JP2003240817A - High frequency characteristic measurement method for high frequency component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To match a design value of a high frequency component with an actual value in its installation to a base board. <P>SOLUTION: Assuming that the high frequency component (a filter, for example) is in a 50 Ω terminal condition, its circuit constant is designated. An S parameter of the filter designed in this way is found by calculation and represented by S<SB>t</SB>. On the other hand, an S parameter of the base board (with a dielectric constant of 2 or more) for mounting the filter is measured. An S parameter in installation of the filter to the base board is represented by S<SB>t</SB>'. Then, the circuit constant of the filter is corrected so that the S parameter S<SB>t</SB>is equalized to the S parameter S<SB>t</SB>'. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to several hundred MHz to several G.
The present invention relates to a measuring method for measuring the high frequency characteristics of high frequency components used in the Hz band.

[0002]

2. Description of the Related Art Generally, in a high frequency component used in a band of several hundred MHz to several GHz, a high frequency characteristic is defined with an ideal state at the termination of 50Ω. In general, when incorporating such a high-frequency component into a high-frequency circuit device, the high-frequency component is mounted on a board on the device side.

[0003]

By the way, as described above, when a high frequency component is mounted on a substrate, the high frequency characteristic of the high frequency component often deviates from the ideal state. That is,
The high frequency characteristics (for example, the amount of attenuation) of the high frequency component are deviated due to the parasitic impedance existing on the substrate. Especially, the terminating impedance is a pure real value of 50 ohm (Ω)
Instead, it often becomes complex impedance with imaginary impedance.

Therefore, in an ideal state, even if a high frequency component is designed by setting a circuit constant, there is a problem that the high frequency component does not exhibit desired high frequency characteristics when mounted on the substrate due to the parasitic impedance of the substrate.

It is an object of the present invention to provide a measuring method capable of measuring the high frequency characteristics of a high frequency component in a state equivalent to that when mounted on a substrate.

[0006]

According to the present invention, there is used a substrate and a high-frequency circuit device having a high-frequency component mounted on the substrate, and a measurement jig having an impedance corresponding to a parasitic impedance existing on the substrate. A high frequency characteristic measuring method for a high frequency component, comprising: a first step of connecting the high frequency component to a tool; and a second step of measuring a characteristic of the high frequency component using the measuring jig. .

Further, according to the present invention, a first step used in a high-frequency circuit device having a substrate and a high-frequency component mounted on the substrate, wherein a high-frequency characteristic of the high-frequency component is measured to obtain a measurement result. Second, the value of the parasitic impedance existing on the substrate is obtained as the parasitic impedance value.
And a third step of obtaining a high-frequency characteristic when the high-frequency component is mounted on the substrate based on the measurement result and the parasitic impedance value. can get.

[0008]

In the present invention, since the circuit constant of the high frequency component is obtained according to the parasitic impedance existing in the substrate (relative permittivity of 1 or more), the high frequency component can be designed in a state when it is incorporated in the high frequency circuit device. It becomes possible to perform commercialization and measurement, and the adjustment process when commercializing and the adjustment process when assembled in an apparatus are unnecessary.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below with reference to Examples.

Example 1 In this example, an antenna duplexer for the 1.5 GHz band was used as a high frequency component. This antenna duplexer has an antenna (ANT) terminal, a transmission (Tx) terminal, and a reception (Rx) terminal, which are a total of three input / output terminals. Here, a band elimination filter and an ANT are provided between the Tx terminal and the ANT terminal. A band pass filter is provided between the terminals and the Rx terminals.

The above-mentioned antenna duplexer is used by being mounted on a substrate of a high-frequency circuit device (for example, a substrate having a relative dielectric constant of 1 or more). When the antenna duplexer is mounted on the device substrate, the above-mentioned three terminals are used. Are connected to pads on the substrate. At this time, the parasitic impedance existing on the substrate appears as a capacitance connected in parallel between the pad and the ground. The measured value of this capacitance is as shown in Table 1.

[0012]

[Table 1]

Referring now to FIG. 1, in FIG.
The dotted line shows the bandpass characteristic of the antenna duplexer at the time of design, the broken line shows the bandpass characteristic of the antenna duplexer when mounted on the substrate, and the solid line shows the bandpass characteristic of the antenna duplexer after correction according to the present invention.

The band-pass characteristics when mounted on the substrate shown by the broken line in FIG. 1 show that there is a deterioration in insertion loss of 0.28 dB in the Tx pass band and 1.31 dB in the Rx pass band. Such deterioration of the insertion loss is due to the parasitic impedance of the substrate described above, but as shown in Table 1, each terminal has only a capacitance of about 1 pF connected in parallel.

However, in the 1.5 GHz band, since 1 pF corresponds to a reactance of about 100Ω, this reactance has an extremely large effect on the bandpass characteristic of the filter as compared with the terminal impedance of 50Ω.

In particular, since it is necessary to secure the antenna radiation power to a predetermined value and increase the output power of the output amplifier by the insertion loss, the Tx insertion loss is extremely important in the structure of the high frequency circuit device. It is a characteristic. In addition, the insertion loss of Rx reduces the reception sensitivity by this insertion loss.
Therefore, by eliminating these factors of characteristic deterioration at the design stage, it is possible to obtain a high frequency component exhibiting a desired pass band characteristic when mounted on a substrate.

In the present invention, the antenna duplexer was designed by the following procedure.

1) Let S _{t be} the S parameter in the ideal state at the end of 50 Ω.

2) S parameter is S_tIn and out of the circuit that is
The parasitic impedance of the board is taken into consideration at the input terminal (specifically
Is added with the capacitance shown in the table) S parameter
Ta S _t′ Is estimated and calculated. S estimated here_t′ Is general
To S_tIs different from. The estimation calculation method is as follows.
It

The S parameter S _t is _replaced by the F parameter (first
F-parameters). This conversion method is described, for example, in Yoshihiro Konishi, “Method of constructing high-frequency / microwave circuit”, 199.
It is shown on page 30 in Jun. 3 pp.

An F parameter (second F parameter) representing a state in which a parallel capacitance is cascade-connected to each terminal.
From the first F parameter.

The second F parameter is reconverted to the S parameter, which is referred to as S _t ′. The reconversion method is described on the same page as the literature cited above.

3) The iterative approximation method is applied, and each circuit constant is sequentially moved so that S _t and S _t ′ are substantially equal to each other to determine a constant that minimizes the error function G.

Here, the error function G is expressed by Equation 1 when the sum for all frequencies within the approximate range is represented by Σ.

[0025]

[Equation 1]

As shown in FIG. 2, S ₁₁ , S ₂₂ , S
₃₃ is the reflection coefficient seen from each terminal, and S ₂₁ and S ₃₁ are the transmission coefficients in the directions shown in FIG.

When the bandpass characteristics of the antenna duplexer thus prepared by determining the circuit constants were measured, the results shown by the solid line in FIG. 1 were obtained. Looking at this measurement result, it was 0.28d at Tx when it was mounted on the device substrate.
It can be seen that the insertion loss in the pass band, which was degraded by 1.31 dB in B and Rx, is restored to the original level by performing the correction according to the present invention. By correcting the circuit constant in consideration of the parasitic impedance of the device board in this way, the characteristics of the antenna duplexer can be made to be close to the characteristics at the time of designing when mounted on the device board.

In this way, by correcting the error based on the parasitic impedance of the board at the design stage, the characteristic deterioration factor can be eliminated and the desired characteristics can be exhibited when mounted on the board.

Embodiment 2 By the way, when the antenna duplexer is designed and manufactured as described above and the characteristics of the antenna duplexer are measured before the substrate is placed, a deviation occurs between the measurement result and the desired characteristics. It will be. Therefore, when measuring the characteristics of the antenna duplexer before mounting the substrate, for example, a measuring jig configured to add the capacitance shown in Table 1 of Example 1 to each terminal as the parasitic impedance of the substrate is used.

Referring to FIG. 3, this measuring jig is equipped with a Tx connection terminal 1, an ANT connection terminal 2 and an Rx connection terminal 3, and these Tx connection terminal 1, ANT connection terminal 2 and
The Tx terminal, the ANT terminal, and the Rx terminal of the antenna duplexer are connected to the Rx connection terminal 3 and the Rx connection terminal 3, respectively.
As shown in the figure, the Tx connection terminal 1, the ANT connection terminal 2, and the Rx connection terminal 3 are attached to the housing, and the work retainer 4 is arranged in the housing and the Tx connection terminal 1, The Tx terminal pad 5, the ANT terminal pad 6, and R facing the ANT connection terminal 2 and the Rx connection terminal 3
An x terminal pad 7 is provided. And these Tx
On the terminal pad 5, the ANT terminal pad 6, and the Rx terminal pad 7, a capacitor 8 corresponding to the Tx terminal portion capacitance, a capacitor 9 corresponding to the ANT terminal portion capacitance, and a capacitor 10 corresponding to the Rx terminal portion capacitance are arranged, respectively. Has been done.

By using the measuring jig shown in FIG. 3, even when the characteristics of the antenna duplexer are measured before mounting the board, the characteristics can be measured in the state where the antenna duplexer is mounted (mounted) on the apparatus board. It is possible to determine the quality of the antenna duplexer in a state where the antenna duplexer is mounted on the device substrate.

Example 3 In this example, a method of obtaining characteristics including parasitic impedance when the antenna duplexer is mounted on the device substrate is shown. That is, a method for obtaining a result equivalent to the characteristic measured using the jig used in the second embodiment will be shown.

The S-parameters of the antenna duplexer are converted into F-parameters (first F-parameters). This method is as shown in Example 1.

The F parameter (second parameter) indicating the capacitance of the antenna duplexer connected in parallel is obtained, and the first F parameter is multiplied by the second parameter. Here, the F parameter representing the capacitance in parallel is expressed by Equation 2.

[0035]

[Equation 2]

The characteristics when the antenna duplexer is mounted on the device substrate are obtained based on the calculation result of. That is, the characteristics are converted from the calculation result of.

In this embodiment, the insertion loss is obtained as a high frequency characteristic. Therefore, if the conversion method is shown, the insertion loss is calculated by the equation 4 when the F parameter is expressed by the equation 3, so that It is sufficient to substitute the calculation result obtained in.

[0038]

[Equation 3]

[Equation 4]

The second embodiment by using the above method
The same effect as that of the jig can be obtained, and the determination when mounted on the device substrate can be performed by measuring the component alone.

Although the antenna duplexer has been described in the above embodiments, the present invention can be similarly applied to other high frequency components.

[0041]

As described above, according to the present invention, the circuit constant of the high frequency component is corrected according to the parasitic impedance of the device substrate and the high frequency component is designed based on the corrected circuit constant. In this case, it is possible to provide the same high frequency characteristics as when mounting on a board, and as a result, it is possible to mount a high frequency component on a board very easily.

Further, according to the present invention, when measuring the characteristics of the high frequency component alone, the characteristics at the time of board mounting can be measured, that is, the pass / fail judgment of the high frequency component can be made substantially in the state of board mounting. As a result, it is possible to avoid inconveniences such as the characteristics of the high-frequency component alone being passed and the characteristics being rejected during mounting.

[Brief description of drawings]

FIG. 1 is a characteristic diagram showing a bandpass characteristic of an antenna duplexer, which is a high-frequency component, where (a) is a diagram showing a relationship between insertion loss and frequency, and (b) is a partially enlarged view of (a). FIG.

FIG. 2 is a diagram for explaining S parameter measurement of an antenna duplexer.

FIG. 3 is a view showing a measuring jig used in the present invention.

[Explanation of symbols]

1 Transmit (Tx) terminal 2 Antenna (ANT) terminal 3 Receive (Rx) terminal 4 Work clamp 5 Tx terminal pad 6 ANT terminal pad 7 Rx terminal pad 8, 9, 10 capacitors

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Ken Yano             6-7-1, Koriyama, Taihaku-ku, Sendai City, Miyagi Prefecture             Tokin Co., Ltd. (72) Inventor Satomi Mori             6-7-1, Koriyama, Taihaku-ku, Sendai City, Miyagi Prefecture             Tokin Co., Ltd. F-term (reference) 2G003 AA00 AE03 AG05 AH03

Claims (3)

[Claims] 1. A high frequency circuit device having a substrate and a high frequency component mounted on the substrate, wherein the high frequency component is connected to a measuring jig having an impedance corresponding to a parasitic impedance existing on the substrate. And a second step of measuring the characteristics of the high-frequency component using the measurement jig. 2. A first step used in a high-frequency circuit device having a substrate and a high-frequency component mounted on the substrate, the first step of measuring a high-frequency characteristic of the high-frequency component to obtain a measurement result, which exists in the substrate. It has a second step of obtaining the value of the parasitic impedance as a parasitic impedance value, and a third step of obtaining a high frequency characteristic when the high frequency component is mounted on the substrate based on the measurement result and the parasitic impedance value. And a method for measuring high frequency characteristics of high frequency components. 3. The high frequency component measuring method according to claim 2, wherein in the first step, a measurement result when the high frequency component is terminated at 50Ω is obtained. High frequency characteristics measurement method.