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STEP 3: Create Models.
ECL100K driver and receiver
These are included in OrCAD's standard libraries.
Shielded ribbon cable with adjacent differential signals
The specifications for the ribbon cable are:
Wire radius (mils) = 7.5
Insulation thickness (mils) = 10.0
Relative dielectric constant of insulation = 3.5
Adjacent wire separation (mils) = 50.0
The L and C matrices are obtained from the 2-D code in [3].
L11=0.74850 uH/m
L12=0.5077 uH/m
L22=0.74850 uH/m
C11=37.432 pF/m
C12=18.716 pF/m
C22=37.432 pF/m
Attenuation curves have been fitted to R and G:
R={851u*sqrt(2*s)} ohms/m
G={-0.340p*abs(s)} siemens-m
The alternate twinax cable has the following specifications:
L11=L22=332.730 nH/m
C11=C22=57.02 pF/m
L12=253.85 nH/m
C12=45.131 pF/m
R={241.315u*sqrt(2*s)} ohms/m
G={-0.140442p*abs(s)} siemens-m
This cable is better matched to the PCBs, but is more expensive.
PCB trace
The ECL clock will be routed on an outer layer of a PCB (microstrip) with the following properties:
An impedance of 75+/-10 ohms will be used. The propagation delay is 0.16 ns/in. Simulations should
investigate the effect of the upper ends of the tolerance range.
D-SUB connector with 2:1 signal to ground pin arrangement
