An adaptive CMOS transmission line driver

Fabrication process tolerances prevent the direct and precise matching of off-chip driver impedances to the impedances of driven transmission lines. The adaptive circuit described automatically adjusts the output impedance of a reference driver to that of a reference transmission line and generates a control voltage for adjusting the output impedances of the other drivers on the same chip to the same impedance. Simulation shows a ten-to-one reduction in the impedance mismatch.<
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