Electronic circuit apparatus for suppressing electromagnetic radiation

• US 6,016,083 A
• Filed: 08/27/1997
• Issued: 01/18/2000
• Est. Priority Date: 08/27/1996
• Status: Expired due to Term

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Satoh, Shunji
• Primary Examiner(s): Bettendorf, Justin P.
• Application Number:
  US08/919,431
• Time in Patent Office: 874 Days
• Field of Search: 333/12, 333/181, 333/182, 333/185, 361/753, 361/816, 361/818, 174/36 GC
• US Class Current: 333/12
• CPC Class Codes: H05K 9/0018 with provisions to reduce aperture leakages in walls, e.g. terminals, connectors, cables

Abstract

It is the object of the invention to suppress electromagnetic radiation caused by the ground potential of a printed-circuit board, which now becomes an important problem, as the bit-rate of digital signals increases. The ground-pattern of an electronic circuit mounted on the printed-circuit board is connected to the shield-case of an electronic circuit apparatus via a conductor-piece, noise generated by the electronic circuit is by-passed, and electromagnetic radiation of noise from a cable connected to the printed-circuit board via a connector can be suppressed.

Claims

1. An electronic circuit apparatus for suppressing electromagnetic radiation comprising:

an electronic circuit mounted on a top surface of a printed-circuit board;

an input-output terminal mounted on said printed-circuit board;

a shield-case for suppressing electromagnetic radiation from said electronic circuit;

a conductor-piece, allocated between said electronic circuit and said input-output terminal and, connecting a first ground-pattern stuck to a bottom surface of said printed-circuit with said shield-case;

means for connecting said first ground-pattern with said input-output terminal via said conductor-piece;

wherein said connecting means is composed of a second ground-pattern stuck to said bottom surface of said printed-circuit board near said input-output terminal and a metallic-connecting-piece for connecting said second ground-pattern with said shield-case.

2. An electronic circuit apparatus for suppressing electromagnetic radiation according to claim 1, wherein the first ground pattern functions as a common return pass for electronic parts of the electronic circuit, and is connected by the conductor piece to a cable.

3. An electronic circuit apparatus for suppressing electromagnetic radiation according to claim 1, wherein:

said input-output terminal is electrically connected with said printed-circuit board only by signal- and ground-pins.

4. An electronic circuit apparatus for suppressing electromagnetic radiation according to claim 1, further comprising a first capacitor inserted between said first ground-pattern and said conductor-piece, and a second capacitor inserted between said second ground-pattern and said metallic-connecting-piece.

5. An electronic circuit apparatus for suppressing electromagnetic radiation according to claim 1, further comprising a four-terminal network for suppressing a common-mode current, being allocated between said input-output terminal and said conductor-piece, wherein:

input-terminals of said four-terminal network are respectively connected to said signal and ground-patterns, and output terminals thereof are respectively connected to two conductors of a cable.

6. An electronic circuit apparatus for suppressing electromagnetic radiation according to claim 1, further comprising a four-terminal network being allocated between said input-output terminal and said conductor-piece, wherein:

input-terminals of said four-terminal network are respectively connected to said signal and ground-patterns, and output-terminal thereof are respectively connected to two conductors of a cable.