The investigation and optimization of the RF frontend of radio frequency identification (RFID) tags represents a crucial topic when looking for an increased tag performance. This work studies the RF frontend of three state-of-the-art passive computational RFID tags: AMS SL900a Dev Kit, Farsens Spider Eval, and WISP 5.1. Given a module-based approach, the antenna, the matching network, the RF energy harvesting, and the load modulation are reviewed both theoretically and experimentally. The influence of a set of properties, corresponding to these modules, on the overall RFID tag performance is evaluated using a tag read range measurement.