  We have conducted a search of 19 southern Galactic globular clusters for
sub-millisecond pulsars at 660 MHz with the Parkes 64-m radio telescope. To
minimize dispersion smearing we used the CPSR baseband recorder, which samples
the 20 MHz observing band at the Nyquist rate. By possessing a complete
description of the signal we could synthesize an optimal filterbank in
software, and in the case of globular clusters of known dispersion measure,
much of the dispersion could be removed using coherent techniques. This allowed
for very high time resolution (25.6 us in most cases), making our searches in
general sensitive to sub-millisecond pulsars with flux densities greater than
about 3 mJy at 50 cm. No new pulsars were discovered, placing important
constraints on the proportion of pulsars with very short spin periods in these
clusters.
