Radio frequency test circuit and radio frequency test machine
By adding filter groups and switch groups to the RF test circuit, the problem of insufficient testing capabilities of RF test machines for high-frequency and low-amplitude harmonic signals is solved, and higher testing sensitivity and accuracy are achieved.
Patent Information
- Application Number
- CN202421091190.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-05-17
- Publication Date
- 2025-01-07
- Estimated Expiration
- 2034-05-17
AI Technical Summary
The existing RF test machines have insufficient frequency index range and are unable to effectively test harmonic signals in high frequency bands and low amplitudes, resulting in insufficient test sensitivity and accuracy.
A radio frequency test circuit is designed to increase the test sensitivity by adding two expandable filter banks and switch groups, combining the out-of-band rejection performance of the filter, covering the wide band and reducing the power of the harmonic signal.
Effective testing of wide-band and low-amplitude harmonic signals is achieved, reducing interference, improving test sensitivity and accuracy, and avoiding equipment damage caused by excessive signal.
Smart Images
Figure CN222321547U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of radio frequency testing, in particular to a radio frequency testing circuit and a radio frequency testing machine. Background Art
[0002] As the usage of the Internet continues to grow, communication technology is increasingly dependent on wireless spectrum. The opening of the WiFi 6E frequency band has brought the wireless spectrum up to 7.125GHz. Harmonic testing is an essential test indicator in mass production testing. When testing the third harmonic of products applied to the 7.125GHz frequency band, the ATE measurement frequency indicator needs to reach above 21.375GHz, which will place very high demands on the frequency indicator of the tester itself. At the same time, the main frequency signal of some products is above 30dBm, and the harmonic signal may be below -50dBm. At this time, the main frequency power and harmonic power of the signal differ greatly, which will place very high demands on the measurement dynamic range of the tester. The measurement dynamic range of the signal refers to the ratio of the maximum value to the minimum value of the variable signal power at the same measurement moment.
[0003] The frequency index range of existing RF testers is 0.915-1.648GHz, and the amplitude index range is greater than or equal to -60dBm. Harmonics with a wider frequency range and lower amplitude cannot be tested. Utility Model Content
[0004] In view of this, the utility model provides a radio frequency test circuit and a radio frequency test machine to solve the problem that the frequency range of harmonics that can be tested in the prior art is narrow and the amplitude is high.
[0005] In a first aspect, the utility model provides a radio frequency test circuit, comprising: a signal source, a switch group, a first filter group and a second filter group cascaded through the switch group, and an output module, wherein:
[0006] A signal source, used for providing a test signal;
[0007] The first filter group includes at least two filters connected in parallel, the passbands of the filters are sequentially arranged, the input end of the filter inputs the test signal, and the output end of the filter is connected to the input end of the external device under test, so as to filter the interference signal in the test signal;
[0008] The test signal generates a harmonic signal through the external device under test, and the harmonic signal includes a fundamental component and a harmonic component;
[0009] A second filter group, comprising at least two filters connected in parallel, wherein the passbands of the filters are sequentially arranged, wherein the input end thereof is connected to the output end of the external device under test, and the output end thereof is connected to the output module, and is used for filtering the fundamental wave component of the harmonic signal;
[0010] The switch group enables a filter in the first filter group and a filter in the second filter group to be connected to the radio frequency test circuit;
[0011] The output module is used for outputting the harmonic components of the harmonic signal.
[0012] The radio frequency test circuit provided by the utility model achieves the effect of being able to test wide frequency bands and lower amplitude harmonics by adding two expandable filter groups, increases the isolation between ports by using a switch group, reduces interference by using the out-of-band suppression performance of the filter group, and improves the test sensitivity.
[0013] In an optional implementation, the radio frequency test circuit further includes: an attenuator, whose input end is connected to the output end of the external device under test, and whose output end is connected to the input end of the second filter circuit, for attenuating the power of the harmonic signal.
[0014] In an optional implementation, the attenuator is a fixed attenuator.
[0015] The radio frequency test circuit provided by the utility model reduces the power of harmonic signals and the signal strength by connecting an attenuator, so as to avoid damage to the test equipment due to excessive signal.
[0016] In an optional implementation, the number of filters in the first filter group is equal to the number of filters in the second filter group.
[0017] The utility model provides a radio frequency test circuit, in which the number of filters in the first filter group is equal to the number of filters in the second filter group. When the frequencies of the test signals are different, a filter is correspondingly selected from the first filter group and the second filter group. The utility model is simple and convenient to use, and has a good filtering effect.
[0018] In an optional implementation, in the first filter group, an upper sideband of a previous filter and a lower sideband of a subsequent filter are the same or differ by less than 0.1 GHz;
[0019] In the second filter group, the upper sideband of the previous filter and the lower sideband of the next filter are the same or differ by less than 0.1 GHz.
[0020] In the radio frequency test circuit provided by the utility model, the passbands of adjacent filters in each filter group are arranged in sequence and continuously, and the upper sideband of the previous filter is the same as the lower sideband of the next filter or differs by less than 0.1GHz, thereby avoiding missing individual frequencies, ensuring complete coverage of a wide range of frequencies, and improving the accuracy of the test.
[0021] In an optional implementation, the filters in the first filter group are low-pass filters, and the filters in the second filter group are high-pass filters.
[0022] The utility model provides a radio frequency test circuit, in which a low-pass filter is selected in the first filter group to allow a test signal to pass through and block an interference signal in a signal source, and in which a high-pass filter is selected in the second filter group to allow a harmonic component in a harmonic signal to pass through and block a fundamental component in the harmonic signal, thereby reducing signal interference and improving test sensitivity.
[0023] In an optional implementation, the switch group includes: a first switch, a second switch, a third switch, and a fourth switch, wherein:
[0024] A first switch, a first end of which is connected to the output end of the signal source, and a second end of which is connected to the input end of the first filter group;
[0025] A second switch, a first end of which is connected to the output end of the first filter group, and a second end of which is connected to the input end of the external device under test;
[0026] A third switch, a first end of which is connected to the output end of the external device under test, and a second end of which is connected to the input end of the second filter group;
[0027] A fourth switch has a first end connected to the output end of the second filter group, and a second end connected to the input end of the output module.
[0028] In the radio frequency test circuit provided by the utility model, a switch is respectively arranged at both ends of the first filter group and the second filter group, so as to increase the isolation between the ports, reduce interference and improve the sensitivity of the test.
[0029] In an optional implementation, the first switch, the second switch, the third switch, and the fourth switch are all single-pole multi-throw switches.
[0030] The radio frequency test circuit provided by the utility model has a single-pole multi-throw switch arranged at both ends of the first filter group and the second filter group respectively, which has a simple structure and is easy to control.
[0031] In an optional implementation, the number of passive contacts of the single-pole multi-throw switch is greater than or equal to the number of filters in the first filter group.
[0032] The radio frequency test circuit provided by the utility model and the number of passive contacts of the single-pole multi-throw switch can ensure that any filter in the first filter group and the second filter group is connected, and that all filters can be connected to the radio frequency test circuit, fully covering a wide range of frequencies.
[0033] In a second aspect, the utility model provides a radio frequency tester, the radio frequency tester comprising the radio frequency test circuit of any one of the first aspects.
[0034] The radio frequency tester provided by the utility model utilizes the radio frequency test circuit of the first aspect and achieves the effect of covering a wide frequency band and lower amplitude harmonics by adding two expandable filter groups. The isolation between ports is increased by using a switch group, and the out-of-band suppression performance of the filter group is used to reduce interference, thereby improving the test sensitivity. BRIEF DESCRIPTION OF THE DRAWINGS
[0035] In order to more clearly illustrate the specific implementation methods of the utility model or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.
[0036] Figure 1 is a schematic structural diagram of a radio frequency test circuit according to an embodiment of the utility model;
[0037] Figure 2 is a structural schematic diagram of another radio frequency test circuit according to an embodiment of the utility model;
[0038] Figure 3 is a structural schematic diagram of another radio frequency test circuit according to an embodiment of the utility model;
[0039] Figure 4 is a structural schematic diagram of yet another radio frequency test circuit according to an embodiment of the utility model;
[0040] Figure 5 It is a structural schematic diagram of a specific embodiment of the radio frequency test circuit according to the embodiment of the utility model;
[0041] Figure 6 It is a structural schematic diagram of a radio frequency testing machine according to an embodiment of the utility model. DETAILED DESCRIPTION
[0042] In order to make the purpose, technical solution and advantages of the embodiment of the utility model clearer, the technical solution in the embodiment of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiment of the utility model. Obviously, the described embodiment is a part of the embodiment of the utility model, not all the embodiments. Based on the embodiment of the utility model, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the utility model.
[0043] The embodiment of the utility model provides a radio frequency test circuit and a radio frequency test machine, which achieve the effect of covering a wide frequency band and low-amplitude harmonic testing by adding two expandable filter groups.
[0044] According to an embodiment of the utility model, a radio frequency test circuit embodiment is provided. Figure 1 is a schematic diagram of the structure of a radio frequency test circuit according to an embodiment of the utility model, such as Figure 1 As shown, the radio frequency test circuit includes:
[0045] A signal source 1, a switch group 2, a first filter group 3 and a second filter group 4 cascaded through the switch group, and an output module 5, wherein:
[0046] The signal source 1 is used to provide a test signal.
[0047] Specifically, the signal source 1 can output a test signal of a fixed frequency and can be a commonly used signal source 1 device, which is not limited here.
[0048] The first filter group 3 includes at least two filters connected in parallel, the passbands of the filters are set successively in sequence, the input end of the filter inputs the test signal, and the output end of the filter is connected to the input end of the external device under test DUT, so as to filter the interference signal in the test signal.
[0049] The test signal generates a harmonic signal through the external device under test (DUT), and the harmonic signal includes a fundamental component and a harmonic component.
[0050] Specifically, the passbands of multiple filters in the first filter group 3 are set successively in sequence, so that the frequency range of the test signal of the RF test circuit is wider. During each test, one filter in the first filter group 3 is selected and connected according to the frequency of the test signal, and the passband range of the selected filter includes the frequency of the fundamental component in the test signal. When the test signal passes through the filter, the fundamental component of the test signal passes through the filter, and the harmonic components of the test signal and other interference signals are blocked, thereby reducing signal interference.
[0051] The second filter group 4 includes at least two filters connected in parallel, the passbands of the filters are set successively in sequence, the input end of the filter is connected to the output end of the external device under test DUT, and the output end of the filter is connected to the output module 5, for filtering the fundamental component of the harmonic signal.
[0052] Specifically, each time a test is performed, a filter in the second filter group 4 is selected according to the frequency of the filter in the first filter group 3. The passband range of the selected filter does not include the frequency of the fundamental component in the test signal. After passing through the external device under test DUT, the harmonic component in the harmonic signal passes through the filter, and the fundamental component in the harmonic signal is blocked, thereby reducing signal interference.
[0053] The filters in the first filter group 3 and the second filter group 4 have extremely high out-of-band suppression performance, and the high suppression degree ensures that the radio frequency test circuit can test harmonics with lower amplitudes.
[0054] The switch group 2 enables a filter in the first filter group 3 and a filter in the second filter group 4 to be connected to the radio frequency test circuit.
[0055] Specifically, the switch group 2 may be a switch provided at both ends of each filter, and the filter connected to the radio frequency test circuit is selected by controlling the opening and closing of each switch, which is only taken as an example, but not limited thereto.
[0056] The output module 5 is used to output the harmonic components of the harmonic signal.
[0057] Specifically, the output module 5 may be a spectrum analyzer, an oscilloscope, etc., which is only taken as an example but not limited thereto, and is used to display the test result of the external device under test DUT.
[0058] The radio frequency test circuit provided by the embodiment of the utility model achieves the effect of covering a wide frequency band and lower amplitude harmonics by adding two expandable filter groups, increases the isolation between ports by using the switch group 2, reduces interference by using the out-of-band suppression performance of the filter group, and improves the test sensitivity.
[0059] In some optional embodiments, such as Figure 2 As shown, the radio frequency test circuit also includes: an attenuator ATT, whose input end is connected to the output end of the external device under test DUT, and whose output end is connected to the input end of the second filter circuit, for attenuating the power of the harmonic signal.
[0060] In some optional embodiments, such as Figure 3 As shown, the attenuator ATT is a fixed attenuator ATT.
[0061] Specifically, the attenuation of the fixed attenuator ATT is related to the maximum output signal of the external device under test DUT, and the signal strength of the maximum output signal of the external device under test DUT after attenuation by the fixed attenuator must be ≤30dBm to ensure that the subsequent single-pole multi-throw switch is not damaged. This is only an example, but not limited to this.
[0062] The radio frequency test circuit provided by the embodiment of the utility model reduces the power of the harmonic signal and the signal strength by connecting the attenuator ATT, so as to avoid the damage of the test equipment due to the excessive signal.
[0063] In some optional embodiments, such as Figure 3 As shown, the number of filters in the first filter group 3 is equal to the number of filters in the second filter group 4.
[0064] In the radio frequency test circuit provided by the embodiment of the utility model, the number of filters in the first filter group 3 is equal to the number of filters in the second filter group 4. When the frequencies of the test signals are different, a filter is correspondingly selected from the first filter group 3 and the second filter group 4. The use is simple and convenient, and the filtering effect is good.
[0065] In some optional implementations, in the first filter group 3, the upper sideband of the previous filter and the lower sideband of the next filter are the same or differ by less than 0.1 GHz.
[0066] In the second filter group 4, the upper sideband of the previous filter and the lower sideband of the next filter are the same or differ by less than 0.1 GHz.
[0067] In the radio frequency test circuit provided by the embodiment of the utility model, the passbands of adjacent filters in each filter group are arranged in sequence and continuously, and the upper sideband of the previous filter is the same as the lower sideband of the next filter or differs by less than 0.1 GHz, thereby avoiding missing individual frequencies, ensuring complete coverage of a wide range of frequencies, and improving the accuracy of the test.
[0068] In some optional embodiments, such as Figure 4 As shown, the filters in the first filter group 3 are low-pass filters, and the filters in the second filter group 4 are all high-pass filters.
[0069] In the radio frequency test circuit provided by the embodiment of the utility model, a low-pass filter is selected in the first filter group 3 to allow the test signal to pass through and block the interference signal in the signal source 1, and a high-pass filter is selected in the second filter group 4 to allow the harmonic components in the harmonic signal to pass through and block the fundamental component in the harmonic signal, thereby reducing signal interference and improving test sensitivity.
[0070] In some optional embodiments, such as Figure 4 As shown, the switch group 2 includes: a first switch 21, a second switch 22, a third switch 23, and a fourth switch 24, wherein:
[0071] The first switch 21 has a first end connected to the output end of the signal source 1 , and a second end connected to the input end of the first filter group 3 .
[0072] The second switch 22 has a first end connected to the output end of the first filter group 3 , and a second end connected to the input end of the external device under test DUT.
[0073] A third switch 23 has a first end connected to the output end of the external device under test DUT, and a second end connected to the input end of the second filter group 4 .
[0074] The fourth switch 24 has a first end connected to the output end of the second filter group 4 , and a second end connected to the input end of the output module 5 .
[0075] Specifically, the first switch 21, the second switch 22, the third switch 23, and the fourth switch 24 can respectively represent multiple switches, each switch is connected to the input end or the output end of a filter. This is just an example, but not limited to this. The first switch 21 and the second switch 22 jointly select a filter in the first filter group 3 to connect to the RF test circuit, and the third switch 23 and the fourth switch 24 jointly select a filter in the second filter group 4 to connect to the RF test circuit. For example, the first switch 21 at the input end of the second filter in the first filter group 3 and the second switch 22 at the output end are turned on at the same time, and the switches at both ends of the other filters are turned off. The second filter in the first filter group 3 is connected to the RF test circuit, and the selection of the filter in the second filter group 4 is similar, which will not be repeated.
[0076] In the radio frequency test circuit provided by the embodiment of the utility model, a switch is respectively arranged at both ends of the first filter group 3 and the second filter group 4, so as to increase the isolation between the ports, reduce interference, and improve the sensitivity of the test.
[0077] In some optional embodiments, such as Figure 5 As shown, the first switch 21, the second switch 22, the third switch 23, and the fourth switch 24 are all single-pole multi-throw switches.
[0078] In the radio frequency test circuit provided by the embodiment of the utility model, a single-pole multi-throw switch is respectively arranged at both ends of the first filter group 3 and the second filter group 4, which has a simple structure and is easy to control.
[0079] In some optional implementations, the number of passive contacts of the single-pole multi-throw switch is greater than or equal to the number of filters in the first filter group 3 .
[0080] Specifically, Figure 5 As shown, when the signal source 1 outputs a test signal of a preset frequency, in order to ensure the signal quality, multiple low-pass filters are connected at the output end of the signal source 1 through the first single-pole multi-throw switch and the second single-pole multi-throw switch, so that the test signal of the preset frequency can pass through, while the harmonics and other signals in the signal source 1 are blocked, thereby reducing the interference of the harmonics in the signal source 1. When the test signal passes through the external device under test DUT, a harmonic signal is generated. In order to ensure the accuracy of the harmonic test, the fundamental component of the test signal needs to be filtered out. Therefore, after passing through the attenuator ATT, the third single-pole multi-throw switch and the fourth single-pole multi-throw switch are connected to multiple high-pass filters of corresponding frequencies, so that the harmonic components in the harmonic signal pass through, while the fundamental components are blocked, so that the accurate harmonic signal of the external device under test DUT is received on the spectrum analyzer. It should be noted that the low-pass filter and the high-pass filter need to be used in pairs, that is, the cut-off frequencies of the low-pass filter and the high-pass filter are the same.
[0081] It should be noted that multiple single-pole multi-throw switches and high-pass filter groups / low-pass filter groups together constitute a switch filter group module. In practical applications, by selecting a high-pass filter group / low-pass filter with high suppression and a single-pole multi-throw switch with high isolation, a wide-band and low-amplitude harmonic test function can be achieved.
[0082] The radio frequency test circuit provided by the embodiment of the utility model and the number of passive contacts of the single-pole multi-throw switch can ensure that any filter in the first filter group 3 and the second filter group 4 is connected, ensuring that all filters can be connected to the radio frequency test circuit and fully cover a wide range of frequencies.
[0083] In a specific embodiment, the low-pass filter in the first filter group 3 allows the fundamental component in the test signal to pass through while suppressing the harmonic component in the test signal by more than 100dBc to reduce the harmonic interference of the signal source 1; the high-pass filter in the second filter group 4 allows the harmonic component in the harmonic signal of the external device under test DUT to pass through while suppressing the fundamental component by more than 100dBc.
[0084] The system noise is generally around -85dBm. Considering the influence of noise and system, the final harmonic test sensitivity reaches -75dBm. Test sensitivity = test signal amplitude - suppression amplitude. In practical applications, when the test signal amplitude is 25dBm, the test sensitivity is equivalent to the system noise amplitude. If the test signal amplitude is less than 25dBm, the sensitivity is lower than the system noise, which will lead to inaccurate testing. Low amplitude is achieved by selecting a high-pass filter / low-pass filter group with high suppression to reduce system interference and crosstalk between frequency bands, so that low-amplitude harmonics can be tested.
[0085] In practical applications, by setting the number of combinations of high-pass filters / low-pass filters and the passband range, the test frequency range covers all frequency points of 0.1GHz-6GHz. For example, the 0.7GHz-3GHz broadband can be divided into 4 sub-bands of 0.7GHz-0.95GHz, 0.95GHz-1.35GHz, 1.35GHz-2.4GHz, and 2.4GHz-3GHz, corresponding to the selection of 4 low-pass filters and 4 high-pass filters; 0.1GHz-6GHz can increase the number of high-pass filter / low-pass filter combinations, and divide it into 6 sub-bands of 0.1GHz-0.7GHz, 0.7GHz-0.95GHz, 0.95GHz-1.35GHz, 1.35GHz-2.4GHz, 2.4GHz-3.6GHz, and 3.6GHz-6GHz, corresponding to the selection of 6 low-pass filters and 6 high-pass filters, which is only an example, but not limited to this. The wider the frequency, the more sub-bands need to be divided, and the more corresponding high-pass filter / low-pass filter combinations there are.
[0086] The present utility model provides a radio frequency tester, such as Figure 6 As shown, the radio frequency tester includes the radio frequency test circuit of any one of the above embodiments.
[0087] Specifically, other components of the radio frequency test machine are the same as those of the existing radio frequency test machine and will not be described in detail here.
[0088] The radio frequency tester provided by the embodiment of the utility model utilizes the radio frequency test circuit of the first aspect and achieves the effect of being able to test harmonics covering a wide frequency band and lower amplitude by adding two expandable filter groups. The switch group 2 is used to increase the isolation between ports, and the out-of-band suppression performance of the filter group is used to reduce interference, thereby improving the test sensitivity.
[0089] Although the embodiments of the present invention are described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations are all within the scope defined by the appended claims.
Claims
1. A radio frequency test circuit, characterized in that: The radio frequency test circuit comprises: a signal source, a switch group, a first filter group and a second filter group cascaded through the switch group, and an output module, wherein: A signal source, used for providing a test signal; A first filter group, comprising at least two filters connected in parallel, wherein the passbands of the filters are sequentially arranged, the test signal is input into the input end thereof, and the output end thereof is connected to the input end of the external device under test, for filtering interference signals in the test signal; The test signal generates a harmonic signal through the external device under test, and the harmonic signal includes a fundamental wave component and a harmonic wave component; A second filter group, comprising at least two filters connected in parallel, wherein the passbands of the filters are sequentially arranged, the input end of the filter is connected to the output end of the external device under test, and the output end of the filter is connected to the output module, for filtering the fundamental component of the harmonic signal; The switch group enables one filter in the first filter group and one filter in the second filter group to be connected to the radio frequency test circuit; An output module is used to output the harmonic components of the harmonic signal.
2. The circuit according to claim 1, characterized in that The radio frequency test circuit further includes: an attenuator, whose input end is connected to the output end of the external device under test, and whose output end is connected to the input end of the second filter group, for attenuating the power of the harmonic signal.
3. The circuit according to claim 2, characterized in that The attenuator is a fixed attenuator.
4. The circuit according to claim 1, characterized in that The number of filters in the first filter bank is equal to the number of filters in the second filter bank.
5. The circuit according to claim 4, characterized in that In the first filter group, the upper sideband of the previous filter is the same as the lower sideband of the next filter or differs by less than 0.1 GHz; In the second filter group, an upper sideband of a previous filter and a lower sideband of a subsequent filter are the same or differ by less than 0.1 GHz.
6. The circuit according to claim 1, characterized in that The filters in the first filter group are low-pass filters, and the filters in the second filter group are high-pass filters.
7. The circuit according to claim 1, characterized in that The switch group includes: a first switch, a second switch, a third switch, and a fourth switch, wherein: A first switch, a first end of which is connected to the output end of the signal source, and a second end of which is connected to the input end of the first filter group; A second switch, a first end of which is connected to the output end of the first filter group, and a second end of which is connected to the input end of the external device under test; A third switch, a first end of which is connected to the output end of the external device under test, and a second end of which is connected to the input end of the second filter group; A fourth switch has a first end connected to the output end of the second filter group, and a second end connected to the input end of the output module.
8. The circuit according to claim 7, characterized in that The first switch, the second switch, the third switch and the fourth switch are all single-pole multi-throw switches.
9. The circuit according to claim 8, characterized in that The number of passive contacts of the single-pole multi-throw switch is greater than or equal to the number of filters in the first filter group.
10. A radio frequency testing machine, characterized in that: The radio frequency tester comprises the radio frequency test circuit according to any one of claims 1 to 9.