JP3488820B2 - Multilayer dielectric filter - Google Patents

Description

Description: BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a laminated dielectric filter, and more particularly to a stripline built in a multilayer substrate used for a high-frequency circuit radio such as a portable telephone. The present invention relates to a laminated dielectric filter such as a low-pass filter. 2. Description of the Related Art Conventionally, a stripline type low-pass filter has been known as a laminated dielectric filter incorporated in a multilayer substrate used for a high-frequency circuit radio such as a portable communication telephone. As shown in FIG. 5, this strip line type low-pass filter is incorporated in a laminate formed by laminating dielectric layers 51 to 54. Specifically, the upper surface of the dielectric layer 51 , A ground electrode 61 are formed. [0004] On the upper surface of the dielectric layer 52 laminated on the dielectric layer 51, a U-shaped strip line 62 having less than one turn, that is, opposite ends, is formed. Are formed with capacitance forming electrodes 63, respectively. [0005] On the upper surface of the dielectric layer 53 laminated on the dielectric layer 52, an electrode 64 for increasing the capacitance between the dielectric layer 53 and the capacitance forming electrode 63 is formed. An earth electrode 65 is formed on the upper surface of the dielectric layer 54 laminated on the dielectric layer 53. FIG. 3 is a circuit diagram of such a laminated dielectric filter. Specifically, the circuit diagram is shown in FIG. And an input / output capacitance 42 for forming an attenuation pole by the capacitance forming electrode 63 and the electrode 64.
Is composed. The strip line 62 forms the inductor 41. Incidentally, input / output electrodes 67 and 68 are formed at the end of the strip line 62. However, in order to increase the input / output capacitance 42, it is necessary to increase the capacitance forming electrodes 63 and 64 in the multilayer dielectric filter. There is a problem in that the size of the device becomes large. In order to obtain desired capacitances 43 and 44 between the ground and a capacitance 42 between the input and the output, a capacitance forming electrode 63 is required.
Therefore, it is difficult to freely and independently control the capacitances 43 and 44 between the ground and the capacitance 42 between the input and the output. That is, the position of the attenuation pole can be controlled by the input / output capacitance 42, and the cutoff frequency, the attenuation in the high frequency region, and the impedance of the circuit can be adjusted by the capacitances 43 and 44 between the grounds. For example, the other characteristic fluctuates with it, and it is difficult to adjust both characteristics simultaneously. SUMMARY OF THE INVENTION It is an object of the present invention to provide a laminated dielectric filter which can be miniaturized, can have a large capacitance between input and output, and can freely and independently control the capacitance between input and output and the capacitance between grounds. . [0011] A laminated dielectric filter according to the present invention comprises an upper ground electrode and a lower ground electrode provided in a laminate formed by laminating a plurality of dielectric layers; An annular strip line having both ends opposed to each other between electrodes, and a pair of input / output capacitance forming electrodes formed at both ends of the strip line and opposed to each other in the stacking direction of the dielectric layer And a ground-capacitance forming electrode formed at each end of the pair of input-output-capacitance forming electrodes and facing the lower ground electrode, and input / output electrodes formed at both ends of the strip line, respectively. It is made. According to the laminated dielectric filter of the present invention, a pair of input / output capacitance forming electrodes formed at both ends of the strip line and opposed to each other in the laminating direction of the dielectric layers. Since the output capacitance can be formed, the input / output capacitance can be determined by the area of the input / output capacitance forming electrode and the distance between the input / output capacitance forming electrodes, and the element size can be reduced while increasing the input / output capacitance. Can be That is, conventionally, as shown in FIG. 5, in order to obtain a capacitance between input and output, a dielectric layer 53 is provided above a capacitance forming electrode 63, and an electrode 64 is formed on the dielectric layer 53.
It is necessary to increase the area of the capacitance forming electrode 63 in order to increase the input-output capacitance. However, the width of the element is reduced by the increased area of the capacitance forming electrode 63. However, in the present invention, by forming the input / output capacitance forming electrode in the direction of lamination of the dielectric layers, the present invention makes effective use of the extra space formed in the center of the annular strip line. It is possible to reduce the size and freely adjust the input-output capacitance. Further, in the multilayer dielectric filter of the present invention, although the capacitance-forming electrode between grounds is connected to the capacitance-forming electrode between input and output, the capacitance-forming electrode between input and output is not opposed to the ground electrode. By changing the area of the inter-earth capacitance forming electrode, it is possible to control only the inter-earth capacitance independently of the input-output capacitance. Therefore, in the laminated dielectric filter of the present invention, the cutoff frequency, the amount of attenuation in the high frequency region, and the impedance of the circuit can be adjusted regardless of the position of the attenuation pole. FIG. 1 is a perspective view showing an electrode of a laminated dielectric filter comprising a stripline type low-pass filter according to the present invention, FIG. 2 is a sectional view, and FIG. It is an equivalent circuit diagram. In the laminated dielectric filter of the present invention, a lower ground electrode 11 and an upper ground electrode 14 are formed in a laminate formed by laminating dielectric layers 1 to 5.
An annular strip line 13 having both ends facing each other is formed between the ground electrodes 11 and 14. That is,
The strip line 13 has a U-shape. The strip line 13 may be U-shaped. At the end of the strip line 13, input / output electrodes 15 and 16 whose end faces are exposed to the outer surface of the laminated body are formed, respectively. At both ends of the strip line 13, a pair of input / output capacitance forming electrodes 21 and Reference numeral 22 is formed over the dielectric layers 3 and 4 in the stacking direction and opposed to each other. At the lower ends of the pair of input / output capacitance forming electrodes 21 and 22, an earth capacitance forming electrode 12 facing the lower ground electrode 11 is formed. More specifically, the laminated dielectric filter of the present invention will be described. A lower earth electrode 11 is formed on the upper surface of the dielectric layer 1, and the dielectric layer 2 is laminated on the upper surface of the dielectric layer 1. A pair of inter-earth capacitance forming electrodes 12 are formed on the upper surface, and a U-shaped strip line 13 and an input / output electrode 1 are formed on the upper surface of the dielectric layer 3 laminated on the upper surface of the dielectric layer 2.
5 and 16 are formed, an upper ground electrode 14 is formed on the upper surface of the dielectric layer 4 laminated on the upper surface of the dielectric layer 3, and the dielectric layer 5 is laminated on the upper surface of the dielectric layer 4. . The dielectric layers 3 and 4 are provided with input / output capacitance forming electrodes 21 and 22 in the direction in which the dielectric layers 1 to 5 are stacked. Since such a laminated dielectric filter has input / output capacitance forming electrodes 21 and 22 formed in the laminating direction of the dielectric layers 1 to 5, it cannot be manufactured by a conventional green sheet laminating method. For example, it is produced by the following special method. First, a slip material containing a ceramic or glass-ceramic dielectric layer material, a photocurable monomer and an organic binder is thinned, exposed and cured to form a dielectric layer molded body. By laminating a plurality of dielectric layer molded bodies, a molded body to be the dielectric layer 1 is formed. Thereafter, a conductive paste is applied to the upper surface of the molded body to be the dielectric layer 1 and dried to form a conductive member to be the ground electrode 11. A molded body to be the dielectric layer 2 is formed in the same manner as the molded body of the dielectric layer 1, and a conductive paste is applied to the upper surface of the molded body and dried to form the inter-earth capacitance forming electrode 12. A conductive member is formed. Next, the above-mentioned slip material is applied to the upper surface of the molded body to be the dielectric layer 2 and dried to form the dielectric layer molded body, and then the through holes for forming the input / output capacitance forming electrodes 21 and 22 are formed. Form a groove. Specifically, a mask is placed on the dielectric layer molded body, a portion other than the through-groove is exposed and developed to form a through-groove in the dielectric layer molded body, and the through-groove is filled with a conductive paste. . By repeating this process, the dielectric layer 3
A molded body is formed, and the input / output capacitance forming electrodes 21 and 2 are formed.
2 are formed in the laminating direction. Further, by applying a conductive paste to the upper surface of the molded body to be the dielectric layer 3, the conductive members to be the input / output electrodes 15, 16 and the strip line 13 are formed. Forming electrodes 21 and 22
Is formed, and a conductive paste is filled into the through groove. Thereafter, formation of a dielectric layer molded body,
The formation of the through-groove and the filling of the conductive paste into the through-groove are repeated to produce a molded body to be the dielectric layer 4. A conductive paste is applied to the upper surface of the molded body to be the dielectric layer 4 so that the upper ground electrode 14
Is formed. A plurality of the above-mentioned dielectric layer molded bodies are stacked on the upper part of the dielectric layer molded body to form a dielectric layer 5.
A molded body is prepared. After the laminated molded body is subjected to a binder removal treatment and then fired, organic components such as a photocurable monomer and an organic binder are scattered, and a laminated dielectric filter as shown in FIG. 1 is obtained. . FIG. 3 shows an equivalent circuit diagram of the laminated dielectric filter of the present invention. In this circuit diagram, the inductor 41
Is formed by the strip line 13 formed on the dielectric layer 3, and the inter-earth capacitances 43 and 44 are formed by the inter-earth capacitance forming electrode 12 and the lower earth electrode 11 formed on the dielectric layer 2, The inter-input / output capacitance 42 is connected to the inter-input / output capacitance forming electrode 2
1 and 22. In such a laminated dielectric filter, the capacitance of the input / output capacitance 42 for coupling between the input and output is changed, that is, the capacitance is formed in the direction of lamination formed on the dielectric layers 3 and 4. Input / output capacitance forming electrodes 21 and 2
2 by changing the facing area and the distance between facing
The position of the attenuation pole formed on the higher frequency side than the cutoff frequency can be controlled, and the attenuation characteristics in the high frequency region can be changed. For example, the input / output capacitance forming electrode 2
1 and 22 are extended toward the center of the strip line 13 so as to increase the opposing area of the inter-input / output capacitance forming electrodes 21 and 22 or reduce the distance between the opposing input / output capacitance forming electrodes 21 and 22 so that Since the adjustment can be performed, the size of the element is not increased. Further, the cutoff frequency, the attenuation in the high frequency region, and the impedance of the circuit are adjusted by changing the capacitances 43 and 44 between the grounds, that is, by changing the area of the electrode 12 forming the capacitance between the grounds. Can be. At this time, the input / output capacitance forming electrodes 21 and 22 in the stacking direction formed on the dielectric layers 3 and 4 are connected to the ground capacitance 4.
3 and 44, the capacitance between the grounds 43,
44 can be controlled by the inter-earth capacitance forming electrode 12 independently of the capacitance of the input / output capacitance 42. FIG. 4 shows the capacitance 4 between the input and output in the equivalent circuit diagram of FIG.
2 shows transmission characteristics obtained by simulating a low-pass filter when the capacitance value of No. 2 is changed. In FIG. 4,
The input / output capacitance 42 was increased in the order of a broken line, a dashed line, and a solid line. According to FIG. 4, it can be seen that the attenuation pole moves to the lower frequency side by increasing the capacitance value of the input / output capacitance 42. The laminated dielectric filter of the present invention has the above-described structure by itself, but may be built in a substrate. In this case, a via-hole conductor or the like is connected to the input / output electrode, and an earth electrode provided on the substrate is used as the earth electrode. The laminated dielectric filter built in such a substrate is used, for example, as a high-frequency module substrate used in a mobile communication device or the like. According to the laminated dielectric filter of the present invention, a pair of input / output capacitance forming electrodes formed at both ends of the strip line and opposed to each other in the laminating direction of the dielectric layers. Since the I / O capacitance can be formed, the I / O capacitance can be determined by the area of the I / O capacitance formation electrode and the distance between the I / O capacitance formation electrodes. Can be downsized. Although the capacitance-forming electrode between grounds is connected to the capacitance-forming electrode between input and output, since the capacitance-forming electrode between input and output is not opposed to the ground electrode, the area of the capacitance-forming electrode between grounds is changed. Thus, it is possible to control only the capacitance between the grounds independently of the capacitance between the input and the output.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing electrodes of a laminated dielectric filter of the present invention. FIG. 2 is a cross-sectional view of the multilayer dielectric filter of the present invention. FIG. 3 is an equivalent circuit diagram of a filter. FIG. 4 is a simulation result when the input / output capacitance according to the present invention is changed. FIG. 5 is an exploded perspective view of a conventional laminated dielectric filter. [Description of Symbols] 1 to 5: Dielectric layers 11, 14: Ground electrode 12: Capacitance forming electrode between grounds 13: Strip lines 15, 16: Input / output electrodes 21, 22 ..Electrode formation electrodes between input and output

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01P 1/203 H01P 1/205

Claims (1)

(57) Claims 1. An upper ground electrode and a lower ground electrode provided in a laminate formed by laminating a plurality of dielectric layers, and both ends are opposed to each other between these ground electrodes. An annular strip line to be formed; a pair of input / output capacitance forming electrodes formed at both ends of the strip line and opposed to each other in the stacking direction of the dielectric layer; It is characterized by comprising an inter-earth capacitance forming electrode formed at an end of the capacitance forming electrode and facing the lower ground electrode, and an input / output electrode formed at each end of the strip line. Stacked dielectric filter.