A device forward nonlinearity testing apparatus and method

Abstract

The present application relates to the technical field of testing, in particular to a device forward nonlinear testing device and testing method, including signal source, spectrum analyzer, duplexer and load, the duplexer is connected with spectrum analyzer, load and the device to be measured respectively, signal source is connected with the device to be measured, spectrum analyzer is used for monitoring the forward nonlinear degree of the device to be measured, so that in the testing process, signal source emits signal to the device to be measured, due to the nonlinear factors of the device to be measured, the harmonic stray and other nonlinear energy are generated, part of the nonlinear energy is reflected, another part of the nonlinear energy continues to transmit after the device to be measured, the nonlinear energy continues to transmit after the device to be measured is transported to the load and spectrum analyzer through the duplexer, at this moment, the forward nonlinear degree of the device to be measured can be monitored on the spectrum analyzer, thereby realizing the testing of the forward nonlinear degree of the device to be measured.

Description

Technical Field

[0001] This invention relates to the field of testing technology, and in particular to a device and method for testing positive nonlinearity. Background Technology

[0002] When two or more signals pass through a nonlinear device, the synthesized signal will produce an intermodulation product (IMP). When this product falls into the passband of a nearby receiver, it forms parasitic interference. Multi-band wireless communication systems, where radio frequency multiplexers are used, are a typical application of multi-band wireless communication. The nonlinearity of passive devices and their related structures is a potential source of passive intermodulation (PIM), and the passive intermodulation product (PIMP) can cause relatively serious electromagnetic interference.

[0003] Passive intermodulation measurement systems can be divided into:

[0004] 1) Radiation type, suitable for the study of radiators (such as antennas, feeders, structural components), placed in an anechoic chamber or open measurement site, and greatly affected by the local signal environment;

[0005] 2) Non-radiative type, suitable for research on nonlinear materials, connectors, coaxial cables, filters and waveguide devices, placed in a shielded room, with a matching load at the end.

[0006] Among them, non-radiative intermodulation testing is divided into two categories: reflection (reverse) intermodulation testing and propagation (forward) intermodulation testing. However, existing non-radiative measurement devices can only test intermodulation products in the reflection (reverse) path and cannot evaluate intermodulation products in the forward transmission. These propagation (forward) intermodulation products are coupled and received by other local antennas and enter other local receivers, thus causing intermodulation interference. In order to comprehensively improve the complex electromagnetic environment and enhance the overall electromagnetic compatibility of the communication system, the magnitude of these propagation (forward) intermodulation products also needs to be quantitatively evaluated, and the root cause needs to be located for improvement and optimization. Therefore, a device and method for measuring the forward nonlinear products of a device are particularly needed. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a device and method for testing the positive nonlinearity of a device, so as to test the degree of positive nonlinearity of the device under test.

[0008] To solve the above-mentioned technical problems, the first technical solution adopted by the present invention is as follows:

[0009] A device for testing forward nonlinearity includes a signal source, a spectrum analyzer, a duplexer, and a load. The duplexer is electrically connected to the spectrum analyzer, the load, and the device under test (DUT). The signal source is electrically connected to the DUT. The spectrum analyzer is used to monitor the degree of forward nonlinearity of the DUT.

[0010] The second technical solution adopted in this invention is:

[0011] A method for testing the forward nonlinearity of a device, applied to the aforementioned device forward nonlinearity testing apparatus, includes the following steps:

[0012] The signal source transmits a signal to the device under test;

[0013] The device under test generates nonlinear energy, part of which is reflected and the other part continues to be transmitted after passing through the device under test;

[0014] The nonlinear energy transmitted through the device under test (DUT) is delivered to the load and the spectrum analyzer via a duplexer, and the positive nonlinearity of the DUT is monitored by the spectrum analyzer.

[0015] The beneficial effects of this invention are as follows:

[0016] This solution involves setting up a signal source, a spectrum analyzer, a duplexer, and a load. The duplexer is electrically connected to the spectrum analyzer, the load, and the device under test (DUT), respectively. The signal source is electrically connected to the DUT. During the test, the signal source transmits a signal to the DUT. Due to the nonlinearity of the DUT, nonlinear energy such as harmonic spurious signals is generated. Part of this nonlinear energy is reflected, while the other part continues to be transmitted after passing through the DUT. The nonlinear energy that continues to be transmitted after passing through the DUT is delivered to the load and the spectrum analyzer via the duplexer. At this point, the positive nonlinearity of the DUT can be monitored on the spectrum analyzer, thereby realizing the testing of the positive nonlinearity of the DUT. Attached Figure Description

[0017] Figure 1 This is a connection block diagram of the device forward nonlinearity testing apparatus of the present invention;

[0018] Figure 2 This is a flowchart of the steps of the device forward nonlinearity testing method of the present invention;

[0019] Label Explanation:

[0020] 1. Signal source; 2. Spectrum analyzer; 3. Duplexer; 301. First bandpass filter; 302. Second bandpass filter; 4. Load; 5. T-joint stub assembly; 501. First transmission line; 502. Second transmission line; 503. Third transmission line; 6. Power amplifier; 7. Device under test. Detailed Implementation

[0021] To explain in detail the technical content, objectives, and effects of the present invention, the following description is provided in conjunction with the embodiments and accompanying drawings.

[0022] Please refer to Figure 1 The first technical solution adopted in this invention is:

[0023] A device for testing forward nonlinearity includes a signal source, a spectrum analyzer, a duplexer, and a load. The duplexer is electrically connected to the spectrum analyzer, the load, and the device under test (DUT). The signal source is electrically connected to the DUT. The spectrum analyzer is used to monitor the degree of forward nonlinearity of the DUT.

[0024] As can be seen from the above description, the beneficial effects of the present invention are as follows:

[0025] This solution involves setting up a signal source, a spectrum analyzer, a duplexer, and a load. The duplexer is electrically connected to the spectrum analyzer, the load, and the device under test (DUT), respectively. The signal source is electrically connected to the DUT. During the test, the signal source transmits a signal to the DUT. Due to the nonlinearity of the DUT, nonlinear energy such as harmonic spurious signals is generated. Part of this nonlinear energy is reflected, while the other part continues to be transmitted after passing through the DUT. The nonlinear energy that continues to be transmitted after passing through the DUT is delivered to the load and the spectrum analyzer via the duplexer. At this point, the positive nonlinearity of the DUT can be monitored on the spectrum analyzer, thereby realizing the testing of the positive nonlinearity of the DUT.

[0026] Furthermore, the duplexer includes a first bandpass filter and a second bandpass filter, wherein the first bandpass filter is electrically connected to the load and the device under test (DUT) respectively, and the second bandpass filter is electrically connected to the spectrum analyzer and the DUT respectively.

[0027] Furthermore, it also includes a T-joint stub assembly, which is a three-port microwave network. The three ports of the T-joint stub assembly are respectively connected to a first bandpass filter, a second bandpass filter, and the device under test.

[0028] As described above, the T-joint stub assembly is a three-port microwave network. Compared with coupling methods using other devices, the T-joint stub assembly has lower insertion loss. Furthermore, the insertion loss of the T-joint stub assembly can be further reduced by adjusting the transmission line length. At the same time, the T-joint stub assembly can adjust the corresponding stub length according to the wavelength of the test microwave frequency, and can adapt to nonlinear measurements of test signals at different frequencies.

[0029] Furthermore, the T-joint stub assembly includes a first transmission line, a second transmission line, and a third transmission line. One end of the first transmission line is electrically connected to one end of the second transmission line and one end of the third transmission line, respectively. The other end of the first transmission line is electrically connected to a first bandpass filter. The other end of the second transmission line is electrically connected to a second bandpass filter. The other end of the third transmission line is electrically connected to the device under test.

[0030] The lengths of the first, second, and third transmission lines are set according to the frequency of the first bandpass filter, the frequency of the second bandpass filter, the impedance of the three ports of the T-joint stub assembly, the dielectric constant of the first, second, and third transmission lines, so as to minimize the insertion loss of the T-joint stub assembly.

[0031] As described above, the T-joint stub assembly includes a first transmission line, a second transmission line, and a third transmission line. By adjusting the length of the transmission lines, the insertion loss of the T-joint stub assembly can be minimized, thereby enabling the transmission of stronger excitation signals, capturing weaker harmonics, and achieving good measurement results even for devices with low nonlinearity.

[0032] Furthermore, the first transmission line, the second transmission line, and the third transmission line are all semi-rigid wires.

[0033] Furthermore, the load is a low intermodulation load.

[0034] As described above, a load with low intermodulation avoids the parasitic intermodulation effects of the load on the measurement of passive devices.

[0035] Furthermore, it also includes a power amplifier, the input of which is electrically connected to a signal source, and the output of which is electrically connected to the device under test.

[0036] As described above, by setting a power amplifier to amplify the signal generated by the signal source, a stronger excitation signal is ensured to be input to the device under test, thereby further enhancing the detection capability of low nonlinear passive devices.

[0037] Please refer to Figure 2 The second technical solution adopted in this invention is:

[0038] A method for testing the forward nonlinearity of a device, applied to the aforementioned device forward nonlinearity testing apparatus, includes the following steps:

[0039] The signal source transmits a signal to the device under test;

[0040] The device under test generates nonlinear energy, part of which is reflected and the other part continues to be transmitted after passing through the device under test;

[0041] The nonlinear energy transmitted through the device under test (DUT) is delivered to the load and the spectrum analyzer via a duplexer, and the positive nonlinearity of the DUT is monitored by the spectrum analyzer.

[0042] Please refer to Figure 1 Embodiment 1 of the present invention is as follows:

[0043] A device for testing positive nonlinearity includes a signal source 1 (with a center frequency of 120MHz, model IFR2025), a spectrum analyzer 2 (with a center frequency of 360MHz, model E4402B), a duplexer 3, and a load 4 (model TF200-LIM-DIN). The duplexer 3 is electrically connected to the spectrum analyzer 2, the load 4, and the device under test 7, respectively. The signal source 1 is electrically connected to the device under test 7. The spectrum analyzer 2 is used to monitor the degree of positive nonlinearity of the device under test 7.

[0044] The duplexer 3 includes a first bandpass filter 301 (with a center frequency of 120MHz, which can be a filter of model XH / BPF-12085) and a second bandpass filter 302 (with a center frequency of 360MHz, which can be a filter of model XH / BPF-36085). The first bandpass filter 301 is electrically connected to the load 4 and the device under test 7, respectively, and the second bandpass filter 302 is electrically connected to the spectrum analyzer 2 and the device under test 7, respectively.

[0045] It also includes a T-joint stub assembly 5, which is a three-port microwave network. The three ports of the T-joint stub assembly 5 are respectively connected to the first bandpass filter 301, the second bandpass filter 302 and the device under test 7.

[0046] The T-joint stub assembly 5 includes a first transmission line 501, a second transmission line 502, and a third transmission line 503. One end of the first transmission line 501 is electrically connected to one end of the second transmission line 502 and one end of the third transmission line 503, respectively. The other end of the first transmission line 501 is electrically connected to a first bandpass filter 301. The other end of the second transmission line 502 is electrically connected to a second bandpass filter 302. The other end of the third transmission line 503 is electrically connected to the device under test 7.

[0047] The lengths of the first transmission line 501, the second transmission line 502, and the third transmission line 503 are set according to the frequency of the first bandpass filter 301, the frequency of the second bandpass filter 302, the impedance of the three ports of the T-joint stub assembly 5, the dielectric constant of the first transmission line 501, the dielectric constant of the second transmission line 502, and the dielectric constant of the third transmission line 503, so as to minimize the insertion loss of the T-joint stub assembly 5.

[0048] The first transmission line 501, the second transmission line 502 and the third transmission line 503 are all semi-rigid wires (or other low intermodulation cables), and the first transmission line 501 and the second transmission line 502 are two semi-rigid wires of specific lengths (the length of the first transmission line 501 is 286.6 mm and the length of the second transmission line 502 is 347 mm), while the third transmission line 503 is a semi-rigid wire of unlimited length.

[0049] The load 4 is a low intermodulation load 4.

[0050] It also includes a power amplifier 6, the input of which is electrically connected to the signal source 1, and the output of which is electrically connected to the device under test 7.

[0051] Based on the PIMP frequency component f in the communication system PIM Statement, f PIM =mf1±nf2, harmonics can be broadly and extended to be understood as a type of nonlinear energy when m=0 and n=2 or n=0 and m=2. This energy, along with the third-order intermodulation nonlinear energy when m=2 and n=1 or n=2 and m=1, can quantitatively characterize the nonlinearity of the device under test (DUT) 7. Furthermore, the two methods are consistent in their qualitative trends. For example, if DUT A is inferior to DUT B in terms of linearity, then DUT A will also be inferior to DUT B in terms of third-order intermodulation and harmonics. This allows us to distinguish the relative quality of A and B, which is particularly important for scheme demonstration and component selection in the research, development, and design of communication systems / equipment.

[0052] The test process is as follows: signal source 1 emits a 120MHz signal, which enters the device under test 7 through linear power amplifier 6. Due to the nonlinearity of the device under test 7, some of the nonlinear energy generated, such as harmonic spurious energy (including second harmonic 240MHz and third harmonic 360MHz), is reflected, while the other part continues to be transmitted after passing through the device under test 7. The remaining excitation transmitted through the device under test 7 is connected to the low intermodulation load 4 through the first bandpass filter 301 of 120MHz. The third harmonic is also sent to the spectrum analyzer 2 with a small insertion loss through the second bandpass filter 302 of 360MHz. At this time, the positive nonlinearity of the device under test 7 can be monitored on the spectrum analyzer 2.

[0053] The device under test (DUT) 7 can be either an active or passive device. The operating frequency of the T-connector stub assembly 5 is determined by the operating frequency of the DUT 7. At the same time, the excitation power output by the power amplifier 6 is also determined by the input power range of the DUT 7.

[0054] Please refer to Figure 2 Embodiment two of the present invention is as follows:

[0055] A method for testing the positive nonlinear products of a device, applied to the device positive nonlinearity testing apparatus in Example 1, is characterized by comprising the following steps:

[0056] The signal source 1 transmits a signal to the device under test 7;

[0057] The device under test 7 generates nonlinear energy, part of which is reflected and the other part continues to be transmitted after passing through the device under test 7;

[0058] The nonlinear energy transmitted through the device under test 7 is delivered to the load 4 and the spectrum analyzer 2 via the duplexer 3, and the positive nonlinearity of the device under test 7 is monitored by the spectrum analyzer 2.

[0059] In summary, the present invention provides a device and method for testing the forward nonlinearity of a device. By setting up a signal source, a spectrum analyzer, a duplexer, and a load, the duplexer is electrically connected to the spectrum analyzer, the load, and the device under test (DUT), respectively. The signal source is electrically connected to the DUT. During the test, the signal source transmits a signal to the DUT. Due to the nonlinearity of the DUT, nonlinear energy such as harmonic spurious emissions is generated. Part of this nonlinear energy is reflected, while the other part continues to be transmitted after passing through the DUT. The nonlinear energy that continues to be transmitted after passing through the DUT is delivered to the load and the spectrum analyzer via the duplexer. At this time, the degree of forward nonlinearity of the DUT can be monitored on the spectrum analyzer, thereby realizing the testing of the degree of forward nonlinearity of the DUT.

[0060] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent modifications made based on the content of the present invention's specification and drawings, or direct or indirect applications in related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A device forward nonlinearity test apparatus, characterized by, The device comprises a signal source, a spectrum analyzer, a duplexer and a load, the duplexer is electrically connected with the spectrum analyzer, the load and the device under test respectively, the signal source is electrically connected with the device under test, and the spectrum analyzer is used for monitoring the forward nonlinearity degree of the device under test. The duplexer comprises a first band-pass filter and a second band-pass filter, the first band-pass filter is electrically connected with the load and the device under test respectively, and the second band-pass filter is electrically connected with the spectrum analyzer and the device under test respectively. The device further comprises a T-junction branch assembly, the T-junction branch assembly is a three-port microwave network, and the three ports of the T-junction branch assembly are connected with the first band-pass filter, the second band-pass filter and the device under test respectively. The device further comprises a power amplifier, the input end of the power amplifier is electrically connected with the signal source, and the output end of the power amplifier is electrically connected with the device under test.

2. The device forward non-linearity test apparatus of claim 1, wherein, The T-junction branch assembly comprises a first transmission line, a second transmission line and a third transmission line, one end of the first transmission line is electrically connected with one end of the second transmission line and one end of the third transmission line respectively, the other end of the first transmission line is electrically connected with the first band-pass filter, the other end of the second transmission line is electrically connected with the second band-pass filter, and the other end of the third transmission line is electrically connected with the device under test. The lengths of the first transmission line, the second transmission line and the third transmission line are set according to the frequency of the first band-pass filter, the frequency of the second band-pass filter, the impedance of the three ports of the T-junction branch assembly, the dielectric constant of the first transmission line, the dielectric constant of the second transmission line and the dielectric constant of the third transmission line, so as to minimize the insertion loss of the T-junction branch assembly.

3. The device forward non-linearity test apparatus of claim 2, wherein, The first transmission line, the second transmission line and the third transmission line are all semi-rigid lines.

4. The device forward non-linearity test apparatus of claim 1, wherein, The load is a low intermodulation load.

5. A method for testing the forward nonlinearity of a device, applied to the device forward nonlinearity testing apparatus of any one of claims 1-4, characterized in that, The device comprises the following steps: The signal source transmits a signal to the device under test; The device under test generates non-linear energy, part of which is reflected, and the other part continues to transmit after passing through the device under test; The non-linear energy that continues to transmit after passing through the device under test is transmitted to the load and the spectrum analyzer through the duplexer, and the forward nonlinearity degree of the device under test is monitored through the spectrum analyzer.

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