Allpass Transfer Function · The expression M AM/(=)=土 2 D M(2 2 implies that the poles and zeros of a real coefficient allpass function exhibit mirror image symmetry in the z-plane 02+0.18z1+0.42+2÷0s A(二)= 1+0.4z-1+0.18z-2-0.2z 0 Real part Copyright C 2001, S K Mitra6 Copyright © 2001, S. K. Mitra Allpass Transfer Function • The expression implies that the poles and zeros of a real￾coefficient allpass function exhibit mirror￾image symmetry in the z-plane ( ) ( ) ( ) D z z D z M M M M A z − −1 =  1 2 3 1 2 3 3 1 0.4 0.18 0.2 0.2 0.18 0.4 ( ) − − − − − − + + − − + + + = z z z z z z A z -1 0 1 2 3 -1.5 -1 -0.5 0 0.5 1 1.5 Real Part Imaginary Part