This paper reviews recent progress and future directions of signal integrity design for high-speed digital circuits, focusing on four areas: signal propagation on transmission lines, discontinuity modeling and characterization, measurement techniques, and link-path design and analysis.

Signal Integrity Design for High-Speed Digital Circuits: Progress and Directions

Printed circuit board

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.

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

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.

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

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.

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

Provided are common mode filtering method and device for use with a defected ground structure, the device including a substrate, coupled microstrip lines formed on the substrate and a ground plane formed underneath the substrate, the common mode filtering method being characterized by forming at least a defected ground structure on the ground plane and making dual mode signals pass through the coupled microstrip lines, thereby using the defected ground structure to suppress dual model noises within a specific frequency band and prevent signal distortion.

Common mode filtering method and device

A novel low-cost filter design for common-mode noise suppression in high-speed differential signals is proposed. It is realized by etching a HU-shaped defected-ground structure (DGS) to perturb the return current of the common-mode noise. A simple LC resonator model for the proposed structure is also developed with good agreement to the full-wave simulation and measurement result. It is found that over 15 dB of common-mode noise suppression can be achieved over a wide frequency ranges from 3.6 to 9.1 GHz, while the differential signals still keep good signal integrity in eye-pattern observation.

A novel HU-shaped common-mode filter for GHz differential signals

The modeling methodology of power distribution system (PDS) in three different levels, chip, package, and PCB for Input/Output (I/O) interface of DDR3 high-speed memory is established. The simulation results are verified with measurement results in frequency domain. Good agreement between them is clearly seen. The co-simulation with three kinds of PDS at the I/O interface and off-chip driver (OCD) circuits is constructed for time-domain simulation. The input impedance of three different PDSs is shown, and the simulation results for voltage variation and eye-patterns are compared with the corresponding input impedance. It is found lower input impedance have better power and signal integrity for the high-speed memory interface circuits. The PDS co-simulation of chip-package-PCB is important for the DDR3 circuit design.

Power integrity chip-package-PCB co-simulation for I/O interface of DDR3 high-speed memory

Provided are a common mode wave filter device and a wave filter method for use with a defected ground structure, the device comprising a substrate, a coupling micro-band wire formed on the substrate and a ground plane formed underneath the substrate, the common mode wave filter method being characterized by forming at least a defected ground structure on the ground plane and passing through dual mode signals on the coupling micro-band wire, thereby using the defected ground structure to suppress dual model noise signals within a specific frequency band and to prevent signals from losing realness

Shu-Jung Wu

Papers

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

Common mode filtering method and device

A novel HU-shaped common-mode filter for GHz differential signals

Power integrity chip-package-PCB co-simulation for I/O interface of DDR3 high-speed memory

Common mode wave filter device and method applicable to defected ground structure