JPH05235619A - Strip line filter - Google Patents

Abstract

PURPOSE:To provide the filter capable of being mounted in high density by inserting a base with a conductor pattern provided thereon between dielectric bases to form the laminated integrated filter and forming a shield and terminals with conductor films formed to the front face and side faces of the laminator. CONSTITUTION:Conductor films formed to major faces being front and rear faces of a laminator and part of side faces are used for a shield electrode and an earth electrode in common, input and output electrodes are formed to one side face while being insulated with the shield and earth electrodes and an electrode connected to the earth electrode is provided between the input and output electrodes while being in crossing with the side face. Concretely a strip line electrode and an input output coupling electrode are formed to a dielectric base 10 inserted between two dielectric bases 20a, 20b, the electrodes are connected to input output terminals 18, 19, and an earth electrode 21 is provided to a front side of the bases 20a, 20b not in contact with the base 10. The electrode 21 is insulated from the electrodes 18, 19 and an electrode 22 formed in crossing between the electrodes 18, 19 is connected to the electrode 21, then leakage of a signal between the electrodes 18, 19 is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stripline filter which can be used in a high frequency band exceeding 100 MHz, and more particularly to a stripline filter package in which a conductor pattern of one turn or more is formed on the surface of a dielectric substrate. And a terminal structure.

[0002]

2. Description of the Related Art There is an increasing demand for resonators and filters that can be used in a high frequency band exceeding several 100 MHz in mobile communication devices. Conventionally, a helical resonator (filter), a dielectric resonator (filter), etc. have been used, but the size is limited by the wavelength of the resonance frequency, so there is a limit to miniaturization. In addition, adjustment is often necessary due to the problem of dimensional accuracy during firing. In addition, a resonator and a filter, which require a large number of man-hours in the assembly process and the like, have high accuracy and are easy to manufacture, are desired.

Further, in the helical filter and the dielectric filter, there is a problem that a harmonic wave three times as high as the fundamental frequency is generated, and how to remove this is a big problem.

In view of this, the inventor has proposed in Japanese Patent Application No. 3-183290 a plurality of inductor conductor patterns that circulate on at least one surface of a dielectric substrate, and the conductor patterns are arranged close to each other. We proposed a stripline filter in which one end of the conductor pattern is connected to the input / output end and the other end is grounded.

3A and 3B are plan views of the stripline filter, in which FIG. 3A shows the upper surface and FIG. 3B shows the lower surface. Conductor striplines 11 and 12 are formed on the front and back surfaces of a ceramic substrate 10 having a dielectric constant of about 20. The strip lines 11 and 12 of this conductor are connected by a through hole 17 formed in the substrate 10 to form one continuous strip line.

The conductor stripline 11 is approximately 1 on the front side.
It is formed as a conductor pattern that circulates for half a turn. The strip line 12 of the conductor on the back surface connected by the through hole 17 is also formed as a conductor pattern that slightly circulates for two turns, and the end portion is extended to the end surface of the substrate. The conductor patterns on the front and back sides are formed so as to overlap and oppose each other on the front and back sides. Since it is formed so as to extend in the same direction, it is impossible to form all the conductor patterns so as to overlap each other, but most of them can be overlapped. This is because a capacitance is provided between the conductor patterns, and it is desirable that the conductor patterns are arranged close to each other so that a capacitance can be obtained between the conductor patterns on the same surface.

The ends of the conductor striplines 11 and 13 are formed so as to face the conductor films 15 and 16 on the back surface, and the input / output coupling capacitance of the filter is obtained. The conductor films 15 and 16 are connected to the input / output terminals.

[0008]

The above stripline filter is also a type of LC filter, and must be shielded so as not to affect other elements when mounted on a circuit board.

Further, it is required that the electronic components be downsized and be capable of surface mounting, and it is desirable that the mounting area be small.

The present invention provides a stripline filter which can be surface-mounted in a small area without increasing the number of parts.

[0011]

According to the present invention, a substrate on which a conductor pattern is formed is sandwiched between dielectric substrates to form a laminated integrated type, and a conductor film formed on the surface and the side surface of the laminated body
The above problems are solved by forming a shield and terminals.

That is, the front and back surfaces of the dielectric substrate are provided with a plurality of conductor patterns which are connected by through holes and circulate.
In a stripline filter in which one end of a conductor pattern is connected to an input / output terminal via a capacitor and the other end is grounded, the dielectric substrate is sandwiched between two dielectric substrates having the same facing portion size. It is an integrated laminated body, and ground electrodes are formed on both main surfaces of the laminated body, and one side surface of the laminated body is insulated from the ground electrode and connected to the capacitance forming electrodes of the dielectric substrate, respectively. It is characterized in that an input / output terminal electrode is formed, and the electrode is provided between the input / output terminal electrodes so as to traverse the side surface of the laminated body and connected to the ground electrode on the surface.

[0013]

The conductive film formed on the main surface, which is the front and back surfaces of the laminate, and a part of the side surface serves as a shield electrode and a ground electrode, and an input / output electrode insulated from it is formed on one side surface. An electrode connected to a ground electrode is formed between the input and output electrodes so as to traverse the side surface, and the side surface enables mounting and connection to a circuit board.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view showing an embodiment of the present invention. Dielectric substrate sandwiched between two dielectric substrates 20a, 20b
The stripline electrode and the input / output coupling electrode as described above are formed on the electrode 10, and the input / output coupling electrode is connected to the input / output terminals 18 and 19. The input / output terminal electrodes 18 and 19 are
Dielectric substrates 20a, 20b and dielectric substrate 10 sandwiched between them
It is preferable to form it on the side surface of the laminated body and to extend it so as to extend over the surfaces of the dielectric substrates 20a and 20b.

A ground electrode 21 is formed on the surface of each of the dielectric substrates 20a and 20b which is not in contact with the dielectric substrate 10. It is desirable that the ground electrode 21 be formed on a side surface other than the side surface on which the input / output electrodes 18 and 19 are formed. This ground electrode is insulated from the input / output terminal electrodes 18 and 19, and
By forming an electrode 22 that is connected to this ground electrode and crosses between the input / output electrodes 18 and 19, it is possible to prevent leakage of signals between the input / output electrodes and to perform all the connections with the circuit board. Can be done on the side.

In the case of a filter for the 800 MHz band, a conductor pattern is formed on a dielectric substrate having a dielectric constant of about 20 and a length of 5.0 mm, a width of 5.7 mm and a thickness of 0.2 mm. It can be constructed by sandwiching it with a 1.2 mm dielectric substrate. The dielectric substrate can be adhered by using glass or the like, and the conductor film on the surface can be formed by printing silver, copper or the like and baking it. The width of the terminal electrode formed on the side surface of the laminated body can be about 1 mm.

FIG. 2 is a perspective view showing a state in which the stripline filter according to the present invention is mounted on a circuit board.
The stripline filter 30 can be soldered to the conductor pattern of the circuit board 40 with the side surface on which the input / output terminal electrodes are formed facing downward. The electrode connected to the ground potential across the input / output electrodes is connected to the ground pattern of the circuit board 40. This makes it possible to reduce the occupied area on the circuit board, prevent leakage of signals between the input and output, and facilitate a stripline filter suitable for a high frequency region.

[0019]

According to the present invention, since the side surface can be mounted so as to face the circuit board, a stripline filter that can be mounted on the circuit board at a high density can be obtained.

Further, since the surface is covered with a conductor film and is grounded, a stripline filter having a large shield effect can be obtained. Further, since it is possible to prevent a signal from leaking between the input and output terminals, it is possible to obtain a filter having a good spurious characteristic even in a high frequency region.

[Brief description of drawings]

FIG. 1 is a perspective view of an embodiment of the present invention.

FIG. 2 is a perspective view showing a mounting structure on a substrate.

FIG. 3 is a plan view showing a conductor pattern of a stripline filter.

[Explanation of symbols]

 10, 20: Dielectric substrate 18, 19: Input / output terminal electrodes

Claims (2)

[Claims] 1. A strip in which a plurality of conductor patterns are provided on the front and back surfaces of a dielectric substrate and connected by through holes to circulate, one end of the conductor pattern is connected to an input / output terminal through a capacitor, and the other end is grounded. In the line filter, the dielectric substrate is a laminated body that is sandwiched between two dielectric substrates having the same size in the facing portion, and ground electrodes are formed on both main surfaces of the laminated body. And an input / output terminal electrode insulated from the ground electrode and connected to the capacitance forming electrode of the dielectric substrate is formed on one of the side surfaces of the laminated body,
A stripline filter comprising an electrode connected between an input / output terminal electrode and the ground electrode on the surface across the side surface of the laminated body. 2. The stripline filter according to claim 1, wherein the input / output terminal electrode is formed so as to extend over the side surface of the laminated body and the main surfaces on both sides thereof.