Signal trace impedance control using a grid-like ground plane

17 Pages·2013·1.33 MB·English

US005818315A
United States Patent [19] [11] Patent Number: 5,818,315
M00ngilan [45] Date of Patent: Oct. 6, 1998
[54] SIGNAL TRACE IMPEDANCE CONTROL Robert E. Collin, “Foundations for Microwave Engineer
USING A GRID-LIKE GROUND PLANE ing,” McGraw—Hill, New York, 1996, pp. 237—251.
Brian J. Minnis, “Designing Microwave Circuits by Exact
[75] Inventor: Dheena Dayalan Moongilan, Marlboro,
Synthesis,” Artech House, Boston, 1996, pp. 222—225 and
NJ.
257—259.
[73] Assignee: Lucent Technologies Inc., Murray Hill, Brian C. Wadell, “Transmission Line Design Handbook,”
NJ. Artech House, Boston, 1991, pp. 324—325.
Marek T. Faber et al., “Microwave and Millimeter—Wave
[21] Appl. No.: 777,831 Diode Frequency Multipliers,” Artech House, Boston, 1995,
pp. 110—113 and 338—340.
[22] Filed: Dec. 31, 1996
[51] Int. Cl.6 ...................................................... .. H01P 3/08 Primary Examiner—Paul Gensler
[52] US. Cl. ................................ .. 333/238; 333/1
[57] ABSTRACT
[58] Field of Search ............... .. 333/1, 238; 174/117 FF,
174/117 M, 32, 36
Methods and apparatus for controlling signal line impedance
in an electronic circuit board by altering the characteristics
[56] References Cited
of a grid-like ground plane. The ground plane is arranged
U.S. PATENT DOCUMENTS adjacent and parallel to a signal plane of the circuit board,
and includes a grid-like pattern of conductors. The grid-like
3,612,744 10/1971 Thomas ............................. .. 333/238 X pattern of conductors forms a large number of grid elements.
4,855,537 8/1989 Nakai et a1. .. 333/238 X
The siZe of the grid elements in a portion of the ground plane
5,300,899 4/1994 Suski .............. .. 333/238 X
5,479,138 12/1995 Kuroda et al. 333/238 X varies along at least a portion of the length of a correspond
ing signal trace of the signal plane in order to provide a
5,568,107 10/1996 Buuck et al. ......................... .. 333/238
desired impedance for the signal trace. The grid element siZe
OTHER PUBLICATIONS
variation may be in accordance with a ramp function, a
Y.P. Tang and S.Y. Yang, “Transient Analysis of Tapered staircase function, a square wave function, as well as suit
Lines Based on the Method of Series Expansion,” IEEE able combinations of these and other functions. This varia
tion of grid element siZe in a grid-like ground plane provides
Transactions on Microwave Theory and Techniques, vol. 44,
cost-effective and ?exible control of signal trace impedance,
No. 10, Oct. 1996, pp. 1742—1744.
Y.P. Tang, Z. Li and S.Y. Tang, “Transient Analysis of without requiring any alteration in signal trace or dielectric
Tapered Transmission Lines Used as Transformers for Short material characteristics.
Pulses,” IEEE Transactions on Microwave Theory and Tech
niques, vol. 43, No. 11, Nov. 1995, pp. 2573—2578. 32 Claims, 9 Drawing Sheets
130
132
134
13E
1311
U.S. Patent 5,818,315
Oct. 6, 1998 Sheet 1 0f 9
FIG. 1A
DISTANCE
FIG. 1B
DISTANCE
FIG. 1C
DISTANCE
5,818,315
U.S. Patent Oct.6,1998 Sheet 2 of9
FIG. 2A
nnnnnn
CHIP 0 j
nCnH IPn nn1 nnj nCnHnI P 2 n5 CHIP 3 j CHIP nn4 nnj nCnHnInPn N nnj
FIG. 2B
,C HfIlP 0 5
H3 Cu
HP CL? ‘HI-‘L3 HP CLN
“c1115 Mann r. “CHIP 5 nn nnnn
CHIP 2 5 CHIP 4 j CHIP N j
5,818,315
U.S. Patent Oct.6,1998 Sheet 3 of9
MTNNANLN
U.S. Patent Oct.6,1998 Sheet 4 of9 5,818,315
FIG. 4A
FIG. 4B
U.S. Patent Oct.6,1998 Sheet 5 of9 5,818,315
FIG. 5
U.S. Patent Oct.6,1998 Sheet 6 of9 5,818,315
FIG. 7
120
d, 1
f 122 f 124 /12B /12B
U.S. Patent Oct.6,1998 Sheet 7 of9 5,818,315
130 FIG. 8
132 W
134 i
135 <
U.S. Patent 0411. 6, 1998 Sheet 8 of9 5,818,315
FIG. 9
/ A \
an; 2112 11 11
f 142 f 144 [145 f14s / 150
SUE 3H3 H
U.S. Patent Oct.6,1998 Sheet 9 of9 5,818,315
15° FIG. 10