Response time conduction type testing device and method for radio frequency channel protection device

Abstract

The invention discloses a response time conduction type testing device and method for a radio frequency channel protection device. The response time conduction type testing device comprises a transient field intensity generating device, an isolator, a directional coupler, a first attenuator, a second attenuator, a third attenuator, a first power meter, a second power meter, a high-speed oscilloscope, a vector network analyzer and a radio frequency channel protection device to be tested. According to the method, the response performance of the protection device under the influence of the transient strong field can be comprehensively, safely and accurately evaluated, the amplitude limiting function of the protection device can still be effectively exerted under the action of the transient strong field with an extremely narrow rising edge, and then subsequent devices, circuits and equipment are prevented from being damaged.

Description

Technical Field

[0001] The present invention relates to the field of electromagnetic protection, and particularly to a response time conduction type testing device and method for a radio frequency channel protection device. Background Art

[0002] Transient strong fields generally refer to high-intensity electric fields generated within an extremely short time, such as high-intensity electromagnetic pulses, high-power microwave pulses, etc. After a transient strong field enters the radio frequency channel of an electronic system, it can damage the core components therein. With the development of pulsed power technology, the rising edge of transient strong fields has become increasingly narrow, posing higher requirements for the safety and protection capabilities of electronic systems. A radio frequency channel protection device is a circuit protection device that can limit the amplitude of a transient strong field within a certain range, such as a limiter, a TVS tube, and a discharge tube, etc., thereby preventing subsequent devices / circuits / equipment from being damaged by the action of the transient strong field. The response time of a radio frequency channel protection device refers to the time when the radio frequency channel protection device starts to perform its amplitude limiting function under the action of a transient strong field. If the response time of the radio frequency channel protection device is too long, a transient strong field with an extremely narrow rising edge will be missed by the radio frequency channel protection device, thus affecting subsequent devices / circuits / equipment. Therefore, by testing the response time of a radio frequency channel protection device under the action of a transient strong field, the protection ability of the radio frequency channel protection device can be clarified. At the same time, it also helps to design a radio frequency channel protection device more efficiently and specifically to improve its protection ability under transient strong fields.

[0003] The current response time test method monitors insufficient parameters. The object tested is usually the output waveform of the protection device, and the response time is obtained based on the waveform. However, the rising edge and power of the transient strong field will also affect the response time test: under different input powers, the conduction time of the semiconductor device in the protection device is different, and the limiting level of the protection device will also be different, resulting in different output waveforms of the protection device; in addition, the difference in the rising edge of the transient strong field will also cause differences in the output waveform of the protection device. The narrow rising edge makes the protection device unable to respond in time, resulting in spike leakage, and the wide rising edge makes the conduction of the protection device slow, and the edge of its output waveform is also necessarily slow. Therefore, it is also very important to obtain the rising edge and power information of the transient strong field during the test; the current response time test method lacks the judgment on whether the protective device is damaged. Once the protective device is damaged under the transient strong field, its performance will change significantly, and the measured response time is no longer reliable; from the perspective of instrument safety, since the working principle of some protective devices is reflective, it is also necessary to monitor the reflected power of the protective device to prevent excessive reflected signals from damaging the power amplifier; in addition, due to different application fields, there are currently different standards for the recognition of response time results. Therefore, in combination with the application of transient strong field protection, it is very necessary to propose a response time test method and device for transient strong field RF channel protection devices. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a response time conductive testing device and method for a radio frequency channel protection device, which can comprehensively, safely and accurately evaluate the protection capability of the radio frequency channel protection device under the action of a transient strong field.

[0005] The object of the present invention is achieved through the following technical solutions: a response time conduction test device for a radio frequency channel protection device, comprising a transient field strength generating device, an isolator, a directional coupler, a first attenuator, a second attenuator, a third attenuator, a first power meter, a second power meter, a high-speed oscilloscope, a vector network analyzer and a radio frequency channel protection device to be tested; The transient field strength generating device is used to generate a transient field strength signal, and is connected to the input port of the directional coupler through an isolator, and the output port of the directional coupler is connected to the input port of the radio frequency channel protection device to be tested; the forward coupling port of the directional coupler is connected to the first power meter through a first attenuator; the reverse coupling port of the directional coupler is connected to the second power meter through a second attenuator; the first power meter and the second power meter are used to monitor the input signal power and the reflected signal power of the radio frequency channel protection device to be tested respectively; The input end of the third attenuator is connected to the output port of the directional coupler or the output port of the radio frequency channel protection device under test, and the output end of the third attenuator is connected to a high-speed oscilloscope for obtaining the response time. A vector network analyzer is also provided between the input port and the output port of the radio frequency channel protection device under test, which is used to test and compare the performance of the protection device under test before and after the response time test, so as to judge whether the radio frequency channel protection device under test is damaged, thereby ensuring the validity of the measured response time data and not connecting it to the circuit during the response time test.

[0006] A conduction test method for the response time of a radio frequency channel protection device includes the following steps: S1. Without connecting the protection device under test, perform the insertion loss IL1 and the rising edge test of the transient strong field of the protection device under test. S101. Connect the third attenuator directly to the output port of the directional coupler without connecting the protection device under test. S102. Use a vector network analyzer to test the insertion loss of the protection device under test, denoted as IL1. S103. Use the control computer to set the parameters of the pulse pattern generator and the radio frequency signal source. After the power amplifier is preheated, set the pulse pattern generator and the radio frequency signal source to start outputting signals. S104. Obtain the output waveform of the transient strong field through a high-speed oscilloscope, read and record the rising edge of the transient strong field. The rising edge refers to the time when the amplitude of the waveform reaches 90% of the peak amplitude - the time when the waveform reaches 10% of the peak amplitude, denoted as t rise ; S105. Set the radio frequency signal source to stop outputting signals.

[0007] S2. With the protection device under test connected, test the response time of the protection device under test. S201. Connect the third attenuator to the output port of the protection device under test and set the radio frequency signal source to start outputting signals. S202. Read and record the input signal power of the protection device under test of the first power meter and the reflected signal power of the protection device under test of the second power meter, denoted as P in and P re ; S203. Store and read the output waveform data of the high-speed oscilloscope, which contains two columns of data. The first column is the time column, denoted as Time, and the second column is the amplitude column of the waveform, denoted as A; S204. Set the threshold amplitude of the non-noise signal as A s , set a loop, and the number of loop times is the length of the sequence A, length(A); i represents the i-th loop. If A(i) ≥ As , then t1 = Time(i); if A(i) = max(A), then t2 = Time(i), and the response time t of the protection device r = t2 - t1; S205. Set the RF signal source to stop outputting signals, and use a vector network analyzer to measure the insertion loss of the protection device under test after the transient strong field test, denoted as IL2; S206. Set the threshold δ of the allowable change in insertion loss before and after the test. If |IL1 - IL2| < δ, it is considered that the protection device is not damaged under the action of the transient strong field, and the test result of the response time can be used. The input signal power is P in The response time under is t r , otherwise the test result of the response time is invalid.

[0008] S3. Change the parameters of the transient field strength generating device, and while ensuring the accuracy and safety of the response time test, execute steps S1~S2 again to obtain the second test result.

[0009] Change the parameters of the pulse pattern generator and the RF signal source, including the power of the RF signal source and the pulse width, duty cycle, and rising edge of the pulse pattern generator; Let the threshold power of the reflected signal allowed by the power amplifier be P th , and the protection power be P safe , and the isolation degree of all isolators after the power amplifier be ISO sum , if P re > ISO sum + P th + P safe , then add one or more isolators after the power amplifier until P re < ISO sum + P th + P safe , ensuring the accuracy and safety of the response time test; After the parameter adjustment is completed, re - execute steps S1~S2 to complete the test after the parameter adjustment.

[0010] The beneficial effects of the present invention are as follows: The present invention effectively improves the comprehensiveness and accuracy of the response time test. By accurately obtaining the rising edge of the transient strong field, the input and reflected powers of the protection device, and the change information of the insertion loss of the protection device before and after the test during the response time test, this method can comprehensively, safely, and accurately evaluate the response performance of the protection device under the influence of the transient strong field, ensuring that its limiting function can still be effectively exerted under the action of the transient strong field with an extremely narrow rising edge, thereby avoiding damage to subsequent devices, circuits, and equipment. The present invention provides support for the design of RF channel protection devices and helps to promote the development of RF protection technology. Brief Description of the Drawings

[0011] Figure 1 It is a schematic diagram of the action process of the transient strong field; Figure 2 It is a schematic diagram of the response time conduction test device for the transient strong field radio frequency channel protection device; Figure 3 It is a schematic diagram of the relationship curve between the input power and the output power of the protection device. Detailed Description of the Preferred Embodiment

[0012] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings, but the protection scope of the present invention is not limited to the following description.

[0013] From the perspective of transient strong field protection, an important function of the radio frequency channel protection device is to protect the devices / equipment at the back end from the influence of the transient strong field. There are many types of transient strong fields, as shown in Figure 1, but what poses a threat to the devices / equipment at the back end is the overshoot / spike of the output waveform caused by the insufficiently fast response time of the protection device. At this time, the power leaking to the devices / equipment at the back end is the largest. Therefore, the response time of the radio frequency channel protection device under the action of the transient strong field is defined as the time difference t1 - t0 between the time t0 when the radio frequency channel protection device starts to have an output signal (excluding the noise part) and the time t1 corresponding to the maximum value (spike) of the output signal waveform. Compared with the method of selecting the time when the waveform is stable as t1, the present invention is applicable to different types of transient strong fields, especially some with very narrow pulse widths and insufficiently fast response times of the radio frequency channel protection device, resulting in no obvious stable segment in the output waveform; and from the perspective of posing a threat to the devices / equipment at the back end, it more conforms to the purpose of transient strong field protection; for a heterogeneous radio frequency channel protection device (two different types of protection devices cascaded together), its output waveform may show two regions with stable waveforms (due to differences in the response times and leakage powers of the two protection devices), and selecting the time when the waveform is stable as t1 will cause ambiguity; As Figure 2 shown, a response time conduction test device for a radio frequency channel protection device includes: a pulse pattern generator, a radio frequency signal source, a power amplifier, an isolator, a directional coupler, an attenuator, a power meter, a high-speed oscilloscope, a vector network analyzer, a computer, and the protection device to be tested. Here, taking high-power microwaves as an example for the transient strong field, the pulse pattern generator, the radio frequency signal source, and the power amplifier are used as the parts for generating the transient strong field. Among them, the attenuator includes a first attenuator (attenuator 1), a second attenuator (attenuator 2), and a third attenuator (attenuator 3); the power meter includes a first power meter (power meter 1) and a second power meter (power meter 2); the entire response time conduction test device is arranged in a microwave anechoic chamber.

[0014] The pulse pattern generator generates a rectangular pulse signal, which forms a pulse modulation signal with the sine signal generated by the RF signal source. In addition, high-power amplifiers usually adopt a pulse system, so the pulse pattern generator is required to additionally generate a trigger signal for clock synchronization to ensure that the pulse modulation signal can be captured and amplified by the power amplifier. The isolator is used to protect the power amplifier from damage caused by reflected signals due to reasons such as reflection from the protection device / link mismatch. The forward coupling port and the reverse coupling port (isolation port) of the directional coupler are each connected to an attenuator and a power meter for protecting the instrument. Power meter 1 and power meter 2 are respectively used to monitor the input signal power and the reflected signal power of the protection device under test. The vector network analyzer is used to test and compare the performance of the protection device under test before and after the response time test to determine whether the protection device under test is damaged, thereby ensuring the validity of the measured response time data. Therefore, it is not connected to the circuit during the response time test. The output port of the protection device under test is connected to an attenuator for protecting the instrument and a high-speed oscilloscope for obtaining the response time.

[0015] The computer includes a control computer and a data processing computer. The control computer is used to connect to the pulse pattern generator, the RF signal source, and the power amplifier, set the parameters of the pulse pattern generator and the RF signal source, and control the preheating, pause of amplifying the signal, and start of amplifying the signal of the power amplifier (for power amplifiers with a traveling wave tube system, it usually needs to be preheated for more than 5 minutes to be used normally. When disassembling cables / instruments, the amplifying signal needs to be paused); the data processing computer is used to obtain the output waveform of the protection device from the high-speed oscilloscope and extract the response time.

[0016] A conduction test method for the response time of an RF channel protection device includes the following steps: 1) Connect the test device according to the block diagram shown in Figure 2 , directly connect the attenuator 3 to the output port of the directional coupler without connecting the protection device under test, and turn on the test instrument.

[0017] 2) Use the vector network analyzer to test the insertion loss of the protection device under test and record it as IL1.

[0018] 3) Under the condition of ensuring test safety (personnel safety, instrument safety), set the parameters of the pulse pattern generator and the RF signal source. After the power amplifier is preheated, set the pulse pattern generator and the RF signal source (when setting for the first time, a smaller power should be selected for the transient strong field to avoid damaging the protection device), and start outputting the signal.

[0019] 4) The result of the response time is related to the rising edge of the input signal. If the rising edge of the input signal itself is relatively slow, then even if the protection device has the ability to respond quickly, the slow rising edge of the input signal cannot trigger the fastest response time of the protection device. Therefore, in the test of the response time, the rising edge of the input signal should be recorded as the input condition of the response time test result to improve the comprehensiveness of the test. Obtain the output waveform of the transient strong field through a high-speed oscilloscope. After checking that there is no problem, read and record the rising edge of the transient strong field (the time when the amplitude of the waveform reaches 90% of the peak amplitude - the time when the waveform reaches 10% of the peak amplitude), denoted as t rise 。

[0020] 5) Set the RF signal source to stop outputting signals, connect the test device according to the block diagram shown in Figure 2 , and set the RF signal source to start outputting signals.

[0021] 6) The result of the response time is also related to the power of the input signal. This is because the limiting ability of the protection device is different under different input powers (input power - output power), as shown in Figure 3 . Read and record the input signal power of the protection device to be measured by power meter 1 and the reflected signal power of the protection device to be measured by power meter 2, denoted as P in and P re respectively.

[0022] 7) Store and read the output waveform data of the high-speed oscilloscope, which contains two columns of data. The first column is the time column, denoted as Time, and the second column is the amplitude column of the waveform, denoted as A.

[0023] 8) Set the threshold amplitude of the non-noise signal to A s , set a loop, and the number of loop times is the length of sequence A, length(A). i represents the i-th loop. If A(i) ≥ A s , then t1 = Time(i); if A(i) = max(A), then t2 = Time(i). The response time t of the protection device r = t2 - t1.

[0024] 9) Set the RF signal source to stop outputting signals, and use a vector network analyzer to test the insertion loss of the protection device to be measured after the transient strong field test, denoted as IL2.

[0025] 10) The protection device generally consists of semiconductor devices and a matching circuit. Under the action of a transient strong field, the damage of the protection device is attributed to the damage of the semiconductor devices. According to the damage mechanism of semiconductor devices, under the action of a transient strong field, the semiconductor devices in the protection device to be tested may suffer current-related thermal damage (such as thermal secondary breakdown, melting of the metal conductive layer, and burnout of the interconnection line, etc.) or voltage-related electrical damage (such as dielectric breakdown, gas arc discharge, and surface breakdown, etc.). Both types of damage will cause a change in the insertion loss of the protection device. Therefore, before and after the response time test, it is possible to determine whether the protection device is damaged based on the change in insertion loss, and thus determine whether the test result of the response time is valid. Set the threshold δ of the allowable change in insertion loss before and after the test (for example, for a protection device with an insertion loss of 1 dB, 0.2 dB can be selected as δ). If |IL1 - IL2| < δ, it is considered that the protection device is not damaged under the action of a transient strong field, and the test result of the response time can be adopted. The response time at the input signal power P in is t r , otherwise the test result of the response time is invalid.

[0026] Change the parameters of the pulse pattern generator and the RF signal source (such as the power of the RF signal source, the pulse width, duty cycle, and rising edge of the pulse pattern generator). Since some protection devices operate in a reflective mode, such as protection devices based on PIN diodes, under the action of a transient strong field, the impedance characteristics of the PIN diodes will change (RF conductance modulation effect), and they will no longer match the circuit, causing the input signal of the protection device to be reflected. Once too much reflected signal acts on the power amplifier, it will cause the performance of the power amplifier to decline or even be damaged, affecting the accuracy and safety of the response time test. Therefore, when adjusting the signal source parameters, refer to P in the previous test re to determine whether the current isolator can protect the power amplifier from the influence of the reflected signal. Let the threshold power of the reflected signal allowed by the power amplifier be P th (typical value such as 18 dBm), and the protection power be P safe (typical value is 3 dB. Considering reasons such as the instability of the power amplifier output, measures cannot be taken when the reflected power is equal to ISO sum +P th ). The isolation degree of all isolators after the power amplifier is ISO sum . If P re >ISO sum +P th +P safe , then one or more isolators need to be added after the power amplifier until P re <ISO sum +P th +P safe, ensure the accuracy and safety of the response time test, and then repeat steps 2) - 10) to test the response time of the protection device under other conditions.

[0027] The above are the preferred embodiments of the present invention. It should be understood that the present invention is not limited to the forms disclosed herein, should not be regarded as excluding other embodiments, but can be used in other combinations, modifications and environments, and can be changed within the scope of the concept described herein through the above teachings or the techniques or knowledge in related fields. And any changes and modifications made by those skilled in the art without departing from the spirit and scope of the present invention shall fall within the protection scope of the appended claims of the present invention.

Claims

1. A response time conduction test device for a radio frequency channel protection device, characterized in that: It includes a transient field strength generating device, an isolator, a directional coupler, a first attenuator, a second attenuator, a third attenuator, a first power meter, a second power meter, a high-speed oscilloscope, a vector network analyzer, and a protection device for the RF channel under test; The transient field strength generating device is used to generate a transient field strength signal, which is connected to the input port of the directional coupler through the isolator. The output port of the directional coupler is connected to the input port of the protection device for the RF channel under test; the forward coupling port of the directional coupler is connected to the first power meter through the first attenuator; the reverse coupling port of the directional coupler is connected to the second power meter through the second attenuator; the first power meter and the second power meter are respectively used to monitor the input signal power and the reflected signal power of the protection device for the RF channel under test; The input end of the third attenuator is connected to the output port of the directional coupler or the output port of the protection device for the RF channel under test, and a high-speed oscilloscope for obtaining the response time is connected to the output end of the third attenuator; A vector network analyzer is also provided between the input port and the output port of the protection device for the RF channel under test, which is used to test and compare the performance of the protection device under test before and after the response time test to determine whether the protection device for the RF channel under test is damaged, so as to ensure the validity of the measured response time data, and it is not connected to the circuit during the response time test.

2. The response time conduction type testing device for a radio frequency channel protection device according to claim 1, characterized in that: The transient field strength generating device includes a pulse pattern generator, a RF signal source, and a power amplifier; The output end of the pulse pattern generator is connected to the modulation input port of the RF signal source. The pulse pattern generator generates a rectangular pulse signal and a sine signal generated by the RF signal source to form a pulse modulation signal, which is transmitted to the power amplifier; The pulse pattern generator additionally generates a trigger signal and transmits it to the external trigger signal port of the power amplifier for clock synchronization. After the power amplifier captures and amplifies the pulse modulation signal, a transient field strength signal is obtained.

3. The response time conduction type test device for a radio frequency channel protection device according to claim 2, wherein: The conduction test device further includes a control computer, which is respectively connected to the pulse pattern generator, the RF signal source, and the power amplifier, and is used to set the parameters of the pulse pattern generator and the RF signal source, and control the preheating, pausing the amplification signal, and starting the amplification signal of the power amplifier.

4. The response time conduction type testing device for a radio frequency channel protection device according to claim 2, characterized in that: The conduction test device further includes a data processing computer, which is used to obtain the output waveform of the protection device from the high-speed oscilloscope and extract the response time.

5. A response time conduction test method for a radio frequency channel protection device, based on the response time conduction test device according to any one of claims 1 to 4, characterized in that: It includes the following steps: S1. Without connecting the protection device under test, perform the insertion loss IL1 and the rising edge test of the transient strong field of the protection device under test; S2. With the protection device under test connected, test the response time of the protection device under test; S3. Change the parameters of the transient field strength generating device, and ensure the accuracy and safety of the response time test, and then execute steps S1~S2 again to obtain the second test result.

6. The response time conduction test method for a radio frequency channel protection device according to claim 5, characterized in that: The step S1 includes: S101. Connect the third attenuator directly to the output port of the directional coupler without connecting the protection device under test; S102. Use the vector network analyzer to test the insertion loss of the protection device under test, denoted as IL1; S103. Set the parameters of the pulse pattern generator and the RF signal source using a control computer. After the power amplifier is preheated, set the pulse pattern generator and the RF signal source to start outputting signals; S104. Obtain the output waveform of the transient strong field through a high-speed oscilloscope, read and record the rising edge of the transient strong field. The rising edge refers to the time when the amplitude of the waveform reaches 90% of the peak amplitude - the time when the waveform reaches 10% of the peak amplitude, denoted as t rise ; S105. Set the RF signal source to stop outputting signals.

7. The response time conduction test method for a radio frequency channel protection device according to claim 5, characterized in that: The step S2 includes: S201. Connect the third attenuator to the output port of the protection device under test, and set the RF signal source to start outputting signals; S202. Read and record the input signal power of the protection device under test of the first power meter and the reflected signal power of the protection device under test of the second power meter, denoted as P in and P re ; S203. Store and read the output waveform data of the high-speed oscilloscope, which contains two columns of data. The first column is the time column, denoted as Time, and the second column is the amplitude column of the waveform, denoted as A; S204. Set the threshold amplitude of the non-noise signal to A s , set a loop, and the number of loop times is the length of sequence A, length(A); i represents the i-th loop. If A(i) ≥ A s , then t1 = Time(i); if A(i) = max(A), then t2 = Time(i), and the response time t of the protection device r = t2 - t1; S205. Set the RF signal source to stop outputting signals, and use a vector network analyzer to measure the insertion loss of the protection device under test after the transient strong field test, denoted as IL2; S206. Set the threshold δ for the allowable change in insertion loss before and after testing. If |IL1 - IL2| < δ, it is considered that the protection device is not damaged under the action of the transient strong field, and the test result of the response time can be used. The response time under the input signal power P in is t r , otherwise the test result of the response time is invalid.

8. The response time conduction test method for a radio frequency channel protection device according to claim 5, characterized in that: The step S3 includes: Change the parameters of the pulse pattern generator and the RF signal source, including the power of the RF signal source and the pulse width, duty cycle, and rising edge of the pulse pattern generator; Let the threshold power of the reflected signal allowed by the power amplifier be P th , and the protection power be P safe . The isolation of all isolators after the power amplifier is ISO sum . If P re > ISO sum + P th + P safe , then add one or more isolators after the power amplifier until P re < ISO sum + P th + P safe , ensuring the accuracy and safety of the response time test; After the parameter adjustment is completed, repeat steps S1~S2 to complete the test after the parameter adjustment.

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