KR20030057910A - Lamination Band Pass Filter - Google Patents

Abstract

PURPOSE: A stack band pass filter is provided to be capable of designing a resonator structure without limitation by realizing distributed elements with a planar circuit using a stack ceramic technique. CONSTITUTION: A stack band pass filter has an input terminal(1) and an output terminal(2) and a pair of resonators(10) which are curved to have a predetermined shape and are installed to be opposite to each other. Each capacitor(C) is formed between each resonator and a ground(G). The resonators has such a structure that one side is opened, and the input terminal and the output terminal are formed at the opened portion.

Description

Lamination Band Pass Filter

The present invention relates to a microstrip line bandpass filter, and more particularly, to a combined strip line bandpass filter using a multilayer ceramic process.

In general, a band pass filter (BPF) is a filter that passes a specific frequency band and blocks other frequency bands, and a low pass filter (LPF) and a high pass filter (HPF). ) Is necessary to effectively use frequency in multi-carrier communication.

In the related art, as shown in FIG. 1, a stepped impedance resonant parallel line bandpass filter in which parallel strip lines are continuously connected in a step shape is shown. In particular, in the case of the ceramic dielectric filter, the shape of the resonator is a bar (BAR), not only to occupy a large volume, but also to limit the miniaturization and thinning, and also to improve the quality factor (Q) of the resonator. In addition, it was difficult to deform the resonator shape, which was entirely dependent on the dielectric constant of the material.

Accordingly, the present invention frees the design of the resonator structure by implementing the distribution element as a parallel circuit using a laminated ceramic technology, and has advantages in the dielectric properties of the material of the existing dielectric filter, An object of the present invention is to invent a bandpass filter having advantages of miniaturization.

1 is a conventional microstrip line bandpass filter

2 is a microstrip line bandpass filter I according to the present invention.

Figure 3 is a microstrip line bandpass filter in accordance with the present invention.

4 is a microstrip line bandpass filter III according to the present invention.

5 is a basic resonator structure according to an embodiment of the present invention.

6 is a simulation result of the HFSS software of FIG.

FIG. 7 is a three-dimensional model for the simulation of FIG. 5.

8 shows the pattern and design parameters of FIG.

9 is an equivalent circuit of FIG.

FIG. 10 is a characteristic of a bandpass filter as a simulation result (reference: g3a2w2) of FIG.

FIG. 11 is a stopband characteristic as a simulation result (reference: g3a2w2) of FIG.

12 is the Smith chart of FIG.

13 is a characteristic of the filter according to the change of the line width a value of the input / output terminal

14 is a characteristic of the filter according to the change of the impedance (w) of the resonator

15 is a change of characteristics of the filter according to the distance g of the resonance period.

16 is a change in bandwidth according to the distance g of the resonance period.

Fig. 17 shows the change of the low pole frequency with the distance g of the resonance period.

Fig. 18 shows the change of the phase polarity according to the distance g of the resonance period.

**** Description of the symbols for the main parts of the drawings ****

1: input 2: output

3: via 4: capacitor pattern

10: resonator

According to the present invention for achieving the above object, in the stacked band pass filter, an input terminal and an output terminal are provided, and a pair of resonators bent in a predetermined form are opposed to each other, and a capacitor mediates between the resonator and ground. The circuit has a basic resonance structure.

FIG. 2 is a preferred embodiment of the first aspect of the present invention, which has an input stage 1 and an output stage 2 when viewed from the front, and a resonator 10 having a bent shape is designed to face left and right. Figure 3 is a preferred embodiment in the second aspect of the present invention, a capacitor is formed between the resonator 10 and ground (ground) in the form of a resonator in order to improve the quality factor of the resonator, more preferably As shown in Fig. 4, each of the input and output terminals 1 and 2 is placed between the bent resonators, that is, in the recessed groove, to achieve a smaller size.

The form of the resonator of the present invention includes all of the bent forms except the ring form.

In addition, the positions of the input and output terminals are irrelevant wherever they are placed. For example, the input and output terminals may be placed in the lower part of the resonator as well as when the input and output terminals are crossed. Preferably, as shown in FIG. 2, the resonator is positioned at one side of the open portion. The reason is that the quality factor Q of the resonator is the best and the size of the resonator is minimum when it is located there than other positions.

Hereinafter, the present invention will be described in specific examples.

5 is a basic resonator type having a two-stage resonator type of which one side is open as shown in FIG. 5, and the structure thereof is a curved resonator, and is not shown, but at the bottom thereof, there is a ground and a capacitor. To induce a capacitor pattern is formed between the resonator and ground. Of course, there is a via between the resonator and the capacitor pattern. The input and output stages are not shown here.

FIG. 6 is a simulation result of the multilayer ceramic bandpass filter of FIG. 5 using HFSS software. Since the unit resonator generates only third-order harmonics, the stopband characteristic, that is, the harmonic characteristic is excellent. Can be. When the resonant frequency used is different, especially when the resonator length is very large, the length of the resonator can be increased by connecting the resonators in multiple layers using vias and inserting ground therebetween.

FIG. 7 is a three-dimensional model for the HFSS simulation of the microstrip line bandpass filter, FIG. 9 is an equivalent circuit of the filter designed in FIG. 7, and FIG. 8 is a plan view of FIG. 7, 8, and 9, the band pass filter is formed at the top of the bent resonator 10 (here, G-type) with one side open to face each other and is not shown, but at the bottom, there is ground. A capacitor pattern for inducing a capacitor is formed between the resonator and the ground, and each of the input and output terminals is formed at an open portion of one side of the resonator. In addition, a connection is made between the resonator and the capacitor pattern as a via.

Referring to FIG. 8, g represents a resonance period distance as a parameter for adjusting the resonance period coupling, w represents an impedance of the resonator, a represents a line width of the resonator as a variable for adjusting the input / output impedance, and these variables are shown in the following table. In order to simulate it.

Table 1. Variable Theorem for Simulation (Unit: mm)

g 0.38 0.40 0.42 0.44 0.46 aw 0.31 0.33 0.35 0.31 0.33 0.35 0.31 0.33 0.35 0.31 0.33 0.35 0.31 0.33 0.35 0.23 g1a1w1 g1a2w1 g1a3w1 g2a1w1 g2a2w1 g2a3w1 g3a1w1 g3a2w1 g3a3w1 g4a1w1 g4a2w1 g4a3w1 g5a1w1 g5a2w1 g5a3w1 0.25 g1a1w2 g1a2w2 g1a3w2 g2a1w2 g2a2w2 g2a3w2 g3a1w2 g3a2w2 g3a3w2 g4a1w2 g4a2w2 g4a3w2 g5a1w2 g5a2w2 g5a3w2 0.27 g1a1w3 g1a2w3 g1a3w3 g2a1w3 g2a2w3 g2a3w3 g3a1w3 g3a2w3 g3a3w3 g4a1w3 g4a2w3 g4a3w3 g5a1w3 g5a2w3 g5a3w3

10 to 12, various experiments were performed based on g3a2w2 (g = 0.42mm, a = 0.33mm, w = 0.25mm) among the design variables, and FIG. 10 shows characteristics of the bandpass filter. 11 also shows stopband characteristics. Here, it can be seen that the stopband attenuation characteristics of the filter are excellent, which means that the quality factor Q of the resonator is increased by attaching a capacitor to the resonator. FIG. 12 illustrates input / output impedance matching characteristics of the bandpass filter of FIG. 11 using a Smith chart, and a voltage standing wave ratio (VSWR) is 1.2 in a passband. This means that impedance matching is good.

13 to 18 show the characteristics of the filter by changing g (resonance period distance), w (impedance of the resonator), and a (resonator line width).

In FIG. 13, the values of g and w are simulated by varying only a (resonator line width) while the values of g and w are fixed. Optimum line width should be implemented. Figure 14 shows the characteristics of the filter according to the change of the impedance of the resonator, it can be seen that the pass band is lowered with the increase of the impedance and the attenuation poles also show the same trend.

FIG. 15 shows the change of the filter characteristics according to the distance g value of the resonance period, but it can be seen that the change of the center frequency is insignificant and the bandwidth and stopband characteristics change according to the g value.

16 shows a change in bandwidth, and it can be seen that the bandwidth decreases as the amount of resonance coupling decreases.

17 and 18 show the change of the attenuation pole frequency according to the change of the g value, which is the resonance period distance. As the coupling amount of the resonance period decreases, the phenomenon that the attenuation poles as well as the bandwidth converge toward the center frequency can be seen. . Therefore, it can be said that an appropriate bandwidth and attenuation pole frequency can be realized by adjusting the resonance period coupling.

By forming the resonator in such a structure, input / output impedance matching and coupling are increased, and the filter can be miniaturized while improving the attenuation characteristics of the filter.

The present invention as described above, by using a laminated ceramic technology to implement the distribution element in a parallel circuit (Planar Circuit) to free the design of the resonator structure and improve the quality factor of the resonator, as well as the thinning and miniaturization of parts Effect also occurred

Claims (2)

In the stacked band pass filter, an input terminal and an output terminal are provided, and a pair of resonators bent in a predetermined form are provided to face each other, and a circuit mediated by a capacitor between the resonator and the ground is used as a basic resonance structure. Stacked Bandpass Filters The multilayer band pass filter of claim 1, wherein one side of the resonator is open, and an input and an output terminal are provided at the open portion.