1430 IEEE ANTENNAS AND WIRELESS PROPAGATION LETTERS, VOL. 11, 2012
Embedded Planar EBG and Shorting Via Arrays
for SSN Suppression in Multilayer PCBs
Jianjie Li, Junfa Mao, Fellow, IEEE, Siwei Ren, and Haoran Zhu
Abstract—This letter presents a comprehensive investigation
of the low-frequency performance of planar electromagnetic
band-gap (PEBG) structures embedded between two shorted
solid planes. It is shown that the low-frequency behavior of the
combination design of embedded PEBG (EP-EBG) and shorting
via arrays is quite different from that of traditional two-layer
PEBG. Techniques for reducing the lower side cutoff frequency of
EP-EBG in multiple plane p airs are then discussed and p resented.
Excellent simultaneous switching noise (SSN) suppression and
signal integrity (SI) can be simultaneously achieved in two plane
pairs of the multi-via mushroom EP-EBG structure. Both the
simulated and measured results are given to validate the ideas.
Index Terms—Planar electromagnetic band-gap (PEBG),
shorting via arrays, simultaneous switching noise (SSN).
I. INTRODUCTION
W
ITH the increase of clock s
peed and decrease of
supply vo ltage, simultaneou s switching noise (SSN)
has become one of the major challenges for high-speed
printed circuit boar
ds (PCBs). In recent years, electromagnetic
band-gap (EBG ) structures have been proposed for minimizing
the SSN coupling between po wer/groun d planes [1]. Mushroom
EBG (MEBG) [2], [ 3]
and planar EBG (PEBG) [4]–[6] are two
mainly studied types of EBG topologies. MEBG consists of
three layers in one plane pair where periodic metallic patches
and vias are ins
erted between the power/ground planes. In order
to reduce fabrication cost, PEBG is developed by designing the
periodic patterns directly on the power or ground metal planes.
However, the
etched slots on the metal layer may cause poten-
tial signal integrity (SI) problem s. Emb edded PEBG (EP-EBG)
is one of the possible solutions to minimize the influence o n
the SI [6]
.
Due to the trend of h igh density and miniaturization, modern
high-speed integrated circuits (ICs) often contain multiple
power/gr
ound planes and hundred s to thousands of vias and
striplines. Evidently, SSN should be simultaneously suppressed
in multiple plane p a ir s to improve the power integrity ( PI) and
SI perf
ormance. Previous PEBG was mainly investigated for
noise su ppression in only one plan e pair and only applicab le
to the outmost layer of multilayer PCBs. EP-EBG is a possible
Manuscript received September 04, 2012; revised October 26, 2012; accepted
November 07, 2012. Date of publication November 20, 2012; date of current
version December 18, 2012. This work was supported by the National Basic
Research Program (973 Program) of China under Grant 2009CB320202.
The authors are with the Key Laboratory of Ministry of Education of China
for Research of Design and Electro magnetic Compatibility of High speed
Electronic Systems, Shanghai Jiao Tong University, Shanghai 200240, China
(e-mail: jfmao@sjtu.edu.cn; mj.li@yahoo.com.cn).
Color versions of one or more of the figures in th is letter are av ailable online
at http://ieeexplore.ieee.org.
Dig
ital Object Identifier 10.1109/LAWP.2012.2228149
solution to achieve n oise s u ppression in multip le plane pairs.
Nevertheless, the application of EP-EBG in mu lti layer PCBs is
not straightforw ard since the stopband of EP-EBG would di-
minish or even disappear when the patterned layer is embedded
between two s olid planes [6]–[8].
Only a few works focused on the case where the PEBG was
laid out in an i nner layer of multilayer PCBs [6]–[8]. In [6]
and [8], a technique for m aintaining the band-gap of EP-EBG
was employed by directly short ing the tw o solid planes, above
and below the PEBG, through a large amount of sh orting vias.
The sho rting via arrays are able to inhibit the reso nance of the
two solid planes for ensuring the designed band-gap. As de-
scribed in [8], the high-frequency performance of EP-EBG com-
bined with shorting via arrays was related to the resonant char-
acteristic of two shorted solid planes. However, the low-fre-
quency performance of EP-EBG com b ined with shorting via ar-
rays is n ot studied up until now.
On the other hand , the lower side cutoff frequency
of
EP-EBG does not vary with the i ncr ease of shorting vias. As
shown in [9], signal transmission quality w as excellent withi n
the stopband of EBG structure as though it was free from cavity
resonances. In contrast, its quality would be seriously degraded
outside the stopban d region. Thus, it is essential to make
of EP-EBG smaller than the clock rate for ensuring good SI
performance.
In this letter, the low-frequency performance of PEBG em-
bedded in two shorted sol id planes is stu died first. The same
low-frequency transm ission characteristics are observed in two
plane pairs of EP-EB G, and a qualitative analysis is given. Then,
design strategies of adding an additional metal layer to simulta-
neously reduce
of EP-EBG in two plane pairs are presented
and discussed. In the end, SI performance of the EP-EBG is
analyzed.
II. L
OW-FREQUENCY PERFO RMAN CE OF EP-EBG COMBINED
WITH SHORTING V IA ARRAYS
The b iggest difference between EP-EBG and two-layer
PEBG is the
band-gap of EP-EBG will disappear or minimize
when PEBG layer is embedded between two solid planes. As
mentioned abo ve, shorting via arrays could be introd uced to
maintai
n the band-gap of EP-EBG. Since the high-frequency
performance o f EP-EBG combined with shorting via arrays
was investigated in [8], we m ainly investigate the low-fre-
quenc
y performance of EP-EBG in this letter. As indicated, the
low-frequency characteristic o f PEBG e m bedded between tw o
shorted solid planes is quite different from that of traditional
two-
layer PEBG.
L-bridged PEBG [10] is ch osen as the etched layer of
EP-EBG. The topology of a typical EP-EBG shorted by peri-
odi
c vias and its corresponding pa ram eters are shown in Fig. 1.
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