  A majority of early-type galaxies contain interstellar dust, yet the origin
of this dust, and why the dust sometimes exhibits unusual polycyclic aromatic
hydrocarbon (PAH) ratios, remains a mystery. If the dust is internally
produced, it likely originates from the large number of AGB stars associated
with the old stellar population. We present GALEX and WISE elliptical aperture
photometry of $\sim310$ early-type galaxies with Spitzer mid-infrared
spectroscopy and/or ancillary data from ATLAS3D, to characterize their
circumstellar dust and the shape of the radiation field that illuminates the
interstellar PAHs. We find that circumstellar dust is ubiquitous in early-type
galaxies, which indicates some tension between stellar population age estimates
and models for circumstellar dust production in very old stellar populations.
We also use dynamical masses from ATLAS3D to show that WISE W1 (3.4 $\mu$m)
mass-to-light ratios are consistent with the initial mass function variation
found by previous work. While the stellar population differences in early-type
galaxies correspond to a range of radiation field shapes incident upon the
diffuse dust, the ratio of the ionization-sensitive $7.7\mu$m to $11.3\mu$m PAH
feature does not correlate with the shape of the radiation field, nor to
variations with the size-sensitive $11.3\mu$m to $17\mu$m ratio. The $7.7\mu$m
to $11.3\mu$m PAH ratio does tend to be smaller in galaxies with proportionally
greater $H_2$ emission, which is evidence that processing of primarily smaller
grains by shocks is responsible for the unusual ratios, rather than substantial
differences in the overall PAH size or ionization distribution.
