JPS6310808A - Resonator - Google Patents

Abstract

PURPOSE:To attain less spurious production and ease of impedance matching by forming an LC series circuit by the 1st capacitor and a coil constituted by a couple of coil patterns connected in series across the 1st capacitor and connecting the 2nd capacitor in parallel with the LC series circuit. CONSTITUTION:Two capacitor electrode patterns 2a, 2b, 3a, 3b and coil patterns 4a, 5a are formed respectively to a front face 1a and a rear face 1b of a dielectric base, the electrode patterns 2a, 3a and 2b, 3b are opposed on the front/rear faces of the dielectric base to form capacitors C1,C2 having a capacitance depending on the dielectric constant, thickness of the base 1 and the opposed area of capacitor electrodes. Then an equivalent circuit where the 2nd capacitor C2 is connected in parallel with an LC series circuit formed by connecting the coils L1,L2 in series with the 1st capacitor C1 is expressed. Since the capacitance of the capacitor is adjusted singly, the ease of impedance matching is attained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a resonator suitable for filters, oscillation elements, etc. used in eight frequency bands including and exceeding the UHF band.

Resonators used for filters, oscillation elements, etc. in the above frequency range are required to have relatively high sharpness (hereinafter referred to as Q), and conventionally, such resonators are There are dielectric resonators, strip lines, etc.

However, the former type of resonator (dielectric coaxial resonator) is relatively expensive, and when used as a filter, simply arranging them in parallel does not constitute a circuit, and requires a separate coupling means such as a capacitor. However, there were problems in that the structure was complicated and large, and the assembly work was time-consuming.

In addition, the latter type of resonator (strip line) has a large shape when the operating frequency is low, such as the 400 MHz band, and on top of that, electrodes are formed on the entire back surface of the substrate, which requires a large amount of electrode material, so high costs can be avoided. There was a problem that there was no.

In view of these problems, the present invention is small, low cost,
It is an object of the present invention to provide a useful resonator which generates less spurious, facilitates impedance mapping, and has a predetermined high Q when used as a filter.

In order to achieve the above object, the resonator according to the present invention includes a pair of coil patterns formed in parallel on the front and back surfaces of a substrate or on the same surface, and first and second capacitors connected to respective ends, and
The first capacitor and the coil formed by the coil pattern connected in series on both sides of the first capacitor form an LC.
A series circuit is formed, and the second
capacitors are connected in parallel.

According to the above configuration, the pair of coils and the first and second capacitors are appropriately electrically coupled on the substrate to obtain a desired resonator circuit.

Figure 1 shows the external configuration of a resonator as an embodiment of the present invention, where Figure (A) is a front view, Figure (B) is a side view, and Figure (C) is a rear view. . In the figure, 1 is a substrate, specifically F
A dielectric substrate made of RDR material or the like is shown, and two capacitor electrode patterns 2a are provided on the front surface 1a and the back surface 1b, respectively.
, 2b, 3a.

3b and coil patterns 4a, 5a stops (for example, formed by screen-printing paste).

The electrode patterns 2a and 3a and 2b and 3b face each other on both sides of the dielectric substrate, and the dielectric constant of the substrate 1,
Capacitors CI and C2 are formed with a capacity determined by the thickness and the facing area of the capacitor electrodes. On the other hand, the coil patterns 4a and 5a are formed to connect two capacitor electrode patterns 2a and 2b and 3a and 3b on each of the front and back surfaces of the substrate, respectively. Each coil pattern 4a, 5
Since a forms a coil in terms of high frequency, if its inductance is Ll and L2, the resonator has coils LL and LL on both sides of the first capacitor C1, as shown in FIG.
A second capacitor C is connected to the LC series circuit in which L2 is connected in series.
This is done using an equivalent circuit in which 2 are connected in parallel.

A resonator with such an equivalent circuit has not existed in the past, and therefore it can be said that it is a new resonator in terms of the equivalent circuit. The two coil patterns 4a + 5a have appropriate lengths to enable magnetic coupling with other resonators, and are formed as close to the edge of the substrate as possible.

Two coil patterns 4a and 5 in the same resonator
It is desirable to space them apart as much as possible so that they are not magnetically coupled or have capacitance.

In order to cause the resonator having the above configuration to resonate at f r =504 MHz, for example, if CI is set as CI=18 pF, Ll and L2 are given by the following equations.

Here, if L1=L2, then L1=L2=2.77nH. C2 can be selected depending on the impedance used, regardless of the resonance frequency. In this example, when the impedance was 50Ω, Q was maximized at C2=53pF, so 53pF was selected. Here, the dielectric constant ε of the substrate 1 is 80. If the thickness is 0.4 mm, CI, C
The capacitance of 2 is 11=7 cranes, J2=1.5 fins, I! 3
= 1w, obtained by setting 14-3.5 dragons. Also, the inductance of Ll and L2 is 15=16=6
This can be obtained by setting it to 1 layer. The widths Wl and W2 of the coil patterns 4a and 5a are not related to the inductance value, but the larger the width, the smaller the resistance, so Q
is high, which is preferable. In this example, W1=W2=
It is set at 1.58. Other dimensions (ll, 12...1
6) and the resonance characteristics when the ε and thickness of the substrate 1 are as described above are shown in FIG. In this case, a very high value of Q of 148 was obtained. The reason why such a high Q was obtained is speculation. Possible reasons include that the resonator has a unique circuit configuration not seen in the past in terms of an equivalent circuit, and that the widths of the coil patterns 4a and 5a are widened to lower the resistance bone.

In the above resonator, the capacitor electrode pattern and the coil pattern are on both the front and back surfaces 1a of the substrate 1.

1b are formed in the same pattern. ``By aligning the patterns on the front and back surfaces 1a and 1b in this way, printing masks with the same pattern can be used during manufacturing, resulting in very high productivity.

Further, in the above embodiment, the substrate 1 is 0.4 m thick, but by changing the thickness, the capacitance of the capacitors CI and C2 changes, and the resonant frequency can be changed. Depending on the relationship, an appropriate thickness may be selected.

Next, FIGS. 4 and 5 show other embodiments of the present invention, respectively. In FIG. 4, two coil patterns 11.12 are formed in parallel on the surface 1a of the substrate 10, and both ends of the coil patterns 11.12 are extended toward the center of the substrate, and the extended portions 13.14.15 16 and electrode patterns 17 and 18 formed on the back surface of the substrate opposite thereto. The second capacitors CI and C2 are formed.

On the other hand, the embodiment shown in FIG. 5 is the same as the above embodiment in that two coil patterns 11 and 12 are formed in parallel on the surface of the substrate, but unlike the above embodiment, the first and second capacitors are Chip capacitors 19.20 are used as C1 and C2. When the chip capacitors 19 and 20 are used in this way, the substrate 1 may be an insulating substrate such as an alumina substrate or a printed circuit board using epoxy instead of a dielectric substrate.

In particular, when a ferrite substrate is used, since ferrite has high magnetic permeability, the inductance value required for the resonator can be obtained even if the length of the coil pattern is shortened, and further miniaturization can be achieved.

It goes without saying that a capacitor with leads can be used instead of the chip capacitor.

As explained above, the present invention has a unique equivalent circuit in which a second capacitor is connected in parallel to an LC series circuit in which coils are connected on both sides of a first capacitor. Since it is a resonator, it has a high Q that is suitable for filters and oscillation elements used at frequencies above 400 MHz, and
Less electrode material is required than in the past, resulting in lower costs. Furthermore, if each coil pattern is formed near the edge of the substrate, by connecting the substrates, they can be easily magnetically coupled to each other, making it possible to form a filter with an extremely simple structure compared to conventional filters. It has a remarkable effect.

In addition, unlike a dielectric coaxial resonator, the capacitance of the capacitor, which is a component of the resonator, can be changed and adjusted independently, which has the effect of facilitating impedance matching.

[Brief explanation of drawings]

FIG. 1(a) is a front view showing a resonator as an embodiment of the present invention, FIG. 1(b) is a side view, FIG. 1(c) is a rear view, and FIG. 3 is a diagram showing the resonance characteristics of the resonator, FIG. 4(a) is a front view showing another embodiment, FIG. 4(b) is a side view of the same, and FIG. 5 is a diagram showing an equivalent circuit. (A) is a front view showing another embodiment, and FIG. 5(B) is a side view of the same. C1...first capacitor, C2...second capacitor, Ll, L2...coil, 1...substrate, 4a,
5all, 12...Coil pattern. Figure 2 Figure 4 Figure 5

Claims (1)

[Claims] (1) 1 formed in parallel on the front and back surfaces of the substrate or on the same surface
The coil pattern includes a pair of coil patterns, and first and second capacitors connected to respective ends of the coil pattern, and the coil pattern is connected in series to both sides of the first capacitor. 1. A resonator, comprising: a coil configured by the above to form an LC series circuit, and further comprising: the second capacitor connected in parallel to the LC series circuit.