KR960011416B1 - High freq. band pass filter - Google Patents

Abstract

The filter for providing an RF(Radio Frequency) band filter by using distribution capacity of a dielectric substrate as a capacitor(C) and a hidden line as an inductor(L), includes an auxiliary substrate implementing coupling points for a ground, the 1st distributed parameter device located vertically on the auxiliary substrate to implement a desired impedance and a high Q and a fixed C for the filter, the 2nd distributed parameter device located horizontally on the auxiliary substrate, an inductor linked to the 2nd device to improve the inner Q, a shield linked to the 1st device to separate an input/output to adjust the final inductance.

Description

High Frequency Bandpass Filter Using Distribution Capacitance of Dielectric Substrate

1 is an exploded view of a conventional ceramic bandpass filter.

2 is a cutaway cross-sectional view of the ceramic resonator of FIG.

3 is a general bandpass filter.

4 is an electrical equivalent circuit diagram of a portion of a conventional ceramic bandpass filter.

5 is a component diagram of the bandpass filter produced in the present invention.

6 is an electrical equivalent circuit of a bandpass filter to which a shielding casing is not attached.

7 is a diagram illustrating transfer characteristics of a parallel resonant circuit expressed in frequency side signal size.

8 is a diagram illustrating transmission characteristics for input and output of a transmission bandpass filter for an automobile wireless telephone using an existing ceramic resonator [(a) S12, (b) S21].

9 is an input pulse impedance characteristic (S11) of a transmission bandpass filter for an automobile radiotelephone using a conventional ceramic resonator.

10 is an output impedance characteristic (S21) of a transmission bandpass filter for an automobile wireless telephone using a conventional ceramic resonator.

11 is a diagram showing transmission characteristics of input / output of a transmission bandpass filter for an automobile wireless telephone manufactured in the present invention ((a) S12, (b) S21).

12 is an input impedance characteristic (S11) of the transmission bandpass filter for automobile radiotelephone manufactured in the present invention.

13 is an output impedance characteristic (S22) of the transmission bandpass filter for automobile radiotelephone produced in the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the manufacture of high frequency (hereinafter referred to as RF) bandpass filters, and in particular, a capacitor using a distribution capacity of a dielectric substrate (hereinafter referred to as C) and an inductance using silver lines (hereinafter referred to as L). The present invention relates to a high frequency band filter having an RF band filtering function.

The conventional high frequency bandpass filter is composed of three ceramic resonators 5, an electrode 54, a dielectric 53, a shield case, and a ground plane 55, as shown in FIG. In addition, in FIG. 1, the ceramic well has an outer area 56 and an inner area 57 as conductors.

2 shows a cutaway cross-sectional view of the ceramic resonator of FIG.

3 shows that the ceramic resonator used in the prior art has its own resonance point according to the area in order to constitute the general bandpass circuit shown.

1 shows only a portion of a conventional bandpass filter in which an electrode 54, a dielectric 53, and two ceramic resonators 50 and 51 are combined. In FIG. 4, the electrode 54, the dielectric 53, and the internal year 53 of the ceramic resonator are connected to represent the capacitor 80 of FIG. 4. The capacitor affects the input / output characteristic impedance of the bandpass filter.

Since the conventional bandpass filter of FIG. 1 has the electrical equivalent circuit of FIG. 3, the electrical operation is operated according to FIG.

As described above, the bandpass filter uses a ceramic resonator to configure parallel resonant circuits of L and C. However, as a result of configuring several resonators in one ceramic dielectric, the parallel resonant circuits determine the pass band of the bandpass filter. Since the individual adjustment is difficult and the size of the ceramic resonator is changed according to the frequency to be manufactured, the external filter size is determined at the corresponding frequency. In addition, since the medium of the ceramic dielectric material is heavy and hard, it is difficult to finely adjust the adjustment method.

In other words, the conventional ceramic filters used in the conventional RF transceiver is an important component that is necessarily used in manufacturing the transceiver, and is determined as an expensive component when manufacturing the transceiver. Ceramic filters are also heavy and large in size, making them less suitable for portable RF transceivers.

Accordingly, an object of the present invention is to provide an RF bandpass filter which can be simply configured using a capacitor C using a distribution capacity of a dielectric substrate and an inductance L using a hidden line.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

5 is a band filter manufactured in the present invention. In order to design the circuit of FIG. 3 to fit a predetermined frequency band, the resonance characteristics of L and C are changed. The resonant circuit characteristics are also affected by the Q of both L and C. The distribution constant of the alumina substrate was used to easily realize the defined impedance of the RF bandpass extrusion force and to realize high Q and uniform C values. L used a hidden line to improve its Q value and covered with a hidden line to prevent contact between the lines. As shown in FIG. 6, the FF bandpass filter includes a vertical C substrate 33, 34, a horizontal C combination substrate 35, an auxiliary substrate 40, an L, and a shield case 42. The vertical C substrates 33 and 34 realize C (10, 11, 13, 15, 16) in FIG. 3 using the distribution constants of the alumina substrate. In addition, L ((31, 32, 36, 37, 38) of FIG. 5 implements L (21, 22, 23, 24, 25) of FIG.

The auxiliary substrate 40 is a substrate for realizing the combination of the L and C resonant circuits shown in FIG. In addition, in the parallel resonant circuit of L (22) and C (12) and L (24) and C (14) of FIG. 3, since the vertical C substrates 33 and 34 are connected in the vertical direction above the horizontal C combination wave, The width can be reduced.

The rear part of the auxiliary substrate of FIG. 5 is composed of three parts of the ground plane and the input / output terminals 204 and 205. The reason for separating the ground plane into three parts is that the resonance characteristics of the resonant circuits 101 to 103 of FIG. These factors are used to determine the passband so that they can be adjusted to have an accurate resonance point.

Since the resonance characteristics of the resonant circuits 101 to 103 of FIG. 3 are factors that determine the pass band of the bandpass filter, they should be individually adjusted to have an accurate resonance point.

The shielding case 42 of FIG. 5 has several characteristics mechanically. The ground terminals 206 and 207 of the shielding case are connected to the ground surface of the back side of the auxiliary substrate of FIG. 5 to become a common ground, and solve the problem of the ground terminal required by the FF component. In addition, the cut portions 208 and 209 of the shielding case 42 are intended to separate the input and output terminals 204 and 205 of the rear surface of the auxiliary substrate 41 from the shielding case. The cut portions 201 and 214 of the upper surface of the shield case 43 are intended to be able to finally adjust the values of L (21 to 25) in consideration of the characteristic change after fabricating the bandpass filter.

In order to manufacture the FF bandpass filter developed in the present invention, after attaching the horizontal C combination substrate 35 on the auxiliary substrate 40, the vertical C (33, 34) is attached vertically on the horizontal combination substrate 25 and horizontal C The combination substrate C is connected to the 215 by L (31) and the C (216) and C (217) by L (32). In addition, it has a form of a band filter connected to the C (215 ~ 217) of the horizontal C combination substrate and the L (36 ~ 38) to the separate ground plane (301 ~ 303) of the auxiliary substrate.

The equivalent circuit of the bandpass filter without the shielding case of FIG. 5 is shown in FIG.

Since the ground plane is separated into three parts of the basic circuit of FIG. 3, it is easy to measure the parallel resonance characteristics of individual L and C. Since the parallel resonance circuit of L and C has infinite impedance at the true point, the transmission characteristic with respect to the frequency shows the lowest value at the frequency corresponding to the resonance point as shown in FIG. In order to adjust the resonant circuit to the corresponding resonance point by using this characteristic, L is adjusted by adjusting C in a fixed state. L is manufactured by winding coated silver wire. When the line spacing is narrowed, the value of L increases, and when the line spacing is widened, the value of L decreases.

The resonant circuits 104 and 105 of L and C of FIG. 3 adjust the L (31-32) after the auxiliary substrate 40 and the shielding case 42 become a common ground as the band filter is an element that determines the blocking characteristic. FF band filter suitable for the characteristics is manufactured.

8 is a transmission characteristic ((a) S12, (b) S21) of the input and output of the transmission bandpass filter for automobile radiotelephone using the existing ceramic resonator.

9 is a diagram illustrating input impedance characteristics (S11) of a transmission bandpass filter for an automobile radiotelephone using a conventional ceramic resonator.

10 is an output impedance characteristic (S22) of the transmission bandpass filter for an automobile wireless telephone using a conventional ceramic resonator.

Fig. 11 is a diagram showing the transfer characteristics ((a) S12, (b) S21) for the input / output of the transmission bandpass filter for automobile radiotelephone manufactured in the present invention.

12 is an input impedance characteristic S11 of the transmission bandpass filter for automobile radiotelephone fabricated in the present invention.

13 is an output impedance characteristic (S22) of the transmission bandpass filter for automobile radiotelephone fabricated in the present invention.

As described above, since the weight is lighter and the external height can be reduced as compared with the conventional ceramic bandpass filter, it is suitable as a component of a portable transceiver, and there is an advantage that it can be produced at a low cost.

Claims (1)

In the high frequency bandpass filter, a first means which is an auxiliary substrate for realizing a coupling point to the ground plane, and is vertically positioned on the auxiliary substrate to implement a predetermined impedance of the RF bandpass filter input and output high Q and uniform C value. A first distribution constant means for realization, a second distribution constant means disposed in parallel on the auxiliary substrate, an inductance means connected to the second distribution constant means to improve its Q value, and the first distribution constant A high frequency bandpass filter using a dielectric distribution capacitor, characterized in that it is connected to the means to be a common stop to separate the input and output terminals and adjust the final inductance.

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