A method and an apparatus are provided for filtering a substantially square
wave signal. At least a portion of the substantially square wave signal is
applied to a first filter adapted to pass a range of frequencies adjacent
the fundamental frequency and produce a first filtered signal. At least a
portion of the substantially square wave signal is also applied to a
plurality of second filters, where each of the second plurality of filters
is adapted to pass a range of frequencies adjacent an odd harmonic
component of the fundamental frequency and produce a second filtered
signal. The first signal and the plurality of second filtered signals are
combined to produce a representation of a square wave signal having a
frequency substantially corresponding to the fundamental frequency.
