JP2005331519A - Method, program and network analyzer for obtaining network characteristic - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for obtaining the absolute characteristics of a fixture in a non-coaxial measurement system. <P>SOLUTION: A network analyzer is connected to the fixture, and the electric length of the fixture, the DUT port of which is opened or short-circuited is measured. A first network characteristics of the fixture, the DUT port of which is opened is obtained by measured by the network analyzer, and a second network characteristics of the fixture, the DUT port of which is short-circuited is obtained by measured by the network analyzer. By using the previously measured electric length, the first network characteristics and the second characteristics are corrected respectively. The network characteristics of the remaining impedance component is calculated from the corrected first network characteristics and the corrected second network characteristics. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a technique for obtaining characteristics of a fixture connected to an electronic measurement apparatus.

  A fixture (jig) is one of the devices that are used supplementarily when measuring an object to be measured with a network analyzer. The fixture is used when the device under test cannot be directly connected to the network analyzer, for example, when the port shape of the network analyzer is different from the terminal shape of the device under test. Since the fixture has a certain electrical characteristic, when the network analyzer measures the object to be measured via the fixture, the measurement result includes the characteristic of the fixture in addition to the characteristic of the object to be measured. Fixture characteristics greatly affect measurement accuracy, such as the reproducibility of measurement results. Therefore, the fixture characteristic is removed from the measurement result.

  When the fixtures connected to each port of the network analyzer can be regarded as independent from each other, the fixture can be characterized by a one-port calibration method (see, for example, Patent Document 1). However, when the device under test has a non-coaxial terminal or port, the 1-port calibration method may not be used. This is because the one-port calibration method requires an open standard, a short standard, and a load standard. Among these standards, the load standard is non-coaxial and has a wide band characteristic, so it is difficult to obtain. Therefore, instead of absolute characterization of the fixture as in the 1-port calibration method, the mutual relationship between the reference measurement device and the actual measurement device is obtained, and the measurement result of the actual measurement device is compared with the measurement result of the reference measurement device. Attempts have also been made to improve reproducibility (see, for example, Patent Document 2).

Japanese Patent Laid-Open No. 11-38054 (pages 2 and 3, FIGS. 6 and 7) JP 2003-240827 A JP 2001-13186 A (page 3, FIG. 7) JP-A-8-15348 JP-A-8-226945

  According to the prior art, in a non-coaxial system, it is difficult to obtain a wide-band load standard device, so high-precision measurement by the 1-port calibration method cannot be expected. Further, in the method for obtaining the mutual relationship, when the reference measuring device is changed, it takes time to newly obtain the mutual relationship. Therefore, a main object of the present invention is to provide a method and an apparatus capable of obtaining the absolute characteristics of a coaxial-non-coaxial fixture without using a load and a load standard.

  The present invention provides a method or apparatus for dividing a fixture characteristic into an electrical length component and a residual impedance component and obtaining each component.

  That is, the first invention is a method for obtaining an electrical length of a fixture connected between an electronic measuring device and a device under test, wherein the fixture port for connecting the device under test is provided. A first step of opening or short-circuiting; a second step of measuring the phase characteristics of the fixture in a predetermined frequency range with the electronic measuring device; and the measurement at a first measurement point in the frequency range. A third step for obtaining the electrical length from the result; a fourth step for correcting all of the measurement results using the electrical length; and the frequency at which the corrected measurement result indicates a maximum value and the correction. The electrical length is obtained from the measurement result at the second measurement point corresponding to an intermediate frequency with the frequency at which the measurement result indicates the minimum value, or the corrected at the second measurement point It is characterized in that and a fifth step of adding the residual electrical length obtained from the constant results in the electrical length.

  The second invention further includes a sixth step of correcting all of the measurement results using the electrical length obtained in the fifth step in the method of the first invention, Of the correction results in the sixth step, the fifth step and the sixth step are alternately repeated until the value at the second measurement point is within a predetermined range or a predetermined value. To do.

  Further, according to the third invention, in the method of the first invention or the second invention, the first measurement point is a measurement point corresponding to the center frequency of the frequency range, or the frequency range It is a measuring point at the high-frequency side end or the low-frequency side end.

  Still further, the fourth invention is a method for obtaining an electrical length of a fixture connected between an electronic measuring device and an object to be measured, wherein the first measuring device connects the electronic measuring device and the fixture. The second step of opening or shorting the fixture port for connecting the object to be measured, and measuring the group delay characteristics of the fixture in a predetermined frequency range with the electronic measuring device. A third step, and a fourth step of obtaining the electrical length from the measurement result at a measurement point corresponding to an intermediate frequency between a frequency at which the measurement result indicates a maximum value and a frequency at which the measurement result indicates a minimum value; It is characterized by including.

  The fifth aspect of the invention is a method for obtaining an electrical length of a fixture connected between an electronic measuring device and a device under test, the step of connecting the fixture to the electronic measuring device, A step of opening or shorting a port of the fixture for connecting a device under test; a step of measuring a phase characteristic of the fixture in a predetermined frequency range by the electronic measuring device; and the measured phase Calculating the electrical length of the fixture from the slope of the approximate line, and the absolute value of the positive maximum value of the error of the approximate line with respect to the measured phase and the absolute value of the negative maximum value of the error Is less than a predetermined value or substantially zero.

  Further, the sixth invention is a method for obtaining an electrical length of a fixture connected between an electronic measuring device and a device under test, the step of connecting the fixture to the electronic measuring device, Opening or shorting a port of the fixture for connecting an object to be measured, measuring a group delay characteristic of the fixture in a predetermined frequency range with the electronic measuring device, and the measured group And calculating the electrical length from an intermediate value between the maximum value and the minimum value of the delay.

  Furthermore, in the method according to any one of the first invention to the sixth invention, the opening is opened at an electrode interval of the object to be measured.

  Further, the eighth aspect of the invention relates to a phase characteristic in a predetermined frequency range of a fixture in which a port for connecting an object to be measured is opened or short-circuited to an electronic measuring device or a device that controls the electronic measuring device, A first step of measuring with the electronic measuring device; a second step of obtaining the electrical length from the result of the measurement at a first measurement point within the frequency range; and the measurement result using the electrical length. A third step of correcting all, and the measurement at a second measurement point corresponding to an intermediate frequency between a frequency at which the corrected measurement result shows a maximum value and a frequency at which the corrected measurement result shows a minimum value Determining the electrical length from the result, or performing a fourth step of adding the residual electrical length obtained from the corrected measurement result at the second measurement point to the electrical length. Is that program.

  Furthermore, in the program according to the eighth invention, the ninth invention uses the electrical length obtained in the sixth step to transmit all of the measurement results to the electronic measuring device or the control device. A seventh step of correction is further executed, and the sixth step and the seventh step until the value at the second measurement point is within a predetermined range or a predetermined value among the correction results in the sixth step. These steps are alternately repeated.

  Furthermore, in the tenth invention, in the program of the eighth invention or the ninth invention, the first measurement point corresponds to a center frequency of the frequency range, or the frequency range. It is a measuring point of the high-frequency side end or the low-frequency side end.

  Further, the eleventh aspect of the present invention is directed to a group delay characteristic in a predetermined frequency range of a fixture in which a port for connecting an object to be measured is opened or short-circuited to an electronic measuring device or a device that controls the electronic measuring device. From the measurement result at a measurement point corresponding to an intermediate frequency between the frequency at which the measurement result indicates the maximum value and the frequency at which the measurement result indicates the minimum value. This is a program for executing the second step for obtaining the electrical length.

  Furthermore, the twelfth aspect of the present invention provides a phase characteristic in a predetermined frequency range of a fixture in which a port for connecting an object to be measured is opened or short-circuited to an electronic measuring device or a device that controls the electronic measuring device. A step of measuring with the electronic measuring device and a step of obtaining an electrical length of the fixture from an inclination of the approximate line with respect to the measured phase, and correcting an error of the approximate line with respect to the measured phase. The difference between the absolute value of the maximum value and the absolute value of the negative maximum value of the error is less than a predetermined value or substantially zero.

  Furthermore, the thirteenth aspect of the present invention is directed to a group delay in a predetermined frequency range of a fixture in which a port for connecting an object to be measured is opened or short-circuited to an electronic measuring device or a device that controls the electronic measuring device. A program for executing a step of measuring characteristics with the electronic measuring device and a step of obtaining the electrical length from an intermediate value between the maximum value and the minimum value of the measured group delay.

  The fourteenth invention is the program according to any one of the eighth to thirteenth inventions, wherein the opening is opened at an electrode interval of the object to be measured. It is.

  Further, the fifteenth aspect of the present invention is an electronic measuring apparatus characterized in that a control device for executing the program according to any of the eighth aspect of the present invention to the fourteenth aspect of the present invention is incorporated or externally connected. It is.

  Furthermore, the sixteenth aspect of the invention is a method for obtaining a network characteristic of a fixture having a symmetry connected between a network analyzer and a device under test, wherein the fixture has a short-circuited port. Measuring a network characteristic with the network analyzer to obtain a first network characteristic; and measuring a network characteristic of the fixture with the port opened with the network analyzer to obtain a second network characteristic. And correcting each of the first network characteristic and the second network characteristic using the electrical length of the fixture measured in advance or a defined value of the electrical length of the fixture, and the fixture, The residual impedance of the fixture is calculated from the corrected first network characteristic and the corrected second network characteristic using the symmetry of It is characterized in that comprises the step of determining the network properties of the scan component.

ただし、

ことを特徴とするものである。 Further, in the seventeenth aspect of the invention, in the method of the sixteenth aspect of the invention, the step of obtaining the network characteristics of the residual impedance component is performed based on the following equation:

However,

It is characterized by this.

  Further, the eighteenth invention is characterized in that, in the method of the fifteenth invention or the sixteenth invention, the opening is opened at an electrode interval of the object to be measured. .

  Still further, the nineteenth aspect of the present invention is a method for obtaining an electrical length of a fixture in which a port for connecting an object to be measured is opened or short-circuited to an electronic measuring device or a device that controls the electronic measuring device; Measuring the network characteristics of the fixture with the port shorted with the network analyzer to obtain a first network characteristic; and measuring the network characteristics of the fixture with the port opened with the network analyzer. Obtaining the second network characteristic, and using the electrical length of the fixture or the defined value of the electrical length of the fixture measured in advance, the first network characteristic and the second network characteristic Respectively, and using the symmetry of the fixture, the calculation is performed from the corrected first network characteristic and the corrected second network characteristic. Is a program for executing the steps of obtaining a more network properties of the residual impedance component of the fixture.

ただし、

ことを特徴とするものである。 In addition, in the program according to the nineteenth aspect of the invention, the step of obtaining the network characteristics of the residual impedance component is performed based on the following formula in the program of the nineteenth aspect of the invention.

However,

It is characterized by this.

  Furthermore, the 21st invention is characterized in that, in the program of the 19th invention or the 20th invention, the opening is opened at an electrode interval of the object to be measured. is there.

Furthermore, the nineteenth invention is a network analyzer characterized in that a control device for executing the program of the sixteenth invention to the twenty-first invention is built in or externally connected. is there.
The network characteristics of the fixture are characterized by a circuit matrix composed of circuit parameters.

  According to the present invention, an absolute characteristic of a fixture can be obtained without using a load and a load standard. Thereby, the error resulting from the fixture can be removed from the measurement result. As a result, for example, in a network analyzer, a value closer to the true characteristic of the object to be measured can be obtained compared to the conventional case. Further, according to the present invention, the electrical length of the fixture can be obtained with higher accuracy than in the past.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. An embodiment of the present invention is a measurement system 1000. First, the configuration of the measurement system 1000 will be described. Reference is now made to FIG. FIG. 1 is a diagram illustrating a measurement system 1000 including a network analyzer 100 that is an example of an electronic measurement apparatus. The network analyzer 100 includes a measurement unit 110, a calculation control unit 120, a memory 130, and an interface unit 140. The measurement unit 110, the calculation control unit 120, the memory 130, and the interface unit 140 are connected to each other via a bus 150. The measurement unit 110 includes coaxial measurement ports 111, 112, and 113. The measurement unit 110 is a device that measures the characteristics of an object to be measured connected via these measurement ports. Hereinafter, the object to be measured is referred to as DUT. In the present embodiment, the number of measurement ports is three, but is not limited to this, and may be one, two, or four or more. The calculation control unit 120 is a device that controls the measurement unit 110 and the like connected via the bus 150 and performs numerical calculation processing such as correction processing and parameter conversion. The arithmetic control unit 120 is configured by, for example, a CPU or a DSP. The memory 130 is a so-called storage device such as a semiconductor memory or a hard disk drive, and stores data and programs. The interface unit 140 is a device that performs input / output between the network analyzer 100 and an external device, or between the network analyzer 100 and an operator. The bus 150 is a signal line for control and data transfer.

  The network analyzer 100 is connected to the fixture 300 via coaxial measurement cables 210, 220 and 230. The measurement cable 210 has the same characteristic impedance as the measurement port of the network analyzer, and includes coaxial connectors 211 and 212 at both ends. The measurement cable 220 includes coaxial connectors 221 and 222 at both ends. The measurement cable 230 includes coaxial connectors 231 and 232 at both ends.

  The fixture 300 is a coaxial-non-coaxial fixture having symmetry. That is, the fixture 300 is a device that converts a coaxial system and a non-coaxial system bidirectionally. The fixture 300 includes coaxial instrument ports 311, 312 and 313 and non-coaxial DUT ports 321, 322 and 323. The DUT ports 321, 322, and 323 are connected to the DUT 400. In addition, the isolation between each measuring instrument port (311-312, 311-313, 312-313) is a characteristic of a part of the fixture 300 related to each measuring instrument port (311, 312, 313) independently. It should be high enough that

  Next, in the measurement system 1000 configured as described above, the procedure for characterizing the fixture 300 and correcting the measurement result of the DUT 400 measured via the fixture 300 with the characterization result of the fixture 300 will be described below. explain. The measurement result is used synonymously with the measurement value.

First, the concept of the characterization method for the fixture 300 will be described. The present invention uses a fixture between a coaxial calibration surface and a non-coaxial measurement surface as a fixture, and characterizes the fixture. Reference is now made to FIG. FIG. 2 is a diagram showing only the fixture 300. As described above, the isolation between each instrument port is sufficiently high so that the fixture 300 can be regarded as an assembly of fixtures 300a and 300b and 300c that are electrically independent of each other. Thus, the present invention characterizes each of the fixtures 300a, 300b and 300c individually. Reference is now made to FIG. FIG. 3 is a diagram illustrating only a measurement system related to the fixture 300a. Since the measurement system in FIG. 3 is a part of FIG. 1, description of each component in the figure is omitted. In FIG. 3, a boundary surface P ₁ between the connector 212 and the measuring instrument port 311 is a coaxial system, and a boundary surface P ₂ between the DUT port 321 and the DUT 400 is a non-coaxial system. Reference is now made to FIG. FIG. 4 is a part of FIG. 3, and the fixture 300a is modeled. In the present invention, the characteristic of the fixture 300a is divided into an electrical length component S _D and a residual impedance component S _Z which is a component other than the electrical length, and each is measured. Overall properties _{S F} fixture 300a is represented by the combination of the electrical length component _{S D} and the residual impedance component _{S Z.} In FIG. 4, S _D and S _Z are S parameter matrices. S ₁₁ , S ₁₂ , S ₂₁ , S ₂₂ are S parameters. Furthermore, θ is the phase shift amount at a certain frequency, in other words, the phase amount that the electrical length inserts into the passing signal at a certain frequency. When the above operations are performed on the fixtures 300a, 300b, and 300c, the overall characteristics of the fixture 300 are revealed. The above is the concept of the characterization method for the fixture 300.

  Next, a procedure for characterizing the fixture 300a and correcting the measurement result will be described. In the following, reference is made to FIG. 3, FIG. 4 and FIG. FIG. 5 is a flowchart showing the overall flow. 5 is performed by the arithmetic control unit 120 executing a program stored in the memory 130 to control the measurement unit 110, the memory 130, the interface unit 140, and the like.

First, the vector calibrated with 1-port calibration at the interface _{P 2} (step S10). Specifically, an open standard, a short standard, and a load standard are connected to the connector 212 in order, and the reflection measurement is performed by the measurement unit 110, and the calculation control unit 120 is based on the three measurement results obtained. Solve the error model to obtain correction data. The obtained correction data is stored in the memory 130. Thus, the boundary surface P ₂ is a calibration surface. Next, the electrical length component _SD of the fixture 300a is obtained (step S20). The electrical length component S _D obtained here is a value (or matrix) such that the ripple appearing in the frequency-phase characteristics of the residual impedance component S _Z swings around 0 ° (open) or 180 ° (short-circuit). ), or the frequency of the residual impedance component S _Z - value as the ripple appearing in the group delay characteristic is amplitude around the zero seconds (or matrix) is obtained. This ripple is caused by the reflected waves of the traveling wave from the network analyzer 100 and the measurement surface P ₂ interferes. Incompleteness of the directional coupler (not shown) in the network analyzer 100 is also a factor that causes ripples. Next, determine the residual impedance component _{S Z} of the fixture 300a (step S30). The overall characteristics _{S F} fixture 300a is represented by the combination of the electrical length component _{S D} and the residual impedance component _{S Z.} The characteristics of the fixture 300a obtained in this way are reflected in data for correcting subsequent measurement results (step S40). Specifically, the characteristic S _F (or each of S _D and S _Z ) of the fixture 300 a is written in the memory 130 as correction data used in the de-embedding function and the port extension correction function. Alternatively, the characteristic S _F (or each of S _D and S _Z ) of the fixture 300a is synthesized with the correction data created at the time of calibration. Then, the measurement unit 110 measures the characteristics of the DUT 400 measured via the fixture 300a, and the calculation control unit 120 corrects the measurement result based on the correction data (step S50). As a result, a value closer to the true characteristic of the DUT 400 is obtained. In the case that the determined overall characteristics S _F fixture 300a is the object, that is, if you do not need the exact value of the electrical length component S _D fixture 300a, electrical fixture 300a in Step 20 instead of measuring the length component _{S D,} to derive a definition of the electrical length component _{S D} fixtures 300a from design information of fixture 300, also it as electrical length component _{S D} fixture 300a, step 20 after You may implement the process of. The series of processes (steps S10 to S50) are performed not only for the fixture 300a but also for the fixtures 300b and 300c. When implemented for fixtures 300b and 300c, the target DUT port is different from that implemented for fixture 300a, but such changes are readily envisioned by those skilled in the art and will not be discussed in detail here. Do not mention.

  Next, the process of step S20 will be described in detail. In the following, reference is made to FIG. 3, FIG. 4 and FIG. FIG. 6 is a flowchart showing the flow of processing in step S20. 6 is performed by the arithmetic control unit 120 executing a program stored in the memory 130 to control the measurement unit 110, the memory 130, the interface unit 140, and the like.

First, the DUT port 321 is opened or short-circuited, the reflection measurement is performed by the measurement unit 110, the frequency-phase characteristic of the fixture 300a is obtained, and the measurement result is stored in the memory 130 (step S21a). Here, the opening is simply opening without connecting anything. Furthermore, it is desirable that the opening be opened at the electrode interval of the object to be measured connected to the DUT port. When the electrode interval of the DUT port is larger than the electrode interval of the device under test, a device having electrodes arranged at the same interval as the electrode interval of the device under test is connected to the DUT port for opening. Moreover, a short circuit means connecting electrically with the shortest distance. Furthermore, it is desirable to reduce the inductance component caused by the short circuit as much as possible. These definitions of open and short are valid throughout this specification. Note that the frequency range for measuring the frequency-phase characteristics of the fixture 300a includes the measurement frequency range of the DUT 400 measured in step S50 (not shown). Next, the arithmetic control unit 120 refers to the measurement result stored in the memory 130 and obtains the electrical length component _SD from the measurement result at the measurement point corresponding to the center frequency of the frequency range in which the phase characteristic is measured (step) S22a). The measurement point corresponding to the center frequency is a measurement point having the center frequency, a measurement point having a frequency lower than the center frequency and closest to the center frequency, or a measurement point having a frequency higher than the center frequency and closest to the center frequency. Either. When the measurement result at the center frequency is frequency-differentiated and further divided by 2, a group delay expressing the electrical length in time is obtained. In reflection measurement, the electrical length component appears to be double, so it is necessary to halve the measurement result at some stage. When the correction data is an S parameter matrix, the electrical length component _SD is expressed as follows. Here, θ is a phase shift amount at a certain frequency f, and is obtained by multiplying the value of the group delay by 2πf.

If the correction data is a time value, the electrical length component _SD is expressed by the group delay value. The electrical length component _SD thus obtained is stored in the memory 130. Next, the arithmetic and control unit 120, by using an electrical length component _{S D} calculated in step S22a, to port extension corrects the measurement result stored in the memory 130 (step S23a). At this time, the port extension correction is applied to the measurement results at all measurement points. The port extension correction is correction for removing a phase shift caused by the electrical length from the measurement result. The measurement result is maintained as it is, and the correction result is newly stored in the memory 130. Next, the arithmetic control unit 120 obtains the electrical length component _SD from the measurement result at the measurement point corresponding to the intermediate frequency between the frequency at which the correction result shows the maximum value and the frequency at which the correction result shows the minimum value (step S24a). . Determination of the electrical length components _{S D} is the same as step S22a. The measurement point corresponding to the intermediate frequency is a measurement point having an intermediate frequency, a measurement point having a frequency lower than the intermediate frequency and closest to the intermediate frequency, or a measurement point having a frequency higher than the intermediate frequency and closest to the intermediate frequency. Either. The electrical length component _SD in the memory 130 is overwritten by the newly obtained electrical length component _SD . Next, the calculation control unit 120 corrects the port extension of the measurement result stored in the memory 130 using the electrical length obtained in step S24a (step S25a). At this time, the port extension correction is applied to the measurement results at all measurement points. The measurement result in the memory 130 is maintained as it is. Also, the correction result in the memory 130 is overwritten with the newly obtained correction result. Then, step S24a and step S25a are alternately repeated until the measurement result at the measurement point corresponding to the intermediate frequency is within a predetermined range or a predetermined value (step S26a). Here, the predetermined value is 0 ° when the DUT port 321 is opened, and 180 ° when the DUT port 321 is short-circuited. The predetermined range is a range centered on the predetermined value. The predetermined range is set to −0.1 ° to 0.1 °, for example, when the DUT port 321 is opened. In step S24a, instead of directly obtaining the electrical length component _SD from the measurement result at the measurement point corresponding to the intermediate frequency, the residual electrical length is obtained from the correction result at the measurement point corresponding to the intermediate frequency to obtain the electrical length component. In addition to _SD , a new electrical length component _SD can be used. The residual electric length means an electric length that is not zero but remains after correction.

The series of processes in step S20 described above causes changes shown in FIGS. 7A to 7D in the graph of the measurement results. 7A to 7D are diagrams illustrating measurement results of frequency-phase characteristics of the fixture 300a when the DUT port 321 is opened. 7A to 7D, the horizontal axis represents frequency, and the vertical axis represents phase. Both axes are displayed on a linear scale. In FIG. 7A, M ₁ is a marker indicating the center frequency of the measurement frequency range. By the process of step S23a, the marker M ₁ is moved on the horizontal axis indicating the phase value of zero. FIG. 7B shows the result. That is, FIG. 7B is a diagram illustrating a result of correcting the measurement result of the frequency-phase characteristic. Reference is now made to FIG. FIG. 7C is a diagram illustrating a result of correcting the measurement result of the frequency-phase characteristic, similar to FIG. 7B. However, the displayed marker is different from FIG. 7B. In Figure 7C, M ₂ is a marker indicating the maximum value of the correction results. Further, M ₃ is a marker that indicates the minimum value of the correction results. Further, M ₄ is a marker indicating an intermediate frequency between the marker M ₂ and the marker M ₃ . By the process of step S25a, the marker M ₄ is moved on the horizontal axis indicating the phase value of zero. FIG. 7D shows the result. The above is the description regarding step S20.

  Next, the process of step S30 will be described in detail. In the following, reference is made to FIG. 3, FIG. 4 and FIG. FIG. 8 is a flowchart showing the flow of processing in step S30. 8 is performed by the arithmetic control unit 120 executing a program stored in the memory 130 to control the measurement unit 110, the memory 130, the interface unit 140, and the like.

First, the measurement unit 110 is caused to measure the network characteristics of the fixture 300a in which the DUT port 321 is short-circuited (step S31). Next, the measurement unit 110 is caused to measure the network characteristics of the fixture 300a in which the DUT port 321 is opened (step S32). The measurements in step S31 and step S32 are reflection measurements. Note that the order in which step S31 and step S32 are performed may be switched. Moreover, since the frequency-phase characteristic is measured in step S20, the measurement result can be used in either step S31 or step S32. In the case of a general network analyzer, in step S31 and step S32, four S parameters are acquired as network characteristic measurement results. Next, based on the electrical length _SD obtained in step S20, the measurement result of the fixture 300a when the DUT port 321 is opened and the measurement result of the fixture 300a when the DUT port 321 is short-circuited are respectively corrected for port extension. To do. Then, based on their correction result, by calculating the following equation to the calculation control unit 120 calculates the residual impedance component S _Z fixture 300a.

However,

The obtained residual impedance component _SZ is stored in the memory 130. The above is the description regarding step S30.

The embodiment described above can be modified in several ways. For example, in step S22a, the electrical length component _SD is obtained from the measurement result at the measurement point corresponding to the center frequency, and in step S23a, the measurement result of the phase characteristic is corrected by the electrical length component _SD . In these steps, it is possible to refer to any measurement point in the measurement frequency range, not limited to the measurement point corresponding to the center frequency. However, from the viewpoint of ease of handling, in addition to the measurement point corresponding to the center frequency, the measurement point at the low frequency side end or the high frequency side end of the measurement frequency range may be suitable.

  Step S20 includes the following three alternative procedures. First, a first alternative example of step S20 will be described. Reference is now made to FIGS. 3, 4 and 9. FIG. FIG. 9 is a flowchart showing the flow of processing in the first alternative of step S20. The processing of each step in the flowchart of FIG. 9 is performed by the arithmetic control unit 120 executing a program stored in the memory 130 to control the measurement unit 110, the memory 130, the interface unit 140, and the like.

First, the DUT port 321 is opened or short-circuited, the reflection measurement is performed by the measurement unit 110, the frequency-phase characteristic of the fixture 300a is obtained, and the measurement result is stored in the memory 130 (step S21b). The frequency range for measuring the frequency-phase characteristic of the fixture 300a includes the measurement frequency range of the DUT 400 measured in step S50. Next, the arithmetic control unit 120 obtains a straight line (approximate straight line) that approximates the measurement result stored in the memory 130, and obtains the electrical length component _SD from the slope of the approximate straight line (step S22b). At this time, an approximate straight line is obtained in which the difference between the absolute value of the positive maximum value of the error of the approximate straight line with respect to the measurement result and the absolute value of the negative maximum value of the error is less than a predetermined value or substantially zero. The electrical length component _SD is a half value of the slope of the approximate line. This completes the description of the first alternative example.

  Next, a second alternative example of step S20 will be described. Reference is now made to FIGS. 3, 4 and 10. FIG. FIG. 10 is a flowchart showing the flow of processing in the second alternative example of step S20. The processing of each step in the flowchart of FIG. 10 is performed by the arithmetic control unit 120 executing a program stored in the memory 130 to control the measurement unit 110, the memory 130, the interface unit 140, and the like.

First, the DUT port 321 is opened or short-circuited, the reflection measurement is performed by the measurement unit 110, the frequency-group delay characteristic of the fixture 300a is obtained, and the measurement result is stored in the memory 130 (step S21c). The frequency range for measuring the frequency-group delay characteristic of the fixture 300a includes the measurement frequency range of the DUT 400 measured in step S50. Next, the arithmetic control unit 120 obtains the electrical length component _SD from the intermediate value between the maximum value and the minimum value of the measurement results stored in the memory 130 (step S22c). The electrical length component _SD is a half value of the intermediate value. The above is the description regarding the second alternative example.

  Next, a third alternative example of step S20 will be described. Reference is now made to FIGS. 3, 4 and 11. FIG. FIG. 11 is a flowchart showing the flow of processing in the third alternative example of step S20. The process of each step in the flowchart of FIG. 11 is performed by the arithmetic control unit 120 executing a program stored in the memory 130 to control the measurement unit 110, the memory 130, the interface unit 140, and the like.

First, the DUT port 321 is opened or short-circuited, the reflection measurement is performed by the measurement unit 110, the frequency-group delay characteristic of the fixture 300a is obtained, and the measurement result is stored in the memory 130 (step S21d). The frequency range for measuring the frequency-group delay characteristic of the fixture 300a includes the measurement frequency range of the DUT 400 measured in step S50. Next, the arithmetic control unit 120 obtains the electrical length component _SD from the measurement result at the measurement point corresponding to the intermediate frequency between the frequency at which the correction result shows the maximum value and the frequency at which the correction result shows the minimum value (step S22d). . The measurement point corresponding to the intermediate frequency is a measurement point having an intermediate frequency, a measurement point having a frequency lower than the intermediate frequency and closest to the intermediate frequency, or a measurement point having a frequency higher than the intermediate frequency and closest to the intermediate frequency. Either. The electrical length component _SD is a half value of the measurement result at the measurement point corresponding to the intermediate frequency. When the correction data is an S parameter matrix, the electrical length component _SD is expressed as follows. Here, θ is the phase shift amount at a certain frequency f, and is obtained by multiplying the value of the group delay as a measurement result by 2πf.

If the correction data is a time value, the electrical length component _SD is expressed with the measurement result as it is. The electrical length component _SD thus obtained is stored in the memory 130. The above is the description regarding the third alternative example.

As described above, the electrical length component _SD can be obtained from the result of the phase characteristic and the result of the group delay characteristic. Reference is now made to FIG. FIG. 12 is a graph showing measurement results of frequency-phase characteristics and frequency-group delay characteristics. In the figure, noise is slightly superimposed on the phase graph. On the other hand, the group delay graph shakes violently. This state is derived from the fact that the group delay is a value obtained by frequency differentiation of the phase. Noise with intense movement is amplified by being differentiated. Such a large swing in the graph of the group delay is difficult to determine the correct electrical length component Z _D. Therefore, if the amount of noise inherent in the measurement system is large, the frequency - how to determine the electrical length component Z _D from the phase characteristics are preferred.

  In this embodiment, the network analyzer operates independently. However, the present embodiment can be modified so that the network analyzer is controlled by an external device. Reference is now made to FIG. FIG. 13 is a diagram showing a measurement system 2000. In FIG. 13, the same components as those in FIG. In FIG. 13, the network analyzer 100 is connected to an external control device 500 such as a computer. The external control device 500 includes an arithmetic control unit 520, a memory 530, and an interface unit 540. The arithmetic control unit 520, the memory 530, and the interface unit 540 are connected to each other via a bus 550. The arithmetic control unit 520 is a device that controls the memory 530 and the like connected via the bus 550 and performs numerical arithmetic processing. The arithmetic control unit 520 is constituted by, for example, a CPU or a DSP. The memory 530 is a so-called storage device such as a semiconductor memory or a hard disk drive, and stores data and programs. The interface unit 540 is an apparatus that performs input / output between the external control device 500 and an external device, or between the external control device 500 and an operator. The bus 550 is a signal line for control and data transfer. The interface unit 140 and the interface unit 540 communicate, and the calculation control unit 520 substitutes the role of the calculation control unit 120, and the memory 530 substitutes the role of the memory 130. The system 2000 configured as described above is suitable, for example, when the processing capability of the arithmetic control unit 140 is poor.

  Finally, actual measurement results for clarifying the effects of the present invention are shown. Reference is now made to FIG. FIG. 14 shows the measurement results near the resonance frequency of the capacitor. FIG. 14 shows three measurement results. One is a measurement result with an impedance analyzer. The remaining two are measurement results with a network analyzer. Further, one of the measurement results of the network analyzer is a corrected one, that is, a fixture characteristic obtained by the technique of the present invention is removed. As is apparent from the figure, the correction provides a value close to the true characteristic of the fixture.

  The method and apparatus of the present invention have a remarkable effect in a non-coaxial measurement system, but can also be applied in a coaxial measurement system. In other words, the fixture characteristics can be obtained using the coaxial open and the coaxial short. In addition, the method of measuring the electrical length can be applied to other electronic measuring devices other than the network analyzer as long as the measuring device can perform frequency-phase measurement or frequency-group delay measurement. Furthermore, the method of measuring the electrical length can be applied to the case of obtaining the electrical length of a device other than the fixture, such as a DUT. In that case, one end of the device other than the fixture may be opened or short-circuited for measurement. Furthermore, in the present invention, the circuit parameter is not limited to the S parameter, and may be another circuit parameter such as a T parameter.

1 is a block diagram showing a configuration of a measurement system 1000. FIG. It is a figure which shows the fixture 300a. It is a figure which shows the measurement system regarding the fixture 300a. In FIG. 3, it is the figure which modeled the fixture 300a. It is a flowchart which shows the general | schematic procedure about the characterization of the fixture 300a, and correction | amendment of a measurement result. It is a flowchart which shows the procedure which calculates | requires electrical length component _SD . It is a figure which shows the measurement result of the frequency-phase characteristic of the fixture 300a. It is a figure which shows the measurement result by which the frequency-phase characteristic of the fixture 300a was correct | amended. It is a figure which shows the measurement result by which the frequency-phase characteristic of the fixture 300a was correct | amended. It is a figure which shows the measurement result by which the frequency-phase characteristic of the fixture 300a was correct | amended. The procedure for obtaining the residual impedance component S _Z is a flowchart showing. It is a flowchart which shows the 1st alternative example of step S20. It is a flowchart which shows the 2nd alternative example of step S20. It is a flowchart which shows the 3rd alternative example of step S20. It is a graph which shows the comparative example of the measured value of a phase characteristic and a group delay characteristic. 2 is a block diagram showing a configuration of a measurement system 2000. FIG. It is a figure which compares the result of an impedance measurement.

Explanation of symbols

100 Network analyzer 110 Measurement unit 111, 112, 113 Measurement port 120, 520 Operation control unit 130, 530 Memory 140, 540 Interface unit 140 Operation control unit 150 Bus 210, 220, 230 Measurement cables 211, 212, 221, 222, 231 , 232 Coaxial connector 300 Fixture 311, 312, 313 Measuring instrument port 321, 322, 323 DUT port 400 Device under test (DUT)
500 External control device 1000, 2000 Measuring system

Claims (7)

A method for obtaining a network characteristic of a fixture having a symmetry connected between a network analyzer and an object to be measured,
Measuring a network characteristic of the fixture with the port short-circuited by the network analyzer to obtain a first network characteristic;
Measuring the network characteristics of the fixture with the port open with the network analyzer to obtain second network characteristics;
Correcting the first network characteristic and the second network characteristic, respectively, using a pre-measured electrical length of the fixture or a defined value of the electrical length of the fixture;
Using the symmetry of the fixture to obtain a network characteristic of the residual impedance component of the fixture by calculation from the corrected first network characteristic and the corrected second network characteristic;
Including methods. Obtaining a network characteristic of the residual impedance component;
Based on the following formula,

However,

The method according to claim 1.   The method according to claim 1, wherein the opening is opened at an electrode interval of the object to be measured. In an electronic measuring device or a device that controls the electronic measuring device,
Measuring a network characteristic of the fixture with the port short-circuited by the network analyzer to obtain a first network characteristic;
Measuring the network characteristics of the fixture with the port open with the network analyzer to obtain second network characteristics;
Correcting the first network characteristic and the second network characteristic, respectively, using a pre-measured electrical length of the fixture or a defined value of the electrical length of the fixture;
Using the symmetry of the fixture to obtain a network characteristic of the residual impedance component of the fixture by calculation from the corrected first network characteristic and the corrected second network characteristic;
A program that executes Obtaining a network characteristic of the residual impedance component;
Based on the following formula,

However,

The program according to claim 4.   6. The program according to claim 4, wherein the opening is opened at an electrode interval of the object to be measured. 7. A network analyzer, wherein a control device for executing the program according to claim 5 or 6 is built in or externally connected.

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