CN107144738B - Multiport automatic clamp loss and phase compensation method based on straight-through line - Google Patents
Multiport automatic clamp loss and phase compensation method based on straight-through line Download PDFInfo
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- CN107144738B CN107144738B CN201710477917.4A CN201710477917A CN107144738B CN 107144738 B CN107144738 B CN 107144738B CN 201710477917 A CN201710477917 A CN 201710477917A CN 107144738 B CN107144738 B CN 107144738B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R35/00—Testing or calibrating of apparatus covered by the other groups of this subclass
- G01R35/005—Calibrating; Standards or reference devices, e.g. voltage or resistance standards, "golden" references
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- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
- G01R27/28—Measuring attenuation, gain, phase shift or derived characteristics of electric four pole networks, i.e. two-port networks; Measuring transient response
Abstract
The invention provides a multi-port automatic clamp loss and phase compensation method based on a straight-through line. The method is based on the loss and phase compensation of the multi-port automatic clamp of the straight-through line, and does not need to use various calibration pieces for de-embedding calculation, thereby reducing the requirements on the calibration pieces and the complexity of calculation and having simple design and realization; according to the invention, the automatic loss and phase compensation algorithm can be carried out on the multi-port non-coaxial clamp, the S parameter testing precision is improved, and the influence of the clamp on the testing result is removed.
Description
Technical Field
The invention relates to the technical field of testing, in particular to a multi-port automatic clamp loss and phase compensation method based on a straight-through line.
Background
In recent years, high-speed circuit boards, backplanes, connectors, and high-speed digital cables have been widely used in the fields of ethernet, 5G mobile communication, satellite navigation, and the like. In many of these fields, high-speed signals are transmitted in a differential multi-port format, and the interfaces are in a non-coaxial format in many cases. Therefore, the high-precision scattering parameter test of the device is very important for the construction of a system, and one of the key points of the test is that the instrument can carry out automatic error calibration and de-embedding.
Currently, only the german corporation (predecessor agilent corporation) software provides an automatic port extension function, but the function still needs a coaxial standard such as a shunt or a short-circuit device, cannot be directly applied to non-coaxial devices, and relevant reports about the method for extending the application of the method to the de-embedding of the multi-port device are not seen. While German Rod, Schwarz and Japan Anli do not provide an automatic clamp loss and phase compensation de-embedding scheme matched with the vector network analyzer, the loss and phase can only be manually set for simple compensation, the operation is complex and the requirement on the experience of a user is high.
The existing calibration de-embedding methods such as SOLT, SOLR and TRL, etc. have some methods which can only be used in coaxial ports and some methods which are complicated in the design and use of calibration parts.
In addition, in the existing scheme, the de-embedding of the multi-port device needs to use various calibration pieces such as short circuit, open circuit, load, direct connection and the like, and various standard pieces need to be completed for many times in the de-embedding process, so that the time is long and the efficiency is low.
Disclosure of Invention
In order to solve the defects in the prior art, the invention provides a multi-port automatic clamp loss and phase compensation method based on a straight-through wire.
The technical scheme of the invention is realized as follows:
a multi-port automatic clamp loss and phase compensation method based on a straight-through line obtains phase offset by using a time domain method, combines the loss of a radial basis function neural network fitting straight-through line, removes the influence of the straight-through line clamp between a coaxial reference surface and a reference surface of a tested piece, and obtains the scattering parameters of the multi-port tested piece.
Optionally, the multi-port automatic clamp loss and phase compensation method based on the straight-through line of the present invention includes the following steps:
the method comprises the following steps: calibrating the multi-port vector network analyzer, and calibrating the test end face to a coaxial reference surface; then, connecting the multi-port straight line clamp to a test port of a multi-port vector network analyzer through a coaxial connector or a probe; then, measuring to obtain frequency domain scattering parameters of the straight line clamp;
step two: using fast Fourier transform to obtain frequency domain scattering parameters S of the through-line clamp of each port obtained in the step oneijConverting into low-pass impulse response, obtaining Delay (i, j) of each port through line clamp by automatically searching maximum value of response, and obtaining Delay (i, j) according to the followingEquation (1) of (a) is converted into a phase shift of the through-wire jig:
φ(i，j)＝360*Freq*Delay(i，j) (1)
phi (i, j) represents the phase shift from a port j to a port i of the multi-port tested piece, Freq is a test frequency point, and Delay (i, j) represents the Delay from the port j to the port i of the multi-port tested piece;
step three: the through line loss is expressed by a function of equation (2):
Loss(Freq)＝Amp·Freqb(2)
wherein Amp is a loss factor, b is a loss index, and the scattering parameter S can be obtained through the test of the first stepijCalculating to obtain;
step four: repeating the second step to the third step until the loss and the phase at each port of the transmission line clamp are obtained, and then performing the fifth step;
step five: and connecting the straight line clamp and the multi-port tested piece to a multi-port vector network analyzer, loading the loss and the phase of the transmission line clamp obtained in the first step to the fourth step to the multi-port vector network analyzer to be embedded into a software module, and testing to obtain accurate frequency domain scattering parameters of the multi-port tested piece.
Optionally, in the third step, the loss function is identified and fitted by using a radial basis function neural network as described in formula (3):
wherein the content of the first and second substances,
representing radial basis functions, cnRepresenting the central vector of the nth neuron, anRepresenting the weight of the neuron.
Optionally, the radial basis function
Selecting a Gaussian base function as in equation (4):
optionally, the radial basis function neural network adopts a two-step learning algorithm to identify and fit the loss function, and the first step is to obtain a central vector c of the neuron based on a K-means clustering methodnAnd the second step is to solve by using a least square method to obtain the weight of the neuron.
The invention has the beneficial effects that:
(1) the loss and phase compensation of the multi-port automatic clamp based on the straight line do not need to use various calibration pieces for de-embedding calculation, the requirements on the calibration pieces and the complexity of calculation are reduced, and the design is simple to realize;
(2) by adopting the automatic loss and phase compensation algorithm for the multi-port non-coaxial clamp, the S parameter testing precision is improved, and the influence of the clamp on the testing result is eliminated.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
FIG. 1a is a schematic diagram of the loss and phase compensation method of the multi-port automatic clamp based on a through line according to the present invention;
FIG. 1b is a test connection diagram of a multi-port automatic clamp loss and phase compensation method based on a straight-through line according to the present invention;
FIG. 2 is a flow chart of a multi-port automatic clamp loss and phase compensation method based on a straight-through line of the present invention;
FIG. 3a is a straight line clamp measurement connection diagram of a straight line based multi-port automatic clamp loss and phase compensation method of the present invention;
FIG. 3b is a schematic diagram of an error model of a multi-port automatic clamp loss and phase compensation method based on a straight-through line according to the present invention;
FIG. 4 is a schematic diagram of clamp de-embedding for a multi-port automatic clamp loss and phase compensation method based on a through line according to the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Aiming at the problem of calibration de-embedding of a multi-port non-coaxial tested piece, the invention provides a multi-port automatic clamp loss and phase compensation method based on a straight-through line, the test principle is shown in a figure 1a and a figure 1b, the invention obtains phase offset by using a time domain method, and removes the influence of the straight-through line clamp between a coaxial reference surface and a reference surface of the tested piece by combining the loss of the straight-through line of a radial basis neural network fitting, thereby obtaining accurate scattering parameters of the multi-port tested piece.
The compensation method of the present invention is described in detail below with reference to the drawings attached to the specification.
As shown in fig. 2, the multi-port automatic clamp loss and phase compensation method based on the straight-through line of the invention comprises the following steps:
the method comprises the following steps: firstly, calibrating a multi-port vector network analyzer, and calibrating a test end face to a coaxial reference surface; then, connecting the multi-port straight line clamp to a test port of a multi-port vector network analyzer through a coaxial connector or a probe; then, the frequency domain scattering parameters of the through line fixture are obtained by measurement, and the specific test connection relationship is shown in fig. 3a and 3 b.
Step two: using Fast Fourier Transform (FFT) to obtain frequency domain scattering parameters S of the through-line clamp of each port obtained in the step oneijTransforming into low-pass impulse response by automatically searching for the maximum value of the responseDelay (i, j) of each port through line clamp is converted into a phase shift of the through line clamp according to the following formula (1):
φ(i，j)＝360*Freq*Delay(i，j) (1)
wherein φ (i, j) represents the phase shift from port j to port i of the multi-port device under test, Freq is the test frequency point, and Delay (i, j) represents the Delay from port j to port i of the multi-port device under test.
Step three: the through-line loss (commonly known as axial loss, microstrip line loss) is expressed as a function of equation (2):
Loss(Freq)＝Amp·Freqb(2)
wherein, Amp and b are loss factor and loss index respectively, and scattering parameter S can be obtained through the test of step 1ijAnd (4) calculating.
In order to more accurately and flexibly describe the loss of various straight-through lines, the invention adopts a Radial Basis Function (RBF) neural network described by the formula (3) to identify and fit a loss function:
wherein the content of the first and second substances,
representing radial basis functions, cnRepresenting the central vector of the nth neuron, anRepresenting the weight of the neuron.
Radial basis function of the invention
Selecting a Gaussian base function as in equation (4):
the radial basis function neural network in the invention adopts a two-step learning algorithm to identify and fit the loss function, and the first step is to obtain a central vector c of a neuron based on a K-mean clustering methodnAnd the second step is to solve by using a least square method to obtain the weight of the neuron.
Step four: and repeating the second step to the third step until the loss and the phase at each port of the transmission line clamp are obtained, and then performing the fifth step.
Step five: and connecting the straight line clamp and the multi-port tested piece to a multi-port vector network analyzer as shown in fig. 4, loading the loss and the phase of the transmission line clamp obtained in the first step to the fourth step to the multi-port vector network analyzer for embedding into a software module, and testing to obtain accurate frequency domain scattering parameters of the multi-port tested piece.
The method is based on the loss and phase compensation of the multi-port automatic clamp of the straight-through line, and does not need to use various calibration pieces for de-embedding calculation, thereby reducing the requirements on the calibration pieces and the complexity of calculation and having simple design and realization; according to the invention, the automatic loss and phase compensation algorithm can be carried out on the multi-port non-coaxial clamp, the S parameter testing precision is improved, and the influence of the clamp on the testing result is removed.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.
Claims (4)
1. A multiport automatic clamp loss and phase compensation method based on a straight-through line is characterized in that a time domain method is used for obtaining phase deviation, the loss of the straight-through line is fitted by combining a radial basis function neural network, the influence of the straight-through line clamp between a coaxial reference surface and a reference surface of a tested piece is removed, and a multiport tested piece scattering parameter is obtained; the method comprises the following steps:
the method comprises the following steps: firstly, calibrating a multi-port vector network analyzer, and calibrating a test end face to a coaxial reference surface; then, connecting the multi-port straight line clamp to a test port of a multi-port vector network analyzer through a coaxial connector or a probe; then, measuring to obtain frequency domain scattering parameters of the straight line clamp;
step two: using fast Fourier transform to obtain frequency domain scattering parameters S of the through-line clamp of each port obtained in the step oneijConverting into low-pass impulse response, obtaining Delay (i, j) of each port through line clamp by automatically searching the maximum value of the response, and converting into phase offset of the through line clamp according to the following formula (1):
φ(i，j)＝360*Freq*Delay(i，j) (1)
phi (i, j) represents the phase shift from a port j to a port i of the multi-port tested piece, Freq is a test frequency point, and Delay (i, j) represents the Delay from the port j to the port i of the multi-port tested piece;
step three: the through line loss is expressed by a function of equation (2):
Loss(Freq)＝Amp·Freqb(2)
wherein Amp is a loss factor, b is a loss index, and a scattering parameter S is obtained through the test of the first stepijCalculating to obtain;
step four: repeating the second step to the third step until the loss and the phase at each port of the transmission line clamp are obtained, and then performing the fifth step;
step five: and connecting the straight line clamp and the multi-port tested piece to a multi-port vector network analyzer, loading the loss and the phase of the transmission line clamp obtained in the first step to the fourth step to the multi-port vector network analyzer to be embedded into a software module, and testing to obtain accurate frequency domain scattering parameters of the multi-port tested piece.
2. The multi-port automatic clamp loss and phase compensation method based on the straight-through line as claimed in claim 1, wherein in the third step, the radial basis function is adopted to identify and fit the loss function as described in formula (3):
wherein the content of the first and second substances,
representing radial basis functions, cnRepresenting the central vector of the nth neuron, anRepresenting the weight of the neuron.
3. The method of claim 2, wherein the radial basis function is a straight-through based multi-port automated chuck loss and phase compensation method
Selecting a Gaussian base function as in equation (4):
4. the method of claim 2, wherein the radial basis function neural network adopts a two-step learning algorithm to identify and fit the loss function, and the first step is to obtain the central vector c of the neuron based on a K-means clustering methodnAnd the second step is to solve by using a least square method to obtain the weight of the neuron.
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| CN108845182B (en) * | 2018-05-29 | 2019-11-22 | 中国电子科技集团公司第四十一研究所 | A kind of phase calculation method applied to fixture parameter extraction |
| CN110333438B (en) * | 2019-07-08 | 2022-01-28 | 深南电路股份有限公司 | Data processing apparatus, data processing method, and readable storage medium |
| CN111988063B (en) * | 2020-08-31 | 2021-10-08 | 中电科思仪科技股份有限公司 | Cable loss compensation method and system for comprehensive tester |
| CN111999587B (en) * | 2020-08-31 | 2023-07-28 | 中电科思仪科技股份有限公司 | Iterative vector error correction method for modulation domain network parameter test |
| CN113204511B (en) * | 2021-05-08 | 2023-01-06 | 山东英信计算机技术有限公司 | Method, system, equipment and medium for correcting USB based on port compensation |
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