ECE 451
Automated Microwave Measurements Laboratory
Experiment No. 12
EYE DIAGRAM SIMULATION USING ADS
1. INTRODUCTION
The performance of high-speed digital systems is a strong function of the input-output bandwidth
of the communication channels. Present-day requires the transmission of data at multi-gigabit
rates over interconnects in which channel signal degradation due to losses and crosstalk are
prominent. Skin effect and dielectric absorption introduce dispersion in these channels and limit
the overall performance at higher data rates.
Intersymbol interference is observed when a symbol sent over a line at a certain time, interferes
with another symbol over the same line at a different time. This is due to the fact that the residual
energy from the transmitted bit can be transfreed to the next bit and thus corrupt the information.
Intersymbol interference limits the maximum data rate that can be applied into a package.
Interconnects are modeled as transmission lines and can be simulated using different design
automation tools such as ADS. The effect of intersymbol interference is analyzed and
demonstrated by using eye diagrams at different bit rates on different types of transmission lines.
2. SIMULATION STEPS IN ADS
To start Agilent Advanced Design System, select Start > Programs > Advanced Design
System 2003 to load the program.
• Create a new project in your network directory, open a schematic window. The
following schematic diagram will be used to illustrate an eye diagram simulation. Draw
the schematic diagrams and run the transient simulation.
After running the simulation, open a data display window. The eye command in ADS will be
used to create a data for the eye diagram plot. Write an equation using eye command and the
output waveform (e.g. Vout).
Synopsis:
y = eye(data, symbolRate{, Cycles{, Delay}})
where
data is either numeric data or a time domain waveform typically from
the I or Q data channel.
