WO2023284679A1 - Apparatus and method for calibrating complex frequency response of sampling oscilloscope - Google Patents

Abstract

An apparatus and method for calibrating a complex frequency response of a sampling oscilloscope, by means of which the problems of poor calibration precision and high uncertainty of existing apparatuses and methods are solved. The apparatus includes: a waveform generation module (1), which is used for generating an excitation signal; a reference signal generation module (2), which is used for receiving the excitation signal, and generating a reference signal; a calibration signal generation module (3), which is used for receiving the excitation signal, and generating a calibration signal; a non-linear vector network analyzer (4), which is used for firstly receiving the reference signal to perform self-calibration, and then switching a channel to receive the calibration signal and deliver same to a calibrated sampling oscilloscope (7); an error correction module (5), which is used for generating two in-phase orthogonal signals to perform time base jitter and distortion error correction on the calibrated sampling oscilloscope (7); and a clock module (6), which is used for providing a synchronization clock signal to the waveform generation module (1), the non-linear vector network analyzer (4), the error correction module (5) and the calibrated sampling oscilloscope (7). By means of the apparatus, a fast complex frequency response and high-precision measurement and calibration of a sampling oscilloscope can be realized.

Description

A sampling oscilloscope complex frequency response calibration device and method

This application claims the priority of the Chinese patent application filed with the State Intellectual Property Office of China on July 12, 2021, with the application number 202110783142.X and the title of the invention "A Device and Method for Calibrating Complex Frequency Response of a Sampling Oscilloscope". The entire content of the prior application is incorporated by reference in this application.

technical field

The invention relates to the technical field of instrument measurement, in particular to a device and method for calibrating the complex frequency response of a sampling oscilloscope.

Background technique

With the rapid development of information technology, many ultra-fast, ultra-high-speed, and ultra-broadband devices and instruments have appeared. Sampling oscilloscopes are widely used in the microwave field because of their strong flexibility, low cost, and growing bandwidth. Applications are increasingly widespread. At present, the photoelectric combination method can be used to calibrate the complex frequency response of ultra-fast, ultra-high-speed, ultra-broadband devices and equipment. This method generates high-speed pulse signals based on photoelectric combination, and then uses the calibrated sampling oscilloscope to measure the high-speed pulse signals. The complex frequency response of the sampling oscilloscope is obtained by the deconvolution of the measured signal and the known high-speed pulse signal. The disadvantage is that in the calibration process, in order to obtain the reflection coefficient of the calibration end face of the sampling oscilloscope, it is necessary to repeatedly connect the measuring instrument, thus increasing the cost. The effects of time base drift and jitter during calibration add to the measurement uncertainty.

Contents of the invention

The invention provides a sampling oscilloscope complex frequency response calibration device and method, which solves the problems of poor calibration accuracy and high uncertainty in the existing devices and methods.

In order to solve the above problems, the present invention is achieved in that:

An embodiment of the present invention provides a sampling oscilloscope complex frequency response calibration device, which is characterized in that it includes: a waveform generation module, a reference signal generation module, a calibration signal generation module, a nonlinear vector network analyzer, an error correction module, and a clock module; The waveform generation module is used to generate an excitation signal; the reference signal generation module is used to receive the excitation signal and generate a reference signal; the calibration signal generation module is used to receive the excitation signal and generate a calibration signal; The error correction module is used to generate two in-phase and quadrature signals to the calibrated sampling oscilloscope for time base jitter and distortion error correction; the nonlinear vector network analyzer is used to first receive the reference signal for self-calibration , then switch channels to receive and transmit the calibration signal to the calibrated sampling oscilloscope, and is also used to calculate the first frequency response of the calibrated sampling oscilloscope according to its frequency response; the clock module is used to provide the waveform generation module, non- The linear vector network analyzer, the error correction module and the calibrated sampling oscilloscope provide the synchronous clock signal.

Further, the device further includes an adapter for connecting the nonlinear vector network analyzer and the calibrated sampling oscilloscope.

Further, both the reference signal generation module and the calibration signal generation module use a comb spectrum generator.

Preferably, the error correction module is a quadrature phase-shift power divider.

Preferably, the waveform generating module is an arbitrary waveform generator.

Preferably, the clock module is a signal source.

Preferably, the clock module is used to generate a first clock signal to the waveform generation module and the error correction module; the waveform generation module is used to receive the first clock signal and generate a coherent second clock signal Give the nonlinear vector network analyzer and the calibrated sampling oscilloscope.

The embodiment of the present invention also provides a sampling oscilloscope complex frequency response calibration method, using the sampling oscilloscope complex frequency response calibration device described in any one of the above, including the following steps: self-calibrating the nonlinear vector network analyzer to obtain its frequency response ; Calculate the corrected frequency response after correcting the time base jitter and distortion error for the calibrated sampling oscilloscope; divide the corrected frequency response by the frequency response of the nonlinear vector network analyzer to obtain the first frequency response of the calibrated sampling oscilloscope.

Further, the method also includes; calculating the second frequency response of the calibrated sampling oscilloscope:

The beneficial effects of the present invention include: the present invention provides a method and device for calibrating the complex frequency response of a sampling oscilloscope, which uses a nonlinear vector network analyzer to calibrate the complex frequency response of a sampling oscilloscope, and the method does not require repeated connection measurements The instrument can effectively reduce the influence of time base drift and jitter related to the repeatability of cables and connectors during the calibration process, and reduce the measurement uncertainty.

Description of drawings

Fig. 1 is a kind of sampling oscilloscope complex frequency response calibration device embodiment;

Fig. 2 is a kind of sampling oscilloscope complex frequency response calibration device embodiment comprising comb spectrum generator;

Fig. 3 is the connection mode embodiment of non-linear vector network analyzer and the sampling oscilloscope being checked;

FIG. 4 is an embodiment of a process flow of a method for calibrating the complex frequency response of a sampling oscilloscope.

detailed description

In order to make the purpose, technical solution and advantages of the present application clearer, the technical solution of the present application will be clearly and completely described below in conjunction with specific embodiments of the present application and corresponding drawings. Apparently, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in this application, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the scope of protection of this application.

With the rapid development of information technology, many ultra-fast, ultra-high-speed, and ultra-broadband devices and instruments have appeared. Sampling oscilloscopes are widely used in the microwave field because of their strong flexibility, low cost, and growing bandwidth. Applications are increasingly widespread. However, it is difficult to measure and calibrate many key indicators of such devices and equipment. When end users use such devices and equipment, they cannot obtain accurate and uniform values, which seriously affects the use of such devices and equipment. The reliability and stability of the system may eventually lead to major losses.

At present, the photoelectric combination method can calibrate the complex frequency response of ultra-fast, ultra-high-speed, ultra-wideband devices and equipment, and its most direct application is to calibrate the complex frequency response of sampling oscilloscopes. This method first generates high-speed pulses based on photoelectric combination Then use the calibrated sampling oscilloscope to measure the high-speed pulse signal, and obtain the complex frequency response of the sampling oscilloscope through the deconvolution of the measured signal and the known high-speed pulse signal. However, in order to obtain the reflection coefficient of the calibration end face of the sampling oscilloscope in the calibration process, this method needs to repeatedly connect the measuring instrument, which increases the influence of time base drift and jitter in the calibration process and increases the measurement uncertainty. In order to solve this problem, the present invention proposes a method and device for calibrating the complex frequency response of a sampling oscilloscope.

The innovations of the present invention are as follows: first, different from measuring the complex frequency response of the calibrated sampling oscilloscope by the traditional photoelectric combination method, the measuring device of the present invention uses a nonlinear vector network analyzer to calibrate the complex frequency response of the calibrated sampling oscilloscope, bringing The advantage of not needing to repeatedly connect the measuring instrument is to reduce the measurement random error; secondly, the present invention corrects the time base jitter and distortion error through the error correction module for the calibrated sampling oscilloscope, so that the measurement accuracy is improved.

The technical solutions provided by various embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings.

Fig. 1 is an embodiment of a sampling oscilloscope complex frequency response calibration device, which can be used to realize fast and accurate calibration of the sampled oscilloscope 7's complex frequency response. As an embodiment of the present invention, a sampling oscilloscope complex frequency response calibration device includes : a waveform generation module 1, a reference signal generation module 2, a calibration signal generation module 3, a nonlinear vector network analyzer 4, an error correction module 5, and a clock module 6.

The waveform generation module is used to generate an excitation signal; the reference signal generation module is used to receive the excitation signal to generate a reference signal; the calibration signal generation module is used to receive the excitation signal to generate a calibration signal; The nonlinear vector network analyzer is used to first receive the reference signal for self-calibration, then switch channels to receive and transmit the calibration signal to the calibrated sampling oscilloscope, and is also used to calculate the calibrated sampling oscilloscope according to its frequency response The first frequency response; the error correction module is used to generate two in-phase and quadrature signals to the oscilloscope to be corrected for time base jitter and distortion error correction; the clock module is used to provide the waveform generation module, A non-linear vector network analyzer, an error correction module and a calibrated sampling oscilloscope provide a synchronous clock signal.

In the embodiment of the present invention, the excitation signal can be used to drive the reference signal generation module and the calibration signal generation module to start working, the excitation signal is divided into two through the power divider, one path is input to the reference signal generation module, and the other path is input to the The calibration signal generation module.

When the device of the present invention works, the nonlinear vector network analyzer is self-calibrated by the reference signal first, and the self-calibration is carried out by using the continuous wave source inside the nonlinear vector network analyzer under default settings, and the nonlinear vector network analyzer is respectively Perform SOLT (short-open-load-thru calibration, S stands for short, O stands for open, L stands for load, T stands for thru), absolute amplitude and absolute phase calibration, and completes the automatic After calibration, switch the working channel of the nonlinear vector network analyzer, access the calibration signal, and transmit the signal to the calibrated sampling oscilloscope.

In the embodiment of the present invention, the specific process for the nonlinear vector network analyzer to calculate the first frequency response of the calibrated sampling oscilloscope based on its frequency response is: divide the modified frequency response by the nonlinear vector network analyzer The frequency response of the calibrated sampling oscilloscope is the first frequency response.

It should be noted that the amplitudes of the two in-phase and quadrature signals output by the error correction module are also the same.

It should also be noted that the synchronous clock signal provided by the clock module to the oscilloscope to be calibrated is connected to the trigger port of the oscilloscope to be calibrated.

In the embodiment of the present invention, preferably, both the reference signal generation module and the calibration signal generation module use a comb spectrum generator, the error correction module is a quadrature phase-shift power divider, and the waveform generation module is any A waveform generator, the clock module is a signal source. It should be noted that the above-mentioned modules may also be other devices with corresponding functions, which are not specifically limited here.

In the embodiment of the present invention, generally, the calibrated sampling oscilloscope and the nonlinear vector network analyzer are connected through an adapter, and the adapter can perform port conversion, but the embodiment of the present invention does not exclude the calibrated sampling oscilloscope and the nonlinear vector network analyzer. The case where the network analyzer is directly connected.

In the embodiment of the present invention, if the nonlinear vector network analyzer is connected to the calibrated sampling oscilloscope through an adapter, the influence of the adapter on the complex frequency response of the calibrated sampling oscilloscope needs to be corrected, specifically:

Wherein, H(ω) is the second frequency response of the calibrated sampling oscilloscope, H'(ω) is the first frequency response of the calibrated sampling oscilloscope, S ₁₁ (ω), S ₁₂ (ω), S ₂₁ ( ω), S ₂₂ (ω) are the first to fourth scattering parameters of the adapter, respectively, a ₁ (ω) and b ₁ (ω) are the first and second measurement parameters of the oscilloscope to be calibrated, and the calibrated Measured with a nonlinear vector network analyzer.

An embodiment of the present invention provides a device for calibrating the complex frequency response of a sampling oscilloscope. The nonlinear vector network analyzer is used to calibrate the complex frequency response of the sampling oscilloscope, which can effectively reduce the time base related to the repeatability of cables and connectors during the calibration process. Drift and jitter effects, reduce measurement uncertainty and improve measurement accuracy.

Fig. 2 is an embodiment of a sampling oscilloscope complex frequency response calibration device comprising a comb spectrum generator. As an embodiment of the present invention, a sampling oscilloscope complex frequency response calibration device includes: an arbitrary waveform generator 11, a first comb Spectrum generator 12, the second comb-shaped spectrum generator 13, nonlinear vector network analyzer 4, adapter 8, quadrature phase-shifting power divider 16, signal source 15, the device of the present invention is used for being checked and sampled oscilloscope 7 to carry out Complex Frequency Response Measurements.

The arbitrary waveform generator is used to generate an excitation signal, which is input to the first comb spectrum generator and the second comb spectrum generator respectively as a driving signal through a power divider; the first comb spectrum generator uses To provide a reference signal for a nonlinear vector network analyzer; the second comb spectrum generator is used to receive the excitation signal and generate a calibration signal; the nonlinear vector network analyzer is used to first receive the reference The signal is self-calibrated, and then the channel is switched to receive and transmit the calibration signal to the calibrated sampling oscilloscope; the quadrature phase-shift power divider is used to generate two in-phase and quadrature signals for the calibrated sampling oscilloscope to perform time base Jitter and distortion error correction; the signal source is used to generate a first clock signal to the arbitrary waveform generator and quadrature phase shift power divider; the arbitrary waveform generator is used to receive the first clock signal , generating a coherent second clock signal to the nonlinear vector network analyzer and the calibrated sampling oscilloscope; the adapter is used to connect the nonlinear vector network analyzer and the calibrated sampling oscilloscope.

When working, first, use the continuous wave source inside the nonlinear vector network analyzer to calibrate the nonlinear vector network analyzer under the default settings, and then connect the calibrated sampling oscilloscope to the test port of the nonlinear vector network analyzer, and the arbitrary waveform The excitation signal output by the signal output terminal of the generator is used as a drive signal and then input into two comb spectrum generators respectively through a power divider, one of which provides a reference signal for the nonlinear vector network analyzer, and the other A comb spectrum generator is used as a standard pulse source to replace the continuous wave source inside the vector network analyzer to calibrate the sampling oscilloscope.

After the signal output from the clock signal output terminal of the arbitrary waveform generator passes through the power divider, one channel is input as a clock signal to the clock signal input terminal of the nonlinear vector network analyzer, and the other channel is input as a trigger signal to the trigger signal input terminal of the calibrated sampling oscilloscope .

A sinusoidal signal generated by an external signal source is used as the main reference signal, and all other signals are locked to this signal. The main reference signal is input to the clock signal input terminal of the arbitrary waveform generator and the quadrature phase-shifting function after passing through the power divider. In the divider, the in-phase and quadrature signals output by the quadrature phase-shift power divider are input to the signal test port of the sampling oscilloscope, which is used to correct the time base jitter and distortion errors in the process of measuring the signal by the sampling oscilloscope. The complex frequency response of the sampling oscilloscope can be calculated by using the measured data of the sampling oscilloscope and the port parameters of the nonlinear vector network analyzer to realize the calibration of the sampling oscilloscope.

The embodiment of the present invention provides a specific device for calibrating the complex frequency response of a sampling oscilloscope. Each instrument is a conventional device for instrument measurement, which has the advantages of convenience, easy engineering implementation, and strong operability.

Fig. 3 is an embodiment of the connection mode between the nonlinear vector network analyzer and the calibrated sampling oscilloscope, which is a connection mode between the nonlinear vector network analyzer and the calibrated sampling oscilloscope.

In the embodiment of the present invention, the nonlinear vector network analyzer is connected to the calibrated sampling oscilloscope through an adapter, and the first input port of the adapter is connected to the output port of the nonlinear vector network analyzer for receiving the output signal of the nonlinear vector network analyzer a ₁ , the first output port of the adapter is connected to the input port of the calibrated sampling oscilloscope, and is used to output the signal a ₂ to the calibrated sampling oscilloscope, the second input port of the adapter is used to receive the output signal b ₂ of the calibrated sampling oscilloscope, the second adapter The output port is used to output the signal b ₁ to the nonlinear vector network analyzer.

In the embodiment of the present invention, the cascaded impulse response of the calibrated sampling oscilloscope and the adapter is h'(t), and the complex frequency response after Fourier transform is H'(ω), and finally the calibrated sampling oscilloscope without the embedded adapter is obtained. Calibrate the complex frequency response of a sampling oscilloscope.

In the embodiment of the present invention, S ₁₁ (ω), S ₁₂ (ω), S ₂₁ (ω), S ₂₂ (ω) are the first to fourth scattering parameters of the adapter, which are the S parameters of the adapter, and the vector The adapter is calibrated by a network analyzer.

Fig. 4 is an embodiment of a method for calibrating the complex frequency response of a sampling oscilloscope, using the device described in any embodiment of the present invention, as an embodiment of the present invention, a method for calibrating the complex frequency response of a sampling oscilloscope, specifically including the following steps 101-104 :

Step 101, self-calibrating the nonlinear vector network analyzer to obtain its frequency response.

In step 101 , after the reference signal is connected externally, the nonlinear vector network analyzer is calibrated with SOLT, absolute amplitude and absolute phase by using the continuous wave source inside the nonlinear vector network analyzer under default settings.

Step 102, calculating the corrected frequency response of the calibrated sampling oscilloscope after correcting the time base jitter and distortion error.

In step 102, the corrected frequency response is calculated by using the self-impulse response of the calibrated sampling oscilloscope and the self-impulse response of the error correction module by using methods such as autocorrelation.

Step 103, divide the modified frequency response by the frequency response of the nonlinear vector network analyzer to obtain the first frequency response of the calibrated sampling oscilloscope.

In step 103, the first frequency response of the calibrated sampling oscilloscope is:

Wherein, H'(ω) is the first frequency response of the calibrated sampling oscilloscope, H _S (ω) is the modified frequency response, and H _CG (ω) is the frequency response of the nonlinear vector network analyzer, which is Frequency response of a calibrated nonlinear vector network analyzer.

In step 103, the impulse response of the cascaded sampling oscilloscope and adapter is h'(t), and its complex frequency response H'(ω) is obtained after Fourier transform; the time base jitter and distortion of the signal measured by the sampling oscilloscope are corrected The impulse response h _S (t) can be obtained after the error, and the complex frequency response H _S (ω) can be obtained after Fourier transform; the output signal of the nonlinear vector network analyzer after calibration is h _CG (t), and its complex frequency response can be obtained after Fourier transform Complex frequency response H _CG (ω).

In step 103, if the nonlinear vector network analyzer is directly connected to the calibrated sampling oscilloscope, the first frequency response of the calibrated sampling oscilloscope is the complex frequency response of the calibrated sampling oscilloscope obtained through calibration.

Further, if the nonlinear vector network analyzer is connected with the calibrated sampling oscilloscope through an adapter or other connection methods, then the method also includes:

Step 104, if the nonlinear vector network analyzer is connected to the calibrated sampling oscilloscope through an adapter, then calculate the second frequency response of the calibrated sampling oscilloscope:

Wherein, H(ω) is the second frequency response of the calibrated sampling oscilloscope, H'(ω) is the first frequency response of the calibrated sampling oscilloscope, S ₁₁ (ω), S ₁₂ (ω), S ₂₁ ( ω), S ₂₂ (ω) are the first to fourth scattering parameters respectively, a ₁ (ω) and b ₁ (ω) are the first and second measurement parameters of the calibrated sampling oscilloscope respectively, and the nonlinear Measured by a vector network analyzer.

In step 104, the complex frequency response of the adapter needs to be de-embedded to obtain the complex frequency response of the calibrated sampling oscilloscope, that is, the second frequency response.

In step 104,

Where Γ _s (ω) is the reflection coefficient of the sampling oscilloscope to be calibrated, since T ₁ (ω) and T ₂ (ω) can be obtained from the calibration measurement of the nonlinear vector network analyzer, it can avoid the separate measurement of Γ _s (ω). Because measuring Γ _s (ω) alone needs to be repeatedly connected to the calibrated sampling oscilloscope, it will increase the influence of time base drift and jitter, resulting in greater measurement uncertainty.

An embodiment of the present invention provides a method for calibrating the complex frequency response of a sampling oscilloscope, which avoids repeated connection of the calibrated sampling oscilloscope, reduces the impact of random errors on measurement, and improves measurement accuracy.

It should be noted that the term "comprises", "comprises" or any other variation thereof is intended to cover a non-exclusive inclusion such that a process, method, article, or apparatus comprising a set of elements includes not only those elements, but also includes none other elements specifically listed, or also include elements inherent in such a process, method, commodity, or apparatus. Without further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article or apparatus comprising said element.

The above descriptions are only examples of the present invention, and are not intended to limit the present invention. Various modifications and variations of the present invention will occur to those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the scope of the claims of the present invention.

Claims (7)

1. A sampling oscilloscope complex frequency response calibration device, characterized in that it comprises: a waveform generation module, a reference signal generation module, a calibration signal generation module, a nonlinear vector network analyzer, an error correction module, a clock module, and an adapter;

   The waveform generation module is used to generate an excitation signal, and is also used to receive the first clock signal, and generate a coherent second clock signal to the nonlinear vector network analyzer and the calibrated sampling oscilloscope;

   The reference signal generating module is configured to receive the excitation signal and generate a reference signal;

   The calibration signal generating module is configured to receive the excitation signal and generate a calibration signal;

   The error correction module is used to generate two in-phase and quadrature signals for the calibrated sampling oscilloscope to correct time base jitter and distortion errors;

   The nonlinear vector network analyzer is used to first receive the reference signal for self-calibration, then switch channels to receive and transmit the calibration signal to the calibrated sampling oscilloscope, and is also used to calculate the calibrated sampling oscilloscope according to its frequency response first frequency response;

   The clock module is used to generate a first clock signal to the waveform generation module and the error correction module, and provide a synchronous clock signal to the waveform generation module, the nonlinear vector network analyzer, the error correction module and the calibrated sampling oscilloscope;

   The adapter is used to connect the nonlinear vector network analyzer and the calibrated sampling oscilloscope.
2. The device for calibrating the complex frequency response of the sampling oscilloscope according to claim 1, wherein the reference signal generation module and the calibration signal generation module both use a comb spectrum generator.
3. The calibration device for sampling oscilloscope complex frequency response as claimed in claim 1, wherein said error correction module is a quadrature phase-shift power divider.
4. The device for calibrating the complex frequency response of the sampling oscilloscope according to claim 1, wherein the waveform generating module is an arbitrary waveform generator.
5. The device for calibrating the complex frequency response of the sampling oscilloscope according to claim 1, wherein the clock module is a signal source.
6. A sampling oscilloscope complex frequency response calibration method, using the sampling oscilloscope complex frequency response calibration device described in any one of claims 1 to 5, characterized in that it comprises the following steps:

   Self-calibration of the nonlinear vector network analyzer to obtain its frequency response;

   Calculate the corrected frequency response after correcting the time base jitter and distortion error of the calibrated sampling oscilloscope;

   The first frequency response of the calibrated sampling oscilloscope is obtained by dividing the modified frequency response by the frequency response of the nonlinear vector network analyzer.
7. The calibration method of sampling oscilloscope complex frequency response as claimed in claim 6, is characterized in that, described method also comprises;

   Calculate the second frequency response of the calibrated sampling oscilloscope:

   

   Wherein, H(ω) is the second frequency response of the calibrated sampling oscilloscope, H'(ω) is the first frequency response of the calibrated sampling oscilloscope, S ₁₁ (ω), S ₁₂ (ω), S ₂₁ ( ω), S ₂₂ (ω) are the first to fourth scattering parameters of the sampled oscilloscope to be calibrated respectively, and a ₁ (ω) and b ₁ (ω) are the first and second measurement parameters of the oscilloscope to be sampled to be calibrated respectively.

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