EVM testing device and testing method thereof

Abstract

The present application discloses an EVM test device and a test method thereof, the device comprising a signal source, a waveform generator, a power amplifier and a spectrum analyzer. The signal source is used to output a radio frequency test signal. The waveform generator is used to output a dynamic synchronization signal to the power amplifier, the signal source and the spectrum analyzer, and the pulse period of the dynamic synchronization signal depends on the signal width, the predetermined protection delay and the dynamic duty cycle of the test signal. The power amplifier is used to receive the test signal and amplify and output it. The spectrum analyzer is used to receive the output signal of the power amplifier and perform demodulation calculation to obtain the EVM test result. The dynamic synchronization signal is turned on and off according to the period of the test signal, or kept on, to obtain the dynamic EVM test result and the static EVM test result respectively.

Description

Technical Field

[0001] The present invention relates to the field of wireless communication technology, and in particular to an EVM testing device and a testing method thereof. Background Art

[0002] In mobile terminals, due to the limited battery capacity, power saving and high efficiency have always been the direction of chip design. In the WIFI system, PA (power amplifier) ​​occupies a considerable part of the system DC power consumption, so new technologies are introduced to solve the PA power consumption problem. One of them is the PA dynamic working mode, which dynamically turns the PA on and off. In this mode, the system will issue an on and off command to control the on and off of the PA. We call this control signal the PA enable signal. This signal cooperates with the input signal of the PA and turns on and off synchronously with the input signal.

[0003] 1. When the signal is transmitted, the PA is turned on at the same time as the signal is transmitted, so that the PA is in working power consumption mode

[0004] 2. When the system is in the mode of receiving signals instead of transmitting signals, or the transmission signal is in the interval between each frame, turn off the PA to save power

[0005] 3. In order to maximize the power saving of PA, steps 1 and 2 need to be switched repeatedly at high speed. Figure 1 Schematic diagram showing PA enable signal and input signal captured by oscilloscope

[0006] The PA power-on and power-off process will bring transient thermal effects to the PA chip core, and the PA's working state and performance will decline. From another indicator, the PA's dynamic EVM (error vector magnitude). Dynamic EVM is a very important indicator of a PA chip. Whether it can be accurately measured and characterized in detail is a key step in PA design and development.

[0007] In WLAN (wireless local area network) systems, such as Wi-Fi 6, the next generation 802.11AX standard, PA is the last stage of the transmitter, and its role is to amplify the transmitted signal, so that the transmitted signal is enhanced and meets the WIFI standard. Among them, the calculation and evaluation of the EVM error vector (including the vector of amplitude and phase) is its core indicator. Since EVM is the preamble frame part in PA transmission, the transient thermal effect is very obvious for the dynamic switching PA, so the frame start performance will affect the test results of the entire EVM.

[0008] refer to Figure 2 As shown, in the above PA amplifier EVM test method, the PA amplifier EVM calculation adopts the following formula:

[0009]

[0010] Among them, I and Q are horizontal and vertical directions respectively. Summary of the invention

[0011] The object of the present invention is to provide an EVM testing device and a testing method thereof, which can accurately measure dynamic EVM.

[0012] The present application discloses an EVM test device, comprising: a signal source, a waveform generator, a power amplifier and a spectrum analyzer, wherein:

[0013] The signal source is used to output a radio frequency test signal;

[0014] The waveform generator is used to output a dynamic synchronization signal to the power amplifier, the signal source and the spectrum analyzer, wherein the pulse period of the dynamic synchronization signal depends on the signal width, the predetermined protection delay and the dynamic duty cycle of the test signal;

[0015] The power amplifier is used to receive the test signal and amplify and output it; and

[0016] The spectrum analyzer is used to receive the output signal of the power amplifier and perform demodulation calculation to obtain the EVM test result;

[0017] The dynamic synchronization signal is turned on and off according to the cycle of the test signal, or remains on, so as to obtain dynamic EVM test results and static EVM test results respectively.

[0018] In a preferred example, the power of the test signal is adjusted and an EVM test is performed until the EVM test result is greater than a target value.

[0019] In a preferred example, the frame length of the test signal is adjusted and an EVM test is performed, and the frame length of the test signal is set to 0.5ms, 1ms, 2ms and 4ms respectively.

[0020] In a preferred example, the dynamic duty cycle is adjusted and an EVM test is performed, and the dynamic duty cycle is set to 10% to 90%.

[0021] In a preferred example, a power supply is also included, and the power supply supplies power to the power amplifier.

[0022] The present application also discloses an EVM testing method including:

[0023] Generate a radio frequency test signal;

[0024] Outputting a dynamic synchronization signal to a power amplifier, wherein a pulse period of the dynamic synchronization signal depends on a signal width of the test signal, a predetermined protection delay, and a dynamic duty cycle;

[0025] The dynamic synchronization signal triggers the test signal to be transmitted to the power amplifier;

[0026] The power amplifier amplifies the test signal and outputs it; and

[0027] The output signal of the power amplifier is demodulated and calculated to obtain an EVM test result, wherein the dynamic synchronization signal is turned on and off according to the cycle of the test signal, or remains on, so as to obtain a dynamic EVM test result and a static EVM test result, respectively.

[0028] In a preferred example, the power of the test signal is adjusted and an EVM test is performed until the EVM test result is greater than a target value.

[0029] In a preferred example, the frame length of the test signal is adjusted and an EVM test is performed. The frame lengths of the test signal are set to 0.5 ms, 1 ms, 2 ms and 4 ms respectively.

[0030] In a preferred example, the dynamic duty cycle is adjusted and an EVM test is performed, and the dynamic duty cycle is set to 10% to 90%.

[0031] Compared with the prior art, the EVM test device and test method of the present application have the following beneficial effects:

[0032] The implementation methods of the present application can accurately measure the dynamic EVM, and with different test parameters and signal conditions, characterize in detail the status and problems of the PA in the EVM index, and provide a comprehensive reference direction for improving the PA design. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is the waveform diagram of PA enable signal and input signal.

[0034] Figure 2 It is a schematic diagram of the EVM test principle.

[0035] Figure 3 Schematic diagram of an EVM testing device in one embodiment of the present invention.

[0036] Figure 4 It is a flow chart of an EVM testing method in one embodiment of the present invention.

[0037] Figure 5 Schematic diagram of comparison of static and dynamic EVM test results in one embodiment of the present invention.

[0038] Figure 6 It is a schematic diagram comparing EVM test results of different frame lengths in one embodiment of the present invention.

[0039] Figure 7 It is a schematic diagram comparing EVM test results with different duty cycles in one embodiment of the present invention. DETAILED DESCRIPTION

[0040] In the following description, many technical details are provided to help readers better understand the present application. However, those skilled in the art can understand that even without these technical details and various changes and modifications based on the following embodiments, the technical solutions claimed in the claims of the present application can be implemented.

[0041] In order to make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0042] In one embodiment of the present application, an EVM testing device is disclosed. Figure 3 A schematic diagram of an EVM test device in an embodiment of the present application is shown. The device includes a signal source 10, a waveform generator 30, a power amplifier 20 and a spectrum analyzer 40. The signal source 10 is used to output a radio frequency test signal. The waveform generator 30 is used to output a dynamic synchronization signal (i.e., an enable signal of the power amplifier 20) to the power amplifier 20, the signal source 10 and the spectrum analyzer 40, and the pulse period of the dynamic synchronization signal depends on the signal width, the predetermined protection delay and the dynamic duty cycle of the test signal. The power amplifier 20 is used to receive the test signal and amplify and output it. The spectrum analyzer 40 is used to receive the output signal of the power amplifier and perform demodulation calculation to obtain the EVM test result. The dynamic synchronization signal is turned on and off according to the period of the test signal, or kept on, to obtain dynamic EVM test results and static EVM test results respectively. In one embodiment, a power supply 50 is also included, and the power supply 50 supplies power to the power amplifier 20.

[0043] In one embodiment, the power of the test signal is adjusted and an EVM test is performed until the EVM test result is greater than a target value. For example, the target value is set to 5%, 10%, etc. When the EVM test result is greater than the target value, the EVM test is stopped.

[0044] In one embodiment, the frame length of the test signal is adjusted and the EVM test is performed. In some embodiments, the frame length of the test signal is set to 0.5ms, 1ms, 2ms and 4ms respectively.

[0045] In one embodiment, the dynamic duty cycle is adjusted and an EVM test is performed. In some embodiments, the dynamic duty cycle is set to 10% to 90% respectively, so as to obtain EVM test results under different PA loads.

[0046] This embodiment provides a device for dynamically evaluating and measuring EVM, which uses an arbitrary waveform generator to control variables such as dynamic duty cycle and signal frame length, and simulates multiple data loads in actual working scenarios (such as 802.11AX scenarios), solving the problem that PA performance does not match the actual working environment in static testing of traditional testing methods. At the same time, detailed graphical comparison results are given to intuitively characterize the characteristics of PA.

[0047] In one embodiment of the present application, an EVM testing method is disclosed. Figure 4 is a flow chart of an EVM testing method in an embodiment, the method comprising:

[0048] Step 101, generating a radio frequency test signal;

[0049] Step 102, outputting a dynamic synchronization signal to a power amplifier, wherein a pulse period of the dynamic synchronization signal depends on a signal width of the test signal, a predetermined protection delay, and a dynamic duty cycle;

[0050] Step 103, the dynamic synchronization signal triggers the test signal to be transmitted to the power amplifier;

[0051] Step 104, the power amplifier amplifies the test signal and outputs it; and

[0052] Step 105, demodulate and calculate the output signal of the power amplifier and obtain an EVM test result, wherein the dynamic synchronization signal is turned on and off according to the cycle of the test signal, or remains on, to obtain a dynamic EVM test result and a static EVM test result, respectively.

[0053] The first embodiment is a device embodiment corresponding to the present embodiment. The technical details in the first embodiment can be applied to the present embodiment, and the technical details in the present embodiment can also be applied to the first embodiment.

[0054] In order to better understand the technical solution of this specification, the following is an explanation with reference to the example of 802.11AX PA (power amplifier). The details listed in this example are mainly for ease of understanding and are not intended to limit the scope of protection of this application.

[0055] Example 1

[0056] The method comprises the following steps:

[0057] 1.1 Produce test signals according to the 802.11AX protocol, including 20MHz, 40MHz, 80MHz, and 160MHz waveform signals input into the RF signal source.

[0058] 1.2 For the generated test signal, it is necessary to simulate the dynamic switching state of the PA in actual operation, so a dynamic synchronization signal is introduced. The dynamic signal is generated by an arbitrary waveform generator, and its amplitude is a 3V pulse waveform. The pulse signal width is the signal length plus a certain protection delay, and the calculation is shown in formula (2)

[0059]

[0060] Taking into account the dynamic changes in the transmission data load during the actual operation of the PA, in this embodiment, a small load (for example, a dynamic duty cycle of 10%), a large load (for example, a dynamic duty cycle of 90%) and a balanced load (for example, a dynamic duty cycle of 50%) can be defined as three test scenarios.

[0061] 1.3 In the simulated WLAN system, one end of the dynamic synchronization signal is connected to the trigger input of the signal source as the dynamic transmission signal of each frame signal; the other end triggers the signal to the spectrum analyzer to trigger the test to start.

[0062] 1.4 First, the dynamic synchronization signal controls the PA to start working, and at the same time triggers the RF signal source to play the test signal. A protection delay is added to the signal source playback configuration. On the other hand, the trigger signal enables the spectrum analyzer to start capturing the test signal, perform demodulation calculations, and finally obtain the EVM result.

[0063] 1.5a Dynamic EVM test, turn off the dynamic synchronization signal, control the PA to be in a non-working state, and wait for the next signal cycle to repeatedly turn on the dynamic synchronization signal.

[0064] 1.5b Static EVM test, keep the dynamic synchronization signal on, PA is always in working state. Repeat the next signal cycle.

[0065] 1.6 Adjust the signal source input power by 1 dB and repeat step 1.4. When the spectrum analyzer EVM calculation result is greater than the preset EVM target, such as 5%, stop the entire test.

[0066] 1.7 Repeat step 1.1, adjust the input signal parameters, and obtain the test results of step 1.6. Finally, draw a comparison chart of the dynamic EVM test results and the static EVM test results, as shown in the figure. Figure 4 shown.

[0067] Example 2

[0068] In order to further evaluate the dynamic EVM performance of the PA, the following method is adopted in other embodiments of the present application:

[0069] 2.1 Generate test signals according to the 802.11AX protocol. Generate different frame length configurations through the MDU in the protocol. The frame lengths are 0.5ms, 1ms, 2ms, and 4ms respectively. The waveform signal is input into the signal source.

[0070] 2.2 For signals with a specific frame length, the pulse signal width of the dynamic synchronization signal is Xi+5us (0.505ms, 1.005ms, 2.005ms, 4.005ms). Based on the pulse period calculation formula (2), the period can be calculated to be 1.01ms, 2.01ms, 4.012ms, and 8.01ms.

[0071] 2.3 Repeat steps 1.3 to 1.7 in Example 1 to obtain a comparison of dynamic EVM test results under different frame lengths, such as Figure 6 shown.

[0072] Example 3

[0073] On the other hand, as another key variable for evaluating EVM, the signal duty cycle determines the proportion of its heating and cooling states. Therefore, another embodiment of the present application proposes a dynamically configured signal duty cycle. The specific embodiments are as follows:

[0074] 3.1 Use the 802.11AX protocol to generate a single length test signal X, for example (1ms).

[0075] 3.2 For a single-length test signal, the pulse signal width of the dynamic synchronization signal is Xi+5us. Considering the change in the signal duty cycle, such as 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, and 90% duty cycles, the pulse signal periods calculated by formula (2) are respectively, with three decimal places.

[0076] Duty cycle (%) 10 20 30 40 50 60 70 80 90 Cycle (ms) 10.05 5.25 3.35 2.513 2.01 1.675 1.436 1.256 1.117

[0077] 3.3 Repeat steps 1.3 to 1.7 in Example 1 to obtain a comparison of the dynamic EVM test results and the static EVM test results under different dynamic duty cycles, as shown in the following table. Figure 7 A comparison of dynamic EVM test results for different duty cycles is shown.

[0078]

[0079] From the results obtained in the above table, the dynamic EVM test results will be different from the conventional static EVM test results within a certain range.

[0080] Traditional EVM testing generally directly tests the EVM of PA statically, lacking simulation with actual application scenarios. The present invention and method provide a method for dynamically evaluating and measuring EVM, which uses an arbitrary waveform generator to control variables such as duty cycle and signal frame length, and simulates multiple data loads in actual 802.11AX working scenarios, solving the problem that PA performance does not match the actual working environment in static testing of traditional testing methods. At the same time, detailed graphical comparison results are given to intuitively characterize the characteristics of PA.

[0081] In the application documents of this patent, relational terms such as first and second, etc. are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the statement "comprise one" do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0082] In some cases, the actions or steps recited in the claims may be performed in an order different from that in the embodiments and still achieve the desired results. In addition, the processes depicted in the accompanying drawings do not necessarily require the specific order or sequential order shown to achieve the desired results.

Claims

1. An EVM test device, It is characterized in that include: Signal source, waveform generator, power amplifier and spectrum analyzer, including: The signal source is used to output a radio frequency test signal; The waveform generator is used to output a dynamic synchronization signal to the power amplifier, the signal source and the spectrum analyzer, wherein the pulse period of the dynamic synchronization signal depends on the signal width, the predetermined protection delay and the dynamic duty cycle of the test signal; The power amplifier is used to receive the test signal and amplify and output it; and The spectrum analyzer is used to receive the output signal of the power amplifier and perform demodulation calculation to obtain the EVM test result; Among them, a dynamic synchronization signal is generated according to the 802.11AX protocol frame length, and the dynamic synchronization signal is a pulse waveform. The duty cycle or signal frame length of the dynamic synchronization signal is adjusted to simulate the load of the power amplifier in an actual working scenario to obtain a dynamic EVM test result.

2. The EVM test device according to claim 1, It is characterized in that The power of the test signal is adjusted and an EVM test is performed until the EVM test result is greater than a target value.

3. The EVM test device according to claim 1, It is characterized in that The frame length of the test signal is adjusted and an EVM test is performed. The frame length of the test signal is set to 0.5 ms, 1 ms, 2 ms and 4 ms respectively.

4. The EVM test device according to claim 1, It is characterized in that The dynamic duty cycle is adjusted and an EVM test is performed, wherein the dynamic duty cycle is set to 10% to 90%.

5. The EVM testing device according to claim 1, It is characterized in that A power supply is also included, and the power supply supplies power to the power amplifier.

6. An EVM test method, It is characterized in that include: Generate a radio frequency test signal; Outputting a dynamic synchronization signal to a power amplifier, wherein a pulse period of the dynamic synchronization signal depends on a signal width of the test signal, a predetermined protection delay, and a dynamic duty cycle; The dynamic synchronization signal triggers the test signal to be transmitted to the power amplifier; the power amplifier amplifies the test signal and outputs it; as well as The output signal of the power amplifier is demodulated and calculated to obtain an EVM test result, wherein a dynamic synchronization signal is generated according to the frame length of the 802.11AX protocol, and the dynamic synchronization signal is a pulse waveform. The duty cycle or signal frame length of the dynamic synchronization signal is adjusted to simulate the load of the power amplifier in an actual working scenario to obtain a dynamic EVM test result.

7. The EVM testing method according to claim 6, It is characterized in that The power of the test signal is adjusted and an EVM test is performed until the EVM test result is greater than a target value.

8. The EVM testing method according to claim 6, It is characterized in that The frame length of the test signal is adjusted and an EVM test is performed. The frame length of the test signal is set to 0.5 ms, 1 ms, 2 ms and 4 ms respectively.

9. The EVM testing method according to claim 6, It is characterized in that The dynamic duty cycle is adjusted and an EVM test is performed, wherein the dynamic duty cycle is set to 10% to 90%.

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