A programmable driver/equalizer with an alterable FIR enables the equalization
of serial links or other transmission systems to adapt to a variety of transmission
media, specifically, intersymbol interference (ISI). Current mode differential
drive circuits are coupled to a transmission media via a Finite Impulse Response
(FIR) filter operating in the Z transform mode. The FIR filter includes A and B
coefficient setting circuit, and is coupled to the drivers. The driver circuit
also includes A coefficient level driver compensation and B coefficient level driver
compensation to reduce self-induced ISI from the driver while the filter coefficients
are activated. The coefficient setting circuit receive a combination of control
bits to select the appropriate response for the driver to the various transmission
media parameters. Adjustments to the driver output current are made at data run
lengths exceeding certain values and subsequent adjustments are made for data run
lengths exceeding larger values.