In this study, conventional band (C band) erbium doped fibre amplifiers (EDFA) and long band (L band) EDFAs are analyzed to obtain better flat gain characteristics. For this purpose, three C band EDFA and two L band EDFA configurations are established. The effects of the fibre Bragg grating (FBG), gain flattening filter (GFF), two stage system, optical feedback loop, and amplified spontaneous emission (ASE) reflection techniques are observed in these configurations. Among all configurations two-stage EDFA with GFF and uniform FBG (UFBG) has the lowest ripple results in C band. In L band, the results of the two-stage EDFA with optical feedback loop are close to other L band structure but have better results.