JPH1051236A - High-frequency circuit such as vco using multi-layer board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the high-frequency circuit, which is not affected by tanδ and moisture absorption of a board. SOLUTION: The high-frequency circuit 20 is shaped to omit a solid ground electrode from a high-frequency circuit with a multi-layer board, in which a tri-plate strip line resonator consisting of a center conductor and two solid ground electrodes with the center conductor inbetween, is formed. In other words, the high-frequency circuit has a multi-layer board in which a circuit pattern 25, an inner electrode 26 including at least a matching line, a resonator line 27 and the solid ground electrodes 28 are formed in different layers, and the resonance line 27 and the solid ground electrodes 28 form a strip line resonator, the solid ground electrodes 28 and the inner electrode 26 are arranged so as to interpose the resonance line 27, and no other solid ground electrode exist between the resonance line 27 and the internal electrode 26.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high frequency circuit such as a VCO (Voltage Controlled Oscillator) using a multi-layer substrate. Also, the present invention relates to an inexpensive high-frequency circuit.

[0002]

2. Description of the Related Art With the widespread use of portable telephones and PHSs, there is a strong demand for VCOs used therein to be reduced in size and cost. One example of a proposal that responds to this is the magazine “Electronic Packaging Technology” published by the Technical Research Institute Co., Ltd.
This is a multilayer chip VCO described on page 5. The cross-sectional view is as shown in FIG. 3, and the multilayer chip VCO includes a multilayer substrate 1 in which many ceramic substrates are stacked. Among these ceramic substrates, a center conductor 2 of a stripline resonator constituting a part of the VCO is formed on one surface of the ceramic substrate located slightly below the center. A first land land electrode 3 is formed on the bottom surface of the multilayer substrate 1 so as to sandwich the center conductor 2 from above and below as a ground conductor plate of the strip line resonator.
The second land land electrode 4 is formed on an appropriate ceramic substrate. Further, the side surface of the multilayer substrate 1 is covered with a side electrode 5, and one end of the center conductor 2 of the strip line resonator is connected to a circuit pattern formed on the surface of the multilayer substrate 1 via a connection conductor 6 in a through hole. Connected to 7,
The other end of the center conductor 2 is connected to the side electrode 5. As a result, a triplate-type stripline resonator having a short-circuited terminal is formed. Second beta land electrode 4 and multilayer substrate 1
An internal electrode 8 serving as a passive circuit such as a matching line or a choke line is formed on the ceramic substrate between the internal electrode 8 and the circuit pattern 7, and between the internal pattern 8 and the circuit pattern electrode 2. The spaces are appropriately connected by connecting conductors. The multilayer chip VCO is configured as described above.

A similar proposal has been made in Japanese Patent Application Laid-Open No. 63-209305, and FIG. 4 shows the structure of an oscillator disclosed in the same document. This oscillator has a first dielectric substrate 11 having a circuit pattern 10 formed on the surface, a second dielectric substrate 13 having a beta land electrode 12 formed on the surface, and a center conductor 14 formed on the surface. A third dielectric substrate 16 having a beta land electrode 15 formed on the back surface;
A fourth dielectric substrate 18 having a circuit pattern 17 formed on the back surface is laminated in the order shown in the drawing, and the side surface is covered with a side electrode 19. Circuit pattern 10,
Reference numeral 17 denotes an oscillator unit of the VCO, and the center conductor 14 and the two beta land electrodes 12 and 15 constitute a VCO triplate stripline resonator.

[0004]

The cost of the multilayer board chip VCO as described above can be reduced by forming a multilayer board by laminating inexpensive printed boards. However, since the printed circuit board has a poor tan δ and relatively easily absorbs moisture, the multilayer chip VCO having the structure shown in FIGS.
Is manufactured using a printed circuit board, the following problem arises because a capacitance is formed between the center conductor and the beta land electrode. That is, as the multilayer chip VCO is reduced in size, one beta land electrodes 4 and 12 of the strip line resonator and the other beta land electrodes 3 and 1 of the strip line resonator are reduced.
5 is extremely narrow, so that the ta of the printed circuit board laminated between the upper and lower beta land electrodes is correspondingly reduced.
The influence of nδ appears greatly, the power loss of the stripline resonator increases, and its Q value decreases.

Another problem stems from the fact that printed circuit boards are relatively easy to absorb moisture. The resonance frequency of a stripline resonator is determined mainly by the inductance of the center conductor, the stray capacitance between the center conductor and the upper and lower beta-land electrodes, and the permittivity of the printed board. The rate changes.
For this reason, there arises a problem that the resonance frequency of the stripline resonator changes due to moisture absorption of the printed circuit board.

The present invention has been proposed to solve the above problems, and has as its object to provide a small and inexpensive high-frequency circuit which is hardly affected by tan δ of the substrate and moisture absorption of the substrate.

[0007]

In order to achieve the above object, the present invention provides a triplate type strip line resonator having a center conductor and two beta land electrodes sandwiching the center conductor. From a high-frequency circuit such as a VCO provided with a circuit pattern electrically connected to the central conductor on one surface of the multilayered substrate, wherein the shape of the beta land electrode closer to the circuit pattern is omitted. And a high-frequency circuit characterized by:

According to another aspect of the high-frequency circuit of the present invention, a circuit pattern, an internal electrode including at least a matching line, a resonance line, and a beta land electrode are formed in different layers. VC provided with a multilayer substrate constituted by a strip line resonator with a ground electrode
O, etc., wherein the land land electrode and the internal electrode are arranged so as to sandwich the resonance line, and no separate land land electrode exists between the resonance line and the internal electrode. It can be said that this is a high-frequency circuit characterized by the following. In this case, a capacitance value that determines a resonance frequency of the strip line resonator is substantially equal to a capacitance value formed between the resonance line and the beta land electrode.

In the high-frequency circuit according to the present invention, it is preferable that the multilayer board is composed of a plurality of laminated printed boards.

[0010]

[Action] Tri-plate type strip line resonator 2
Since there is no beta land electrode closer to the internal electrode among the two beta land electrodes, the capacitance between this beta land electrode and the resonance line is eliminated. As a result, the capacitance value that determines the resonance frequency of the stripline resonator is
It is substantially equal to the value of the capacitance formed between the resonance line and the beta land electrode, and the tan of the substrate to the high frequency circuit is reduced.
The effect of δ is reduced. In addition, the degree to which the resonance frequency of the strip line resonator fluctuates due to a change in the dielectric constant of the substrate due to moisture absorption of the substrate is reduced.

[0011]

FIG. 1 is a sectional view schematically showing an embodiment of a high-frequency circuit according to the present invention. The high-frequency circuit 20 has a plurality of layers (first to
It has a multilayer board in which printed boards 21, 22, 23 and 24 (fourth layer) are laminated. A circuit pattern 25 that is an electrode of the first layer is formed on the surface of the printed circuit board 21 of the first layer, and a circuit component is attached to the circuit pattern 25. The second layer printed circuit board 22 has a second layer
An internal electrode 26 including a passive circuit such as a matching line or a choke line, which is an electrode of a layer, is formed. On the surface of the printed circuit board 23 of the third layer, a resonance line 27 of a strip line resonator is formed as an electrode of the third layer. On the surface of the printed circuit board 24 of the fourth layer, a beta land electrode 28 of a strip line resonator is formed as an electrode of the fourth layer.
In the high-frequency circuit of FIG. 1, the first to fourth layer electrodes are formed on the first to fourth layer printed circuit boards 21 to 24, respectively, and then laminated, and the side electrodes 30 are formed on the side surfaces thereof. It is produced by doing. Printed circuit boards 21 and 2
4 are formed at required positions, and a conductor is formed on an inner surface of the through hole to form a circuit pattern 25,
It goes without saying that the internal electrode 26 and the center conductor 27 are appropriately connected to form a high-frequency circuit.

As is apparent from FIG. 1, the high-frequency circuit according to the present invention is a solid circuit which is closer to the internal electrode of the two ground electrodes of the conventional triplate strip line resonator shown in FIGS. It is characterized in that it has a shape omitting the ground electrode. A conventional triplate stripline resonator has a structure in which a center conductor is sandwiched between top and bottom electrodes via a dielectric substrate from above and below.
In addition, one beta land electrode is arranged between the internal electrode and the central conductor, and the distance between the beta land electrode and the central conductor is small, so that it is formed between the central conductor and the above and below beta land electrodes. The capacitance value greatly changes due to the tan δ of the stacked printed circuit boards and the moisture absorption of the printed circuit boards. As described above, the characteristics of the stripline resonator, that is, the characteristics of the high-frequency circuit such as the VCO fluctuate, as described above.

In order to prevent this, in the present invention, of the two beta land electrodes of the conventional triplate type strip line resonator, the beta land electrode closer to the internal electrode is omitted. . As a result, the capacitance formed between the center conductor of the conventional triplate strip line resonator and the beta land electrode closer to the internal electrode is removed.

Accordingly, the stripline resonator of the high-frequency circuit according to the present invention has a smaller capacitance than that of the conventional triplate type stripline resonator. Therefore, the degree of influence by the tan δ and the dielectric constant of the printed circuit board is small. Lower. As a result of omitting the land land electrode closer to the internal electrode, the resonance line 27 can be arranged apart from the land land electrode 28, so that the capacitance between the resonance line 27 and the land land electrode 28 can be reduced. Therefore, the fluctuation of the resonance frequency of the strip line resonator can be reduced. Further, as compared with a conventional high frequency circuit using a triplate strip line resonator, the number of electrode layers is reduced by one, so that the manufacturing cost is reduced.

Hereinafter, specific examples of the first to fourth layer electrodes will be described with reference to FIG. The conductors forming the circuit patterns and the electrodes are blacked out, and the white portions are the surfaces of the printed circuit board.

FIG. 2A shows a first-layer printed circuit board 2.
1 shows an example of a circuit pattern 25 which is a first-layer electrode formed on the surface of a first layer. The circuit pattern 25 has a required shape so as to constitute an amplifier, an oscillator, and the like of the high-frequency circuit 20, and circuit components are electrically connected to the circuit pattern 25.

FIG. 2B shows an example of an internal electrode 26 which is a second layer electrode formed on the surface of the second layer printed board 22. The internal electrode 26 includes a passive circuit such as a matching line or a choke line for a high-frequency circuit. The internal electrode 26 and the circuit pattern 25 are electrically connected at predetermined locations via the through holes 31.

FIG. 3C shows an example of a resonance line 27 which is a third layer electrode formed on the surface of the third layer printed circuit board 23. In this figure, the resonance line 27 has a meandering shape so as to resonate at a predetermined frequency.

FIG. 2D shows an example of a land land electrode 28 formed on the surface of the fourth-layer printed circuit board 24. Terminal electrodes are formed on the back surface (not shown).
In addition, when the terminal electrode is unnecessary, the beta land electrode 2
8 may be formed on the back surface of the printed circuit board 23 of the third layer, and the printed circuit board 24 of the fourth layer and the terminal electrodes may be omitted.

[0020]

EXAMPLE A high-frequency circuit having the structure described above with reference to FIGS. 1 and 2 was manufactured in a size of 5.0.times.5.0.times.0.8 mm. When its characteristics were measured, the Q value of the stripline resonator was improved, the C / N was improved by 5 dB at the maximum, and the frequency fluctuation when this high-frequency circuit absorbed moisture was reduced by 50% as compared with the conventional one. Was.

[0021]

As is apparent from the above description of one embodiment with reference to the drawings, the present invention provides a triplate-type strip line resonator having an internal electrode formed of two beta land electrodes. Since the shape of the near land electrode is omitted, the stripline resonator is less affected by tan δ of the substrate,
The Q value of the stripline resonator can be improved. In addition, even if the dielectric constant of the substrate changes due to moisture absorption of the substrate, the degree of change in the resonance frequency of the stripline resonator can be made extremely small as compared with the conventional case.

Further, according to the present invention, since the effects of tan δ and moisture absorption of the substrate are reduced, a multilayer substrate can be formed using an inexpensive printed circuit board, so that an inexpensive high-frequency circuit can be provided. Become.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically showing a configuration of one embodiment of a high-frequency circuit according to the present invention.

FIG. 2 is a diagram illustrating an example of a shape of a circuit pattern of each layer of the high-frequency circuit of FIG. 1;

FIG. 3 is a cross-sectional view illustrating an example of a conventional high-frequency circuit.

FIG. 4 is a diagram for explaining another example of a conventional high-frequency circuit.

[Explanation of symbols]

20: high-frequency circuit, 21: first-layer printed circuit board, 2
2: Printed board of the second layer, 23: Printed board of the third layer, 24: Printed board of the fourth layer, 25: Circuit pattern, 26: Internal electrode, 27: Resonant line, 28: Betagland electrode, 30: Side electrode, 31: Through hole

Claims (4)

[Claims] 1. A triplate-type strip line resonator comprising a center conductor and two beta land electrodes sandwiching the center conductor, and electrically connected to the center conductor on one surface of a multilayer substrate formed therein. A high-frequency circuit having a shape obtained by omitting the beta land electrode closer to the circuit pattern from a high-frequency circuit such as a VCO provided with a circuit pattern provided. 2. A strip line resonator comprising: a circuit pattern; an internal electrode including at least a matching line; a resonance line; and a land land electrode formed in different layers. A high-frequency circuit such as a VCO including a multilayer substrate, wherein the beta land electrode and the internal electrode are arranged so as to sandwich the resonance line, and another solid line is provided between the resonance line and the internal electrode. A high-frequency circuit having no ground electrode. 3. The high-frequency circuit according to claim 2, wherein a capacitance value for determining a resonance frequency of the strip line resonator is a capacitance value formed between the resonance line and the beta land electrode. A high frequency circuit characterized by being substantially equal. 4. The high-frequency circuit according to claim 1, wherein said multi-layer substrate is composed of a plurality of laminated printed boards.