The EXO programme is a two-phase experiment to search for neutrinoless double beta decay. The first phase, EXO-200, yielded the first measurement of two neutrino double beta decay in Xenon and one of the most sensitive searches for neutrinoless double beta decay. The second phase, nEXO, is a proposed 5 tonne liquid xenon time projection chamber (TPC) that will implement several improvements over EXO-200. One such improvement is the usage of silicon photomultipliers (SiPMs) instead of avalanche photodiodes (APDs) as scintillation light detectors. By optimizing the light collection, reducing electronic noise and improving the SiPM performance, we can achieve a 1% energy resolution at the Xe-136 double beta decay end point. In this presentation, I will discuss the electronics readout of large area FBK UV sensitive SiPMs at liquid xenon temperatures and the digital filtering of SiPM waveforms.