JP2004336321A - High frequency signal transmission line substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high frequency signal transmission line substrate which propagates high frequency signals, provided with a chip resistor mounting area for sufficient isolation, and has stable transmission characteristics. <P>SOLUTION: In the high frequency signal transmission line substrate 10 having a Wilkinson type circuit on which a transmission line 12 extended from an input terminal 14 formed on a dielectric substrate 11 is divided into two transmission lines at a branch point 15, and a chip resistor 18 is joined with the transmission line 12 extended from the branch point 15 to an output terminal 17, a connecting pad 19 having the length of wavelength/4 is attached to the transmission line 12; a first intermediate line 21 is connected between the connecting pad 19 and an output side line 20 to match characteristic impedance; and a second intermediate line 23 is connected between a branch line 16 formed between the connecting pad 19 and the branch line 15, and an input side line 22 to match characteristic impedance. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a high-frequency signal transmission line substrate for passing a high-frequency signal through a transmission line, and more particularly, to a high-frequency signal transmission line substrate having a transmission line formed of a Wilkinson-type circuit.
[0002]
[Prior art]
With the recent increase in the frequency of modules, a high-frequency signal transmission line substrate for mounting a semiconductor element and transmitting a high-frequency signal requires only simple electrical connection, for example, reflection of a signal transmitted through a signal line, crosstalk, and the like. Since the electromagnetic wave behavior as a transmission line such as the above becomes remarkable, it is necessary to take measures against various noises such as reflection noise and unnecessary electromagnetic radiation (EMI). This high-frequency transmission line substrate can respond to high-speed operation on a dielectric substrate made of ceramic or plastic, and can be used to conduct signal lines, grounds, etc. with conductive metal while taking into account electrical design to reduce noise generation factors. It is formed and manufactured.
[0003]
Normally, when performing high-output amplification using a high-frequency signal transmission line substrate, a plurality of amplifiers, rather than one amplifier, are mounted on the high-frequency signal transmission line substrate for reasons such as withstand power of the amplifier. . In this case, in order to input a signal to a plurality of amplifiers, it is necessary to branch the transmission line on the input side to the amplifier. Alignment needs to be done. The alignment method, for example, the characteristic impedance when the _{Z 0,} may be provided a wavelength / 4 line characteristic impedance ^1/2 1/2 · _{Z 0} before branching, or characteristic impedance ^{2 1/2} after the branch - it has been made by providing a transformer having a wavelength / 4 line of Z _0. As shown in FIG. 4, the calculation of the characteristic impedance to connect the transmission line 52 of the transmission line 51 and the characteristic impedance Z ₂ of the characteristic impedance Z ₁ in alignment is ₌ intermediate characteristic impedance Z _M ( _{Z 1} · Z ²⁾ are calculated from the principles of the may be provided a transmission line 53 of the length of the wavelength / 4 ^1/2.
[0004]
Since sufficient isolation may be required between the two transmission lines after branching, a transmission line having a Wilkinson-type circuit is used. With reference to FIG. 5, a transmission line using this Wilkinson transmission line will be schematically described. For example, the wavelength / 4 transformer 62 is used so that the signal input from the port 1 is split in two directions at the branch point 61 and passes through the port 2 and the port 3 without causing reflection. Is consistent. Further, for example, in order to prevent the noise generated at the port 2 from transmitting to the port 3, the length from the position A to the position B is set to a wavelength / 4, and the length from the position B to the position C through the position A is set. The length is wavelength / 2. Further, when the length from the position B to the position C through the resistor 63 is smaller than the wavelength / 2, the noise generated at the port 2 is the noise at the time of reaching the position C through the position A. And the phase of the noise that reaches the position C directly through the resistor 63 is different by 180 degrees. Therefore, by setting the resistance value R of the resistor 63 to R = 2 · Z ₀ , the absolute values of the noise reaching the position C become equal, and the noises cancel each other out so that the noise does not reach the port 3. I have. In the transmission line constituted by this Wilkinson-type circuit, the isolation between the two transmission lines after branching can be maintained by installing the resistor 63 having an optimized size.
[0005]
In a conventional high-frequency signal transmission line substrate, for example, an input side strip line and an output side strip line are formed with a line width having a characteristic impedance of 50Ω on a dielectric substrate, and a signal in a microwave band is inputted to a branch point. There is proposed a device which branches at a point and transmits power to a circuit having the same characteristic impedance connected to the subsequent stage. The wavelength / 4 transformer formed on the high-frequency signal transmission line substrate is set to have different widths corresponding to the power distribution ratio, and the connection step due to the different line widths is shifted from the center line of the input side strip line to the input side strip line. There has been proposed a line which is set to be shifted toward the output side strip line within the range of the line width of one side of the line (for example, see Patent Document 1).
[0006]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 2002-135015
[Problems to be solved by the invention]
However, the conventional high-frequency signal transmission line board as described above has the following problems.
(1) When the high-frequency signal transmission line substrate is a dielectric substrate made of alumina (Al ₂ O ₃ ) and the transmission line substrate has a frequency of, for example, about 20 GHz or higher, a high-frequency signal transmission line substrate has a microstrip line structure. In order to reduce the generation of surface waves, the thickness of the substrate is reduced to, for example, 0.25 mm or less, and the transmission line width is also reduced to match the substrate thickness for the characteristic impedance design, for example, 0.25 mm or less. Need to be Also in the grounded coplanar line structure, the transmission line width needs to be narrower, for example, 0.2 mm or less, in order to shift the resonance to a higher frequency side. In such a transmission line width structure, the mounting pad for mounting the chip resistor is insufficient in width, so that it becomes difficult to mount the chip.
[0008]
(2) When a resistor is provided as a thick film or a thin film on a dielectric substrate, the cost increases. Therefore, it is desired to mount a chip resistor. As shown in FIG. 6, the mounting pad 65 for mounting the chip resistor 64 needs a sufficient mounting area, for example, an area having a width of 0.4 mm and a length of 0.5 mm. When the area of 65 is increased, the characteristic impedance of the mounting pad 65 is smaller than the transmission line 66 on the input side or the transmission line 67 on the output side as a mismatching point of the characteristic impedance, and the transmission characteristic is greatly deteriorated.
[0009]
(3) The lower layer of the transmission line substrate made of a laminated body in order to prevent the characteristic impedance of the mounting pad from being lower than the transmission line on the input side or the output side as a mismatching point of the characteristic impedance and to prevent the transmission characteristics from being greatly deteriorated. It is possible to reduce the capacitance by partially removing only the area immediately below the mounting pad from the ground pattern, and make the characteristic impedance on the input and output sides close to, for example, 50Ω. Problem occurs. Further, even if resonance does not occur, there is a problem that characteristics are not stable due to misalignment of the ceramic green sheets and misalignment of the printed wiring pattern.
[0010]
(4) In the method of simply matching the characteristic impedance by changing the width of the branched transmission line, if sufficient isolation is required between the two transmission lines after branching, sufficient isolation is obtained. I can't.
The present invention has been made in view of the above circumstances, and provides a high-frequency signal transmission line substrate that can transmit a high-frequency signal, has a sufficient mounting area for a chip resistor for isolation, and has stable transmission characteristics. The purpose is to do.
[0011]
[Means for Solving the Problems]
According to the high frequency signal transmission line substrate of the present invention, the transmission line extending from the high frequency signal input terminal formed on the dielectric substrate is divided into two at the branch point and extended from the branch point to the output terminal. A high-frequency signal transmission line substrate having a Wilkinson-type circuit formed by joining a chip resistor between transmission lines provided, wherein a connection for mounting the chip resistor on the transmission line has a length of wavelength / 4. And a first intermediate line is provided between the connection pad and the output line to match the characteristic impedance between the connection pad and the output line. A second intermediate line is provided between the input-side line and a branch line provided between the input line and the branch line, and matching of characteristic impedances of the connection pad, the branch line, and the input-side line is measured. Thus, the connection pad for mounting the chip resistor has a length of / 4 while securing the width, and the first intermediate line that matches the characteristic impedance between the connection pad and the output line. Is provided, and the second intermediate line for matching the characteristic impedance is provided between the connection pad and the input-side line, so that the chip resistor can be easily mounted on the connection pad and the characteristic impedance mismatch. It is possible to provide a high-frequency signal transmission line substrate having stable transmission characteristics, which has no portions, is less affected by resonance, lamination shift, printing shift, and the like. In addition, since a resistor is provided between the two transmission lines after branching, isolation between the transmission lines can be measured, and a resistor provided between the two transmission lines after branching is a chip resistor. Thus, an inexpensive high-frequency signal transmission line substrate can be obtained.
[0012]
Here, the high-frequency signal transmission line substrate, when the length of the first intermediate line is, the respective characteristic impedance of the connection pads and the output line Z _p, and _{Z 0, (Z 0 · Z} p) 1 ^When the characteristic impedance of the branch line and the input side line is Z _m and Z ₀ , respectively, the length of the second intermediate line is (0.5 · Z _m). ² · Z ₀ / Z _p ) It is preferable to have a wavelength of / 4 having a characteristic impedance of ^1/2 . As a result, it is possible to eliminate a mismatching point between the characteristic impedances of the input-side and output-side transmission lines with the connection pad for mounting the chip resistor therebetween.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, embodiments of the present invention will be described with reference to the accompanying drawings to provide an understanding of the present invention.
Here, FIGS. 1A and 1B are a perspective view and a magnified plan view of a branch portion of a high-frequency signal transmission line substrate according to an embodiment of the present invention, respectively, and FIGS. 2A and 2B are the same. FIGS. 3A to 3C are graphs showing simulation results of transmission characteristics of a high-frequency signal transmission line substrate according to the present invention and a conventional high-frequency signal transmission line substrate, respectively.
[0014]
As shown in FIGS. 1A and 1B, a high-frequency signal transmission line substrate 10 according to an embodiment of the present invention is a laminate of ceramic, plastic, or the like formed by laminating and laminating a plurality of substrates. Transmission line 12 made of a metal conductor for a signal line for passing a high-frequency signal through one main surface of a dielectric substrate 11 made of a semiconductor device, a semiconductor element mounting pad 13 for mounting a semiconductor element, and a semiconductor element A wire bonding pad (not shown) is provided around the mounting pad 13. In the intermediate layer immediately below one main surface of the dielectric substrate 11, a ground metal conductor made of a solid pattern or an island-like pattern using substantially the same metal conductor as the metal conductor of the transmission line 12 is used. It has a pattern (not shown). Further, a wiring pattern (not shown) and upper and lower wiring patterns are connected to one main surface of the dielectric substrate 11 and a predetermined intermediate layer in order to establish electrical conduction with the semiconductor element. (Not shown).
[0015]
In the high-frequency signal transmission line substrate 10, a transmission line 12 extending from an input terminal 14 is branched at a branch point 15 into a Ω-shaped or O-shaped branch line 16 having a wavelength of / 4. It is divided into two in a T-shape, and is provided to extend to the output terminal 17 with the semiconductor element mounting pad 13 interposed therebetween while being extended. The high-frequency signal transmission line substrate 10 is a Wilkinson-type circuit in which a resistor is provided between the two transmission lines 12 on the output side. For this resistor, a chip resistor 18 that can be mounted later with solder or the like is used. In order to mount the chip resistor 18, a connection pad 19 having a wavelength of / 4 is provided on the transmission line 12 on the output side. Along with the connection pad 19, a first intermediate line 21 is provided between the connection pad 19 and an output-side line 20 extending to the output terminal 17 on the output-side transmission line 12. The first intermediate line 21 allows the high-frequency signal transmission line substrate 10 to match the characteristic impedance between the connection pad 19 and the output line 20.
[0016]
The high-frequency signal transmission line substrate 10 includes a branch line 16 having a wavelength of / 4 provided between the connection pad 19 and the branch point 15, and an input-side line 22 extending to the input terminal 14. A second intermediate line 23 is provided therebetween. The second intermediate line 23 allows the high-frequency signal transmission line substrate 10 to match the characteristic impedance of the connection pad 19 with the characteristic impedance of the branch line 16 and the input side line 22.
[0017]
A modified example of the high-frequency signal transmission line substrate 10 according to one embodiment of the present invention will be described with reference to FIGS. One of the modifications is as shown in FIG. 2A, via a branch line 16a in which the input side line 22 and the transmission line 12 of the second intermediate line 23 branch at the branch point 15 into a U-shape. It is divided into two in a T shape. The connection pad 19a is provided to be bent at an angle with respect to the input side line 22 and the second intermediate line 23 so that two of them are opened outward, and the first intermediate line 21 and the output side line are provided. 20 is formed so as to be perpendicular to the input side line 22 and the second intermediate line 23. Another modification is a branch line 16b in which the input side line 22 and the transmission line 12 of the second intermediate line 23 branch in a Y-shape at the branch point 15, as shown in FIG. Are divided into two in a T-shape via a. The connection pad 19b is provided to be bent in the same manner as the connection pad 19a, and is formed on the first intermediate line 21 and the output side line 20 at right angles to the input side line 22 and the second intermediate line 23. Are formed so as to be connected to each other. In particular, in the high-frequency signal transmission line substrate 10 having these shapes, by providing the intervals A and B between the branch lines 16a and 16b, the occurrence of current leakage can be reduced, and the stubs are connected to the connection pads 19a and 19b. Can be prevented from occurring, so that the signal can be sent smoothly and at the same time, the occurrence of noise can be prevented.
[0018]
The length of the first intermediate line 21 of the high-frequency signal transmission line substrate 10, connection pads 19, 19a, the characteristic impedance of 19b _{Z p,} the characteristic impedance of the output side line 20 when the _{Z 0, (Z 0} (Z _p ) It is preferable that the wavelength is / 4 having a characteristic impedance of ^1/2 . When the characteristic impedance of the branch lines 16, 16a and 16b is Z _m and the characteristic impedance of the input side line 22 is Z ₀ , the length of the second intermediate line 23 is (0.5 · Z _m ² · Z ₀ / _Z ^p) may comprise a wavelength / 4 ^1/2 of the characteristic impedance. With the first intermediate line 21 and the second intermediate line 23, a high-frequency signal from the input terminal 14 can be distributed to the two output terminals 17 without causing a mismatch in characteristic impedance.
[0019]
【Example】
Three layers each having a thickness of 0.20 mm are laminated to form an alumina (Al ₂ O ₃ ) substrate having an outer shape of 40 mm × 40 mm, and the transmission line is made of a conductive metal made of tungsten. The connection pad on which the chip resistor is mounted has a length of wavelength / 4, and the connection pad has a structure in which a stub is unlikely to be generated. The connection pad is sandwiched between the first and second intermediate portions. A line was provided, and an example in which the width of the input and output lines was 0.20 mm was manufactured. In addition, as a comparative example, with the same dimensions, the same substrate, and the same metal conductor as those of the example, the transmission line is divided into two at the branch point of the transmission line into an Ω shape, and the area of the mounting portion of the chip resistor is 0.4 mm × 0.2 mm. 5 mm, the first and second intermediate lines are not provided, the input side line having a width of 0.20 mm is connected at the branch point, and 0 mm is directly connected to the area of the mounting portion of the chip resistor of 0.4 mm × 0.5 mm. An output line having a width of .20 mm was prepared. For the example and the comparative example, the reflection coefficient as S11, the transmission coefficient as S21, and the isolation coefficient as S32 of the S parameters were simulated and investigated.
[0020]
As shown in FIGS. 3 (A) to 3 (C), the result of performing the S-parameter simulation shows that the reflection coefficient S11 of the example is a good result when the reflection coefficient S11 is −25 dB or less in a high frequency region around 25 GHz. The result is much better than the example (see FIG. 3A). Further, the pass coefficient S21 of the embodiment is a good result when it is -4 dB or more, and shows a better result than the comparative example (see FIG. 3B). Furthermore, the isolation coefficient S32 of the example is a good result when it is -20 dB or less, and shows a result comparable to that of the comparative example (see FIG. 3C). It was found that the example had better transmission characteristics than the conventional example.
[0021]
【The invention's effect】
In the high-frequency signal transmission line substrate according to the first and second aspects, the transmission line extending from the input terminal for the high-frequency signal formed on the dielectric substrate is divided into two at the branch point, A high-frequency signal transmission line substrate having a Wilkinson-type circuit formed by joining a chip resistor between transmission lines extending from an output terminal to an output terminal, and the length for mounting the chip resistor on the transmission line is a wavelength. / 4, a first intermediate line is provided between the connection pad and the output line, and a branch line is provided between the connection pad and the branch point. Since the second intermediate line is provided between the input side line and the input side line, a chip resistor can be easily mounted on the connection pad, and there is no characteristic impedance mismatching portion, and resonance, lamination displacement, printing displacement, etc. It can be a high-frequency signal transmission line substrate having no stable transmission characteristics. In addition, a resistor is provided between the two transmission lines after branching to measure isolation between the transmission lines, and the resistor provided between the two transmission lines after branching is a chip resistor. The substrate can be made inexpensive.
[0022]
In particular, in the high-frequency signal transmission line substrate according to the second aspect, when the length of the first intermediate line is Z _p , Z ₀ , respectively, the characteristic impedances of the connection pad and the output-side line are (Z _0. Z _p ) ^1/2 of the characteristic impedance wavelength / 4, and the length of the second intermediate line is (0 _.Zp ) when the characteristic impedances of the branch line and the input side line are Z _m and Z ₀ , respectively. since consisting ^{_{5 · Z m 2 · Z 0}} / Z p) wavelength / 4 ^1/2 of the characteristic impedance, the characteristic impedance of the transmission line on the input side and the output side across the connection pads of the chip resistor mounted non A high-frequency signal can be distributed to two output terminals by eliminating a matching portion.
[Brief description of the drawings]
FIGS. 1A and 1B are a perspective view and an enlarged plan view of a branch portion of a high-frequency signal transmission line substrate according to an embodiment of the present invention, respectively.
FIGS. 2A and 2B are enlarged plan views of a branch portion of a modified example of the high-frequency signal transmission line substrate.
3 (A) to 3 (C) are graphs of simulation results of transmission characteristics of the present invention and a conventional high-frequency signal transmission line substrate, respectively.
FIG. 4 is an explanatory diagram of a conventional method for calculating a characteristic impedance.
FIG. 5 is an explanatory diagram of a conventional transmission line having a Wilkinson-type circuit.
FIG. 6 is an enlarged plan view of a branch portion of a comparative example which is a conventional high-frequency signal transmission line substrate.
[Explanation of symbols]
10: high-frequency signal transmission line substrate, 11: dielectric substrate, 12: transmission line, 13, semiconductor device mounting pad, 14: input terminal, 15: branch point, 16, 16a, 16b: branch line, 17: output Terminal, 18: chip resistor, 19, 19a, 19b: connection pad, 20: output side line, 21: first intermediate line, 22: input side line, 23: second intermediate line

Claims (2)

A transmission line extending from an input terminal for a high-frequency signal formed on a dielectric substrate is divided into two at a branch point, and a chip resistor is joined between the transmission lines extending from the branch point to an output terminal. A high-frequency signal transmission line substrate having a Wilkinson-type circuit to be formed,
A connection pad having a wavelength of / 4 for mounting the chip resistor on the transmission line is provided, and a first intermediate line is provided between the connection pad and the output line. A characteristic impedance between the connection pad and the output line is matched, and a second intermediate line is provided between the input line and a branch line provided between the connection pad and the branch point. Wherein the characteristic impedances of the connection pad, the branch line, and the input line are matched. 2. The high-frequency signal transmission line board according to claim 1, wherein the length of the first intermediate line is (Z ₀₎ when the characteristic impedances of the connection pad and the output-side line are Z _p and Z ₀ , respectively. · Z _p) consists wavelength / 4 ^1/2 of the characteristic impedance, the length of the second intermediate line is, each of the characteristic impedance of the branch line and the input side line when a Z _m, Z ₀ , the high-frequency signal transmission line substrate, characterized in that it consists of ^{_{(0.5 · Z m 2 · Z}} 0 / Z p) wavelength / 4 ^1/2 of the characteristic impedance.

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