Embedded local oscillator multi-stage frequency conversion vector testing device and method

Abstract

The invention discloses an embedded local oscillator multi-stage frequency conversion vector testing device and method, and belongs to the technical field of testing. Only one independent local oscillator source needs to be configured in the vector network analyzer, so that the instrument cost is low; the phase difference of the main and auxiliary dual-tone signals of the reference receiver and the measurement receiver adopts the technical scheme of time-sharing synchronous measurement, and group delay and phase-frequency characteristic test of the frequency converter can be completed; the calibration mixer can be represented according to the frequency band of the tested piece, so that the test requirements of different frequency bands can be met, and the efficiency is high; the single-tone output of the main tone signal and the combined dual-tone output of the main tone signal and the consonant signal can be switched through a switch, and the amplitude-frequency and phase-frequency characteristic test of the frequency converter can be completed through mutual cooperation.

Description

Technical Field

[0001] The invention belongs to the field of testing technology, and in particular relates to an embedded local oscillator multi-stage frequency conversion vector testing device and method. Background Art

[0002] The frequency converter is a key component of microwave transmission and return transmission. To ensure the accuracy of signal transmission and reception, it is necessary to accurately test the frequency conversion transmission amplitude characteristics and phase characteristics of the frequency converter, that is, the vector frequency conversion transmission characteristics, to measure the impact of the frequency conversion link on the signal transmission quality of the entire system. In actual engineering applications, multi-stage frequency converters with embedded local oscillator structures are usually used as core components for signal conversion. Such components have neither local oscillator output interfaces nor reference signal intervention interfaces. The phase response test accuracy of frequency conversion transmission is easily affected by the phase drift and phase noise of the embedded local oscillator, and the test results are unstable. Therefore, the vector test of embedded local oscillator multi-stage frequency conversion has always been a difficult test problem in actual engineering applications.

[0003] The prior art proposes a dual-tone test technology for frequency conversion module and channel group delay testing. The two internal excitation sources are combined through the directional coupler of ZVA port 3, and the dual-tone signal is output to the device under test through port 1. The difference between the phase difference of the dual-tone signal on the input side and the phase difference on the output side of the device under test and the dual-tone frequency interval are used to calculate the group delay. However, this technical solution requires that the dual-tone signals of the reference receiver (R receiver) and the measurement receiver (B receiver) be measured simultaneously to complete the test. Therefore, a second local oscillator signal source is additionally configured inside the instrument, increasing the research and development cost of the instrument. In addition, this technical solution only tests the group delay and phase response of the frequency conversion transmission, and cannot complete the port reflection of the frequency converter and the amplitude measurement of the frequency conversion transmission, and cannot comprehensively measure the vector reflection and transmission characteristics of the frequency converter.

[0004] The existing technical solutions have the following disadvantages:

[0005] (1) The vector network analyzer is required to have two independent local oscillator sources inside, which increases the instrument cost;

[0006] (2) Group delay calibration can only be achieved through a mixer with known characteristics, which limits the test scenario and is inefficient.

[0007] (3) Only the phase response test of the variable frequency transmission group delay can be completed, but the reflection of the port and the amplitude measurement of the variable frequency transmission cannot be completed. Summary of the invention

[0008] In view of the above technical problems existing in the prior art, the present invention proposes an embedded local oscillator multi-stage frequency conversion vector testing device and method, 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] An embedded local oscillator multi-level frequency conversion vector test device,

[0011] It includes a vector network analyzer, a calibration mixer and a frequency converter to be tested; the vector network analyzer is internally configured with an independent local oscillator source for completing the group delay and phase-frequency characteristic test of the frequency converter;

[0012] When the vector network analyzer is connected to the calibration mixer, when the internal combining switch of the vector network analyzer is placed in the non-combining position, the first port of the vector network analyzer is connected to the radio frequency port, i.e., the RF port, of the calibration mixer, and the intermediate frequency port, i.e., the IF port, of the calibration mixer is respectively connected to the open circuit, short circuit, and matched load calibration components;

[0013] When the internal combining switch of the vector network analyzer is placed in the combining position, the first port of the vector network analyzer is connected to the radio frequency port of the calibration mixer, that is, the RF port, and the second port of the vector network analyzer is connected to the intermediate frequency port of the calibration mixer, that is, the IF port, to complete the dual-tone excitation down-conversion group delay calibration;

[0014] When the vector network analyzer is connected to the inverter to be tested, the first port of the vector network analyzer is connected to the RF port of the inverter to be tested, the second port of the vector network analyzer is connected to the IF port of the inverter to be tested, and the internal combiner switch of the vector network analyzer is placed in the non-combining position to complete the port matching and variable frequency transmission amplitude test;

[0015] The internal combiner switch of the vector network analyzer is placed in the combine position, so that the first port outputs the main and auxiliary dual-tone signals. Under the dual-tone excitation state, the variable frequency transmission group delay and phase-frequency characteristic test is completed.

[0016] In addition, the present invention also provides an embedded local oscillator multi-level frequency conversion vector test method, which adopts the embedded local oscillator multi-level frequency conversion vector test device as described above, and specifically includes the following steps:

[0017] Step 1: Under the stimulation of the main tone signal, use mechanical or electronic calibration components to complete the full two-port calibration of the vector network and obtain the calibration error term;

[0018] Step 2: The main tone signal excites the calibration mixer to obtain the frequency conversion characteristic parameters of the calibration mixer;

[0019] Step 3: The main and auxiliary dual-tone signals excite the calibration mixer to complete the frequency conversion group delay calibration;

[0020] Step 4: The main tone signal excites the inverter under test to complete the port matching and frequency conversion transmission amplitude test;

[0021] Step 5: The main and auxiliary dual-tone signals stimulate the inverter under test to complete the frequency conversion transmission group delay and phase-frequency characteristic test;

[0022] Step 6: Combine the frequency conversion amplitude parameter and phase parameter of the inverter to obtain the vector transfer characteristic of the inverter.

[0023] Preferably, in step 1, the internal combining switch of the vector network analyzer is placed in the non-combining position, so that the first port of the vector network analyzer outputs a single-tone signal, i.e., the main tone signal. Under the excitation of the main tone signal, a mechanical or electronic calibration component is used to complete the full dual-port calibration of the vector network analyzer, and the calibration error terms EDF, ESF, ERF, ETF, EDR, ESR, ERR, and ETR are obtained, and the test end face is extended to the end face of the device under test.

[0024] Preferably, in step 2, a reciprocal mixer covering the input and output frequencies of the device under test is selected as the calibration mixer, the first port of the vector network analyzer is connected to the radio frequency port of the calibration mixer, that is, the RF port, the third port of the vector network analyzer is connected to the LO port of the calibration mixer for providing a local oscillator input, and the intermediate frequency port of the calibration mixer, that is, the IF port, is respectively connected to an open circuit, a short circuit, and a matched load calibration piece to obtain a calibration error term EDF cal_mixer , ESF cal_mixer , ERF cal_mixer , complete the calibration mixer characterization, and obtain the calibration mixer frequency conversion characteristic parameters according to formula (1):

[0025]

[0026] Preferably, according to SC21 cal_mixer Characterize the data and group delay aperture size to calculate the frequency conversion group delay parameters of the calibration mixer SC21 delay .

[0027] Preferably, in step 3, the internal combining switch of the vector network analyzer is placed in the combining position, so that the first port of the vector network analyzer outputs the main and auxiliary dual-tone signals, and the dual-tone signal interval is Δf, and the IF output port of the calibration mixer is connected to the second port of the vector network analyzer, and the change in the phase difference between the input and output dual-tone signals is measured under the dual-tone signal excitation. According to formula (2), the group delay parameter in the frequency conversion state is calculated as follows:

[0028]

[0029] Preferably, the group delay result obtained in step 3 includes the group delay introduced by the test cable and the vector network transmission path and the group delay caused by the calibration mixer itself. According to steps 2 and 3, the group delay introduced by the test cable and the vector itself is Delay system =Delaycal_mixer&system -SC21 delay , through this error, the error can be eliminated when testing the device under test later, completing the frequency conversion group delay correction.

[0030] Preferably, in step 4, the frequency converter to be tested is connected, the first port of the vector network analyzer is connected to the RF port of the frequency converter to be tested, the second port of the vector network analyzer is connected to the IF port of the frequency converter to be tested, and the internal combiner switch of the vector network analyzer is placed in the non-combining position to test the input / output matching, input / output power and frequency conversion transmission amplitude of the frequency converter to be tested.

[0031] Preferably, in step 5, the internal combiner switch of the vector network analyzer is placed in a combining position, and the frequency conversion group delay and phase of the frequency converter to be tested are tested in a dual-tone excitation state.

[0032] Beneficial technical effects brought by the present invention:

[0033] The vector network analyzer of the present invention only needs to be configured with an independent local oscillator source, and the instrument cost is low; the phase difference between the main and auxiliary dual-tone signals of the reference receiver and the measuring receiver adopts a technical solution of time-sharing synchronous measurement, which can complete the group delay and phase-frequency characteristic test of the frequency converter; the calibration mixer can be characterized according to the frequency band of the device under test, which can meet the test requirements of different frequency bands and has high efficiency; the main tone signal single-tone output and the main tone and consonant signal combined dual-tone output can be switched through a switch, and cooperate with each other to complete the amplitude-frequency and phase-frequency characteristic test of the frequency converter device. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 is a flow chart of the method of the present invention;

[0035] Figure 2 Schematic diagram of a mixed test mode of tonic and consonant signals;

[0036] Figure 3 Schematic diagram of the time-sharing synchronous acquisition mode of the main and auxiliary dual-tone signals of the reference receiver and the measurement receiver. DETAILED DESCRIPTION

[0037] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments:

[0038] The vector test of the traditional mixer / converter needs to use a reference mixer or phase calibration component to complete the nonlinear phase calibration of the RF and IF ends. The test steps are cumbersome and the connection is complicated, which has certain limitations in actual engineering applications. The traditional two-tone test technology can only test the transmission group delay and phase characteristics of the frequency conversion device, cannot measure the amplitude information, and requires two local oscillators to complete the test. In view of this, the present invention proposes an embedded local oscillator multi-stage frequency conversion vector test device and method based on single-tone and dual-tone signal mixing technology, which can complete the vector frequency conversion test without the help of a reference mixer. The receiver power and full dual-port calibration of the RF and IF ends of the vector network analyzer are completed using a single-tone signal to realize the amplitude-frequency characteristic test of the mixer / converter. Through the internal combiner switch, a consonant signal is added, and the measured mixer / converter is stimulated by two-tone. The phase difference between the two carriers is measured at the input and output ends of the measured device, and then the ratio of the difference between the output and input carrier phase difference and the frequency difference (the frequency difference of the two-tone signal, that is, the group delay aperture) is taken to obtain the group delay parameter. This technology is very effective in measuring the group delay of mixers / converters with embedded local oscillators, and can eliminate the frequency and phase effects brought by the local oscillator of the measured mixer / converter. In addition to measuring the group delay, the phase information of the measured mixer / converter device can be obtained by integrating the group delay.

[0039] 1. Specific implementation process (the process is as follows Figure 1 As shown) as follows:

[0040] (1) Figure 2 As shown, the internal combiner switch of the vector network analyzer is placed in position ①, so that port 1 of the vector network analyzer outputs a single-tone signal (main tone signal), and mechanical or electronic calibration components are used to calibrate ports 1 and 2 of the vector network analyzer, and calibration error terms EDF, ESF, ERF, ETF, EDR, ESR, ERR, and ETR are obtained, and the test end face is extended to the end face of the device under test;

[0041] (2) Select a reciprocal mixer that covers the input and output frequencies of the DUT as the calibration mixer. Connect port 1 of the vector network analyzer to the radio frequency (RF) port of the calibration mixer, and connect port 3 of the vector network analyzer to the LO port of the calibration mixer to provide a local oscillator (LO) input. Connect the intermediate frequency (IF) port of the calibration mixer to open-circuit, short-circuit, and matched load calibration components, respectively, to obtain the calibration error term EDF. cal_mixer , ESF cal_mixer , ERF cal_mixer , complete the calibration mixer characterization and calculate the vector transmission frequency conversion parameters:

[0042]

[0043] (3) According to SC21 cal_mixerCharacterize the data and group delay aperture size, calculate and extract the frequency conversion group delay parameter SC21 of the calibration mixer delay ;

[0044] (4) Figure 2 Set the internal combiner switch in position ②, so that port 1 of the vector network analyzer outputs the main and auxiliary dual-tone signals, and the dual-tone signal interval is Δf. Connect the IF output port of the calibration mixer to port 2 of the vector network analyzer, and measure the change in the phase difference between the input and output dual-tone signals under the dual-tone signal excitation. The group delay parameters in this frequency conversion state are calculated according to the following formula:

[0045]

[0046] (5) The group delay result obtained in step (4) includes the group delay introduced by the test cable and the vector network transmission path and the group delay caused by the calibration mixer itself. According to steps (3) and (4), the group delay introduced by the test cable and the vector network itself can be obtained as Delay system =Delay cal_mixer&system -SC21 delay , through this error, the error can be eliminated in the subsequent testing of the DUT, completing the frequency conversion group delay correction;

[0047] (6) Connect the embedded local oscillator converter under test (CUT), connect port 1 of the vector network analyzer to the RF port of the CUT, and port 2 to the IF port of the CUT. Set the internal combiner switch to position ① to test the input / output matching, input / output power, and frequency conversion transmission amplitude of the CUT.

[0048] (7) Set the internal combiner switch to position ② and test the CUT's frequency conversion group delay and phase under dual-tone excitation;

[0049] 2. Main and auxiliary dual-tone frequency conversion signal acquisition and calibration process

[0050] The existing technical solution requires that the RF dual-tone signal and the intermediate frequency dual-tone signal must be collected synchronously at the same time, so a second local oscillator signal source is configured. The method proposed in this patent adopts the solution of time-sharing synchronous collection of RF and intermediate frequency dual-tone signals, and only an independent local oscillator source needs to be built in to achieve measurement. The main and consonant dual-tone signal collection process at the RF end and the intermediate frequency end is as follows:

[0051] (1) Set the source 1 signal frequency to f1, and the source 1 signal is expressed as The frequency of source 2 signal is f1+Δf, and the signal is Output dual-tone signal at port 1 through internal combiner;

[0052] (2) Figure 2 Turn the switch in to position ② and set the vector network local oscillator frequency to f LO =f1+f IF +Δf,f IF is the fixed intermediate frequency received by the vector network, and the local oscillator signal is expressed as At time t1, at the vector network reference receiver (R receiver), the main and auxiliary dual-tone signals and the local oscillator signal are down-converted to obtain two intermediate frequency reference signals: and The ADC collects the main and auxiliary dual-tone intermediate frequency signals for digital intermediate frequency processing. To process dual-tone signals simultaneously, Figure 3 As shown, the receiver uses two frequencies, f IF +Δf and f IF The NCO (numerically controlled oscillator) performs digital down-conversion on the main and auxiliary dual-tone signals simultaneously to complete the data acquisition at the reference receiver end. The phases of the collected dual-tone signals are and

[0053] (3) Figure 2 As shown in the figure, after the main and auxiliary dual-tone signals pass through the device under test, the dual-tone signals are expressed as:

[0054]

[0055] in, and is the phase shift caused by the mixer itself, f DUT is the local oscillator frequency of the frequency conversion device, is the phase shift caused by the local oscillator signal of the device under test, and M is the amplitude of the local oscillator signal of the device under test;

[0056] (4) At time t1+Δt, the local oscillator frequency is switched to f1+f IF +Δf-f DUT At the vector network measurement receiver end (B receiver end), the main and auxiliary dual-tone signals and the local oscillator signal are analog down-converted to obtain the intermediate frequency signals at the B receiver end:

[0057]

[0058] like Figure 3 As shown, the two frequencies of the measurement receiver are f IF +Δf and f IF The NCO of the dual-tone signal is used to perform digital down-conversion on the main tone and the consonant tone signals at the same time, and the data acquisition at the measurement receiver is completed. The phases of the dual-tone signals collected are and

[0059] (5) Calculate the phase difference of the dual-tone signal at receiver B The phase difference of the two-tone signal at the receiver R is The phase shift caused by the mixer itself can be expressed as Eliminates the embedded local oscillator The introduced phase offset is used to calculate the group delay GDL (Group Delay) of the frequency point based on the frequency interval Δf (group delay aperture) of the dual-tone signal:

[0060]

[0061] (6) Change the frequencies of source 1 and source 2, and repeat steps (1) to (5) in sequence to complete the swept frequency measurement of the frequency conversion device.

[0062] The present invention is based on an independent local oscillator source, and the phase difference of the main and auxiliary dual-tone signals of the reference receiver and the measurement receiver adopts a time-sharing synchronous measurement technical solution, which can complete the group delay and phase-frequency characteristic test of the frequency converter; the calibration mixer can be characterized according to the frequency band of the device under test, and can meet the test requirements of different frequency bands; the main tone signal single-tone output and the main tone and consonant signal combined dual-tone output can be switched through a switch, and cooperate with each other to complete the vector test of the embedded local oscillator frequency converter.

[0063] 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. An embedded local oscillator multi-level frequency conversion vector test device, characterized in that: It includes a vector network analyzer, a calibration mixer and a frequency converter to be tested; the vector network analyzer is internally configured with an independent local oscillator source for completing the group delay and phase-frequency characteristic test of the frequency converter; When the vector network analyzer is connected to the calibration mixer, when the internal combining switch of the vector network analyzer is placed in the non-combining position, the first port of the vector network analyzer is connected to the radio frequency port, i.e., the RF port, of the calibration mixer, and the intermediate frequency port, i.e., the IF port, of the calibration mixer is respectively connected to the open circuit, short circuit, and matched load calibration components; When the internal combining switch of the vector network analyzer is placed in the combining position, the first port of the vector network analyzer is connected to the radio frequency port of the calibration mixer, that is, the RF port, and the second port of the vector network analyzer is connected to the intermediate frequency port of the calibration mixer, that is, the IF port, to complete the dual-tone excitation down-conversion group delay calibration; When the vector network analyzer is connected to the inverter to be tested, the first port of the vector network analyzer is connected to the RF port of the inverter to be tested, the second port of the vector network analyzer is connected to the IF port of the inverter to be tested, and the internal combiner switch of the vector network analyzer is placed in the non-combining position to complete the port matching and variable frequency transmission amplitude test; The internal combiner switch of the vector network analyzer is placed in the combine position, so that the first port outputs the main and auxiliary dual-tone signals. Under the dual-tone excitation state, the frequency conversion transmission group delay and phase-frequency characteristic test of the inverter to be tested are completed.

2. An embedded local oscillator multi-level frequency conversion vector test method, characterized in that: The embedded local oscillator multi-level frequency conversion vector test device as claimed in claim 1 specifically comprises the following steps: Step 1: Under the stimulation of the main tone signal, use mechanical or electronic calibration components to complete the full two-port calibration of the vector network and obtain the calibration error term; Step 2: The main tone signal excites the calibration mixer to obtain the frequency conversion characteristic parameters of the calibration mixer; Step 3: The main and auxiliary dual-tone signals excite the calibration mixer to complete the frequency conversion group delay calibration; Step 4: The main tone signal excites the inverter under test to complete the port matching and frequency conversion transmission amplitude test; Step 5: The main and auxiliary dual-tone signals stimulate the inverter under test to complete the frequency conversion transmission group delay and phase-frequency characteristic test; Step 6: Combine the frequency conversion amplitude parameter and phase parameter of the inverter to obtain the vector transfer characteristic of the inverter.

3. The embedded local oscillator multi-level frequency conversion vector test method according to claim 2 is characterized in that: In step 1, the internal combining switch of the vector network analyzer is placed in the non-combining position, so that the first port of the vector network analyzer outputs a single-tone signal, i.e., the main tone signal. Under the excitation of the main tone signal, a mechanical or electronic calibration component is used to complete the full two-port calibration of the vector network analyzer, and the calibration error terms EDF, ESF, ERF, ETF, EDR, ESR, ERR, and ETR are obtained, and the test end face is extended to the end face of the device under test.

4. The embedded local oscillator multi-level frequency conversion vector test method according to claim 3 is characterized in that: In step 2, a reciprocal mixer covering the input and output frequencies of the device under test is selected as the calibration mixer. The first port of the vector network analyzer is connected to the radio frequency port of the calibration mixer, that is, the RF port. The third port of the vector network analyzer is connected to the LO port of the calibration mixer to provide the local oscillator input. The intermediate frequency port of the calibration mixer, that is, the IF port, is respectively connected to the open circuit, short circuit and matched load calibration parts to obtain the calibration error term EDF. cal_mixer , ESF cal_mixer , ERF cal_mixer , complete the calibration mixer characterization, and obtain the calibration mixer frequency conversion characteristic parameters according to formula (1):

5. The embedded local oscillator multi-level frequency conversion vector test method according to claim 4 is characterized in that: In step 2, according to SC21 cal_mixer Characterize the data and group delay aperture size to calculate the frequency conversion group delay parameters of the calibration mixer SC21 delay .

6. The embedded local oscillator multi-level frequency conversion vector test method according to claim 5 is characterized in that: In step 3, the internal combining switch of the vector network analyzer is placed in the combining position, so that the first port of the vector network analyzer outputs the main and auxiliary dual-tone signals, and the dual-tone signal interval is Δf. The IF output port of the calibration mixer is connected to the second port of the vector network analyzer, and the change in the phase difference between the input and output dual-tone signals is measured under the dual-tone signal excitation. According to formula (2), the group delay parameter in the frequency conversion state is calculated as follows:

7. The embedded local oscillator multi-level frequency conversion vector test method according to claim 6 is characterized in that: The group delay result obtained in step 3 includes the group delay introduced by the test cable and the vector network transmission path and the group delay caused by the calibration mixer itself. According to steps 2 and 3, the group delay introduced by the test cable and the vector itself is Delay system =Delay cal_mixer&system -SC21 delay , through this error, the error can be eliminated when testing the device under test later, completing the frequency conversion group delay correction.

8. The embedded local oscillator multi-level frequency conversion vector test method according to claim 7 is characterized in that: In step 4, the inverter to be tested is connected, the first port of the vector network analyzer is connected to the RF port of the inverter to be tested, the second port of the vector network analyzer is connected to the IF port of the inverter to be tested, and the internal combiner switch of the vector network analyzer is placed in the non-combining position to test the input / output matching, input / output power and frequency conversion transmission amplitude of the inverter to be tested.

9. The embedded local oscillator multi-level frequency conversion vector test method according to claim 8, characterized in that: In step 5, the internal combiner switch of the vector network analyzer is placed in the combiner position, and the frequency conversion group delay and phase of the inverter under test are tested in a dual-tone excitation state.

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