CN106885935A - Time domain voltage measuring method, measurement calibration method and measurement calibration verification method - Google Patents

Abstract

The invention relates to a time-domain voltage measurement method, a measurement calibration method and a measurement calibration verification method. The measurement method includes: fixing the relative position of the microstrip line of the PCB board to be tested and the voltage probe, and moving the microstrip line of the PCB board to be tested. When inputting the board-level radio frequency voltage to be tested, the voltage probe is placed above the microstrip line of the PCB board to be tested, so that the projection of the center of the bottom end of the voltage probe falls on the microstrip line of the PCB board to be tested , and the voltage probe is perpendicular to the microstrip line of the PCB board to be tested; through the voltage probe, the electric field coupling is used to induce the RF voltage of the board level to be tested to be generated around the microstrip line of the PCB board to be tested An induced electromotive force; collecting the induced electromotive force through an oscilloscope connected to the output end of the voltage probe; calculating the board-level RF voltage to be tested through a computer according to the induced electromotive force collected by the oscilloscope.

Description

Time Domain Voltage Measurement Method, Measurement Calibration Method and Measurement Calibration Verification Method

technical field

The invention relates to the technical field of radio frequency voltage frequency domain measurement, in particular to a time domain voltage measurement method, a measurement calibration method and a measurement calibration verification method.

Background technique

The so-called time domain measurement is to measure the change data of the variable with time. Non-contact board-level RF voltage time-domain measurement is an important test topic extended after the current high-precision test technology is becoming more and more advanced. Most current voltage tests require direct contact with the measured point, but such direct contact usually requires non-interference with the system under test. With the increasing complexity of the measured object, quite a few people want to measure the voltage without modifying the system or stopping the system. At this time, non-contact board-level RF voltage time domain measurement is very necessary.

The traditional non-contact board-level RF voltage time-domain measurement method is suitable for the detection of large voltages. When the voltage is small, the measurement accuracy is low.

Contents of the invention

Based on this, it is necessary to provide a time-domain voltage measurement method, a measurement calibration method, and a measurement calibration verification method for the problem of low measurement accuracy when the voltage is small.

A time-domain voltage measurement method, comprising the following steps:

Fix the relative position of the microstrip line of the PCB board to be tested and the voltage probe. Above the strip line, the projection of the bottom center of the voltage probe falls on the microstrip line of the PCB board to be tested, and the voltage probe is perpendicular to the microstrip line of the PCB board to be tested;

Using the electric field coupling to induce the induced electromotive force generated around the microstrip line of the PCB board to be tested by the board-level radio frequency voltage to be tested by the voltage probe;

collecting the induced electromotive force through an oscilloscope connected to the output end of the voltage probe;

The computer is used to calculate the board-level RF voltage to be tested according to the induced electromotive force collected by the oscilloscope.

The above time-domain voltage measurement method, by placing the voltage probe at a specified position, detecting and collecting the induced electromotive force around the microstrip line of the PCB board to be tested, and calculating the board-level radio frequency voltage to be tested according to the collected induced electromotive force, can accurately The time-domain waveform of the board-level radio frequency voltage is accurately measured, and the measurement accuracy is improved.

A time-domain voltage measurement calibration method, comprising the following steps:

Fix the relative position of the calibration PCB board microstrip line and the voltage probe, when inputting the calibration board-level RF voltage to the calibration PCB board microstrip line, place the voltage probe on the calibration PCB board microstrip line Above, make the projection of the center of the bottom end of the voltage probe fall on the microstrip line of the calibration PCB board, and the voltage probe is perpendicular to the microstrip line of the calibration PCB board;

Test the two-port network formed by the calibration PCB board microstrip line and the voltage probe by a network analyzer to obtain a calibration factor for measuring and calibrating the board-level RF voltage of the PCB board microstrip line to be tested;

Wherein, the first port of the network analyzer is connected to one end of the calibration PCB microstrip line, the second port of the network analyzer is connected to the output end of the voltage probe, and the calibration PCB microstrip The other end of the line is connected to an impedance-matched load.

The above time-domain voltage measurement and calibration method, by placing the voltage probe at the specified position, and testing the two-port network composed of the calibration PCB microstrip line and the voltage probe through the network analyzer, can accurately calculate the The calibration factor for measuring and calibrating the board-level RF voltage of the microstrip line to be tested, thereby improving the accuracy of time-domain voltage measurement.

A time-domain voltage measurement calibration verification method, comprising the following steps:

Fix the relative position of the calibration PCB board microstrip line and the voltage probe, when inputting the calibration board-level RF voltage to the calibration PCB board microstrip line, place the voltage probe on the calibration PCB board microstrip line Above, make the projection of the center of the bottom end of the voltage probe fall on the microstrip line of the calibration PCB board, and the voltage probe is perpendicular to the microstrip line of the calibration PCB board;

Input an arbitrary waveform voltage signal to one end of the calibration PCB board microstrip line through an arbitrary waveform generator;

Using the electric field coupling to induce the induced electromotive force generated by the voltage signal around the microstrip line of the calibration PCB board through the voltage probe;

Connect the first channel of the oscilloscope to the output end of the voltage probe, and collect the induced electromotive force output by the voltage probe through the first channel;

The second channel of the oscilloscope is connected to the other end of the microstrip line of the calibration PCB board, and the second calibration verification voltage on the microstrip line of the calibration PCB board is collected through the second channel;

The computer calculates the first calibration verification voltage according to the induced electromotive force collected by the oscilloscope, and verifies the calibration factor according to the first calibration verification voltage and the second calibration verification voltage; wherein, the calibration factor is used for the test The board-level RF voltage of the PCB microstrip line to be tested is measured and calibrated.

The above time-domain voltage measurement calibration verification method, by placing the voltage probe at a specified position, inputting an arbitrary waveform voltage signal to one end of the microstrip line of the calibration PCB board through an arbitrary waveform generator, collecting the induced electromotive force and calibrating the PCB through an oscilloscope The second calibration verification voltage on the microstrip line of the board, the first calibration verification voltage is calculated according to the collected induced electromotive force, and the calibration factor is verified according to the first calibration verification voltage and the second calibration verification voltage, which can improve the use of The accuracy of the calibration factor for measuring and calibrating the board-level RF voltage of the microstrip line of the PCB board to be tested is used to improve the accuracy of time-domain voltage measurement.

Description of drawings

Fig. 1 is the schematic diagram of the voltage probe of an embodiment;

Fig. 2 is a structural schematic diagram of a time-domain voltage measuring device of an embodiment;

Fig. 3 is a flow chart of the time-domain voltage measurement method of an embodiment;

Fig. 4 is a structural schematic diagram of a time-domain voltage measurement and calibration device of an embodiment;

Fig. 5 is the schematic diagram of the calibration PCB board microstrip line of an embodiment;

FIG. 6 is a flowchart of a method for measuring and calibrating time-domain voltage in an embodiment;

FIG. 7 is a schematic structural diagram of a time-domain voltage measurement calibration verification device of an embodiment;

FIG. 8 is a flow chart of a time-domain voltage measurement calibration verification method according to an embodiment;

Fig. 9 is a schematic diagram of a calibration factor of an embodiment;

Fig. 10 (a) is the output voltage of the voltage probe in the calibration verification link of an embodiment;

Fig. 10(b) is the first calibration verification voltage calculated and restored according to the output voltage of the voltage probe in the calibration verification link of an embodiment;

Fig. 10(c) is the actual measured board-level RF voltage of an embodiment.

detailed description

The technical solution of the present invention will be described below in conjunction with the accompanying drawings.

This embodiment provides a time-domain voltage measuring device, which may include a microstrip line of a printed circuit board (Printed Circuit Board, PCB) to be tested, a voltage probe, an oscilloscope and a computer. The functions of each part are as follows:

Voltage probe: It can be made of coaxial cable, and uses electric field coupling to detect the electric field generated by radio frequency voltage. In one embodiment, the probe can consist of a coaxial cable with an impedance of 50Ω. As shown in Figure 1, the detection part is formed by the extension of the inner conductor. In one embodiment, the extension length is about 1mm-3mm. If it is too short, the signal coupling will be too weak, and if it is too long, it will cause too much interference. The principle is to detect the electric field Ev generated by the board-level RF voltage on the measured microstrip line through electric field coupling. The measured board-level RF voltage v(t) generates an alternating electric field in space, and the voltage probe uses electric field coupling to induce The induced electromotive force generated by this alternating electric field connects the inner conductor of the voltage probe to the SMA (SubMiniature version A, ultra-small A type) head, and the formed induced electromotive force v _P (t) passes through the inner conductor of the probe and the SMA head to the signal acquisition equipment for transmission, usually, there are and That is, the induced electromotive force detected by the voltage probe is proportional to the electric field generated by the measured board-level RF voltage in space, and the electric field generated by the measured board-level RF voltage in space is proportional to the measured RF voltage. Therefore, the measured board-level RF voltage v(t) can be deduced by collecting the signal of v _P (t).

Oscilloscope: the voltage signal acquisition of the voltage probe, one channel (for example, channel 1) of the oscilloscope is connected to the voltage probe to read the voltage waveform collected by the probe. In one embodiment, the termination impedance of the channel is set to 50Ω. In order to form impedance matching with the oscilloscope, the impedance of the microstrip line can be designed as 50Ω.

Computers: Process data.

The schematic diagram of the connection structure of the above-mentioned time-domain voltage measurement device is shown in Figure 2. The voltage probe is placed above the microstrip line of the PCB board to be tested, so that the projection of the center of the bottom end of the voltage probe falls on the surface to be tested. The microstrip line of the PCB board, and the voltage probe is perpendicular to the microstrip line of the PCB board to be tested, the output end of the voltage probe is connected to the first channel of the oscilloscope, and the output end of the oscilloscope is connected to the oscilloscope. The computer is connected; the voltage probe uses electric field coupling to induce the induced electromotive force generated around the microstrip line of the PCB board to be tested by the board-level radio frequency voltage to be tested, and the oscilloscope collects the induced electromotive force and sends it to the computer. The computer calculates the board-level RF voltage to be tested according to the induced electromotive force.

Optionally, in one embodiment, in order to facilitate the placement of the voltage probe, the time-domain voltage measurement device of this embodiment may further include a fixture, a bracket and a sample stage. The functions of each part are as follows:

Clamp: used to fix the voltage probe. Since the voltage probe needs to be connected to a coaxial cable, and the coaxial cable has certain rigidity, the clamp is required to fix the position of the voltage probe.

Bracket: used to fix the voltage probe fixture, thereby fixing the spatial position of the voltage probe. This is because during the entire detection process, the spatial position of the voltage probe will affect the acquisition of the detected signal; in addition, the spatial position of the voltage probe will affect the size of the calibration factor and the frequency response of the system. Therefore, a bracket can be provided to fix the spatial position of the voltage probe.

Sample stage: place the sample, the so-called sample is the microstrip line of the PCB board to be tested that is input with the RF voltage of the board level to be tested. The microstrip line of the PCB board to be tested can be welded on the PCB board through the SMA head.

The voltage probe can be fixed on the clamp, and the clamp installed with the voltage probe is fixed on the support, so that the voltage probe is perpendicular to the PCB board; the PCB board to be tested is slightly The strip line is fixed on the sample stage; the sample stage is adjusted so that the projection of the center of the bottom end of the voltage probe falls on the microstrip line of the PCB board to be tested. Further, in order to improve the measurement accuracy, the sample stage can be adjusted so that the plane of the bottom end of the voltage probe is parallel to the surface of the microstrip line of the PCB board to be tested, and the projection of the center of the bottom end of the voltage probe is on the surface of the to-be-tested PCB board. Measure the center of the microstrip line of the PCB board, and make the distance between the bottom end of the voltage probe and the surface of the microstrip line of the PCB board to be tested be 1 mm (the error can be controlled at 0.1 mm). In one embodiment, after the clamp is fixed on the support, the support can be adjusted horizontally and vertically. When the center of the voltage probe is projected on the center of the microstrip line of the PCB board to be tested, at a fixed height, the electric field induced by the probe is the strongest, which is most suitable for calibrating the probe.

As shown in FIG. 3, the present embodiment provides a time-domain voltage measurement method, which may include the following steps:

S101, fixing the relative position of the microstrip line of the PCB board to be tested and the voltage probe, and placing the voltage probe on the microstrip line of the PCB board to be tested when inputting the board-level radio frequency voltage to the PCB board to be tested Above the line, the projection of the bottom center of the voltage probe falls on the microstrip line of the PCB board to be tested, and the voltage probe is perpendicular to the microstrip line of the PCB board to be tested;

S102, using the electric field coupling to induce the induced electromotive force generated by the board-level radio frequency voltage to be tested around the microstrip line of the PCB to be tested through the voltage probe;

S103, collecting the induced electromotive force through an oscilloscope connected to the output terminal of the voltage probe;

S104. Calculate the board-level RF voltage to be tested by using the computer according to the induced electromotive force collected by the oscilloscope.

The computer can calculate the board-level RF voltage to be tested according to the induced electromotive force and a pre-calculated calibration factor. In one embodiment, the board-level RF voltage to be tested can be calculated according to the following formula:

v(t)=IFFT[F _PK (ω)] (1)

in,

F _P (ω) = FFT[v _P (t)] (3)

In the formula, v(t) is the radio frequency voltage of the board to be tested, vP(t) is the induced electromotive force, _K (ω) is the calibration factor, FFT means Fourier transform, IFFT means inverse Fourier leaf transformation.

The time-domain voltage measurement method of this embodiment can be implemented based on the time-domain voltage measurement device provided in the above-mentioned embodiments.

As shown in Figure 4, the present embodiment provides a kind of time-domain voltage measurement calibration measurement, which may include: calibration PCB board microstrip line, voltage probe, network analyzer and load; one end of the calibration PCB board microstrip line is connected to the The first port (i.e. port 1 in the figure) of the network analyzer, the other end of the calibration PCB board microstrip line is connected to the load, and the voltage probe is placed above the calibration PCB board microstrip line, Make the projection of the center of the bottom end of the voltage probe fall on the microstrip line of the calibration PCB board, and the voltage probe is perpendicular to the microstrip line of the calibration PCB board, and the output terminal of the voltage probe is connected to the network analysis The second port (i.e. port 2 in the figure) of the instrument is connected; the network analyzer tests the two ports formed by the calibration PCB board microstrip line and the voltage probe through the first port and the second port network to obtain a calibration factor for measuring and calibrating the board-level RF voltage of the microstrip line of the PCB board to be tested.

The above-mentioned time-domain voltage measurement and calibration device can accurately calculate the voltage for the PCB board to be tested by placing the voltage probe at a specified position and testing the two-port network composed of the calibration PCB microstrip line and the voltage probe through a network analyzer. The calibration factor for measuring and calibrating the board-level RF voltage of the microstrip line to be tested, thereby improving the accuracy of time-domain voltage measurement.

As shown in FIG. 5 , the calibration PCB board microstrip line is used as a calibration item to obtain and determine the calibration factor of the probe. Wherein, the impedance of the microstrip line of the calibration PCB board is 50 ohms, and the higher the applicable frequency, the better, usually at least above 2 GHz. The impedance of the calibration PCB board microstrip line can be designed to form an impedance match with the signal acquisition device and the signal output device, so as to ensure that the signal is not reflected during the transmission process, thereby ensuring the accuracy of the calibration.

The function of the network analyzer is to measure the transmission characteristics of the two-port network system composed of the voltage probe and the microstrip line of the calibration PCB board, so as to obtain the calibration factor. In the network system, the calibration PCB board microstrip line is usually used as port 1, and the voltage probe is used as port 2, and the network analyzer is used to measure the amplitude attenuation and phase change of signal transmission, and the measured The mode is frequency sweep. Before using the network analyzer, self-calibration of the network analyzer can be performed, and the scanning frequency range, output power and bandwidth of the network analyzer can be set. The calibration factor algorithm is as follows: K(ω)=S ₂₁ . S ₂₁ is the transmission coefficient measured by the network analyzer.

Optionally, the time-domain voltage measurement calibration measurement in this embodiment may also include a fixture, a support, and a sample stage. In one embodiment, before using the network analyzer for calibration, the voltage probe can be fixed on the fixture, and the fixture installed with the voltage probe can be fixed on the bracket, so that the voltage The probe is perpendicular to the microstrip line of the calibration PCB board; the microstrip line of the calibration PCB board is fixed on the sample stage; the sample stage is adjusted so that the projection of the center of the bottom end of the voltage probe falls on the calibration PCB microstrip line. Further, in order to improve the measurement accuracy, the sample stage can be adjusted so that the plane of the bottom end of the voltage probe is parallel to the microstrip line plane of the calibration PCB board, and the projection of the center of the bottom end of the voltage probe is on the calibration PCB The center of the microstrip line of the board, and the distance between the bottom end of the voltage probe and the surface of the microstrip line of the calibration PCB board is 1 mm (the error can be controlled within 0.1 mm). In one embodiment, after the clamp is fixed on the support, the support can be adjusted horizontally and vertically. When the center of the voltage probe is projected on the center of the microstrip line of the calibration PCB board, at a fixed height, the electric field induced by the probe is the strongest, which is most suitable for calibrating the probe. Embodiments of the components such as the above-mentioned voltage probes, fixtures, brackets, and sample stages may be the same as those of the corresponding components in the embodiments of the time-domain voltage measurement device, and will not be repeated here.

In practical applications, the calibration factor can be obtained first through the time-domain voltage measurement calibration device of this embodiment, and then the calibration factor can be used in the time-domain voltage measurement device for time-domain voltage measurement. In this way, higher measurement accuracy can be obtained.

As shown in FIG. 6, this embodiment provides a time-domain voltage measurement and calibration method, which may include the following steps:

S201, fixing the relative position of the microstrip line of the calibration PCB board and the voltage probe, and placing the voltage probe on the microstrip line of the calibration PCB board when inputting the calibration board level radio frequency voltage to the microstrip line of the calibration PCB board Above the strip line, the projection of the bottom center of the voltage probe falls on the microstrip line of the calibration PCB board, and the voltage probe is perpendicular to the microstrip line of the calibration PCB board;

S202, testing the two-port network composed of the calibration PCB board microstrip line and the voltage probe by a network analyzer, and obtaining a calibration factor for measuring and calibrating the board-level radio frequency voltage of the PCB board microstrip line to be tested ;

Wherein, the first port (i.e. port 1 in the figure) of the network analyzer is connected to one end of the calibration PCB board microstrip line, and the second port (i.e. the port 2 in the figure) of the network analyzer is connected to The output end of the voltage probe is connected, and the other end of the calibration PCB board microstrip line is connected to an impedance-matched load.

The above time-domain voltage measurement and calibration method, by placing the voltage probe at the specified position, and testing the two-port network composed of the calibration PCB microstrip line and the voltage probe through the network analyzer, can accurately calculate the The calibration factor for measuring and calibrating the board-level RF voltage of the microstrip line to be tested, thereby improving the accuracy of time-domain voltage measurement.

The time-domain voltage measurement and calibration method of this embodiment can be implemented based on the above-mentioned time-domain voltage measurement and calibration device. In practical applications, the calibration factor may be first obtained through the time-domain voltage measurement calibration method of this embodiment, and then the calibration factor is used in the time-domain voltage measurement method to perform time-domain voltage measurement. In this way, further higher measurement accuracy can be obtained. Specifically, after the calibration factor is obtained, the calibration factor can be substituted into formula (2), so as to calculate the board-level RF voltage to be tested according to the calibration factor and the induced electromotive force.

As shown in Figure 7, an embodiment of the present invention provides a time-domain voltage measurement calibration verification device, which may include: calibration PCB board microstrip line, voltage probe, arbitrary waveform generator, oscilloscope and computer. The voltage probe is placed on the Calibrate above the microstrip line of the PCB board, so that the projection of the center of the bottom end of the voltage probe falls on the microstrip line of the calibration PCB board, and the voltage probe is perpendicular to the microstrip line of the calibration PCB board, and the voltage The output end of probe is connected with the first channel of described oscilloscope; The output channel of described arbitrary waveform generator is connected to the second channel of described oscilloscope by the microstrip line of described calibration PCB board; Described arbitrary waveform generator is to The calibration PCB board microstrip line input voltage signal, the voltage probe utilizes electric field coupling to induce the induced electromotive force generated around the calibration PCB board microstrip line by the voltage signal, and the oscilloscope passes through the first channel Collect the induced electromotive force output by the voltage probe, and collect the second calibration verification voltage on the microstrip line of the calibration PCB board through the second channel, and the computer calculates the first calibration verification voltage according to the induced electromotive force collected by the oscilloscope , and verify the calibration factor according to the first calibration verification voltage and the second calibration verification voltage; wherein, the calibration factor is used to measure and calibrate the board-level RF voltage of the microstrip line of the PCB board to be tested.

The above-mentioned time-domain voltage measurement calibration verification device, by placing the voltage probe at a specified position, inputting an arbitrary waveform voltage signal to one end of the microstrip line of the calibration PCB board through an arbitrary waveform generator, collecting the induced electromotive force and calibrating the PCB through an oscilloscope The second calibration verification voltage on the microstrip line of the board, the first calibration verification voltage is calculated according to the collected induced electromotive force, and the calibration factor is verified according to the first calibration verification voltage and the second calibration verification voltage, which can improve the use of The accuracy of the calibration factor for measuring and calibrating the board-level RF voltage of the microstrip line of the PCB board to be tested is used to improve the accuracy of time-domain voltage measurement.

The arbitrary waveform generator is applied to the calibration verification part, and an arbitrary waveform is input to one end of the microstrip line of the calibration PCB board. The internal impedance of the arbitrary waveform generator can be set to match the internal impedance of the acquisition device (that is, the oscilloscope). For example, when the internal impedance of the acquisition channel of the oscilloscope is 50Ω, the internal impedance of the arbitrary waveform generator is also 50Ω. The waveform input to the microstrip line of the calibration PCB board may be a square wave, a triangle wave or a sawtooth wave or the like.

The oscilloscope is used as signal acquisition in the system verification part. One of the channels of the oscilloscope is connected to the voltage probe to read the voltage waveform collected by the voltage probe, the internal impedance of the channel is set to 50Ω, the voltage waveform is used to restore the measured voltage, the restored The measured voltage is used as the first calibration verification voltage; at the same time, another channel of the oscilloscope also sets the internal impedance to 50Ω, and connects the other end of the calibration PCB microstrip line to monitor the calibration PCB microstrip line The voltage on the above, the voltage waveform is used as the second calibration verification voltage, compared with the first calibration verification voltage to verify the correctness of the calibration factor.

Optionally, clamps, holders and sample stages can also be included. In one embodiment, before using the arbitrary waveform generator to input a voltage signal, the voltage probe can be fixed on the fixture, and the fixture installed with the voltage probe can be fixed on the bracket, so that The voltage probe is perpendicular to the microstrip line of the calibration PCB board; the microstrip line of the calibration PCB board is fixed on the sample stage; the sample stage is adjusted so that the projection of the center of the bottom end of the voltage probe falls on The calibration PCB board microstrip line. Further, in order to improve the measurement accuracy, the sample stage can be adjusted so that the plane of the bottom end of the voltage probe is parallel to the plane of the microstrip line of the calibration PCB, and the projection of the center of the bottom end of the voltage probe is on the plane of the microstrip line of the calibration PCB board. center, and the distance between the bottom end of the voltage probe and the surface of the microstrip line of the calibration PCB board is 1 mm (the error can be controlled within 0.1 mm). In one embodiment, after the clamp is fixed on the support, the support can be adjusted horizontally and vertically. When the center of the voltage probe is projected on the center of the microstrip line of the calibration PCB board, at a fixed height, the electric field induced by the probe is the strongest, which is most suitable for calibrating the probe. Embodiments of the components such as the above-mentioned voltage probes, fixtures, brackets, and sample stages may be the same as those of the corresponding components in the embodiments of the time-domain voltage measurement device, and will not be repeated here.

In practical applications, the calibration factor can be first obtained by the above-mentioned time-domain voltage measurement calibration device, and then the obtained calibration factor can be calibrated and verified by the time-domain voltage measurement calibration verification device of this embodiment. If the verification is successful, it means that the calibration factor conforms to the actual Conditions, the calibration factor can be used in the time-domain voltage measurement device for time-domain voltage measurement; if the verification fails, it means that the calibration factor does not meet the actual conditions, and the calibration factor can be obtained again through the above-mentioned time-domain voltage measurement calibration device. In this way, higher measurement accuracy can be obtained.

As shown in FIG. 8, this embodiment provides a time-domain voltage measurement calibration verification method, which may include the following steps:

S301, fixing the relative position of the microstrip line of the calibration PCB board and the voltage probe, and placing the voltage probe on the calibration PCB when inputting the calibration board-level RF voltage to the microstrip line of the calibration PCB board Above the microstrip line of the board, the projection of the bottom center of the voltage probe falls on the microstrip line of the calibration PCB board, and the voltage probe is perpendicular to the microstrip line of the calibration PCB board;

S302, inputting a voltage signal of an arbitrary waveform to one end of the microstrip line of the calibration PCB board through an arbitrary waveform generator;

S303, using the electric field coupling to induce the induced electromotive force generated by the voltage signal around the microstrip line of the calibration PCB board through the voltage probe;

S304. Connect the first channel of the oscilloscope to the output end of the voltage probe, and collect the induced electromotive force output by the voltage probe through the first channel;

S305. Connect the second channel of the oscilloscope to the other end of the microstrip line of the calibration PCB board, and collect the second calibration verification voltage on the microstrip line of the calibration PCB board through the second channel;

S306, using the computer to calculate the first calibration verification voltage according to the induced electromotive force collected by the oscilloscope, and verify the calibration factor according to the first calibration verification voltage and the second calibration verification voltage; wherein the calibration factor is used for Measure and calibrate the board-level RF voltage of the microstrip line of the PCB board to be tested.

The above time-domain voltage measurement calibration verification method, by placing the voltage probe at a specified position, inputting an arbitrary waveform voltage signal to one end of the microstrip line of the calibration PCB board through an arbitrary waveform generator, collecting the induced electromotive force and calibrating the PCB through an oscilloscope The second calibration verification voltage on the microstrip line of the board, the first calibration verification voltage is calculated according to the collected induced electromotive force, and the calibration factor is verified according to the first calibration verification voltage and the second calibration verification voltage, which can improve the use of The accuracy of the calibration factor for measuring and calibrating the board-level RF voltage of the microstrip line of the PCB board to be tested is used to improve the accuracy of time-domain voltage measurement.

The time-domain voltage measurement calibration verification method of this embodiment can be implemented based on the above-mentioned time-domain voltage measurement calibration verification device. In practical applications, the calibration factor can be first obtained through the above-mentioned time-domain voltage measurement calibration method, and then the obtained calibration factor can be calibrated and verified through the time-domain voltage measurement calibration verification method of this embodiment. If the verification is successful, it means that the calibration factor conforms to the actual Conditions, the calibration factor can be used in the time-domain voltage measurement method for time-domain voltage measurement; if the verification fails, it means that the calibration factor does not meet the actual conditions, and the calibration factor can be obtained again through the above-mentioned time-domain voltage measurement calibration method. In this way, further higher measurement accuracy can be obtained.

In one embodiment, the first calibration verification voltage can be calculated according to the following formula:

v _MK (t) = IFFT[F _MK (ω)] (5)

in,

F _MK (ω) = F _M (ω)·K(ω) (6)

F _M (ω) = FFT[v _M (t)] (7)

In the formula, v _M (t) is the induced electromotive force, v _MK (t) is the first calibration verification voltage, and K(ω) is a calibration factor.

If the difference between the first calibration verification voltage and the second calibration verification voltage is less than the preset threshold, it is determined that the verification is successful, and the calibration factor can be substituted into formula (2) for calculation to obtain the The time-domain waveform of the board-level RF voltage; otherwise, if it is determined that the verification fails, the calibration factor is recalculated.

It is worth mentioning that the positions of the voltage probe and the microstrip line of the PCB board (including the microstrip line of the calibration PCB board and the microstrip line of the PCB board to be tested) in the calibration part, the calibration verification part and the measurement part should be Try to be as consistent as possible. The better the agreement, the higher the measurement accuracy.

FIG. 9 shows a typical measured parameter of S ₂₁ , that is, the calibration factor K(ω). Fig. 10(a) and Fig. 10(b) respectively show the output voltage of the voltage probe in the calibration verification link and the first calibration verification voltage calculated and restored according to the output voltage. FIG. 10( c ) is the actually measured board-level RF voltage, that is, the second calibration verification voltage.

The technical features of the above-mentioned embodiments can be combined arbitrarily. To make the description concise, all possible combinations of the technical features in the above-mentioned embodiments are not described. However, as long as there is no contradiction in the combination of these technical features, should be considered as within the scope of this specification.

The above-mentioned embodiments only express several implementation modes of the present invention, and the descriptions thereof are relatively specific and detailed, but should not be construed as limiting the patent scope of the invention. It should be pointed out that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent for the present invention should be based on the appended claims.

Claims (10)

1. A time domain voltage measurement method is characterized by comprising the following steps:

fixing the relative position of a micro-strip line of a PCB to be detected and a voltage probe, and placing the voltage probe above the micro-strip line of the PCB to be detected when inputting board-level radio frequency voltage to the micro-strip line of the PCB to be detected, so that the projection of the center of the bottom end of the voltage probe falls on the micro-strip line of the PCB to be detected, and the voltage probe is vertical to the micro-strip line of the PCB to be detected;

inducing induced electromotive force generated around the microstrip line of the PCB to be tested by the board-level radio-frequency voltage to be tested by the voltage probe through electric field coupling;

acquiring the induced electromotive force through an oscilloscope connected with the output end of the voltage probe;

and calculating the board-level radio-frequency voltage to be measured by the computer according to the induced electromotive force acquired by the oscilloscope.

2. The time domain voltage measuring method of claim 1, wherein the step of placing the voltage probe above the microstrip line of the PCB board to be tested comprises:

fixing the voltage probe on a clamp, and fixing the clamp provided with the voltage probe on a bracket to ensure that the voltage probe is vertical to the microstrip line of the PCB to be tested;

fixing the micro-strip line of the PCB to be tested on a sample stage;

and adjusting the sample stage to enable the projection of the center of the bottom end of the voltage probe to fall on the micro-strip line of the PCB to be detected.

3. The time-domain voltage measuring method according to claim 2, wherein the step of adjusting the sample stage so that the projection of the center of the bottom end of the voltage probe falls on the microstrip line of the PCB board to be measured comprises:

and adjusting the sample stage to enable the plane of the bottom end of the voltage probe to be parallel to the surface of the micro-strip line of the PCB to be detected, enabling the projection of the center of the bottom end of the voltage probe to be at the center of the micro-strip line of the PCB to be detected, and enabling the distance between the bottom end of the voltage probe and the surface of the micro-strip line of the PCB to be detected to be 1 mm.

4. The time domain voltage measuring method of claim 3, wherein the holder is adjustable in a horizontal direction and a vertical direction after the holder is fixed to the holder.

5. The time-domain voltage measuring method according to any one of claims 1 to 4, wherein the step of calculating the board-level radio-frequency voltage to be measured by the computer according to the induced electromotive force collected by the oscilloscope comprises:

calculating the radio frequency voltage of the board level to be measured according to the following modes:

v(t)＝IFFT[F_PK(ω)]；

wherein, F_PK(ω)＝F_P(ω)·K(ω)；

F_P(ω)＝FFT[v_P(t)]；

Where v (t) is the RF voltage of the board to be tested, v_P(t) is the induced electromotive force, and K (ω) is a calibration factor.

6. A time domain voltage measurement calibration method, comprising the steps of:

fixing the relative positions of a calibration PCB microstrip line and the voltage probe, and placing the voltage probe above the calibration PCB microstrip line when a calibration board-level radio frequency voltage is input to the calibration PCB microstrip line, so that the projection of the center of the bottom end of the voltage probe falls on the calibration PCB microstrip line, and the voltage probe is perpendicular to the calibration PCB microstrip line;

testing a two-port network formed by the calibration PCB microstrip line and the voltage probe through a network analyzer to obtain a calibration factor for measuring and calibrating the to-be-measured board-level radio frequency voltage of the to-be-measured PCB microstrip line;

the first port of the network analyzer is connected with one end of the calibration PCB microstrip line, the second port of the network analyzer is connected with the output end of the voltage probe, and the other end of the calibration PCB microstrip line is connected with a load matched with impedance.

7. The time domain voltage measurement calibration method of claim 6, wherein the network analyzer further calculates a calibration factor according to the following formula:

K(ω)＝S₂₁；

in the formula, K (omega) is a calibration factor, S₂₁The transmission coefficient measured by the network analyzer.

8. A time domain voltage measurement calibration verification method is characterized by comprising the following steps:

fixing the relative positions of a calibration PCB microstrip line and the voltage probe, and placing the voltage probe above the calibration PCB microstrip line when a calibration board-level radio frequency voltage is input to the calibration PCB microstrip line, so that the projection of the center of the bottom end of the voltage probe falls on the calibration PCB microstrip line, and the voltage probe is perpendicular to the calibration PCB microstrip line;

inputting a voltage signal with an arbitrary waveform to one end of the calibration PCB microstrip line through an arbitrary waveform generator;

inducing induced electromotive force generated around the calibration PCB microstrip line by the voltage signal by the voltage probe through electric field coupling;

connecting a first channel of an oscilloscope with the output end of the voltage probe, and acquiring induced electromotive force output by the voltage probe through the first channel;

connecting a second channel of the oscilloscope with the other end of the calibration PCB microstrip line, and collecting a second calibration verification voltage on the calibration PCB microstrip line through the second channel;

calculating a first calibration verification voltage according to the induced electromotive force acquired by the oscilloscope through a computer, and verifying a calibration factor according to the first calibration verification voltage and a second calibration verification voltage; the calibration factor is used for measuring and calibrating the board-level radio frequency voltage to be measured of the PCB microstrip line to be measured.

9. The time-domain voltage measurement calibration verification method according to claim 8, wherein the step of calculating, by a computer, a first calibration verification voltage from the induced electromotive force collected by the oscilloscope comprises:

the first calibration verification voltage is calculated according to the following formula:

v_MK(t)＝IFFT[F_MK(ω)]；

wherein, F_MK(ω)＝F_M(ω)·K(ω)；

F_M(ω)＝FFT[v_M(t)]；

In the formula, v_M(t) is the induced electromotive force, v_MK(t) is the first calibration verify voltage, and K (ω) is a calibration factor.

10. The time-domain voltage measurement calibration verification method of claim 8, wherein the step of verifying a calibration factor based on the first calibration verification voltage and the second calibration verification voltage comprises:

if the difference value of the first calibration verification voltage and the second calibration verification voltage is smaller than a preset threshold value, judging that the verification is successful;

otherwise, the verification is judged to fail.