A Time to Digital Converter was designed (CMOS 0.35 $\mum) in order to be
used in Liquid Xenon PET prototype. The circuit proved to be able to work at
-120 degrees C, while showing a resolution of 250 ps. The circuit enables a low
readout dead time (<90 ns) and provides a fully synchronous digital interface
for easy data retrieval.Comment: 4 pages, submitted to IEEE Transactions on Nuclear Scienc