A comprehensive review and fair comparison of previous priority encoder (PE) designs over the past one and a half decades are presented using a 45 nm technology. Further, potential limitations of existed PEs are identified, based on which we propose a robust PE design. The new PE is able to eliminate race condition and charge sharing problem which are suffered by almost all the previous designs. Besides, the proposed PE can also be used in comprising higher order PEs by incorporating a carefully designed look-ahead structure. Simulation results demonstrate that our design can achieve one of the best power and delay performance among previous PEs and are free from potential risks.