Simple FIR Digital Filters The 3-db cutoff frequency of a cascade of m sections is given by O=2 cOS (2-12M ·ForM=3, the above yields o=0.302兀 Thus the cascade of first-order sections yields a sharper magnitude response but at the expense of a decrease in the width of the passband Copyright C 2001, S K. MitraCopyright © 2001, S. K. Mitra 11 Simple FIR Digital Filters • The 3-dB cutoff frequency of a cascade of M sections is given by • For M = 3, the above yields • Thus, the cascade of first-order sections yields a sharper magnitude response but at the expense of a decrease in the width of the passband 2cos (2 ) 1 1/ 2M c − − w = wc = 0.302p