  A new high time resolution observing mode for the Murchison Widefield Array
(MWA) is described, enabling full polarimetric observations with up to 30.72
MHz of bandwidth and a time resolution of ~0.8 $\mu$s. This mode makes use of a
polyphase synthesis filter to "undo" the polyphase analysis filter stage of the
standard MWA's Voltage Capture System (VCS) observing mode. Sources of
potential error in the reconstruction of the high time resolution data are
identified and quantified, with the S/N loss induced by the back-to-back system
not exceeding -0.65 dB for typical noise-dominated samples. The system is
further verified by observing three pulsars with known structure on microsecond
timescales.
