IBIS Pulldown IV Curve

Pulldown IV Curve

By Timothy Coyle

How to Generate the Pulldown IV Curve

We are going to use the CMOS totem pole architecture as our example buffer in the next few sections. What we talk most about at the end of the day with Signal Integrity is the drive strength of the buffer in terms of impedance.

The Pulldown IV Curve Sweep

The Pulldown IV curve represents the drive strength of the buffer when driving low. The input of the buffer is set to a logic low and a DC voltage source is placed on the output. The voltage is varied from –Vcc to 2*Vcc and the current is measured. The data is then compiled into the IBIS IV (current-voltage) table.

References and Links

“IBIS Modeling Cookbook for IBIS Version 4.0”, IBIS Open Forum, 2005.

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