W-band mixer test fixture

Abstract

The invention provides a W-band mixer test fixture and a test method. The W-band mixer test fixture comprises an intermediate frequency interface, a local oscillator interface, a structural upper cavity, a structural lower cavity and a radio frequency interface, after the structural upper cavity and the structural lower cavity are spliced, a circular flange radio frequency interface is formed outside, and a signal transmission line is formed inside. According to the test fixture provided by the invention, the tested mixer is connected with the test instrument, so that various performance index data of the mixer can be conveniently obtained, and powerful support is provided for design, optimization and production of the mixer.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of high-frequency microwave testing, and particularly relates to a W-waveband mixer test fixture. BACKGROUND

[0002] W-waveband (75-110 GHz) has wide applications in communication, radar, measurement and other fields. The electromagnetic waves in this frequency band have extremely wide frequency bands and rich spectrum resources, which make them show great potential in high-speed data transmission, high-precision positioning, high-resolution imaging and other aspects. However, the development of millimeter wave technology also faces many challenges, one of which is how to realize efficient and stable signal processing and conversion in the high frequency band.

[0003] The mixer is a key component in the millimeter wave system, which can mix the radio frequency signal with the local oscillator signal to generate an intermediate frequency signal. In this process, the performance of the mixer directly affects the performance of the entire system, including signal conversion loss, isolation, phase noise, etc. Therefore, accurate testing of the mixer to ensure its stability and reliability in complex environments is an indispensable part of the development of millimeter wave technology.

[0004] In the testing process of the mixer, the test fixture, as a bridge connecting the device under test and the test instrument, is self-evident. A well-designed test fixture can ensure the accuracy and reliability of the test results, improve the test efficiency and reduce the test cost. Specifically, the test fixture needs to meet the following requirements: 1. Frequency band coverage: the test fixture needs to cover the entire frequency band range of the W-waveband to ensure that the mixer under test can be effectively tested in the entire frequency band.

[0005] 2. Impedance matching: in order to achieve the best signal transmission efficiency, the test fixture needs to achieve good impedance matching with the input and output ports of the mixer under test.

[0006] 3. Electromagnetic shielding: W-waveband signals are sensitive to electromagnetic interference, so the test fixture needs to have good electromagnetic shielding performance to prevent external electromagnetic signals from interfering with the test results.

[0007] 4. Heat dissipation design: the mixer will generate heat during operation, and a reasonable heat dissipation design can ensure that the mixer under test maintains a stable temperature during testing, avoiding performance degradation or damage due to high temperature.

[0008] 5. Stability and durability: the test fixture needs to have high stability and durability, and can withstand multiple plugging and long-term use without damage or performance degradation.

[0009] With the continuous development of millimeter wave technology and the continuous expansion of application fields, the technology of W-band mixer test fixture is also constantly improving. Modern test fixtures not only focus on basic requirements such as frequency band coverage and impedance matching, but also pay more attention to electromagnetic shielding, heat dissipation design, and intelligent and automated testing. For example, some advanced test fixtures use advanced electromagnetic shielding materials and structural design to further improve the accuracy of test results; At the same time, intelligent test systems are introduced to realize automatic control and data analysis of the test process. In order to better meet various test requirements and application scenarios, it is necessary to optimize the design of the W-band mixer fixture. SUMMARY

[0010] In view of the defects in the prior art, the purpose of the present application is to provide a W-band mixer test fixture.

[0011] According to the W-band mixer test fixture provided by the present application, the W-band mixer test fixture comprises: an intermediate frequency interface, a local oscillator interface, a structure upper cavity, a structure lower cavity, and a radio frequency interface. The structure upper cavity and the structure lower cavity are spliced to form a circular flange radio frequency interface on the outside and a signal transmission line on the inside. A microstrip line is used as a signal transmission line, the intermediate frequency interface is connected to the microstrip line, the microstrip line transmits the intermediate frequency signal to the intermediate frequency interface of the mixer, the local oscillator interface is connected to a local oscillator frequency multiplication link, and the microwave signal is multiplied to a millimeter wave signal to provide a local oscillator signal for the mixer; The radio frequency signal generated after mixing is output through the microstrip line to the waveguide to the microstrip line conversion interface, that is, the radio frequency interface; The radio frequency interface adopts a WR-10 standard flange.

[0012] Preferably, the impedance of the microstrip transmission line is matched with the input and output ports of the mixer under test.

[0013] Preferably, a waveguide-to-microstrip conversion structure is used to realize the conversion of waveguide signals and microstrip signals, and the conversion structure is a W-band coupling probe transition structure.

[0014] Preferably, a local oscillator frequency multiplication link is used, an external local oscillator provides a microwave signal, and an internal frequency multiplication generates a W-band local oscillator signal.

[0015] Preferably, the intermediate frequency interface, the local oscillator interface, and the radio frequency interface each have a signal attenuator and a filter for adjusting the amplitude of the test signal and filtering out interference signals.

[0016] Preferably, the intermediate frequency interface, the local oscillator interface, and the radio frequency interface are provided with transmission lines.

[0017] Preferably, the intermediate frequency interface and the local oscillator interface are located on one side of the spliced structure upper cavity and structure lower cavity, and the radio frequency interface is located on the other side of the spliced structure upper cavity and structure lower cavity.

[0018] According to the test method provided by the application, the W-band mixer test fixture is used for testing.

[0019] Preferably, comprising: Step 1) generating radio frequency / intermediate frequency signals and local oscillator signals by using a signal source; Step 2) inputting the intermediate frequency signals and the local oscillator signals into the mixer to be tested through the corresponding intermediate frequency interfaces and local oscillator interfaces of the fixture respectively, connecting the radio frequency port to the instrument test corresponding radio frequency index interface, testing the up-conversion performance of the mixer; inputting the radio frequency signals and the local oscillator signals into the mixer to be tested through the corresponding intermediate frequency interfaces and local oscillator interfaces of the fixture respectively, connecting the intermediate frequency port to the instrument test corresponding intermediate frequency index interface, testing the down-conversion performance of the mixer; Step 3) the mixer mixes the radio frequency / intermediate frequency signals and the local oscillator signals to generate intermediate frequency / radio frequency signals; Step 4) the intermediate frequency / radio frequency signals are output to the spectrum analyzer and other instruments for measurement and analysis through the intermediate frequency interface and the radio frequency interface of the fixture.

[0020] Preferably, during the test, the key data is recorded in real time by using data recording software, wherein the key data includes conversion loss, isolation, and phase noise. After the test is completed, the recorded data is sorted and analyzed to evaluate whether the performance of the mixer meets the design requirements; meanwhile, the results under different test conditions are compared to analyze possible influencing factors and error sources.

[0021] Compared with the prior art, the application has the following beneficial effects: 1) The test fixture provided by the application connects the mixer to be tested with the test instrument, so that the performance index data of the mixer can be easily obtained, thereby providing strong support for the design, optimization and production of the mixer.

[0022] 2) The local oscillator interface only needs to be connected with a microwave signal source to generate the millimeter wave local oscillator signal required by the W-band mixer, thereby greatly reducing the test difficulty and simplifying the test process; the positioning pin adopts a high-precision mechanical structure to ensure the position accuracy when the mixer upper and lower cavities are installed and ensure the stability of the mixer during the test.

[0023] 3) The application reserves a certain length of transmission line at the three ports of the mixer, and by adjusting the length of the transmission line of each port, different models of mixers can be tested adaptively, and good universality is achieved.

[0024] 4) The application adopts a WR-10 waveguide port design, which can completely adapt to the market W-band standard instrument interface. BRIEF DESCRIPTION OF DRAWINGS

[0025] Other features, objects, and advantages of the application will become more apparent from the following detailed description when read in conjunction with the accompanying drawings: Figure 1 The W-band mixer test fixture structure described in the present application is shown in the schematic diagram; Figure 2 The upper cavity structure of the W-band mixer test fixture structure described in the present application is shown in the schematic diagram; Figure 3 The lower cavity structure of the W-band mixer test fixture structure described in the present application is shown in the schematic diagram.

[0026] The drawings show: DETAILED DESCRIPTION

[0027] The present application will be described in detail below with specific embodiments. The following examples will help those skilled in the art to further understand the present application, but do not limit the present application in any form. It should be noted that for those skilled in the art, without departing from the concept of the present application, a number of changes and improvements can be made. These are within the scope of the present application.

[0028] In today's increasingly mature millimeter wave technology, W-band mixer as a key component plays an important role in radar, communication and other fields. In order to accurately evaluate the performance of the mixer, the present application provides a W-band mixer test fixture, which relates to the field of high-frequency microwave test technology, is made of low-loss and high-stability materials, has good electromagnetic shielding performance and heat dissipation performance; the mixer fixing device has a precise positioning mechanism to ensure the stable fixation and precise docking of the mixer under test during the test; specifically includes: intermediate frequency interface, positioning pin, local oscillator interface, structure upper cavity, structure lower cavity, radio frequency interface. Each port has good isolation to avoid signal crosstalk. The plurality of test interfaces are respectively used to connect the radio frequency signal source, the local oscillator signal source and the intermediate frequency output end, which adopts international general interface standard, and is convenient for connecting different types of test equipment; the signal transmission line adopts microstrip line structure, which has high impedance matching and low loss characteristics, to ensure the stability and accuracy of the signal in the transmission process.

[0029] The intermediate frequency interface is connected with the microstrip line, which transmits the intermediate frequency signal to the intermediate frequency interface of the mixer; the local oscillator interface is connected with the local oscillator frequency multiplication link, which multiplies the microwave signal to millimeter wave signal to provide the local oscillator signal for the mixer; the radio frequency signal generated after mixing is output through the microstrip line to waveguide to microstrip conversion interface, i.e. radio frequency interface.

[0030] Specifically, the clamp contains an intermediate frequency interface, a local oscillator interface, and a radio frequency interface, mainly used for performance testing of W-band mixers. The performance test includes key indicators such as conversion loss, isolation, and phase noise. By connecting the mixer under test with the test instrument through the test fixture, the performance data of the mixer can be easily obtained, providing strong support for the design, optimization, and production of mixers. The fixture body needs to be made of low-loss and high-stability materials, such as copper-plated gold materials, which can ensure good radio frequency performance, electromagnetic shielding effect, and thermal stability at high frequencies. The interface standard uses international standard interfaces, and the radio frequency and intermediate frequency ports use SMA-K connectors, and the radio frequency interface uses WR-10 standard flanges, which can be connected to different types of test instruments and devices under test.

[0031] In the preferred embodiment, the mixer fixing device further includes a fixable mounting hole to accommodate different sizes and shapes of test platforms and reduce the impact of vibration on test results. The compact structure of the clamp is designed with mounting holes on the outside of the interface, which can facilitate installation and removal while ensuring accurate and stable interface connection with the mixer under test.

[0032] The test interface also includes a signal attenuator and a filter to adjust the amplitude of the test signal and filter out interference signals, improving test accuracy.

[0033] The clamp uses a microstrip line as the signal transmission line, and the microstrip line substrate is a dielectric plate with a thickness of 5 mil. The microstrip line is arranged on the dielectric plate, which has the advantages of small size, light weight, easy integration, and is suitable for transmitting signals at high frequencies. The impedance of the microstrip transmission line is well matched with the input and output ports of the mixer under test, reducing signal reflection and energy loss, and improving the accuracy of test results.

[0034] The clamp body is internally designed with a waveguide-to-microstrip conversion structure, which realizes smooth conversion of waveguide signals and microstrip signals and reduces signal loss. Since the rectangular waveguide has the characteristics of large power capacity, small loss, no radiation loss, simple structure and high Q value, it is widely used in microwave and millimeter wave circuits and systems. The input and output ports of many millimeter wave laboratory equipment are in the form of waveguide. Conversion between these two transmission line forms is often required in microwave / millimeter wave circuits and systems, and this conversion is completed by a waveguide-microstrip transition circuit. There are many forms of standard rectangular waveguide-to-microstrip conversion, and the commonly used ones are waveguide-ridge waveguide-microstrip transition, waveguide-finned line-microstrip transition, and waveguide-probe-microstrip transition. Among them, the waveguide-probe-microstrip transition is widely used due to its low loss, wide frequency band, simple structure, small size and reliability. Therefore, a W-band coupling probe transition structure is adopted, a three-dimensional electromagnetic simulation software HFSS is used for simulation, and a physical object is made and tested. The experimental results show that in the range of 75-110GHz, the insertion loss is <0.5dB, which is consistent with the software simulation results, and the flatness is good, which meets the engineering requirements. By designing the above conversion structure, smooth transition from waveguide transmission line to microstrip transmission line can be realized. The conversion structure adopts advanced processing technology and accurate simulation optimization to ensure that the signal loss is minimized during the conversion process, and also effectively improves the return loss of the port.

[0035] The clamp body is internally designed with a local oscillator frequency multiplication link, and a microwave signal is provided from the outside local oscillator, that is, a W-band local oscillator signal is generated by internal frequency multiplication, which greatly reduces the test difficulty.

[0036] The test clamp is designed by fully considering the compatibility problem, and can be applied to test a plurality of models of W-band mixers. At the same time, the possibility of future technology upgrading is also considered, leaving room for future expansion. High-precision numerical control machine tools and processing technology are used for processing to ensure that the dimensions of each part of the clamp are accurate and the surface is smooth. During assembly, assembly and debugging are strictly carried out according to the process requirements to ensure that each index of the clamp meets the design requirements.

[0037] The present application will be described in more detail below.

[0038] The present application aims to design a W-band mixer test clamp, which can ensure the accuracy of the test results of the mixer during the test process, such as Figures 2-3As shown, a W-band mixer test fixture includes a W-band mixer test fixture structure upper cavity and a W-band mixer test fixture structure lower cavity. When the W-band mixer test fixture structure upper cavity and the W-band mixer test fixture structure lower cavity are spliced (i.e., upper and lower cavities), the position accuracy after installation of the upper and lower cavities can be ensured by coincidence of the positioning hole of the W-band mixer test fixture structure upper cavity and the positioning pin of the W-band mixer test fixture structure lower cavity. After splicing of the upper and lower cavities, a circular flange radio frequency interface is formed.

[0039] Before mixer testing, the following steps are performed: Preparation step S1: Check whether the test fixture and test equipment are intact, calibrate the test equipment, and ensure that the test environment meets the requirements.

[0040] Install the mixer under test step S2: accurately install the mixer under test on the test fixture to ensure accurate and stable interface docking.

[0041] Configure test parameters step S3: configure the output frequency, power, and other parameters of the signal source, as well as the measurement range and resolution of the spectrum analyzer, according to the test requirements.

[0042] Test step S4: start the test equipment and perform testing according to the predetermined test procedure. Record key data and phenomena during testing.

[0043] Adjust and optimize step S5: fine-tune the test parameters and optimize the test conditions according to the test results to obtain more accurate test results.

[0044] The specific test procedure is as follows: Step 1) Use a high-precision signal source to generate radio frequency / intermediate frequency signals and local oscillator signals.

[0045] Step 2) When testing the up-conversion performance of the mixer, input the intermediate frequency signal and the local oscillator signal to the mixer under test through the corresponding intermediate frequency interface and local oscillator interface of the fixture, respectively, and connect the radio frequency port to the corresponding radio frequency index interface of the instrument for testing; when testing the down-conversion performance of the mixer, input the radio frequency signal and the local oscillator signal to the mixer under test through the corresponding intermediate frequency interface and local oscillator interface of the fixture, respectively, and connect the intermediate frequency port to the corresponding intermediate frequency index interface of the instrument for testing.

[0046] Step 3) The mixer mixes the radio frequency / intermediate frequency signals and the local oscillator signals to generate intermediate frequency / radio frequency signals.

[0047] Step 4) The intermediate frequency / radio frequency signals are output to the spectrum analyzer and other instruments for measurement and analysis through the intermediate frequency interface and the radio frequency interface of the fixture.

[0048] During the test, key data such as frequency conversion loss, isolation, phase noise, etc. are recorded in real time using data recording software. After the test is completed, the recorded data is sorted and analyzed to evaluate whether the performance of the mixer meets the design requirements. At the same time, the results under different test conditions are compared to analyze possible influencing factors and error sources.

[0049] To verify the accuracy and reliability of the test results, the following measures are taken: Step 1) Use standard parts for calibration and verification to ensure the performance of the test equipment and test fixture is stable and reliable.

[0050] Step 2) Compare the test results of different test equipment, analyze the differences and reasons.

[0051] Step 3) Invite third-party testing agencies to verify and recognize the test results.

[0052] Through the above measures, the accuracy and reliability of the test results are ensured, providing strong support for the research and application of W-band mixers.

[0053] With the continuous development and popularization of millimeter wave technology, W-band mixers will be more and more widely used in radar, communication, electronic countermeasures and other fields. Therefore, designing an efficient and accurate W-band mixer test fixture has important application prospects and market value. In the future, with the continuous progress of technology and the continuous expansion of the market, the test fixture is expected to become one of the standard configurations in the field of millimeter wave testing.

[0054] In the description of the present application, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore cannot be understood as a limitation on the present application.

[0055] The specific embodiments of the present application have been described above. It should be understood that the present application is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which does not affect the essential content of the present application. In the case of no conflict, the embodiments of the present application and the features in the embodiments can be arbitrarily combined.

Claims

1. A W-band mixer test fixture, characterized in that, include: Intermediate frequency interface, local oscillator interface, upper cavity of structure, lower cavity of structure, radio frequency interface; After the upper cavity and the lower cavity of the structure are spliced ​​together, a circular flange radio frequency interface is formed on the outside, and a signal transmission line is formed inside. Microstrip lines are used as signal transmission lines. The intermediate frequency interface is connected to the microstrip lines, and the microstrip lines transmit intermediate frequency signals to the intermediate frequency interface of the mixer. The local oscillator interface is connected to the local oscillator frequency multiplication link to multiply the microwave signal to a millimeter-wave signal, providing the local oscillator signal for the mixer; the RF signal generated after mixing is output through the microstrip line to waveguide to microstrip line conversion interface, i.e., the RF interface; The radio frequency interface uses the WR-10 standard flange.

2. The W-band mixer test fixture according to claim 1, characterized in that, The impedance of the microstrip transmission line is matched to the input and output ports of the mixer under test.

3. The W-band mixer test fixture according to claim 1, characterized in that, A waveguide-to-microstrip conversion structure is adopted to realize the conversion between waveguide signals and microstrip signals. The conversion structure is a W-band coupled probe transition structure.

4. The W-band mixer test fixture according to claim 1, characterized in that, The system employs a local oscillator frequency doubling link, where an external local oscillator provides the microwave signal, and an internal frequency doubling mechanism generates the W-band local oscillator signal.

5. The W-band mixer test fixture according to claim 1, characterized in that, The intermediate frequency interface, local oscillator interface, and radio frequency interface each have signal attenuators and filters to adjust the amplitude of the test signal and filter out interference signals.

6. The W-band mixer test fixture according to claim 1, characterized in that, Transmission lines are reserved for the intermediate frequency interface, local oscillator interface, and radio frequency interface.

7. The W-band mixer test fixture according to claim 1, characterized in that, The intermediate frequency interface and the local oscillator interface are located on one side of the spliced ​​upper cavity and lower cavity of the structure, while the radio frequency interface is located on the other side of the spliced ​​upper cavity and lower cavity of the structure.

8. A testing method, characterized in that, The test was performed using the W-band mixer test fixture as described in any one of claims 1 to 7.

9. The test method according to claim 8, characterized in that, include: Step 1) Generate RF / IF signals and local oscillator signals using a signal source; Step 2) Input the intermediate frequency (IF) signal and local oscillator (LO) signal to the mixer under test through the corresponding IF and LO ports of the fixture, respectively. Connect the RF port to the instrument's corresponding RF performance test interface to test the mixer's up-conversion performance. Input the RF signal and LO signal to the mixer under test through the corresponding IF and LO ports of the fixture, respectively. Connect the IF port to the instrument's corresponding IF performance test interface to test the mixer's down-conversion performance. Step 3) The mixer performs frequency mixing on the RF / IF signal and the local oscillator signal to generate the IF / RF signal; Step 4) The intermediate frequency (IF) / radio frequency (RF) signals are output to instruments such as a spectrum analyzer through the IF and RF interfaces of the fixture for measurement and analysis.

10. The test method according to claim 9, characterized in that, During the test, data logging software was used to record key data in real time, including frequency conversion loss, isolation, and phase noise. After the test is completed, the recorded data is organized and analyzed to evaluate whether the mixer's performance meets the design requirements; at the same time, the results under different test conditions are compared to analyze possible influencing factors and sources of error.

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