Software for a Monte Carlo based simulation of a future Time-of-Flight (TOF) Positron Emission Tomography (PET) system's scintillator geometry, multi-pixel silicon photomultiplier and high-speed Analog to Digital Converter (ADC) readout system has been developed. Results from running simulations with different ADC sampling-rates and analog filter time constants are being presented. A trigger-system suitable for running real time in FPGAs, a digital constant fraction zero crossing discriminator, are used to determine the full system time resolution.