US Patent 7126378 High speed signaling system with adaptive transmit pre-emphasis

A signaling system having first and second sampling circuits and an output driver circuit. The first sampling circuit samples a first signal generated by the output driver circuit to determine whether the first signal exceeds a first threshold. The second sampling circuit samples the first signal to determine whether the first signal exceeds a second threshold. The drive strength of the output driver circuit is adjusted based, at least in part, on whether the first signal exceeds the first and second thresholds, and the second threshold is adjusted based, at least in part, on whether the first signal exceeds the second threshold.