This paper presents a simple method to design an efficient comb-based decimation filter with low power, high aliasing attenuation, and low passband deviation, thus satisfying high requirements in different applications. More specifically, we present here how to improve the passband characteristic of a low-power comb-based decimator with a high aliasing rejection, proposed in the literature. We proposed a low complexity multiplierless compensator to correct for the passband droop. First, the optimal compensator was designed using a Particle Swarm Optimization (PSO). Next, the compensator parameters are expressed in the Signed-Power-of-Two (SPT) form to obtain a multiplierless design since the SPT parameters are implemented using shifts and add. The proposed design is compared with the original comb-based decimation filter and one relevant literature work. Our comparison clearly demonstrates the advantages of our proposed design over existing methods, thereby highlighting its potential for practical applications.