In this study four proposed structures for the digital decimation filter which is used in ΣΔ A/ D converters of Asymmetrical Digital Subscriber Line (ADSL) are presented. Single multi rate (Finite Impulse Response) FIR, single multi rate (Infinite Impulse Response) IIR, three stages comb-FIR-FIR and comb-IIR-FIR are the four proposed structures. The hardware minimization is considered for each structure. The simulation results and the implementation of each structure are presented. Finally, a comparison between the four proposed structures is done to choose the best proposed structure based on the hardware cost.