Harmonic distortion test system
By using a phase-shifting unit to cancel the fundamental signal in the harmonic distortion testing system and directly inputting it into the harmonic testing equipment, the cost and accuracy problems of attenuators and high-pass filters in traditional systems are solved, realizing low-cost and high-precision harmonic signal testing.
Patent Information
- Application Number
- CN202423135351.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-18
- Publication Date
- 2025-11-07
- Estimated Expiration
- 2034-12-18
AI Technical Summary
In traditional harmonic distortion testing systems, attenuators and high-pass filters need to be set after the object under test to suppress the fundamental signal power, resulting in high system cost and affecting test accuracy.
By splitting the fundamental signal of the signal generator into two paths, using a phase-shifting unit to make the two signals out of phase, and canceling the fundamental signal when combining them, the harmonic signal is directly input into the harmonic test equipment, avoiding the use of attenuators and high-pass filters.
This reduces system costs, improves test accuracy, avoids the influence of attenuators and high-pass filters on harmonic signals, ensures sufficient harmonic signal power, and enhances the accuracy of test results.
Smart Images
Figure CN223528079U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the field of radio frequency, in particular to a harmonic distortion test system. BACKGROUND
[0002] The radio frequency harmonic distortion test is a test method for evaluating the harmonic components in the output signal of a to-be-tested object. The radio frequency harmonic distortion refers to the harmonic components with integer times of the fundamental frequency signal generated due to the nonlinear characteristics of the to-be-tested object in the transmission, processing or amplification process of the radio frequency signal, and the harmonic components are harmonic signals. For example, in the single-tone IIP3 (Input Third-order Intercept Point) test, the fundamental wave signal is sent to the to-be-tested object, and the to-be-tested object will be excited to generate the third harmonic signal. The to-be-tested object can be a to-be-tested device, a to-be-tested chip or a to-be-tested radio frequency substrate, etc.
[0003] In order to accurately measure the power of the third harmonic signal generated by the to-be-tested object, it is necessary to have a large power of the fundamental wave signal passing through the to-be-tested object, and the fundamental wave signal will be output together with the third harmonic signal by the to-be-tested object. If the spectrum analyzer is directly connected to the to-be-tested object to test the third harmonic signal, the high-power fundamental wave signal will damage the spectrum analyzer. Therefore, an attenuator and a high-pass filter must be added after the to-be-tested object to suppress the power of the fundamental wave signal, and then the third harmonic signal can be input into the spectrum analyzer to prevent the spectrum analyzer from being damaged due to the excessive input power. Therefore, in the traditional harmonic distortion test system, the attenuator and the high-pass filter must be set in the subsequent circuit of the to-be-tested object. If the harmonic performance of the attenuator and the high-pass filter is insufficient, the test accuracy will be affected. CONTENT OF THE INVENTION
[0004] The present application proposes a harmonic distortion test system, which does not need to set an attenuator and a high-pass filter after the to-be-tested object, reduces the system cost, and avoids the influence of the attenuator and the high-pass filter on the test accuracy.
[0005] The system comprises: a signal generator configured to generate a fundamental wave signal; a first power divider configured to divide the fundamental wave signal into a first signal and a second signal; a first branch into which the first signal enters; a second branch into which the second signal enters; wherein the first branch has a connection position of the object to be measured; the first branch or the second branch has a phase shift unit, the phase shift unit satisfies: the first signal passes through the first branch and outputs a first branch signal, the first branch signal contains a harmonic signal of the object to be measured; the second signal passes through the second branch and outputs a second branch signal; the phase of the first signal in the first branch signal is opposite to the phase of the second signal in the second branch signal; a second power divider connected to the output end of the first branch and the output end of the second branch, configured to combine the first branch signal and the second branch signal, and output a combined signal to a harmonic test device.
[0006] Optionally, the phase shift unit is located in the second branch and configured to receive the second signal and shift the phase of the second signal by 180 degrees.
[0007] Optionally, the phase shift unit is located in the first branch.
[0008] The phase shift unit is connected between the first power divider and the object to be measured, or the phase shift unit is connected between the object to be measured and the second power divider, and the phase shift unit also shifts the phase of the first signal by 180 degrees.
[0009] Optionally, the system further comprises:
[0010] A power amplifier connected between the signal generator and the first power divider, configured to amplify the fundamental wave signal generated by the signal generator.
[0011] A filtering device connected between the power amplifier and the first power divider, configured to filter out interference signals generated by the power amplifier.
[0012] Optionally, the filtering device is a low-pass filter; and
[0013] The first power divider further divides the harmonic signal of the low-pass filter into a first interference signal and a second interference signal.
[0014] The phase shift unit is further configured to shift the phase of the first interference signal or the second interference signal by 540 degrees.
[0015] Optionally, the phase shift unit is a transmission line phase shifter.
[0016] Optionally, the harmonic test device is a spectrum analyzer.
[0017] Optionally, the first power divider and / or the second power divider is any one of a resistive power divider, a waveguide power divider, a coaxial power divider or a microstrip power divider.
[0018] Optionally, the first signal and the second signal have the same power.
[0019] The test system provided in the present application divides the fundamental wave signal generated by the signal generator into a first signal and a second signal through the first power divider, the first signal enters the first branch, and the second signal enters the second branch; the to-be-tested object is located in the first branch and generates a harmonic signal based on the first signal; the phase shift unit is located in the first branch or the second branch and is used for phase shifting the first signal or the second signal, so that the phases of the first signal and the second signal (the fundamental wave signal divided by power) are opposite, so that when the second power divider combines the signals of the first branch and the second branch, the first signal and the second signal are cancelled, and only the harmonic signal is reserved, which can effectively test the harmonic signal of the to-be-tested object.
[0020] In the scheme, since the input signal of the harmonic analysis device only includes the harmonic signal of the to-be-tested object, the power of the harmonic signal is much smaller than that of the fundamental wave signal, the harmonic signal can be directly connected to the harmonic analysis device (without causing high-power damage) and does not excite the nonlinearity of the harmonic analysis device. The scheme does not need to add an attenuator after the to-be-tested object to reduce the power of the fundamental wave signal, so the harmonic signal will not be attenuated, so that the power of the harmonic signal entering the harmonic analysis device is large enough, further improving the test accuracy.
[0021] The scheme of the present application does not need to add an attenuator after the to-be-tested object to reduce the power of the fundamental wave signal, and does not need to add a high-pass filter after the attenuator to filter out the fundamental wave signal, avoiding the use of high-cost attenuators and high-pass filters, which is beneficial to reduce the cost.
[0022] In addition, the scheme of the present application does not need to use an attenuator and a high-pass filter, which can avoid the generation of harmonic signals by the attenuator, the high-pass filter and the like, thereby avoiding the influence on the harmonic signal of the to-be-tested object, and improving the test accuracy.
[0023] In some embodiments, a power amplifier and a filter device are further included in front of the object to be measured, the power amplifier is used to amplify the fundamental wave signal, and the filter device is used to filter out the interference signal generated by the power amplifier. Because the filter device can generate its harmonic signal, it can affect the harmonic signal of the object to be measured. In the present scheme, the first power divider further divides the harmonic signal of the low-pass filter into a first interference signal and a second interference signal; the phase shift unit is further used to shift the phase of the first interference signal or the second interference signal by 540 degrees. Therefore, when the second power divider combines the signals of the first branch and the second branch, the first interference signal or the second interference signal is cancelled out, and only the harmonic signal is retained, which can effectively test the harmonic signal of the object to be measured. Because the harmonic signal of the filter device is also cancelled out, the filter device does not need to use expensive and high-performance equipment, and the overall test accuracy can be improved. BRIEF DESCRIPTION OF DRAWINGS
[0024] Figure 1 A third harmonic measurement system.
[0025] Figure 2 A structure diagram of a harmonic distortion test system according to an embodiment of the present application.
[0026] Figure 3 A structure diagram of another harmonic distortion test system according to an embodiment of the present application. DETAILED DESCRIPTION
[0027] As Figure 1 shown, a third harmonic measurement system generally includes the following parts:
[0028] Signal generator: generates a fundamental wave signal (frequency f1, corresponding wavelength λ1), and the signal generator generates a third harmonic signal (frequency f3, corresponding wavelength λ3, where f3 = f1 x 3, λ3 = λ1 / 3);
[0029] Power amplifier: amplifies the fundamental wave signal generated by the signal generator, and the power amplifier generates a third harmonic signal (frequency f3, corresponding wavelength λ3, where f3 = f1 x 3, λ3 = λ1 / 3);
[0030] Low-pass filter: filters out the third harmonic signal generated by the signal generator and the power amplifier, and ensures that the fundamental wave signal entering the device to be measured is relatively pure;
[0031] Device to be measured: receives the fundamental wave signal and generates a third harmonic signal of the device to be measured;
[0032] Attenuator: attenuate the power of fundamental wave signal and third harmonic wave signal output by the device under test, reduce the influence of high-power fundamental wave signal on the later-stage device, and reduce the signal power reflected from the high-pass filter to the device under test;
[0033] High-pass filter: filter out the fundamental wave signal and retain the third harmonic wave signal of the device under test, so as to ensure that the fundamental wave signal does not excite the self-harmonic wave signal of the spectrum analyzer.
[0034] After the fundamental wave signal generated by the signal generator passes through the above devices in turn, only the third harmonic wave signal generated by the device under test (including the device under test or the element under test) will enter the spectrum analyzer for testing in an ideal state. However, since the fundamental wave signal can also excite the passive devices such as the attenuator and the high-pass filter to generate harmonic wave signals, the detection result of the third harmonic wave signal of the device under test is affected.
[0035] Therefore, the present application proposes a new harmonic distortion test system, which does not need to set an attenuator and a high-pass filter after the device under test, reduces the system cost, and avoids the influence of the attenuator and the high-pass filter on the test accuracy.
[0036] Figure 2 A structure diagram of the harmonic distortion test system of the present application is shown in the figure, which mainly includes a signal generator 201, a first power divider 202, a first branch 203, a second branch 204, and a second power divider 205. The signal generator 201 is used to generate a fundamental wave signal to excite the device under test to generate the third harmonic wave signal required for testing. The first power divider 202 is connected to the output end of the signal generator 201, and is used to divide the fundamental wave signal into first and second signals with the same power. The first signal enters the first branch 203, and the second signal enters the second branch 204. The first branch 203 has a connection position for connecting the device under test 206. The second power divider 205 is connected to the output end of the first branch 203 and the output end of the second branch 204, and is used to combine the first branch signal output by the first branch 203 and the second branch signal output by the second branch 204, and output the combined signal to a harmonic test device 207, such as a spectrum analyzer. The first branch signal includes the third harmonic wave signal of the device under test. In addition, the first power divider and / or the second power divider can include any one of a resistive power divider, a waveguide power divider, a coaxial power divider, or a microstrip power divider.
[0037] In order to eliminate the fundamental wave signal, a phase shift unit 208 can be arranged in the first branch 203 or the second branch 204, so that the phase of the first signal in the first branch signal and the phase of the second signal in the second branch signal are opposite. Thus, the first signal and the second signal after combination can cancel each other out, and only the third harmonic wave signal of the device under test is input to the harmonic test device. The phase shift unit 208 is preferably a transmission line phase shifter.
[0038] In some embodiments, such as Figure 2 As shown, when the phase-shifting unit 208 is located in the second branch 204, it receives the second signal and shifts its phase by 180 degrees. Therefore, when the second power divider 205 combines the first branch signal output from the first branch 203 with the second branch signal output from the second branch 204, the phase-shifted second signal in the second branch 204 is out of phase with the first signal in the first branch 203. The phase-shifted second signal cancels out the first signal, and the harmonic signal of the object under test 206 in the first branch 203 is retained. Therefore, the combined signal includes the harmonic signal of the object under test 206 but does not include the high-power fundamental signal. This scheme eliminates the need to add an attenuator after the object under test to reduce the power of the fundamental signal, thus avoiding attenuation of the harmonic signal. This ensures that the power of the harmonic signal entering the harmonic analysis equipment is sufficiently high, further improving the test accuracy.
[0039] The solution proposed in this application eliminates the need for an attenuator after the object under test to reduce the power of the fundamental signal, and also eliminates the need for a high-pass filter after the attenuator to filter out the fundamental signal. This avoids the use of costly attenuators and high-pass filters, thus reducing costs. Furthermore, the solution eliminates the need for attenuators and high-pass filters, preventing the generation of harmonic signals by these components and thus avoiding their influence on the harmonic signals of the object under test, thereby improving the accuracy of the test.
[0040] In addition, in some cases, a power amplifier 209 and a filter 210 can be installed in front of the object under test 206, such as... Figure 2 As shown in the diagram. Power amplifier 209 is connected between signal generator 201 and first power divider 202 to amplify the fundamental signal generated by signal generator 201. A filter device is connected between power amplifier 209 and first power divider 202 to filter out interference signals generated by power amplifier 209. The filter device 210 can be a low-pass filter, which, when excited by the high-power fundamental signal, generates an interfering third harmonic signal. After passing through the first power divider 202, the interfering third harmonic signal is divided into a first interference signal and a second interference signal. The first interference signal enters the first branch 203, and the second interference signal enters the second branch 204. Based on the position of the phase shifting unit 208, the phase shifting unit 208 shifts the second interference signal by 180 × 3 = 540 degrees, which is equivalent to shifting its phase by 180 degrees. The phase of the first interference signal remains unchanged, so the phase-shifted second interference signal cancels out the first interference signal after combining, and does not interfere with the test results.
[0041] The phase shifting unit 208 can be a transmission line phase shifter. A transmission line phase shifter is a device that adjusts the phase of a signal using the characteristics of a transmission line. It changes the phase of the signal as it passes through the transmission line by altering the electrical or physical length of the transmission line and by utilizing specific material properties (such as dielectric constant), without changing the signal amplitude. The energy of the harmonic signals generated by this transmission line phase shifter is far less than that generated by other devices and the object under test, thus avoiding any impact on the test results. Furthermore, the phase shift angle of the third harmonic signal by the transmission line phase shifter is three times that of the fundamental signal, which facilitates achieving phase reversal between the first and second signals, and between the second and first interference signals.
[0042] In some embodiments, such as Figure 3 As shown, the phase shifting unit 208 can also be set in the first branch 203. Figure 3 The illustrated embodiments and Figure 2 The difference in the embodiment shown is that the phase shifting unit 208 is located in the first branch 203.
[0043] like Figure 3 As shown, when the phase shifting unit 208 is located in the first branch 203, it can be connected between the first power divider 202 and the object under test 206, or it can be located between the object under test 206 and the second power divider 205. The phase shifting unit 208 can shift the phase of the first signal by 180 degrees. The second signal in the second branch 204 is not shifted. Therefore, when combined, the phases of the first and second signals are opposite and cancel each other out. The harmonic signals of the object under test 206 in the first branch 203 are retained. Thus, the combined signal includes the harmonic signals of the object under test 206 but does not include the high-power fundamental signal. This scheme eliminates the need to add an attenuator after the object under test to reduce the power of the fundamental signal, thus avoiding attenuation of the harmonic signals. This ensures that the power of the harmonic signals entering the harmonic analysis equipment is sufficiently high, further improving the test accuracy.
[0044] A power amplifier 209 and a filter 210 can also be installed in front of the object under test 206, such as... Figure 3The power amplifier 209 is connected between the signal generator 201 and the first power divider 202, and is configured to amplify the fundamental wave signal generated by the signal generator 201. The filter device is connected between the power amplifier 209 and the first power divider 202, and is configured to filter out the interference signal generated by the power amplifier 209. The filter device 210 can be a low-pass filter. When the low-pass filter is excited by the high-power fundamental wave signal, the interference third harmonic signal is generated. After passing through the first power divider 202, the interference third harmonic signal is divided into the same first interference signal and the second interference signal. The first interference signal enters the first branch 203, and the second interference signal enters the second branch 204. Based on the position of the phase shift unit 208, the phase shift unit 208 will phase shift the first interference signal by 180 x 3 = 540 degrees, which is equivalent to phase shifting the first interference signal by 180 degrees. The phase of the second interference signal remains unchanged. Therefore, the first interference signal after phase shift and the second interference signal after phase shift are cancelled out after combination, and do not interfere with the test results.
[0045] The above describes the embodiments of the application by specific examples. Those skilled in the art can easily understand other advantages and effects of the application from the disclosure. Although the description of the application is introduced in combination with the preferred embodiments, it does not mean that the features of the application are limited to the embodiments. In addition, in order to avoid confusion or obscure the focus of the application, some specific details will be omitted in the description. It should be noted that the embodiments in the application and the features in the embodiments can be combined with each other without conflict.
[0046] In addition, various operations will be described as multiple discrete operations, which will be performed in a manner most helpful to understanding the illustrative embodiments; however, the order of the operations is not to be construed as a requirement. In particular, the operations can not be performed in the order presented.
[0047] Unless otherwise defined, the terms "comprises", "comprising", and "including" are synonymous with the term "comprising". The phrase "A / B" means "A or B". The phrase "A and / or B" means "(A and B) or (A or B)".
[0048] As used herein, the terms "module" or "unit" can refer to, be or include an application specific integrated circuit (ASIC), an electronic circuit, a processor and / or memory (shared, dedicated, or group) that execute one or more software or firmware programs, a combinational logic circuit, and / or other suitable components that provide the described functionality.
[0049] In the drawings, some structural or methodological features are shown in particular arrangements and / or orders. However, it should be understood that such particular arrangements and / or orders can not be required. In some embodiments, these features can be arranged in a different manner and / or order than shown in the illustrative drawings. Additionally, inclusion of a structural or methodological feature in a particular figure is not meant to imply that such feature is required in all embodiments, and in some embodiments, these features can not be included or can be combined with other features.
[0050] It should be understood that, although terms such as "first," "second," and the like can be used herein to describe various elements or data, these elements or data should not be limited by these terms. These terms are only used to distinguish one feature from another. For example, a first feature could be termed a second feature, and, similarly, a second feature could be termed a first feature without departing from the scope of the example embodiments.
[0051] It should be noted that in this specification, similar reference numbers and letters in the drawings represent similar items, and thus, once an item is defined in one drawing, it need not be further defined and explained in subsequent drawings.
[0052] While the present application has been illustrated and described in connection with certain preferred embodiments thereof, it will be readily apparent to those of ordinary skill in the art that various changes in form and detail can be made therein without departing from the spirit and scope of the application.
Claims
1. A harmonic distortion test system characterized by, A system for harmonic testing of a DUT, comprising: a signal generator for generating a fundamental signal; a first power divider for dividing the fundamental signal into a first signal and a second signal; a first branch into which the first signal is inputted; a second branch into which the second signal is inputted; wherein the first branch has a connection position of the DUT; the first branch or the second branch has a phase shift unit, which satisfies: the first signal is outputted as a first branch signal after passing through the first branch, and the first branch signal contains harmonic signals of the DUT; the second signal is outputted as a second branch signal after passing through the second branch; the phase of the first signal in the first branch signal is opposite to the phase of the second signal in the second branch signal; a second power divider connected to the output end of the first branch and the output end of the second branch for combining the first branch signal and the second branch signal, and the combined signal is outputted to a harmonic testing device.
2. The system of claim 1, wherein the phase shift unit is located in the second branch for receiving the second signal and shifting the phase of the second signal by 180 degrees.
3. The system of claim 1, wherein, the phase shift unit is located in the first branch; the phase shift unit is connected between the first power divider and the DUT, or the phase shift unit is connected between the DUT and the second power divider, and the phase shift unit also shifts the phase of the first signal by 180 degrees.
4. The system of claim 1, wherein, further comprising: a power amplifier connected between the signal generator and the first power divider for amplifying the fundamental signal generated by the signal generator; a filtering device connected between the power amplifier and the first power divider for filtering out interference signals generated by the power amplifier.
5. The system of claim 4, wherein, the filtering device is a low-pass filter; and the first power divider also divides harmonic signals of the low-pass filter into a first interference signal and a second interference signal; the phase shift unit is also used for shifting the phase of the first interference signal or the second interference signal by 540 degrees.
6. The system of any one of claims 1-5, wherein, the phase shift unit is a transmission line phase shifter.
7. The system of any of claims 1-5, wherein, the harmonic testing device is a spectrum analyzer.
8. The system of any one of claims 1-5, wherein, the first power divider and / or the second power divider is any one of a resistive power divider, a waveguide power divider, a coaxial power divider or a microstrip power divider.
9. The system of any of claims 1-5, wherein, the power of the first signal and the power of the second signal are the same.