JPH0481885B2 - - Google Patents

Description

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

Conventional technology and its problems Resonators used in filters, oscillation elements, etc. in the above frequency range are required to have a relatively high sharpness (hereinafter referred to as Q), and such resonators are conventionally , 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 resonator (stripline) is
When the frequency used is low, such as the 400 MHz band, the size becomes large, and since electrodes are formed on the entire back surface of the substrate, a large amount of electrode material is required, which inevitably increases costs.

In view of these problems, the present invention provides a useful resonator that is small, low cost, generates little spurious when used as a filter, facilitates impedance matching, and has a predetermined high Q. is intended to provide.

Means for Solving the Problems In order to achieve the above object, a 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 a pair of coil patterns formed in parallel on the front and back surfaces of a substrate or on the same surface. a first capacitor and a second capacitor connected to each end, and a coil composed of the first capacitor and the coil pattern connected in series on both sides of the first capacitor; A series circuit is formed, and the second capacitor is connected in parallel to this LC series circuit.

Effects 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.

Embodiment FIG. 1 shows the external configuration of a resonator as an embodiment of the present invention, in which figure A is a front view, figure B is a side view, and figure C is a rear view. In the figure, reference numeral 1 denotes a substrate, specifically a dielectric substrate made of FRDR material, etc., and its front side 1a and back side 1b have two capacitor electrode patterns 2a, 2b, 3a, 3b and a coil pattern, respectively. 4a and 5a are formed by screen printing silver paste, for example. The electrode patterns 2a and 3a and 2b and 3b face each other on both the front and back surfaces of the dielectric substrate, forming capacitors C1 and C2 with a capacity determined by the dielectric constant and thickness of the substrate 1 and the facing area of the capacitor electrodes. There is. 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. Since each coil pattern 4a, 5a forms a coil in terms of high frequency, if the inductance thereof is L1, L2, the above-mentioned resonator
As shown in the figure, it is represented by an equivalent circuit in which a second capacitor C2 is connected in parallel to an LC series circuit in which coils L1 and L2 are connected in series on both sides of a first capacitor C1.

A resonator with such an equivalent circuit has not existed in the past, and therefore it can be said that the resonator is novel in terms of the equivalent circuit. The two coil patterns 4a and 5a have appropriate lengths to enable magnetic coupling with other resonators, and are formed as close to the edge of the substrate as possible.
Also, two coil patterns 4 in the same resonator
It is desirable to space them apart as much as possible so that a and 5a are not magnetically coupled or have capacitance.

To make the resonator with the above configuration resonate at fr=504MHz, for example, if C1 is set as C1=18pF, L1 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 is 50Ω, C2
= 53pF has the maximum Q, so I chose 53pF.
Here, if the dielectric constant ε of the substrate 1 is 80 and the thickness is 0.4 mm, the capacitances of C1 and C2 are l1 = 7 mm, l2 =
This can be obtained by setting 1.5 mm, l3=7 mm, and l4=3.5 mm. Further, the inductances of L1 and L2 are obtained by setting l5=l6=6 mm. Although the widths W1 and W2 of the coil patterns 4a and 5a are not related to the inductance value, the larger the width, the smaller the resistance, and therefore the higher the Q, which is preferable. In this embodiment, W1=W2=1.5 mm. Other dimensions (l1, l2…l6) and board 1
FIG. 3 shows the resonance characteristics when the ε and thickness of are set as above. In this case, a very high Q value 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 made wider to lower the resistance.

In addition, in the above-mentioned resonator, the capacitor electrode pattern and the coil pattern are formed 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,
Very productive.

Further, in the above embodiment, the substrate 1 is 0.4 mm thick, but by changing the thickness, the capacitance of the capacitors C1 and C2 changes, and the resonant frequency can be changed. An appropriate thickness may be selected depending on the relationship.

Next, FIGS. 4 and 5 show other embodiments of the present invention, respectively. FIG. 4 shows 2
Two coil patterns 11 and 12 are formed in parallel, and both ends of the coil patterns 11 and 12 are extended toward the center of the board, and this extended portion 1
3, 14, 15, 16 and electrode patterns 17, 18 formed on the back surface of the substrate opposite thereto form first and second capacitors C1, C2.

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 and 20 are used as C1 and C2. When the chip capacitors 19 and 20 are used in this manner, 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.

Effects of the Invention As explained above, according to the present invention, the resonator has a unique equivalent circuit in which the second capacitor is connected in parallel to the LC series circuit in which coils are connected on both sides of the first capacitor. It has a high Q value suitable for filters, oscillation elements, etc. used at frequencies above 400 MHz, and requires less electrode material than conventional methods, 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, making impedance matching easier.

[Brief explanation of drawings]

FIG. 1A is a front view showing a resonator as an embodiment of the present invention, FIG. 1B is a side view, FIG. 1C is a rear view, and FIG. 2 is a diagram showing an equivalent circuit of the resonator. 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 A is a front view showing another embodiment. , FIG. 5B is a side view of the same. C1...first capacitor, C2...second capacitor, L1, L2...coil, 1...substrate,
4a, 5a, 11, 12...Coil pattern.

Claims (1)

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