Hspice TUTORIAL


Reflected Wave Simulation


Let us remove the termination resistor by commenting out the termination resistance as

*Rtermination 4 0 50

This creates a circuit situation similar to the PCI Bus. The waveform gets reflected at the receiver and doubles. Here is the hspice code. 

* Stripline circuit
.Tran 50ps 3.5ns
.OPTION Post Probe
VIN 1 0 PWL 0 0v 250ps 0v 350ps 3.3v
Rsource 1 2 50
Tfirst 2 0 3 0 ZO=50 TD=0.17ns
*C2 3 0 2p
Tsecond 3 0 4 0 ZO=50 TD=500ps
*Rtermination 4 0 50
.Probe v(1) v(2) v(3) v(4)
.End


The waveforms produced by simulation looks similar to the figure below.



Reflected wave simulation waveform.

In the next page we will see the effect of source impedance.