Compact broadband common-mode filter

Patent metadata

Field	Value
Publication number	US-10411670-B2
Application number	US-201715633865-A
Country	US
Kind code	B2
Filing date	Jun 27, 2017
Priority date	Jun 27, 2017
Publication date	Sep 10, 2019
Grant date	Sep 10, 2019

Abstract

Disclosed herein are printed circuit boards with at least one signal trace situated over or under a reference plane. The reference plane includes a broadband common-mode filter that comprises looping and parallel structures etched into the reference plane. The looping structure includes an even number of side arms, and the parallel structure comprises an even number of interior arms, wherein each of the side arms extends toward the parallel structure, and each of the interior arms extends toward the looping structure. The at least one signal trace is substantially parallel to the side arms and to the interior arms, and is situated between a first half of the even number of side arms and a second half of the even number of side arms and between a first half of the even number of interior arms and a second half of the even number of interior arms.

First claim

What is claimed is:

1. A printed circuit board, comprising:
at least one signal trace extending in a first direction; and
a first signal reference plane comprising a pattern, the pattern comprising:
a first base having a first end and a second end, the first base extending in a second direction, the second direction being substantially perpendicular to the first direction;
a second base having a first end and a second end, the second base being substantially parallel to the first base;
a first side arm connected to the first end of the first base, wherein the first side arm is substantially parallel to the at least one signal trace and extends toward the second base;
a second side arm connected to the second end of the first base, wherein the second side arm is substantially parallel to the first side arm and extends toward the second base;
a first interior arm connected to the second base at a first distance from the first end of the second base, wherein the first interior arm is substantially parallel to the first side arm and extends toward the first base; and
a second interior arm connected to the second base at a second distance from the second end of the second base, the second distance being substantially equal to the first distance, wherein the second interior arm is substantially parallel to the first side arm and extends toward the first base,

wherein:
the at least one signal trace is situated between the first and second side arms and between the first and second interior arms,
a length of the first side arm is approximately equal to a length of the second side arm, and
a length of the first interior arm is approximately equal to a length of the second interior arm.

2. The printed circuit board recited in claim 1 , further comprising a second signal reference plane comprising the pattern, wherein a location of the pattern in the second signal reference plane is substantially identical to a location of the pattern in the first signal reference plane, and wherein the at least one signal trace resides between the first and second signal reference planes.

3. The printed circuit board recited in claim 1 , wherein the at least one signal trace comprises a single-ended signal trace.

4. The printed circuit board recited in claim 1 , wherein the at least one signal trace comprises a first signal trace and a second signal trace, and wherein the first and second signal traces convey a differential-mode signal.

5. The printed circuit board recited in claim 1 , wherein a length of the first base is substantially equal to a length of the second base.

6. The printed circuit board recited in claim 1 , wherein a distance between the first base and the second base is between approximately 2 mm and 5 mm.

7. The printed circuit board recited in claim 1 , further comprising at least one capacitor coupled between the first and second side arms.

8. The printed circuit board recited in claim 1 , wherein the pattern further comprises:
a third side arm connected to the first base between the first side arm and the second side arm at a third distance from the first end of the first base, the third distance being less than the first distance, the third side arm being substantially parallel to the first side arm; and
a fourth side arm connected to the first base between the first side arm and the second side arm at a fourth distance from the second end of the first base, the fourth distance being less than the second distance, the fourth side arm being substantially parallel to the first side arm,
and wherein a length of the third side arm is approximately equal to a length of the fourth side arm.

9. The printed circuit board recited in claim 8 , wherein the length of the third side arm differs from the length of the first side arm.

10. The printed circuit board recited in claim 8 , further comprising at least one capacitor coupled between the first and third side arms, between the first and second side arms, between the third and fourth side arms, or between the second and fourth side arms.

11. The printed circuit board recited in claim 1 , wherein the pattern further comprises:
a third side arm connected to the first base between the first side arm and the second side arm at a third distance from the first end of the first base, the third distance being greater than the first distance, the third side arm being substantially parallel to the first side arm; and
a fourth side arm connected to the first base between the first side arm and the second side arm at a fourth distance from the second end of the first base, the fourth distance being greater than the second distance, the fourth side arm being substantially parallel to the first side arm,
and wherein a length of the third side arm is approximately equal to a length of the fourth side arm.

12. The printed circuit board recited in claim 11 , wherein the length of the third side arm differs from the length of the first side arm.

13. The printed circuit board recited in claim 11 , further comprising at least one capacitor coupled between the first and second side arms.

14. A method of manufacturing the printed circuit board recited in claim 1 , the method comprising etching the pattern into the first reference plane.

15. A data storage device comprising the printed circuit board recited in claim 1 .

16. A printed circuit board, comprising:
at least one signal trace extending in a first direction, the at least one signal trace for conveying a signal on the printed circuit board; and
a broadband common-mode filter, comprising:
a looping structure etched into a signal reference plane of the printed circuit board, the looping structure comprising an even number of side arms, the even number of side arms being four, each of the side arms being substantially parallel to all of the other side arms; and
a parallel structure etched into the signal reference plane, the parallel structure comprising an even number of interior arms, the even number of interior arms being two, each of the interior arms being substantially parallel to the other interior arm and to all of the side arms,

wherein:
each of the side arms extends toward the parallel structure,
each of the interior arms extends toward the looping structure,
the at least one signal trace is substantially parallel to the side arms and to the interior arms,
the at least one signal trace is situated between a first half of the even number of side arms and a second half of the even number of side arms,
the at least one signal trace is situated between a first half of the even number of interior arms and a second half of the even number of interior arms,
a first interior arm of the two interior arms is situated between a first side arm of the four side arms and a second side arm of the four side arms, and
a second interior arm of the two interior arms is situated between a third side arm of the four side arms and a fourth side arm of the four side arms.

17. The printed circuit board recited in claim 16 , wherein the at least one signal trace comprises a first signal trace and a second signal trace, and wherein a first distance between the first signal trace and a first nearest side arm of the four sides arms is approximately equal to a distance between the second signal trace and a second nearest side arm of the four sides arms.

18. The printed circuit board recited in claim 16 , wherein the at least one signal trace comprises a first signal trace and a second signal trace, and wherein a first distance between the first signal trace and a first n

Assignees

• Western Digital Tech Inc

Inventors

• Xing Xinzhi
• Wallash Albert
• Contreras John

Classifications

• H05K1/0245

  Lay-out of balanced signal pairs, e.g. differential lines or twisted lines · CPC title

• H05K1/0225

  Single or multiple openings in a shielding, ground or power plane (H05K1/0227 takes precedence) · CPC title

• H01P3/026

  Coplanar striplines [CPS] · CPC title

• H01P1/2013 Primary

  Coplanar line filters · CPC title

• H03H7/427

  Common-mode filters (H02J3/01 and H02M1/126 takes precedence) · CPC title