Previous approach: lumped RLC method

• Segment line into lumped R,L,C elements [Dommel 69]

R

C

L

m Internal nodes emulate line's internal behaviour

m Problems in long lines and fast waveforms

m Fast edges Þ cluster internal nodes close together

to capture edges accurately Þ fine segmentation

Ô Long lines Þ many segments Þ large ckt. matrix

Ô LC lumping Þ resonance Þ spurious responses

Previous slide Next slide Back to the first slide View Graphic Version

Notes:

Other methods exist for the simulation of lossy transmission lines.

The pseudo-lumped method is a variant of the lumped-RLC method.

In this method, the line is segmented, but the inductors and capacitors in each segment are replaced by a lossless transmission line.

In the convolution method, to be described in more detail later, the linearity of the line is exploited by convolving the impulse-respones of the line with the voltages and currents at the end of the line.

Waveform relaxation has recently been used for lossy line simulation - the key feature here is to solve the circuit's equations in both the time and frequency domains.

FFTs are used to switch domains when necessary