A transmission line equalizer, communication system, and method are
provided for adaptively compensating for changes in transmission path
length and transmission path medium. Within the equalizer is a filter
that exhibits a high pass characteristic and, more specifically, has an
inverse frequency response to that of the transmission path. The inverse
filter can include a pair of amplifier stages coupled in parallel, with a
mixer chosen to adaptively select portions of one stage over than of the
other. The dual stage inverse filter can, therefore, adapt to greater
transmission path lengths and/or attenuation. A feedback architecture is
used to set the inverse filter response by measuring the amplitude of a
communication signal output from the inverse filter during periods of low
frequency. A peak detector will capture a peak-to-peak voltage value
during those periods, and adjust the output of the slicer to match a
launch amplitude of the communication signal. The peak detector within
the feedback architecture helps ensure the predicted amplitude matches
the launch amplitude to minimize over-compensation or under-compensation
even though a different integrator might register no difference in
integrated voltage or energy at the output of the inverse filter compared
to the output of the slicer.