A method and apparatus for analog compensation of driver output signal slew
rate against device impedance variation is described. The method includes
a signal termination device coupled to a driver output pad. The driver
includes a plurality of pull-up devices where each pull-up device is
coupled between a driver supply voltage and the signal termination device.
In addition, corresponding pull-down devices are coupled between a driver
ground and the signal termination device. The driver includes pull-up and
pull-down compensation resistive elements coupled in series between
selected pull-down/pull-up devices and the signal termination device.
Accordingly, the pull-up and pull-down compensation resistive elements
provide analog compensation of a driver output signal slew rate against
device impedance variation. Also, a slew rate of the driver output signal
is within a predetermined slew rate range in order to avoid uncontrolled
fast switching as well as unnecessarily slow switching in the driver
output signal.