The performance of an active power filter (APF) depends on the inverter characteristics, applied control method, and the accuracy of the reference signal generator. The accuracy of the reference generator is the most critical item in determining the performance of APFs. This paper introduces an efficient reference signal generator composed of an improved adaptive predictive filter. The performance of the proposed reference signal generator was first verified through a simulation with MATLAB. Furthermore, the application of feasibility was evaluated through experimenting with a single-phase APF prototype based on the proposed reference generator, which was implemented using the TMS320C31 floating-point signal processor. Both simulations and experimental results confirm that our reference signal generator can be used successfully in practical APFs.