JPH09130103A - Band pass filter provided with multi-layered substrate-incorporated trap - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive and compact band pass filter provided with trap of 800MHz to 2GHz band by using a standard organic multilayered substrate and a capacitor ship on the market. SOLUTION: This band pass filter provided with trap of 800MHz to 2GHz band consists of conductor layers 5 to 8, an organic dielectric layer, a multilayered substrate, and a capacitor chip 9 mounted on the multilayered substrate, and components of the filter other than the capacitor 9 and an input/ output terminal 11 are provided on internal conductor layers. Conductor layers 5 to 8 constituting the filter are electrically connected to each other via through hole 12 to 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile phone and a PH.
S (personal handy phones)
800MHz used for portable radios for tem)
The present invention relates to a high-frequency bandpass filter of 2 GHz band, and more specifically, to a multilayer substrate inner layer type bandpass filter with a trap formed in an inner layer of an organic multilayer substrate.

[0002]

2. Description of the Related Art Due to the rapid spread of mobile phones and PHS, there is a strong demand for improvement in performance and miniaturization of portable radios. Regarding general electronic circuits, miniaturization of high-frequency bandpass filters in the 800 MHz to 2 GHz band is strongly desired, especially as more circuit elements are accommodated in one chip and miniaturization progresses. Further, there is an urgent need to solve existing problems such as reduction of manufacturing cost and simplification of the whole manufacturing process.

[0003] Conventionally, a technique of incorporating components of a bandpass filter such as a capacitor and a coil into a ceramic multilayer substrate is well known. Since such a bandpass filter can be housed in a ceramic substrate together with other circuit elements, a separate manufacturing process for the bandpass filter alone is not required, and the circuit can be downsized. Had an advantage.

However, ceramic multilayer substrates are generally difficult to handle because of (1) low strength and easy cracking, and (2) high permittivity, making design difficult.
(3) Since the process of baking is required, there are problems that the manufacturing cost is very high and the delivery time is long, and there are still only a few examples as products. Bandpass filters using ceramics have already been sold as filter chips for mobile phones, but the size of the mounting area for such chip components is considerable, and it is possible to reduce the size of the entire circuit using them. Is hindering Then, there is a problem that the ceramic multilayer substrate generally has.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide an inexpensive and compact bandpass filter with a trap in the 800 MHz to 2 GHz band using a standard organic multilayer substrate and a commercially available capacitor chip. With the goal.

[0006]

The present invention comprises a multi-layer substrate including a plurality of conductor layers and a plurality of organic dielectric layers, and a capacitor chip surface-mounted on the multi-layer substrate.
Provided is a bandpass filter with a trap in the 800 MHz to 2 GHz band, in which the constituent elements of the filter other than the capacitor and the input / output terminal are provided in an internal conductor layer. Furthermore, the present invention provides the above-mentioned bandpass filter with a trap, in which the conductor layers forming the filter are electrically connected by through-holes.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The capacitor chip used in the present invention may be a capacitor chip that is widely available on the market. The capacitance of the capacitor is about 0.5 pF to about 3 pF. The size of the capacitor chip currently on the market is about 1 mm to about 2 mm.
It is of the order of magnitude. As described above, the size of the capacitor chip itself is small, so that the size of the entire bandpass filter can be made small, and the present invention has an advantage that the circuit can be downsized. Further, the use of the capacitor chip has an advantage that the influence of the dielectric loss of the organic substrate material is reduced.

For the conductor layer in the present invention, the conductor portion for mounting the chip capacitor on the surface is counted as one layer, and at least two layers are required together with the strip line which constitutes the main part of the filter circuit. Usually, at least four layers are required together with two layers of the conductor film for shielding. But,
The number of dielectric layers is similar, but there may be any number of conductor layers above that.

The organic dielectric for the substrate used in the bandpass filter of the present invention is not particularly limited, but glass epoxy resin or the like can be preferably used. The number of dielectric layers is not particularly limited. When there are four conductor layers including two shield layers as described above, the number of dielectric layers may be three or more, and there is no particular upper limit.

In particular, since the bandpass filter of the present invention uses the organic dielectric material that is generally widely used as the substrate material, one multilayer structure other than the filter, for example, a low noise amplifier or a mixer circuit is used. It is characterized in that it can be formed in a substrate. In such cases, it may be advantageous to use more than three dielectric layers.

The portion constituting the I / O terminal for input / output can be provided on the surface on which the chip capacitor is surface-mounted, but other configurations are also possible. For example, when the bandpass filter of the present invention is provided on the same multilayer substrate as other circuits, it may be preferable to perform input / output not on the surface of the multilayer substrate but inside thereof. Further, the electrical connection between the conductor layers can be made by the through holes, but in the case of the present invention, since the layer structure can be simplified, this connection should be made by the through holes instead of the blind through holes. You can When electrical connection is made using through-holes, holes are made through the conductor layer and each dielectric layer, and then the holes are filled with conductors by plating, etc. The process becomes simpler.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration and characteristics of the bandpass filter of the present invention will be described in more detail below with reference to specific circuit configurations. However, the following examples are given merely as examples and do not limit the scope of the invention described in the claims. FIG. 1 shows a circuit configuration of a bandpass filter in which traps are provided above and below a pass band according to an embodiment of the present invention. This circuit is designed for PHS. In this embodiment, the capacitance Cm of the capacitor 1 is set to 1 pF, and a commercially available 1005 chip is used. The main striplines 2 and 3 are shown, and the coupling constant between the striplines 3 is M. There is a terminal 4 for input / output.

Further, FIG. 2 shows patterns of the conductor layers 5 to 8 for realizing the circuit configuration of FIG. In FIG. 2, only the patterns of the conductor layers 4 to 5 and the through through holes 12 to 14 for electrically connecting them are shown. A chip capacitor 9 is placed on the first layer 5 constituting the surface, and a terminal portion 10 for connecting the capacitor and a conductor portion 11 for input / output are provided. This first layer 5
All through holes 12-14 are visible on the surface of the.
The second layer 6 is an inner layer that forms a ground shield layer,
The through holes 13 and 14 respectively connected to the capacitor chip terminal 10 and the input / output terminal 11 are not electrically connected to this shield layer. However, the ground through hole 12 is electrically connected to the second layer 6. Furthermore, in the other inner layer, the third layer 7,
The strip line 15 which is a circuit element other than the capacitor of the filter of the present invention is formed of a conductor film. 3
All of the through holes 12 to 14 of the set of 6 are the third
Somehow electrically connected to the layer conductors. The conductor of the fourth layer 8 forms a shield layer corresponding to the back surface.
Only the ground through hole 12 is electrically connected to the shield conductor film, and the other through holes 13 and 14 are exposed on the back surface, but the shield conductor film is electrically connected to the shield conductor film. Not connected.

In FIG. 2, only the conductor pattern and the through holes are shown. In order to form an actual circuit, an organic dielectric layer is arranged between the conductor layers. In this embodiment, as the material of the dielectric layer, EL240 manufactured by Mitsubishi Gas Chemical Co., Ltd. was used, and the layer thickness was about 0.3 mm per layer. The conductor layer had a thickness of about 18 μm.

FIG. 3 shows a plan view of this conductor pattern and its size. The vertical and horizontal dimensions of the pattern were about 5.5 mm and about 9 mm, respectively. The size of each element in the pattern is shown in a substantially reduced scale in the lengths of the vertical and horizontal sides.

FIG. 4 schematically shows a cross section of the laminated dielectric layer 16 and conductor layer. In this figure, it can be seen that the through-holes 12 and 13 penetrate and appear on the front and back surfaces.

FIG. 5 and FIG. 6 show the results of actual measurement of the characteristics of the bandpass filter with a trap of this embodiment. FIG. 5 shows the pass characteristic as a function of frequency. FIG. 6 also shows the return loss characteristic as a function of frequency.

[0018]

As described above, according to the present invention, the structure of the conductor layer can be simplified. Therefore, for example, a bandpass filter with a trap can be configured with only four layers of conductors and through-holes. Further, since the chip capacitor is used, the filter circuit can be downsized. Furthermore, since an organic multi-layer substrate used for general circuits is used, other circuits, such as an amplifier circuit and a mixer circuit, can be formed in the same substrate as the filter of the present invention, so that a circuit required for a communication device Helps reduce overall size.

[Brief description of the drawings]

FIG. 1 shows a circuit diagram of an embodiment of the present invention.

FIG. 2 shows a pattern of conductor layers and through-holes for realizing the circuit of the embodiment of FIG.

FIG. 3 shows a pattern of conductor layers for realizing the circuit of the embodiment of FIG.

FIG. 4 is a schematic view of a cross section of the filters according to the above-described embodiments that are stacked.

FIG. 5 shows frequency pass characteristics of the filter of the above embodiment.

FIG. 6 shows frequency return loss characteristics of the filter of the above embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Capacitor 2, 3 Stripline 4 Input / output terminal 5 1st conductor layer (front surface) 6 2nd conductor layer 7 3rd conductor layer 8 4th conductor layer (back surface) 9 Capacitor chip 10 Capacitor chip conductor 11 Input / output terminal conductor 12 ground through hole 13, 14 through through hole 15 stripline conductor 16 dielectric layer

Claims (2)

[Claims] 1. A multilayer substrate including a plurality of conductor layers and a plurality of organic dielectric layers, and a capacitor chip surface-mounted on the multilayer substrate. A bandpass filter with a trap in the 800 MHz to 2 GHz band, in which constituent elements are provided in a conductor layer inside the multilayer substrate. 2. A bandpass filter with a trap in the 800 MHz to 2 GHz band according to claim 1, wherein the conductor layers forming the filter are electrically connected through through holes.