JP4984769B2 - Method for calibrating high-frequency characteristic measuring probe and method for measuring high-frequency characteristic of electronic device using this probe - Google Patents

Description

The present invention relates to a method for calibrating a high frequency characteristic measuring probe used for measuring high frequency characteristics of an electronic device. Specifically, the present invention relates to a method for correcting a measurement error of a probe when measuring an impedance value, a Q value, or the like of an electronic device with a measuring instrument such as a network analyzer.

The high-frequency measurement probe is a probe that measures high-frequency electrical characteristics of a high-frequency electronic component such as a millimeter-wave band product. In order to measure the true value of the high frequency characteristics of the device, it is necessary to calibrate at the tip of the probe that contacts the device. When measuring the millimeter wave band product using a probe, if the probe is not calibrated, the value including the error term of the probe is measured in addition to the characteristics of the millimeter wave band product. The true value cannot be obtained. Therefore, calibration that removes the error term of the probe is required.

As a method for calibrating a high-frequency characteristic measuring probe, a method disclosed in Non-Patent Document 1 is known. This calibration method measures the state in which the probe is in contact with each short load through reference formed on the calibration board and the open state in which nothing is in contact with the probe, and uses the measured values to perform SOLT calibration. Is done by doing. 1A shows a connection state of a short circuit, FIG. 1B shows a load state, and FIG. 1C shows a through state. The probe 1 shown in FIG. 1 is an air coplanar probe. The probe 1 has a signal terminal 2 in the center and GND terminals 3 on both sides. On the calibration substrate 4, a short reference 5, a load reference 6, and a through reference 7 are formed.

The calibration substrate 4 is formed of an alumina substrate whose electrical characteristics are unlikely to change, and each reference characteristic of short load through is built on the calibration substrate 4, so that it is very expensive. In particular, it is necessary to adjust the reference characteristic of the load to 50Ω ± 0.3% (DC) with high accuracy. Further, when the probe 1 is brought into contact with the calibration substrate 4, there is a pressing process called overdrive, and the tip of the probe 1 slides while being pressed on the reference of the calibration substrate 4. At that time, since the contact portion is scratched, the characteristics of the calibration substrate 4 change when used about 50 times. That is, the calibration board 4 is a consumable item and requires a great deal of cost. In addition, since the pitch between the terminals of the probe 1 and the reference pitch of the calibration board 4 with which the probe 1 is brought into contact with each other are the same, when using a probe with a different pitch between the terminals, a calibration board corresponding to that is purchased separately. There was a need.

Patent Document 1 discloses a novel calibration method using a planar transmission line. This calibration method (hereinafter referred to as RRR calibration) uses a calibration board having a planar transmission line whose electrical characteristics per unit length are known, and at least three points between the signal conductor and the ground conductor of the planar transmission line. In this method, the reflection coefficient when short-circuited is measured, and the error term (and the transmission rate and phase constant of the transmission line) from the calibration board connector to the calibration surface can be calculated from these measurement data.

In the case of this calibration method, an inexpensive substrate such as a coplanar substrate can be used as the calibration substrate, so that the cost can be greatly reduced. Furthermore, since calibration can be performed simply by short-circuiting the signal conductor and the ground conductor at at least three locations on the substrate, there is an advantage that the calibration operation is simple and errors can be reliably removed.
"Introduction to on-wafer high-frequency measurement" published by Cascade Microtech Co., Ltd., May 2001 WO2005 / 101035A1

Accordingly, an object of the present invention is to provide a method for calibrating a high-frequency characteristic measuring probe that can calibrate the probe without using an expensive calibration substrate, and a method for measuring the high-frequency characteristic of an electronic device using this calibration method. It is to provide.

The high-frequency characteristic measuring probe calibration method according to the present invention includes the first step of connecting a calibration board having a planar transmission line to one measurement port of a measuring instrument, and the error correction method using the calibration board. A second step of deriving an error from a predetermined calibration surface on the calibration substrate to the measuring device, a third step of connecting the probe to another measurement port of the measuring device, and a calibration surface of the calibration substrate The probe tip is brought into contact with the probe, and the error obtained in the second step is removed from the fourth step in which the electrical characteristics are measured by the measuring instrument and the measurement value obtained in the fourth step. And a fifth step of deriving an error from the measuring instrument to the tip of the probe and creating a calibration surface at the tip of the probe.

The present invention pays attention to the fact that if a calibration board having a planar transmission line as disclosed in Patent Document 1 is used, the calibration of the probe can be easily performed at low cost. That is, a calibration board having a flat transmission line is connected to one measurement port of the measuring instrument, and an error from a predetermined calibration surface on the calibration board to the measuring instrument is derived by a one-port error correction method using the calibration board. To do. Calibration from the connector of the calibration board to the calibration surface can be performed by the method shown in Patent Document 1 (RRR method), and calibration from the connector to the measuring instrument can be easily performed by using a known method such as the SOLT method. it can. Next, the probe is connected to the other measurement port of the measuring instrument, and the tip of the probe is brought into contact with the calibration surface of the calibration board to measure the electrical characteristics. Then, the error from the measuring instrument to the probe is derived by removing the error from the calibration surface of the calibration board to the measuring instrument. That is, the tip of the probe can be used as a calibration surface.

The transmission path of the calibration board only needs to have a uniform characteristic impedance in the length direction, and it is not necessary to create special reference characteristics (short, load, and through) unlike the conventional calibration board. Therefore, an inexpensive substrate such as a coplanar substrate can be used. Even if the electrodes of the calibration board are worn while repeating the calibration work by bringing the probe into contact with the calibration board, the replacement cost can be reduced as compared with the conventional technique. Furthermore, even if the pitch of the probe changes, a calibration board can be easily manufactured according to it. As a result, the cost for calibration of the high frequency characteristic measurement probe can be greatly reduced, and the measurement cost of the high frequency product can be reduced.

According to a preferred embodiment, the calibration board is a board having a signal conductor and a ground conductor and having a planar transmission line having a constant electrical characteristic per unit length, and the first step includes the signal conductor. And connecting one end of the ground conductor to the measurement port of the measuring device, and the second step is to connect the signal conductor and the ground conductor in at least three locations in the length direction of the signal conductor. A first sub-step for measuring a reflection coefficient, and a second sub-step for deriving an error from the calibration surface of the calibration board to the measuring device from the measured value in the connected state and the electrical characteristics of the planar transmission line. It is good to include. When calibrating, the calibration coefficient can be measured easily and accurately because the reflection coefficient can be measured with the signal conductor and ground conductor connected at three or more locations with the calibration board and measuring instrument connected with a coaxial cable or the like. It is. Note that any one of the three or more connection locations and the calibration surface need not be the same location, but if any one location is at the same position as the calibration surface, the calibration is further simplified. When the signal conductor and the ground conductor are connected, it is desirable to use a short-circuit reference for short-circuiting the two. Since this is almost totally reflected in the short circuit state, it is not affected by the terminal end of the signal conductor, and in the frequency range where the target transmission line operates in the TEM single mode, the short circuit characteristic This is because there is substantially no influence of a dielectric material, and its electric characteristics can be predicted with high accuracy by electromagnetic field simulation.

According to a preferred embodiment, the probe comprises a substrate having a signal conductor and a ground conductor, forming a planar transmission line having a constant electrical characteristic per unit length, and the distance between the signal conductor and the ground conductor. Is equal to the distance between the signal conductor and the ground conductor of the calibration board, and the dielectric constant of the board is preferably substantially equal to the dielectric constant of the calibration board. In this case, since the probe and the calibration board have substantially the same structure, the mutual impedance can be matched. Therefore, calibration with higher accuracy is possible.

The calibration substrate that can be used in the present invention is not limited to a coplanar substrate, but may be a slot line as long as it has a uniform characteristic impedance in the length direction. The coplanar substrate is suitable for measuring high frequency characteristics up to 10 GHz, and the slot line is suitable for measuring high frequency characteristics up to 10 GHz. Further, the probe used in the present invention is not limited to the coplanar structure, and a probe having an arbitrary structure can be used.

If the tip of the probe calibrated as described above is brought into contact with the electronic device to be measured, its electrical characteristics are measured by a measuring instrument, and the error of the probe obtained in the fifth step is removed from the measured value, the measured device The true value of the high frequency electrical characteristics of the electronic device can be obtained with high accuracy.

According to a preferred embodiment, a coplanar type planar transmission line having a signal conductor and ground conductors on both sides thereof on a resin substrate and having a constant electrical characteristic per unit length is printed and wired. A coaxial connector is attached to one end of the substrate in the length direction, and the signal line of the connector is attached to the signal conductor, and the ground portion of the connector is connected to the ground conductor. A contact piece that is narrower than the main body of the resin substrate and elastically deformable is integrally formed on the other end side in the direction, and the signal conductor and the ground conductor are extended at a constant interval on the contact piece. It is possible to use a high-frequency measurement probe. Since this probe can be formed of a printed circuit board, it is very inexpensive and has a coplanar structure, so that the high frequency characteristics of the subject can be measured with high accuracy. Since the contact piece can be elastically deformed by the elasticity of the resin substrate, it can be stably brought into contact with the I / O pad of the subject. Since the signal conductor and the ground conductor are formed at the same interval on the probe main body and the contact piece, the transmission path characteristics hardly change between the main body and the contact piece, and high-precision measurement can be performed. .

According to a preferred embodiment, the contact piece of the probe may be provided with a slit passing between the signal conductor and the ground conductor, and the slit length may be a half wavelength of the measurement target frequency. In this case, since the contact piece is provided with the slit, the contact piece provided with the signal conductor and the contact piece provided with the ground conductor can be independently elastically deformed. Moreover, when the slit is formed, impedance mismatching occurs. However, if the slit length is set to a half wavelength of the frequency to be measured, impedance mismatching can be mitigated.

According to a preferred embodiment, the slit width is preferably set to a quarter wavelength or less of the measurement target frequency. That is, if the slit width is set to a quarter wavelength or less of the measurement target frequency, signal emission can be suppressed and loss can be reduced.

According to a preferred embodiment, it is preferable that a protruding contact is formed at each of the signal conductor extended to the tip of the contact piece and the tip of the ground conductor. By forming a protruding contact at the tip of the contact piece, the contact position is stabilized during calibration and measurement, and measurement variations are reduced.

Hereinafter, a method for calibrating a high-frequency characteristic measuring probe according to the present invention will be described in detail with reference to examples. Here, an example using the RRR calibration method disclosed in Patent Document 1 as a calibration method will be described.

-Preparation of calibration board-
As shown in FIG. 2, a calibration board 10 manufactured by a printed board having a coplanar waveguide (CPW) transmission path structure is prepared. The calibration substrate 10 of this embodiment has a narrow signal conductor 12 extending over the entire length in the length direction on the upper surface of a dielectric substrate 11, and wide ground conductors 13 and 13 spaced apart at both sides thereof. Are provided. The dielectric substrate 11 may be an alumina substrate or a Teflon (registered trademark) substrate, but may also be a PCB substrate such as an epoxy substrate or a glass-epoxy substrate. Note that the transmission path of the calibration board 10 may be at any interval as long as it has a uniform characteristic impedance in the length direction. A connector 14 is attached to one end in the length direction of the calibration board 10, and the signal line 14 a of the connector 14 is connected to the signal conductor 11 and the GND portion 14 b is connected to the ground conductor 13. The connector 14 is connected to the measurement port 16 b of the measuring instrument 16 through the coaxial cable 15. Here, a three-port network analyzer was used as the measuring device 16.

-RRR calibration of calibration board-
Next, the signal conductor 12 and the ground conductor 13 are short-circuited at four positions (P _{1 to} P ₄ ) at arbitrary intervals from the other end of the calibration substrate 10 (see FIG. 2). For short circuit, for example, the short circuit reference 17 is pressed against the calibration substrate 10. It is not necessary to short-circuit the signal conductor 12 and both ground conductors 13, and the signal conductor 12 and one of the ground conductors 13 may be short-circuited. Here, it is assumed that the electrical characteristics per unit length of the calibration substrate 10 are unknown, and the circuit is short-circuited at four points. However, when the electrical characteristics per unit length are known, the number may be three. Using the measurement data in the short-circuit state, an error term (scattering parameter) E _RRR to the calibration surface of the calibration substrate 10 is obtained. Here, the calibration surface is, for example, the position P ₁ .

-Calculation of error coefficient of RRR calibration error model-
An error model of RRR calibration is shown in FIG. The reflection method is a method of observing how much of the electromagnetic wave incident on the subject is reflected from one port (connector 14) and obtaining an impedance or the like from this. As shown, there are only four error factors E ₁₁ , E ₂₁ , E ₁₂ , and E ₂₂ . Since the scattering coefficient measurement is a ratio measurement, if E ₂₁ = 1, there are three error factors E ₁₁ , E ₁₂ , and E ₂₂ . In the figure, S _11M is a measured value of the reflection coefficient, and S _11A is a true value of the scattering coefficient of the subject.

数式１の具体的な導出方法は、特許文献１に示された通りであるため、ここでは説明を省略する。 Now, the error coefficients E ₁₁ , E ₁₂ , and E ₂₂ in FIG. D ₁ is an intermediate variable.

Since the specific derivation method of Formula 1 is as shown in Patent Document 1, description thereof is omitted here.

ここで、αはＲＲＲ校正によって算出した校正基板伝送路の伝達度であり、βはＲＲＲ校正によって算出した校正基板伝送路の位相定数であり、Ｌは短絡基準の幅である。 When obtaining the error term of the calibration substrate 10, as shown in FIG. 4, the error term (scattering parameters) the width of the short circuit reference 17 for short-circuiting the signal conductor 12 at the RRR calibration grounding conductor 13 E _L is not negligible In some cases, E _L needs to be determined. The error term E _L of the short-circuit reference width can be calculated as Equation 2 using the transmissibility / phase constant calculated at the time of RRR calibration.

Here, α is the transmission degree of the calibration board transmission path calculated by RRR calibration, β is the phase constant of the calibration board transmission path calculated by RRR calibration, and L is the width of the short circuit reference.

Using the calculated error terms E _L and E _RRR , the error term of the calibration substrate 10 is obtained by Equation 3. In the calculation, first, the scattering parameters E _L and E _RRR are converted into the transmission parameters T _L and T _RRR , respectively, and the transmission parameter T _CAL of the error term of the calibration substrate 10 can be obtained by the product of these parameters.

Based on the error term T _CAL of the calibration substrate 10 obtained as described above, the tip P ₁ of the calibration substrate 10 can be used as the calibration surface. The RRR calibration can calibrate from the connector 14 of the calibration board 10 to the calibration plane P _1, but the SOLT from the connection portion with the connector 14 of the coaxial cable 15 connected to the calibration board 10 to the measurement port 16 b of the network analyzer 16. Needless to say, it is necessary to calibrate in advance by a known calibration method such as a method.

-Probe preparation-
FIG. 5 shows an example of a probe 20 made of a printed circuit board (PCB) having a coplanar waveguide (CPW) transmission line structure. The transmission path of the probe 20 may be at any interval as long as it has a uniform characteristic impedance in the length direction. Here, a CPW having the same shape as the calibration substrate 10 (however, the length and the shape of the contactor are different) was used as the probe 20. That is, on the surface of the resin substrate 21, the signal conductor 22 and the ground conductor 23 are provided at regular intervals on both sides thereof, and the connector 24 is attached to one end side in the length direction of the probe 20. The signal line 24 a of the connector 24 is connected to the signal conductor 22, and the GND portion 24 b is connected to the ground conductor 23. The resin substrate 21 may be a Teflon (registered trademark) substrate, for example, but an inexpensive PCB material such as an epoxy substrate or a glass-epoxy substrate can be used. The signal line 24 a and the GND portion 24 b of the connector 24 are connected to another measurement port 16 a of the network analyzer 16 via the coaxial cable 25.

As shown in FIG. 6, a contact piece 20a that is narrower than the main body of the probe 20 is integrally formed at the tip of the probe 20 (the end opposite to the connector), and the signal conductor 22 extends to the tip of the contact piece 20a. The ground conductor 23 is extended. The contact piece 20a is a band plate part integral with the resin substrate 21, and no slits or the like are formed. The distance between the signal conductor 22 and the ground conductor 23 in the contact piece 20a is equal to the distance in the main body portion of the probe 20 and the contact piece 20a continuously extends from the resin substrate 21. The transmission line characteristics do not change between them, and impedance mismatch does not occur. The tip portions of the signal conductor 22 and the ground conductor 23 extended on the contact piece 20a form contact portions 22a and 23a, respectively. The contact piece 20a preferably has a predetermined spring elasticity, and its width and length can be arbitrarily set.

-Probe calibration-
As shown in FIG. 7, the contact portions 22a and 23a of the probe 20 are brought into contact with the calibration surface of the calibration substrate 10 for which RRR calibration has been completed. That is, the signal conductor 22 of the probe 20 is brought into contact with the signal conductor 12 of the calibration board 10, and the ground conductor 23 of the probe 20 is brought into contact with the ground conductor 13 of the calibration board 10. Measuring the scattering parameter S _M in this state. The measured scattering parameters S _M into a transmission parameter T _M, by multiplying the inverse matrix T _CAL ^-1 transmission Patameta T _CAL calibration substrate 10 in this transmission parameter T _M, of the probe 20 as in Equation 4 The transmission parameter T _probe can be determined. The transmission parameter T _probe is an error term of the probe 20 when the tip (contact portion 22a, 23a) of the probe 20 is used as a calibration surface.

A model diagram of the error term of the probe 20 and the error term of the calibration board 10 is shown in the lower part of FIG. In the model diagram, it is indicated by E parameter. Similar to the calibration work on the calibration board 10, the range from the connection portion of the coaxial cable 25 connected to the probe 20 to the measurement port 16a of the network analyzer 16 is measured by a known calibration method such as the SOLT method. It is necessary to calibrate in advance.

−Preparation and calibration of another probe−
As will be described later, when a pair of probes is used in measuring an electronic device (when measuring the transmission IL characteristics of the electronic device), another probe having the same shape as the probe 20 is used as shown in FIG. 20 ′ is prepared, and calibration is performed in the same manner as in FIG. That is, the probe 20 ′ is connected to another measurement port 16c of the network analyzer 16 via the coaxial cable 25 ′, and the contact portions 22a ′ and 23a ′ of the probe 20 ′ are connected to the calibration surface of the calibration board 10 after the RRR calibration. And the scattering parameter in that state is measured, and the transmission parameter of the probe 20 ′ is obtained in the same manner as in Equation 4. The range from the connection portion of the coaxial cable 25 ′ to the connector 24 ′ to the measurement port 16 c of the network analyzer 16 is preferably calibrated in advance by a known calibration method such as the SOLT method.

-Measurement of electronic devices-
When measuring the transmission (IL) characteristics of an electronic device, a pair of calibrated probes 20 and 20 'are prepared, and contact portions 22a and 23a of the pair of probes 20 and 20' are prepared as shown in FIG. , 22a ′ and 23a ′ are brought into contact with terminals of the electronic device 30, and the high-frequency electrical characteristics thereof are measured. Since the calibrated probes 20 and 20 ′ have the tip portions (contact portions 22a, 23a, 22a ′, and 23a ′) as calibration surfaces, the electrical characteristics of the electronic device 30 can be accurately measured.

In the above embodiment, since the three-port measuring device 16 is used, two probes 20 and 20 ′ and one calibration substrate 10 can be connected to the measuring device 16 at the same time. Measurement work can be performed. When the measuring instrument has only two ports, one probe 20 is calibrated using the calibration board 10, then the probe 20 is detached from the measuring instrument and another probe 20 ′ is connected, and the calibration board 10 is used. And calibrate. Thereafter, the calibration board 10 is removed from the measuring instrument, and the calibrated probe 20 is reconnected to the measuring instrument, whereby the transmission characteristics of the electronic device can be measured.

In the above embodiment, the example of measuring the transmission (IL) characteristic of the electronic device has been described. However, when the reflection (RL) characteristic is measured, the measurement can be performed with only one probe. . In this case, the three-port measuring device 16 is not necessary, and at least two ports are sufficient. Specifically, after the calibration shown in FIG. 7 is performed, the reflection characteristic can be measured by bringing the calibrated probe 20 into contact with the terminal of the electronic device as it is.

-Experimental example-
Next, in order to evaluate the calibration method of the present invention, the short state of the probe 20 was measured and compared with a simulation value (using Sonnet). As shown in FIG. 10, the tip of the probe 20 calibrated by the calibration method of the present invention is short-circuited by the short tip 31, and the short-circuit measurement results are shown in FIGS. FIG. 11 shows the amplitude error, and FIG. 12 shows the phase error.

The measurement conditions are as follows.
[Measurement instrument] Network analyzer E8364B (Agilent Technologies)
(Frequency range) 5 GHz to 20 GHz
[Data points] 401 points [IF bandwidth] 100Hz (No averaging)
Both the probe and the calibration board are printed on a CPW transmission line structure with a 15μm single-sided copper foil (with Ni-plated Au plating) and a 0.5mm thick resin board (dielectric constant ε: 4.8, dielectric loss tangent tan δ: 0.015) A substrate was used. The dimensions of the CPW transmission line are a signal transmission line width of 1.35 mm and an insulation groove width of 0.15 mm. When the transmission line length of the probe is 72.3 mm, the transmission line loss is about −9 [dB] (0.125 dB / mm × 72.3 mm). The length of the calibration substrate is 15 mm.

As is clear from FIGS. 11 and 12, when the calibration result according to the present invention is compared with the simulation value, the amplitude error is ± 0.5 [dB] and the phase error is ± 3 [deg], which are almost the same. Therefore, according to the present invention, it can be seen that the probe tip is accurately calibrated.

FIG. 13 shows a second embodiment of the probe. Similar to the first embodiment, this probe 40 is also manufactured by a printed circuit board (PCB) having a coplanar waveguide (CPW) transmission path structure. A signal conductor 42 and ground conductors 43 and 43 are formed on the surface of the resin substrate 41. And a connector (not shown) is attached to one end of the probe 40 in the longitudinal direction. Three claw-like contact pieces 40a to 40c separated by two slits 45a and 45b are integrally formed at the tip (end opposite to the connector) of the probe 40, up to the tip of each contact piece. The signal conductor 42 and the ground conductors 43, 43 extend. The distance between the signal conductor 42 and the ground conductor 43 in the contact piece is equal to the distance between the signal conductor 42 and the ground conductor 43 in the main body. Protruding contacts 46a to 46c are formed at positions where the signal conductors 42 and the ground conductors 43 and 43 extending to the tips of the contact pieces 40a to 40c are arranged in the width direction, respectively.

Since the contact pieces 40a to 40c are separated due to the slits 45a and 45b provided between the contact pieces 40a to 40c, impedance mismatch occurs, but the length of the slits 45a and 45b is set to the measurement wavelength of the measurement target. By setting the half wavelength, impedance mismatch can be alleviated and measurement accuracy can be improved. In addition, signal emission can be suppressed by setting the width of the slits 45a and 45b to a quarter wavelength or less of the frequency to be measured. For example, when the measurement target frequency is 37 to 39 GHz, when the length of the slits 45a and 45b is 3.3 mm and the width is 0.5 mm or less, the reflection characteristic (RL) of the slit portion is −17 [ dB] or less, and the mismatch was alleviated.

In the case of this embodiment, since the three contact pieces 40a to 40c are separated by the slits 45a and 45b, it is easy to impart desired spring elasticity to the individual contact pieces 40a to 40c. Therefore, the contacts 46a to 46c can be stably brought into contact with the height of the I / O pad of the subject. Since the protruding contacts 46a to 46c are formed at the tips of the contact pieces 40a to 40c, the contact position is stabilized during calibration and measurement, and measurement variation is small.

The calibration method according to the present invention is not limited to a probe manufactured by a printed circuit board having a CPW transmission line structure as in the above embodiment, and can be applied to calibration of any shape of probe. That is, the present invention can also be applied to a general probe formed of a metal material, for example, an existing probe as shown in FIG. Further, the calibration substrate is not limited to a printed circuit board having a CPW transmission path structure, and a substrate having a planar transmission path formed on the surface of a ceramic substrate such as an alumina substrate may be used. Further, the probe and the calibration board are not limited to the CPW transmission path structure, but may be a slot line structure.

It is a figure which shows the method of making a conventional probe contact a calibration board | substrate, and (a) is a short circuit, (b) is a load, (c) shows each connection state of through. It is a figure explaining the calibration method of the calibration board | substrate used by this invention. It is a figure which shows the error model of RRR calibration. It is a figure which shows the method of correct | amending the error term for the width | variety of a short circuit standard. It is a figure which shows the state which connected the 1st Example of the probe concerning this invention to the measuring device. FIG. 6 is a partial perspective view of the probe shown in FIG. 5. It is a figure which shows the method of making a probe contact a calibration board | substrate and calibrating. It is a figure which shows the method of making another probe contact a calibration board | substrate and calibrating. It is a figure which shows the method of measuring the electrical property of an electronic device using the calibrated probe. It is the figure which made the front-end | tip of a probe the short state in order to evaluate the calibration method concerning this invention. It is the figure which compared the amplitude of the calibration value and simulation value in a short state. It is the figure which compared the phase of the calibration value in a short state, and a simulation value. It is a fragmentary perspective view of 2nd Example of the probe concerning this invention.

Explanation of symbols

10 Calibration board 11 Dielectric board 12 Signal conductor 13 Ground conductor 14 Connector 15 Coaxial cable 16 Measuring instrument (network analyzer)
16a to 16c Measurement port 17 Short-circuit reference 20, 20 'Probe 20a Contact piece 21 Resin substrate 22 Signal conductor 23 Ground conductor 22a, 23a Contact portion 24, 24' Connector 25, 25 'Coaxial cable 30 Electronic device under test 40 Probe 40a- 40c Contact piece 41 Resin substrate 42 Signal conductor 43 Ground conductors 45a and 45b Slits 46a to 46c Contacts

Claims (4)

In the calibration method of the probe for measuring high frequency characteristics,
A first step of connecting a calibration board having a planar transmission line to one measurement port of the measuring instrument;
A second step of deriving an error from a predetermined calibration surface on the calibration substrate to the measuring device by an error correction method using the calibration substrate;
A third step of connecting the probe to another measurement port of the measuring device;
A fourth step of bringing the tip of the probe into contact with the calibration surface of the calibration substrate and measuring its electrical characteristics with the measuring instrument;
By removing the error obtained in the second step from the measurement value obtained in the fourth step, the error from the measuring instrument to the tip of the probe is derived, and a calibration surface is placed on the tip of the probe. And a fifth step of creating the calibration method. The calibration board is a board having a signal conductor and a ground conductor, and having a flat transmission line with a constant electrical characteristic per unit length,
The first step is to connect one end of the signal conductor and the ground conductor to the measurement port of the measuring instrument;
The second step includes
A first sub-step for measuring a reflection coefficient by connecting a signal conductor and a ground conductor in at least three locations in a length direction of the signal conductor; a measurement value in the connection state; and an electrical characteristic of the planar transmission line The calibration method according to claim 1, further comprising: a second sub-step for deriving an error from a calibration surface of the calibration board to the measuring instrument. The probe comprises a substrate having a signal conductor and a ground conductor, and a flat transmission line having a constant electrical characteristic per unit length, and the interval between the signal conductor and the ground conductor is the same as that of the signal conductor of the calibration substrate. The calibration method according to claim 1, wherein the calibration constant is equal to a distance from the ground conductor, and a dielectric constant of the substrate is substantially equal to a dielectric constant of the calibration substrate. Contacting the tip of a pair of probes calibrated using the calibration method according to any one of claims 1 to 3 with an electronic device to be measured, and measuring the electrical characteristics with the measuring device;
Removing the error obtained in the fifth step from the measured value of the electronic device to be measured to obtain a true value of the electric characteristic of the electronic device to be measured, Method.

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