RU2373621C1 - Electromagnet noise suppression filter - Google Patents

Abstract

FIELD: radio engineering.

SUBSTANCE: invention is related to electronic engineering and may be used to suppress electromagnet noise in power supply circuits for telecommunication equipment, HF and SHF equipment and in other devices of signal digital processing. Electromagnet noise suppression filter consists of induction coils (2) made on substrate with maximum possible magnetic permeability, their mutual location increases their inductivity. To prevent connection of coils along electric field, there is an electrostatic screen (3) arranged between them. Electrostatic screen is arranged on substrate with maximum dielectric permeability, in screen centre there is a small opening for electric connection of central terminals of coils. Electrostatic screen (3) and external plates (1), which are also made on substrate with maximum dielectric permeability, are plates of capacitors, the second plate is represented by the coils themselves. Metallisation of electrostatic screen must not possess magnetic properties, metallisation of external plates may possess magnetic properties, which will result in minimisation of external magnetic fields radiated by filter.

EFFECT: improved efficiency of radio element supply voltages filtration.

2 dwg

Description

The invention relates to electronic equipment and can be used to suppress electromagnetic interference in the power circuits of telecommunications equipment, RF and microwave equipment and other digital signal processing devices.

Known low-pass filters made on discrete elements, designed to filter DC voltage in the power supply circuits of electronic devices (see Baskakov S.I. Radio-technical circuits and signals: Textbook for universities on special. "Radio engineering". - 2nd ed. , revised and add-M: Higher school, 1988 - 448 pp. - prototype).

The main disadvantage of existing filters for suppressing electromagnetic interference is low efficiency at frequencies above 100 MHz.

The objective of the invention is to increase the maximum operating frequency and the efficiency of the filter for suppressing electromagnetic interference in the working band.

The problem is solved in that the electromagnetic interference suppression filter contains alternating substrates on which capacitive and inductive elements are formed by thin-film or thick-film technology. The substrates can be made of a layered or bulk composite magnetoelectric material of the composition ferrite - piezoceramics.

To explain the invention, drawings are provided. The device (Fig. 1) consists of external metallized plates of piezoelectric ceramics 1, a flat inductor on a ferrite substrate 2 and an internal plate of piezoelectric ceramics 3, interconnected, and is an elementary cell of an electromagnetic interference suppression filter. To increase the efficiency of the filter, a series connection of the cells is possible.

Figure 2 presents the equivalent circuit of the filter for suppressing electromagnetic interference, the proposed filter contains capacitors C1 ... C3 and inductors L1 and L2. The input and output of the filter are shown conditionally.

The device operates as follows.

Inductors 2 are made on a substrate with the greatest possible magnetic permeability, their mutual arrangement is such that when the current flows through them, the magnetic fields of the coils are directed in one direction, which increases their inductance. To prevent the coils from communicating over the electric field, an electrostatic screen 3 is placed between them. The electrostatic screen is made on a substrate with maximum dielectric constant, and there is a small hole in the center of the screen for electrical connection of the central leads of the coils. The electrostatic screen 3 and the outer plates 1, which are also made on a substrate with maximum dielectric constant, are plates of capacitors C1 ... C3, the second plate is the coils themselves. The metallization of the electrostatic screen should not have magnetic properties, the metallization of the outer plates may have magnetic properties, which will minimize the external magnetic fields emitted by the filter.

To eliminate interference in digital electronic devices, ceramic capacitors with capacities from 0.1 μF to 1 nF or capacitor filters for suppressing electromagnetic interference are used.

When the unit cell size of the filter is 10 × 10 × 0.5 mm (the thickness of each layer is 0.1 mm) at ε = 1500, the capacitance of the capacitor is about 0.05 μF, and at μ = 2000, the coil inductance is about 8 μG. In this case, the filter cutoff frequency is about 250 kHz. The values obtained are comparable with the ratings of the components used to filter DC voltage in the power circuits of digital devices. If it is necessary to reduce the cutoff frequency of the filter, it is possible to use two or more cells.

Thus, the present invention improves the filtering efficiency of the supply voltage of the radioelements. The design of the proposed electromagnetic interference suppression filter is more complicated than the prototype design, but unlike the prototype, it is a full-fledged inductive-capacitive low-pass filter, which is made of a multilayer or bulk magnetoelectric composite material of the composition ferrite - piezoceramics. In the manufacture of an electromagnetic interference suppression filter, well-developed ceramic technologies are used, which leads to its low cost.

Claims (1)

An electromagnetic interference suppression filter containing inductors and capacitors interconnected, characterized in that the filter contains alternating substrates in the form of external metallized plates made of piezoceramics, flat inductors on a ferrite substrate with the highest possible permeability, the mutual arrangement of which is such that during leakage along them the current, the magnetic fields of the coils are directed in one direction, and the electrostatic screen located between them, in the center of which is made TIFA to electrically connect the coils of central terminals, wherein the electrostatic shield and the external electrode are electrodes of capacitors C1 ... C3, and the second electrode are themselves coil.

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