JPS6327109A - Lc low pass filter - Google Patents

Abstract

PURPOSE:To improve the characteristic by winding overlappingly a ground winding under a coil at the 2nd stage of an LPF circuit of ladder constitution in the same direction of the turns of the coil so as to provide the 2nd attenuation pole at a high frequency. CONSTITUTION:The ladder type LPF circuit consists of a coil 7, a capacitor 8 and the coil 10 to provide an attenuation pole at high frequencies. The 2nd attenuation pole is provided at high frequencies by winding the ground winding 11 under the coil 7 of the 2nd stage of the pass filter in the same direction as the winding direction of the coil 7. In adjusting number of turns of the winding 11, the position of the low attenuation pole is moved freely. Thus, the characteristic is improved inexpensively without increasing number of components.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an LC low-pass filter used in various electronic devices.

BACKGROUND OF THE INVENTION In recent years, electronic devices have become increasingly lighter, thinner, and smaller, and in order to increase the density of electronic components used in these electronic devices, miniaturization of components has become important. Also in the field of high-frequency coils, miniaturized components have begun to be provided.

The conventional LC low-pass filter mentioned above will be explained below with reference to the drawings.

FIG. 4 shows an equivalent circuit diagram of a conventional LCC series transmission circuit. As shown in FIG. 5, the LC low-pass filter has an attenuation pole in the high frequency range.

In FIG. 4, 1 is a coil, 2 is a capacitor, 3 is a grounding section, and 4 is a coil connected in series with the capacitor to provide an attenuation pole in the high range.

In the equivalent circuit diagram shown in Fig. 4, if the attenuation pole and the amplitude frequency characteristics in the higher range than the attenuation pole are not good, connect the capacitor 5 in parallel with the coil 1 as shown in Fig. 6, or connect the capacitor 5 in parallel with the coil 1 as shown in Fig. 7. Furthermore, a coil 6 was connected in series with the capacitor 2, forming an equivalent circuit with a second attenuation pole in the high frequency range, as shown in FIG.

Problems to be Solved by the Invention However, in the configurations shown in FIGS. 6 and 7, the capacitor 5
Alternatively, the number of coils 6 is increased by one, resulting in high cost and a large size.

The present invention overcomes the above drawbacks and provides an LC low-pass filter that can be constructed at low cost without increasing the number of capacitors or coils or increasing the size.

Means for solving the problem In order to achieve this object, the LC low-pass filter of the present invention has an attenuation pole composed of a first stage capacitor and a series resonant coil, and is arranged in a ladder shape with L and C. second to be done
It is constructed by winding a ground winding under the coil of the tier in the same direction as this coil in one turn or more.

Effect: With this configuration, a second attenuation pole can be provided without increasing the number of coils or capacitors, and the frequency of the attenuation pole can be freely set by controlling this earth winding. .

EXAMPLE Hereinafter, an example of the present invention will be described with reference to the drawings.

Figure 1 shows the case where a ground winding is wound one turn or more in the same direction as the coil under the second-stage coil in the low-pass section of a ladder-type circuit consisting of a coil, a capacitor, and an LC series resonant circuit. It shows an equivalent circuit diagram. In Figure 1, 7 is a coil, 8 is a capacitor, 9 is a ground part, and 1
0 has an attenuation pole in the high range, so the coil is connected in series with the capacitor. 11 has a second attenuation pole in the high range, so it is installed below the second stage coil 7 in the same direction as this coil 7. This is a ground winding that is wound over one turn or more.

FIG. 2 is a perspective view of a multiple bobbin in which a ground winding is wound one or more turns below the second-stage coil in the low-pass section in the same direction as that coil.

In Figure 2, 7 is a coil, 8 is a capacitor, 9 is a grounding section, 1o is a coil that has an attenuation pole in the high range and is connected in series with capacitor 8, and 11 has a second attenuation pole in the high range. In order to provide this, a ground winding is wound under the second stage coil 7 in the same direction as this coil, 12 is a terminal, and 13 is a multiple coil bobbin.

The operation of the LC low-pass filter configured as described above will be described below.

By winding the ground winding 11 overlapping one turn or more in the same direction as the coil 7 under the second stage coil 7 of the low-pass section shown in FIG. The second attenuation pole can be freely moved in the high frequency range as shown in FIG.

FIG. 3 is an amplitude frequency characteristic diagram when the ground winding 11 is wound under the second stage coil 7 in the low-pass section in the same direction as the coil 7 by one or more turns.

In Figure 3, person is an amplitude frequency characteristic diagram when the earth winding 11 has 2 turns, B is an amplitude frequency characteristic diagram when the earth winding 11 is 3 turns, and C is an amplitude frequency characteristic diagram when the earth winding 11 is made 3 turns.
It is an amplitude frequency characteristic diagram when 5 turns are made.

As described above, the LC low-pass filter according to the present embodiment can achieve a high frequency range by overlapping the ground winding 11 by one or more turns in the same direction as the coil 7 under the second stage coil of the CI-Has section. The attenuation pole can be changed freely, and it is possible to construct an inexpensive LC low-pass filter with a predetermined attenuation pole without increasing the size.
This industrial effect is significant.

In this example, a ladder-type LC low-pass filter composed of three coils and three capacitors was described, but in the case of an LC low-pass filter composed of more coils and capacitors, the second stage coil is also used. A similar effect can be obtained by wrapping a ground winding under the coil in the same direction as the coil.

Furthermore, it has been experimentally confirmed that even if the earth winding is wound in the opposite direction by more than one turn, it is not possible to provide a second attenuation pole.

Effects of the Invention As described above, the present invention allows the second attenuation pole in the high range to be freely created by overlapping the earth winding in the same direction as the second stage coil of the low-pass section. It has the advantage of being able to be changed to a different size, without increasing its size, and being significantly advantageous in terms of cost, so it has great practical value.

[Brief explanation of drawings]

Fig. 1 is an equivalent circuit diagram of a La low-pass filter according to an embodiment of the present invention, and Fig. 2 is an equivalent circuit diagram of a La low-pass filter according to an embodiment of the present invention. Figure 3 is a perspective view of the case where the wires are overlapped and wound. Figure 3 is an amplitude frequency characteristic diagram when the earth winding is overlapped and wound in the same direction as that coil under the second stage coil of the low-pass section.
The figure is an equivalent circuit diagram of a conventional LC low-pass filter with an attenuation pole, Figure 5 is an amplitude frequency characteristic diagram of a conventional LC low-pass filter with an attenuation pole, and Figure 6 is a diagram of a conventional LC low-pass filter with an attenuation pole. Figure 7 is an equivalent circuit diagram when a capacitor is connected in parallel with the coil to provide a second attenuation pole in the high range, and Figure 8 is an equivalent circuit diagram when a coil is connected in series with a capacitor to provide a second attenuation pole in the high range. It is an amplitude frequency characteristic diagram when a capacitor is connected in parallel with a coil in order to provide a second attenuation pole in a high frequency range, and when a coil is connected in series with a capacitor. 7-... Coil, 8... Capacitor, 9...
...°Earth part, 10... Koinope 11.
...Earth winding. Name of agent: Patent attorney Toshio Nakao and 1 other person7,
/ρ---Carp 2 Shizuichi---Kotsukosensa Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 51% 8

Claims (1)

[Claims] It has an attenuation pole composed of a first stage capacitor and a series resonant coil, and below the second stage coil configured in a ladder shape, one or more turns of the earth winding are stacked in the same direction as this coil. Wrapped LC low pass filter.