Re: FW: [SI-LIST] : Output Impedance

skaufer@ix.netcom.com
Fri, 3 Apr 1998 02:50:47 -0600 (CST)

Regarding the simple Spice simulation to determine driver impedance:

The reason to prefer a transmission line to a resistor is pure laziness: with the t-line, you don't need to change the pull-
up/down voltage to go from one edge to the other. But of course the resistor does work just as well.

The formula as originally posted was indeed incorrect. It is Rdrv = Z0*((Vfinal/Vstep) - 1).

Steve Kaufer,
HyperLynx

On 04/01/98 13:34:00 you wrote:
>
>
>Text item:
>
>You might as well just use a resistor to Vcc for falling edges and a resistor to
>GND for rising edges, after all an (infinitely) long transmission line looks the
>same as a resistor to the driver...
>
>Arpad
>================================================================================