JPH05347501A - Filter utilizing skin resistance - Google Patents

Abstract

PURPOSE:To obtain a flat loss characteristic of a noise extending over a wide range by constituting an insulator layer, a resistance conductor layer, a good conductor layer, etc., and allowing the filter to have a low-pass filter characteristic by utilizing a frequency characteristic of a composite skin effect by a multi- layer conductor layer. CONSTITUTION:A noise filter of a composite film is constituted by executing vacuum deposition of an advance deposition film as a resistance conductive part 2 to the surface and the reverse side of a ceramic substrate supporting insulator part 3, and subsequently, forming copper as a good conductive part 1 by vacuum deposition or plating, etc. Also, by utilizing a frequency characteristic of a composite skin effect by this multi-layer conductor layer, this filter is allowed to have a low-pass filter characteristic. Moreover, this noise filter uses a distributed constant circuit, and does not contain inductance as a lumped constant element, therefore, does not resonate theoretically. Furthermore, as for a resistance, a skin resistance of a resistance film which can determine its resistivity independently from a conductor which becomes a core is used, therefore, it is possible to allow this filter to have a loss characteristic of a prescribed value or above in a wide band against a high frequency noise.

Description

[Detailed Description of the Invention] [Industrial field of application]
A noise filter that is inserted in the output circuit to prevent the circuit from spreading and transmitting noise. Alternatively, a noise filter inserted in the input circuit of the signal line receiving unit or the power line receiving unit for the purpose of preventing reception of high frequency noise.

[Prior Art] A conventional noise filter for both balanced and unbalanced modes is generally configured by using a capacitor, a resistor, and a coil wound around a magnetic loss core. Therefore, in this type of filter, it is difficult to obtain a flat loss characteristic over a wide band because the resonance characteristic of the magnetic material and the circuit appears in the frequency characteristic of the total loss.

[Problems to be Solved by the Present Invention] In order to solve the above problems, the present invention uses a distributed constant circuit and does not include an inductance as a lumped constant element, so that it does not resonate in principle. Also, as the resistance, the skin resistance of the resistance film, whose resistivity can be determined independently of the conductor that will be the core, is used. The cutoff frequency can be freely designed according to Next, the principle will be described. First, FIG. 1 shows a three-dimensional view of a line cross section of the present invention. In the figure, 1 is a good conductor and 2 is a resistive film for attenuating high frequency noise components. Further, FIG. 2 is an equivalent circuit thereof. In a cross section of a line composed of a single resistive conductor, the alternating current generally has a high density near the surface of the line due to the skin effect, and the current density decreases as it goes inside. Further, this tendency becomes more remarkable as the frequency becomes higher. If this current density is expressed as J (x) as a function of the depth x from the conductor surface, the distribution in the cross section is as shown in FIG. Where the abscissa of curve A is J (x) at low frequency
, And that of curve B shows J (x) at high frequencies. Also, J (x) is 1 / e (”of the surface current density J (0).
If e () is the value that becomes the base of the natural logarithm, J (δ), then
δ _A ″ and “δ _B ” are the skin depths at low and high frequencies, respectively. Here, as shown in FIG. 4, the thickness d of this resistive conductor has a relationship of δ _B << d << δ _A. If it is selected to be valid and the inside is a good conductor with a resistivity ρ, the current distribution curve B at high frequencies does not change, but that at low frequencies changes from A to A '. Therefore, conduction is relatively low at low frequencies. It is possible to make a low-frequency reactor wave line with no improvement in resonance characteristics.

Example 1 An example will be described below with reference to the drawings. FIG. 5A is a cross-sectional view of a planar type (parallel plate line or strip line). The advanced vapor deposition film is vacuum-deposited on the front and back of the ceramic substrate 3 as a resistive conductive part, and then copper is vacuum-deposited as a conductive part, or a noise filter of a composite film formed by plating is shown in Table-3. Thus, very good low frequency wave characteristics were obtained. Needless to say, a noise filter can be made even if a nichrome film is used for the resistance conductive portion.

Example 2 FIG. 5B is a sectional view of a two-layered planar type (parallel plate line or strip line). This is an advanced vapor deposition film vacuum-deposited on the front and back of the ceramic substrate 3 as a resistive conductive part, and then vacuum vapor-deposited copper as a conductive part, or two slabs composed of a composite film by plating etc. As shown in Table 3, good low-frequency wave characteristics were obtained with this noise filter.
Further, the same results as in Example 1 were obtained even when the nichrome coating was used for the resistance conductive portion.

Example 3 FIG. 5C is a coaxial sectional view. The advanced coating is vacuum-deposited on the inner and outer walls of these ceramic cylindrical columns as a resistive conductive part, and then copper is vacuum-deposited as a conductive part.
Table 3 shows the low-frequency wave characteristics of a noise filter made of a composite film formed by plating or the like.
The electric constants of the materials used in Examples 1, 2 and 3 in FIG. 5 are shown in Table-1, and the structural dimensions and manufacturing method are shown in Table-2. In theory that ignores the coupling of input and output circuits, the attenuation [d
B / m] results in Table-3. That is, in the case of a reactor designed for commercial power supply frequency, when the length (L) = 10 mm, sufficient attenuation is obtained at a frequency of 1 MHz or higher.

[Brief description of drawings]

FIG. 1 is a structural diagram of the present invention. Figure 2 is an equivalent circuit diagram. FIG. 3 is a partial sectional view of a structure in which the conductor is only a resistance layer, and a current density distribution diagram. FIG. 4 is a partial sectional view of the structure and a current density distribution diagram when the resistive conductor layer and the good conductor layer are in close contact with each other.
FIG. 5 shows an embodiment. Here, 1: good conductor part 2: resistive conductor part 3: ceramic substrate (dielectric) supporting insulator part.

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[Procedure amendment]

[Submission date] February 7, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Title of invention

[Correction method] Change

[Correction content]

[Title of Invention] Reactor using skin resistance

Claims (1)

[Claims] Insulator layers, resistive conductor layers, good conductor layers, etc. are constructed using vapor deposition, sputtering, plating, coating technology, etc., and low frequency wave characteristics are provided by utilizing the frequency characteristics of the composite skin effect of the multilayer conductor layers. Transmission line or single wire.