Analysis of Crosstalk Between Parallel Striplines
Using the Finite-Difference Time-Domain Method
Aug 23, 1996
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- Abstract
- The impact of interconnects on circuit performance in both the
analog and digital domains is ever increasing. No longer can
interconnects be treated as mere delays or lumped RC networks.
Crosstalk, ringing and reflection are just some of the issues
that need to be understood then circumvented or utilized.
The most common simulation model for interconnects is the
distributed RLCG model. Unfortunately, this model has many
limitations which can lead to inaccurate simulations if not
used correctly. This report uses the FDTD method to investigate
crosstalk between transmission lines. The actual electromagnetic
waves that propagate along striplines are computed allowing a
direct, physical simulation of the coupling between striplines.
The results are compared to theoretical and HSPICE computations.
While all three computations agree qualitatively, the
magnitudes of the crosstalk signals are quite different. The
HSPICE computation is incorrect because the calculated coupling
parameters are too large. The FDTD results, on the other hand,
are within 25% of theory and can be further improved by using
finer discretizations.
The FDTD method produces useful and accurate resuls in the
simple problem of analyzing crosstalk between parallel coplanar
transmission lines. However, its distinguishing characteristic
is its ability to simulate 3-D interconnect structures or
structures exhibiting the skin effect. Since the FDTD method can
be parallelized easily, this method is likely to be used to
analyze ever more complex interconnects on massively parallel
computer.
- FDTD simulation of Gaussian pulse propagating down a stripline
Schematic drawing of the coupled striplines
Theoretical voltage waveforms on the passive line
FDTD and HSPICE voltage waveforms on the passive line
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