering the performance indicators of the mixing / conversion link can we ensure that the designed system can work accurately.

[0003] Measuring the port match of a frequency converter is very easy because for reflection measurements, the incident and test signal frequencies are the same and conventional S-parameter tests can be used. However, transmission phase measurements of frequency converter devices are particularly challenging because the input and output frequencies are different, so a direct receiver ratio measurement cannot be used.

[0004] The existing technical solution uses up-conversion and down-conversion methods to convert the variable frequency nonlinear system into a same frequency linear system to complete the vector test. Figure 1 As shown, a characterized reciprocal reference mixer (SC21=SC12) is used as an inverting mixer, which has the same frequency range as the mixer under test and has the opposite frequency conversion direction. The inverting mixer is connected in series with the mixer under test (MUT), and the input and output signals of the link are converted into co-frequency signals after up- and down-conversion. The transmission characteristics of the link after series connection can be directly measured using a calibrated vector network analyzer, i.e., the product of the transmission characteristics of the MUT and the inverting mixer. The transmission parameters of the link after series connection are subtracted from the transmission influence of the inverting mixer to obtain the frequency conversion transmission characteristic parameters of the MUT.

[0005] The prior art has the following disadvantages:

[0006] (1) The measured signal is greatly affected by the local oscillator drift and local oscillator phase noise of the local oscillator source. This influence cannot be eliminated through calibration, and the accuracy of the inverter transmission parameter test is low;

[0007] (2) The inverter mixer and the mixer to be measured must share the same local oscillator source. For frequency conversion devices with built-in local oscillators, this method cannot measure frequency conversion transmission. Summary of the invention

[0008] In view of the above technical problems existing in the prior art, the present invention proposes a frequency conversion system vector testing device and method based on dual-tone re-frequency conversion, which has a reasonable design, overcomes the shortcomings of the prior art, and has good effects.

[0009] In order to achieve the above object, the present invention adopts the following technical solution:

[0010] A frequency conversion system vector test device based on dual-tone re-conversion includes an inverter, a low-pass filter and a mixer / converter to be tested, wherein the inverter mixer, the low-pass filter and the mixer / converter to be tested are connected in sequence through lines.

[0011] In addition, the present invention also mentions a frequency conversion system vector test method based on dual-tone re-frequency conversion, the method adopts a frequency conversion system vector test device based on dual-tone re-frequency conversion as described above, and specifically comprises the following steps:

[0012] Step 1: Connect the characterized inverter mixer, low-pass filter and the mixer under test in series;

[0013] Step 2: Place the internal combiner of the vector network analyzer in the combining position, so that the two excitation sources inside the vector network analyzer are in the combining state;

[0014] Step 3: Set the input frequency f and the interval Δf of the high-frequency signal, and the input bass signal Signal1 frequency to f 1 =f, the frequency of the high-frequency signal Signal2 is f 2 =f+Δf, the dual-tone signal is expressed as:

[0015]

[0016] Among them, φ 1in and φ 2in Represent the phases of signals Signal1 and Signal2, respectively, measured by the R1 receiver of the vector network analyzer;

[0017] Step 4: The dual-tone signal output after frequency conversion by the inverter mixer and low-pass filter combination is used as the input signal of the IF port of the mixer / converter under test, expressed as:

[0018]

[0019] Among them, f 1 ′ = ff LO ,f 2 ′=f+Δf-f LO Respectively represent the frequencies of the dual-tone signals Signal1 and Signal2 after down-conversion by the inverting mixer, φ 1out_mid and φ 2out_mid Indicates the input signal phase φ 1in and φ 2in The phase change after down-conversion by the inverter mixer, error1(φ LO ) represents the error introduced by factors including inverter mixer local oscillator drift and phase noise;

[0020] Step 5: After the dual-tone signal is up-converted by the mixer / converter under test, the dual-tone signal output by the RF port is expressed as:

[0021]

[0022] After the dual-tone signal is up-converted by the mixer / converter under test, the output signal frequencies are f 1 =f,f 2 =f+Δf is the same frequency as the input signal, the dual-tone same-frequency test link is built, and the output and input signals can be ratio-measured;

[0023] Step 6: Use the measurement receiver B of the vector network analyzer to measure the phase of the output dual-tone signal:

[0024]

[0025] Step 7: The overall phase shift of the dual-tone signals Signal1 and Signal2 from the inverter mixer RF port input to the mixer / converter RF port output under test is:

[0026]

[0027] This phase offset includes the sum of the phase offsets caused by the inverse frequency mixer and the measured mixer frequency conversion; the phase offset caused by the measured mixer is

[0028] Δφ=Δφ total -Δφ cal =(φ 2out -φ 1out )-(φ 2in -φ 1in )-Δφ cal (6);

[0029] When the incident signal is a swept frequency signal, Δφ is the phase difference between adjacent frequency points. According to the phase difference between the frequency points, the phase reconstruction of each frequency point can be completed, and the phase test of the variable frequency transmission parameters can be completed;

[0030] Step 8: After the acquisition of the frequency conversion phase information of the device under test is completed, the internal combiner of the vector network analyzer is placed in the non-combining position, and the frequency conversion loss of the mixer under test is obtained by measuring the ratio of the measurement receiver and the reference receiver. Combined with the phase of each frequency point reconstructed in step 7, the vector frequency conversion transmission characteristics of the mixer / converter are obtained.

[0031] Beneficial technical effects brought by the present invention:

[0032] The present invention proposes a mixer / frequency conversion vector test device and method based on up- and down-conversion of dual-tone signal excitation. An inverter mixer and a mixer to be tested do not need to share the same local oscillator source. An inverter is connected in series with the mixer / frequency converter to be tested, and a frequency conversion link is converted into a co-frequency link for measurement, thereby ensuring that a vector network analyzer can complete the vector test of the mixer under a standard measurement state. Through the internal combiner of the vector network analyzer, the excitation and measurement signals of the port are dual-tone signals, thereby solving the problem that the traditional up- and down-conversion method cannot realize the vector test of the local oscillator embedded frequency converter; the introduction of the dual-tone signal eliminates the influence of the local oscillator drift and the local oscillator phase noise of the local oscillator source on the vector frequency conversion transmission, thereby improving the accuracy of the frequency converter transmission parameter test, and the phase-frequency characteristic test result has higher accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a schematic diagram of the technical solution of up and down frequency conversion method;

[0034] Figure 2 The figure is a connection diagram of a mixer / converter vector test device based on inversion frequency. DETAILED DESCRIPTION

[0035] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments:

[0036] The present invention proposes a vector frequency conversion system test device and method based on dual-tone inverse frequency conversion. In order to implement the scheme of the present invention, a characterized reciprocal mixer is required. The frequency range of the mixer and the tested mixer are the same, and the frequency conversion direction is opposite.

[0037] The present invention mainly solves the phase measurement problem of frequency conversion transmission. If the reflection test of the mixer and the amplitude test of frequency conversion transmission are realized, Figure 2 The closing switch in the circuit breaker is placed in position ② to change Figure 1 The measurements were performed using the technical solution shown.

[0038] The present invention provides a frequency conversion system vector testing method based on dual-tone re-frequency conversion, which specifically includes the following steps:

[0039] Step 1: Connect the characterized inverter mixer, low-pass filter and mixer under test in series, such as Figure 2 As shown;

[0040] Step 2: The internal combiner of the vector network analyzer is placed in the combining position, i.e., position ①, and the dual excitation sources are placed in the combining state;

[0041] Step 3: Set the input frequency f and the interval Δf of the high-frequency signal, and the input bass signal Signal1 frequency to f 1 =f, the frequency of the high-frequency signal Signal2 is f 2=f+Δf, the dual-tone signal is expressed as:

[0042]

[0043] Among them, φ 1in and φ 2in Represent the phases of signals Signal1 and Signal2, respectively, measured by the R1 receiver of the vector network analyzer;

[0044] Step 4: The output dual-tone signal after frequency conversion by the inverter mixer and low-pass filter combination is used as the input signal of the IF port of the mixer / converter under test, which is expressed as:

[0045]

[0046] Among them, f 1 ′ = ff LO ,f 2 ′=f+Δf-f LO Respectively represent the frequencies of the dual-tone signals Signal1 and Signal2 after down-conversion by the inverting mixer, φ 1out_mid and φ 2out_mid Indicates the input signal phase φ 1in and φ 2in The phase change after down-conversion by the inverter mixer, error1(φ LO ) represents the error introduced by factors including inverter mixer local oscillator drift and phase noise;

[0047] Step 5: After the dual-tone signal is up-converted by the mixer / converter under test, the dual-tone signal output by the RF port is expressed as:

[0048]

[0049] After the dual-tone signal is up-converted by the mixer / converter under test, the output signal frequencies are f 1 =f,f 2 =f+Δf is the same frequency as the input signal, the dual-tone same-frequency test link is built, and the output and input signals can be ratio-measured;

[0050] Step 6: Use the measurement receiver B of the vector network analyzer to measure the phase of the output dual-tone signal:

[0051]

[0052] Step 7: The overall phase shift of the dual-tone signals Signal1 and Signal2 from the inverter mixer RF port input to the mixer / converter RF port output under test is:

[0053]

[0054] This phase offset includes the sum of the phase offsets caused by the inverse frequency mixer and the measured mixer frequency conversion; the phase offset caused by the measured mixer is

[0055] Δφ=Δφ total -Δφ cal =(φ 2out -φ 1out )-(φ 2in -φ 1in )-Δφ cal (6);

[0056] When the incident signal is a swept frequency signal, Δφ is the phase difference between adjacent frequency points. According to the phase difference between the frequency points, the phase reconstruction of each frequency point can be completed, and the phase test of the variable frequency transmission parameters can be completed.

[0057] Step 8: After obtaining the frequency conversion phase information of the DUT, Figure 2 The combining switch in is placed in the non-combining position, i.e., position ②. By measuring the ratio of the measuring receiver to the reference receiver (B / R), the conversion loss of the measured mixer is obtained. Combined with the phase of each frequency point reconstructed in step 7, the vector frequency conversion transmission characteristics of the mixer / converter can be obtained.

[0058] The present invention optimizes the traditional up-conversion and down-conversion mixer test scheme, and introduces a dual-tone signal to excite the inverse frequency conversion and the tested mixer / conversion series link by controlling the internal combiner of the vector network analyzer. The vector test problem of the embedded local oscillator mixer / converter can be completed under the standard measurement class of the vector network analyzer, and the error introduced by the embedded local oscillator in the multi-stage frequency conversion module is solved, thereby improving the test accuracy.

[0059] Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by technicians in this technical field within the essential scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. A frequency conversion system vector test device based on dual-tone re-frequency conversion, characterized in that: It includes an inverter, a low-pass filter and a mixer / converter to be measured. The inverter mixer, the low-pass filter and the mixer / converter to be measured are connected in sequence through lines.

2. A frequency conversion system vector test method based on dual-tone re-frequency conversion, characterized in that: The frequency conversion system vector test device based on dual-tone re-frequency conversion as claimed in claim 1 specifically comprises the following steps: Step 1: Connect the characterized inverter mixer, low-pass filter and the mixer under test in series; Step 2: Place the internal combiner of the vector network analyzer in the combining position, so that the two excitation sources inside the vector network analyzer are in the combining state; Step 3: Set the input frequency f and the treble signal with an interval of Δf. The input bass signal Signal1 frequency is f1=f, and the treble signal Signal2 frequency is f2=f+Δf. The dual-tone signal is expressed as: Among them, φ 1in and φ 2in Represent the phases of signals Signal1 and Signal2, respectively, measured by the R1 receiver of the vector network analyzer; Step 4: The output dual-tone signal after frequency conversion by the inverter mixer and low-pass filter combination is used as the input signal of the IF port of the mixer / converter under test, which is expressed as: Where f1′=ff LO ,f2′=f+Δf-f LO Respectively represent the frequencies of the dual-tone signals Signal1 and Signal2 after down-conversion by the inverting mixer, φ 1out_mid and φ 2out_mid Indicates the input signal phase φ 1in and φ 2in The phase change after down-conversion by the inverter mixer, error1(φ LO ) represents the error introduced by factors including inverter mixer local oscillator drift and phase noise; Step 5: After the dual-tone signal is up-converted by the mixer / converter under test, the dual-tone signal output by the RF port is expressed as: After the dual-tone signal is up-converted by the mixer / converter under test, the output signal frequencies are f1=f and f2=f+Δf, which are the same frequency as the input signal. The dual-tone same-frequency test link is built, and the output and input signals can be ratio-measured. Step 6: Use the measurement receiver B of the vector network analyzer to measure the phase of the output dual-tone signal: Step 7: The overall phase shift of the dual-tone signals Signal1 and Signal2 from the inverter mixer RF port input to the mixer / converter RF port output under test is: This phase offset includes the sum of the phase offsets caused by the inverse frequency conversion mixer and the measured mixer; the phase offset caused by the measured mixer is: Df=Df total -Df cal =(φ 2out -f out )-(φ 2in -f 1in )-D cal (6); When the incident signal is a swept frequency signal, Δφ is the phase difference between adjacent frequency points. According to the phase difference between the frequency points, the phase reconstruction of each frequency point can be completed, and the phase test of the variable frequency transmission parameters can be completed; Step 8: After the acquisition of the frequency conversion phase information of the device under test is completed, the internal combiner of the vector network analyzer is placed in the non-combining position, and the frequency conversion loss of the mixer under test is obtained by measuring the ratio of the measurement receiver and the reference receiver. Combined with the phase of each frequency point reconstructed in step 7, the vector frequency conversion transmission characteristics of the mixer / converter are obtained.

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