Tzong-Lin Wu

Electromagnetic bandgap power/ground planes for wideband suppression of ground bounce noise and radiated emission in high-speed circuits

A power/ground planes design for efficiently eliminating the ground bounce noise (GBN) in high-speed digital circuits is proposed by using low-period coplanar electromagnetic bandgap (LPC-EBG) structure. Keeping solid for the ground plane and designing an LPC-EBG pattern on the power plane, the proposed structure omnidirectionally behaves highly efficiently in suppression of GBN (over 50 dB) within the broad-band frequency range (over 4 GHz). In addition, the proposed designs suppress radiated emission (or electromagnetic interference) caused by the GBN within the stopband. These extinctive behaviors of low radiation and broad-band suppression of the GBN is demonstrated numerically and experimentally. Good agreements are seen. The impact of the LPC-EBG power plane on the signal integrity for the signals referring to the power plane is investigated. Two possible solutions, differential signals and an embedded LPC-EBG power plane concept, are suggested and discussed to reduce the impact.

An Embedded Common-Mode Suppression Filter for GHz Differential Signals Using Periodic Defected Ground Plane

A novel low-cost filter design for common-mode noise suppression in high-speed differential signals is proposed. It is realized by periodically etching the dumbbell-shape defected ground structure (DGS) to perturb the return current of the common- mode noise. A transmission-line model for the proposed structure is also developed with good agreement to the full-wave simulation and measurement result. It is found that over 20 dB suppression of common-mode noise can be achieved over a wide frequency range from 3.3 to 5.7 GHz with 3 cascaded DGS cells, while the differential signals still keep good signal integrity in eye-pattern observation. The common-mode current, which generally results in common-mode EMI, on the attached input/output cable is also proved to be efficiently suppressed (15 dB in average) within the stopband by the proposed filter.

A novel power plane with super-wideband elimination of ground bounce noise on high speed circuits

A novel L-bridged electromagnetic bandgap (EBG) power/ground planes is proposed with super-wideband suppression of the ground bounce noise (GBN) from 600Mz to 4.6GHz. The L-shaped bridge design on the EBG power plane not only broadens the stopband bandwidth, but also can increase the mutual coupling between the adjacent EBG cells by significantly decreasing the gap between the cells. It is found the small gap design can prevent from the severe degradation of the signal quality for the high-speed signal referring to the perforated EBG power plane. The excellent GBN suppression performance with keeping reasonably good signal integrity for the proposed structure is validated both experimentally and numerically. Good agreement is seen.

A Novel Wideband Common-Mode Suppression Filter for Gigahertz Differential Signals Using Coupled Patterned Ground Structure

A wideband and compact filter design for common-mode noise suppression in high-speed differential signals is proposed based on two U-shaped and one H-shaped coupled patterned ground structure. An equivalent model of three coupled LC resonators to predict the common-mode suppression characteristics is also developed with good agreement to the full-wave simulation and measurement result. A test sample is designed and fabricated on a standard printed circuit board (PCB). It is found the common-mode noise can be reduced by the filter over 15 dB from 3.6 to 9.1 GHz and over 75% of amplitude in the time domain. More important, the differential signal integrity, in terms of insertion loss and group delay in the frequency domain and eye diagrams in the time domain, is not degraded within the wide bandwidth. The fractional bandwidth of the stopband can reach 87% and the filter size is about 0.44 lambdag times 0.44 lambdag. The radiation caused by the common-mode current on the attached I/O cables is also efficiently suppressed by 10 dB on average within the designed stopband. To our best knowledge, it is the first low-cost common-mode filter designed for the gigahertz high-speed signals with the largest fractional bandwidth and most compact size on a PCB.

Overview of Power Integrity Solutions on Package and PCB: Decoupling and EBG Isolation

Mitigating power distribution network (PDN) noise is one of the main efforts for power integrity (PI) design in high-speed or mixed-signal circuits. Possible solutions, which are based on decoupling or isolation concept, for suppressing PDN noise on package or printed circuit board (PCB) levels are reviewed in this paper. Keeping the PDN impedance very low in a wide frequency range, except at dc, by employing a shunt capacitors, which can be in-chip, package, or PCB levels, is the first priority way for PI design. The decoupling techniques including the planes structure, surface-mounted technology decoupling capacitors, and embedded capacitors will be discussed. The isolation approach that keeps part of the PDN at high impedance is another way to reduce the PDN noise propagation. Besides the typical isolation approaches such as the etched slots and filter, the new isolation concept using electromagnetic bandgap structures will also be discussed.

A novel ultraflattened dispersion photonic Crystal fiber

A novel four-ring photonic crystal fiber (PCF) structure with two different air-hole sizes is proposed with nearly zero ultraflattened dispersion characteristics. Through optimizing only three geometrical parameters, two air-hole diameters, and one hole pitch, the ultraflattened zero dispersion PCF can be efficiently designed. As an example, a four-ring PCF with flattened dispersion of /spl plusmn/0.25 ps/km/nm from 1.295- to 1.725-/spl mu/m wavelength is numerically demonstrated. The corresponding design procedures for the novel PCF are also presented in this letter.

A Broadband and Miniaturized Common-Mode Filter for Gigahertz Differential Signals Based on Negative-Permittivity Metamaterials

A novel wideband and miniaturized common-mode noise suppression filter is proposed based on the concept of an effective negative-permittivity metamaterial (MM) transmission line (TL). The propagation properties for the odd and even modes in the proposed structure are derived from the TL theory and Bloch theorem. Two- and four-port equivalent-circuit models are developed to explain the common-mode suppression characteristics. The dispersion relation has a good agreement with the full-wave simulation and measurement result. Based on the low-temperature co-fired ceramic fabrication technology, miniaturized common-mode filters with four and eight cells are realized using the concept of the effective negative-permittivity MM. For the four-cell structure, the filter size is 0.16 ¿g × 0.26 ¿g with the corresponding real size of 3.2 mm × 5.12 mm. It is found that the common-mode noise can be reduced over 10 dB from 3.8 to 7.1 GHz with the fractional bandwidth of 60% in the frequency domain, and is reduced over 50% for voltage amplitude in the time domain. More importantly, the differential signal integrity, in terms of insertion loss and group delay in the frequency domain and eye diagrams in the time domain, is not degraded within the wide stopband. To our best knowledge, it is the first broadband common-mode filter designed for gigahertz differential signals based on the concept of MM TL with most compact size.

A novel power planes with low radiation and broadband suppression of ground bounce noise using photonic bandgap structures

A novel power/ground planes design for eliminating the ground bounce noise (GBN) in high-speed digital circuits is proposed by using low-period photonic bandgap (PBG) structure. Keeping solid for the ground plane and designing low-period PBG pattern on the power plane, the proposed structure omni-directionally behaves highly efficient suppression of GBN (over 50 dB) within broadband frequency range from 1 GHz to 4 GHz. Although the power plane has low-period perforation, the proposed structure still performs with relatively low radiation within the stopband compared with the solid power/ground planes. The low radiation and high suppression of the GBN for the proposed structure are checked both experimentally and numerically. Good consistency is seen.

Numerical and experimental investigation of radiation caused by the switching noise on the partitioned DC reference planes of high speed digital PCB

Influence of the partitioning and bridging of the power/ground planes on the radiation caused by the switching noise on the dc reference planes is investigated both theoretically and experimentally. Based on the three-dimensional finite-difference time-domain modeling, the electromagnetic interference (EMI) performance of the partitioned power/ground planes is studied. Radiated emission at the 3-m distance from the tested boards is measured in a fully anechoic chamber. The measured and the numerical results agree generally well. The radiation behavior of four kinds of partitioned configuration of the power/ground planes is studied. It is found that completely isolating the noise source by the etched slits, or moats, significantly reduces the radiation level at the frequencies near resonance. However, bridges connecting two sides of the moat not only significantly degrade the ability of the EMI protection of the moat, but also excite a new low-frequency resonant mode. The effect of the geometrical parameters, such as the moat size, moat location, bridge width, and bridge position, on the radiation behavior of the printed circuit board is considered. The radiation mechanism of the EMI behavior of the partitioned dc reference planes is discussed.

Overview of Signal Integrity and EMC Design Technologies on PCB: Fundamentals and Latest Progress

This paper reviews the fundamentals and latest progress of modeling, analysis, and design technologies for signal integrity and electromagnetic compatibility on PCB and package in the past decades. Most results in this field are based on the very rich and highly educational literature produced by Prof. C. Paul in his long scientific career. The inclusion of parameters variability effects is also considered, and it is demonstrated how statistical simulations can become affordable by means of recently-introduced stochastic methods. Finally, the necessity of practical training of designers is mentioned, and an experience relying on realistic PCB demonstrators is illustrated.