Allpass Transfer Function (2)The magnitude function of a stable allpass function A(z)satisfies <1,.for|z>1 A(=)=1,r=1 1. for z<1 B3)Let to) denote the group delay function of an allpass filter A2),1.e T()=-o(0 17 Copyright C 2001, S K Mitra17 Copyright © 2001, S. K. Mitra Allpass Transfer Function • (2) The magnitude function of a stable allpass function A(z) satisfies: • (3) Let t(w) denote the group delay function of an allpass filter A(z), i.e.,        = =   1 for 1 1 for 1 1 for 1 z z z A z , , , ( ) t(w) = − [q (w)] w c d d