JPH0563403A - Triplet filter - Google Patents

Abstract

PURPOSE:To obtain the compact and stable triplet filter capable of characteristic adjustment by trimming the through-hole on a grounding conductor. CONSTITUTION:The response frequency is adjusted by trimming a grounding conductor 3 near the short-circuited end part through hole 5 of a distributed constant type filter pattern 6 formed on a induction substrate 1. Especially, more effective by performing a circular trimming around the through-hole 5. In short, by trimming the grounding conductor 3 near the through-hole 5, the leakage of the magnetic field is generated, resulting in reducing the reactance on an equivalent circuit and deteriorating the response frequency. Therefore, the distributed constant type filter pattern 6 is designed to respond to the higher frequency than the prescribed frequency, and the pattern can be further reduced. Thus, the compact and stable triplet filter can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a triplate filter used in a microwave band.

[0002]

2. Description of the Related Art Filters currently used in the microwave band include a filter using a coaxial type resonator and a filter using a stripline type resonator. A filter based on a 1/4 wavelength resonator that resonates at 1/4 wavelength of the frequency f ₀ is well known. Among them, a filter made of a material having a high dielectric constant (ε _r ≈40 to 90) has come to be used as a small size filter.

The demand for further miniaturization is increasing with the development of mobile communication, and in particular, the demand for miniaturization with the development of mobile phones is remarkable, and in particular, the demand for low profile is severe. Therefore, as a filter having the most effective structure for reducing the height, there is a tri-plate type filter in which a distributed constant type filter pattern is sandwiched by a ground conductor via a dielectric. However, in such a triplate filter,
When a sintered body such as ceramics is used as the dielectric material, there is a problem that variations in the dielectric constant cause variations in the filter characteristics.

For this reason, it has been proposed to improve the yield by adjusting the characteristics using the method described in Japanese Patent Publication No. Sho 61-19122 (H01P1 / 203). That is, this prior art is a transmission line type filter composed of ground plate conductor means and conductor resonance means, and the response frequency is adjusted by trimming the ground plate conductor means located on the open end side of the conductor resonance means. To adjust.

[0005]

FIG. 4 is an equivalent circuit diagram of the transmission line type filter according to the above-mentioned prior art. In this prior art, the ground plate conductor located on the open end side of the conductor resonance means. Is trimmed to reduce the capacitance 11 in the figure, thereby adjusting the frequency to be high. Therefore, it can only be adjusted to increase the response frequency,
It is necessary to form the conductor resonance means so as to respond to a frequency lower than a predetermined response frequency, which has a drawback that the size of the component is increased.

Further, in this conventional technique, it is necessary to trim the ground plate conductor relatively large, and when a conductive member such as a metal chassis is arranged in the vicinity of the ground plate conductor surface, there is a drawback that characteristic variation occurs. there were.

The present invention proposes a tri-plate type filter which can be easily manufactured as compared with the conventional one, and whose characteristics can be adjusted, and also provides a tri-plate type filter which is small and has high stability. is there.

[0008]

A triplate type filter according to the present invention has a stripline type filter pattern in which a plurality of resonant lines are arranged in parallel on a joint surface of two laminated dielectric substrates. In a triplate filter in which a ground conductor is arranged on the other surface of the surface on which the filter pattern is arranged, and a resonator pattern forming the filter pattern is connected to the ground conductor through a through hole, the ground conductor side The filter characteristic is adjusted by trimming the vicinity of the through hole.

[0009]

By trimming the ground conductor in the vicinity of the through hole, a magnetic field leaks, and as a result, the reactance 12 in the equivalent circuit diagram shown in FIG. 4 becomes small and the response frequency drops.

[0010]

1 to 3 show an embodiment of a triplate filter according to the present invention. In FIG. 1, 1 and 2 are made of TiO ₂ —SnO ₂ —ZrO ₂ system dielectric ceramics. Dielectric substrate, and ground conductor layers 3, 4 on one surface thereof
And the through hole 5 on the other side.
It has distributed constant type filter patterns 6 and 7 based on the 1/4 wavelength type resonance line connected to the grounding conductors 3 and 4 through. The distributed constant type filter patterns 6 and 7 of the dielectric substrates 1 and 2 are formed in a mirror image relationship with each other, and the two dielectric substrates are stacked so that the distributed constant type filter patterns 6 and 7 face each other. The triplate filter 8 is configured.

FIG. 2 is a diagram showing a method of adjusting the response frequency by trimming. In the triplate filter according to the present invention, the response frequency is adjusted by trimming (3a) the ground conductor 3 in the vicinity of the short-circuited end through hole 5 of the distributed constant filter pattern 6 formed on the one dielectric substrate 1. It Particularly, it is effective to perform trimming in an arc shape with the through hole 5 as the center. That is, by trimming the ground conductor 3 in the vicinity of the through hole 5, leakage of a magnetic field occurs, and as a result, the reactance 12 in the equivalent circuit diagram shown in FIG. 4 becomes small and the response frequency drops. Therefore, since the distributed constant type filter pattern 6 is designed to respond to a frequency higher than a predetermined frequency, the pattern can be made smaller than in the prior art, and the size of the component can be reduced. The closer the trimming position is to the through hole 5, the more effective it is, and the most effective way is to trim the boundary corner between the through hole 5 and the ground conductor 3.

As shown in FIG. 3, a dielectric member 9 is arranged on the ground conductor 3 and the upper surface of the triplate filter 8 whose response frequency is adjusted is shielded by a shield case 10. By arranging this dielectric member 9, even if the shield case 10 is attached after the adjustment, the characteristic does not change.

[0013]

According to the present invention, the characteristics of the triplate filter can be adjusted, and the shield structure, which has been a drawback of the triplate filter that has been adjusted in the past, can be improved and the size thereof can be reduced. Can be measured. This makes it possible to reduce the housing volume of a small RF circuit typified by a mobile phone.

[Brief description of drawings]

FIG. 1 is a diagram showing a triplate filter according to the present invention.

FIG. 2 is a top view of a triplate filter according to the present invention.

FIG. 3 is a cross-sectional view of a triplate filter according to the present invention.

FIG. 4 is an equivalent circuit diagram of a conventional filter.

[Explanation of symbols]

 1 Dielectric Substrate 2 Dielectric Substrate 3 Grounding Conductor 3a Trimming Part 4 Grounding Conductor 5 Through Hole 6 Distributed Constant Type Filter Pattern 7 Distributed Constant Type Filter Pattern 8 Triplate Filter 9 Dielectric Member 10 Shield Case

Claims (3)

[Claims] 1. A stripline type filter pattern having a plurality of resonance lines arranged in parallel on a joint surface of two laminated dielectric substrates, and the stripline type filter pattern is provided on the other surface of the surface on which the filter patterns are arranged. In a triplate filter in which a ground conductor is arranged and a resonator pattern forming the filter pattern is connected to the ground conductor through a through hole, the filter characteristics are adjusted by trimming the vicinity of the through hole on the ground conductor side. A triplate-type filter characterized by performing 2. The triplate filter according to claim 1, wherein a trimming opening is provided with a shield case for preventing an influence of an external electromagnetic field. 3. The triplate filter according to claim 2, wherein a dielectric member is arranged in a gap between the grounding conductor having a trimming opening and the shield case.