Allpass Transfer Function Figure below shows the principal value of the phase of the 3rd-order allpass function 0.2+0.18z-1+0.4z-2+ A3(=) 1+0.4x-1+0.18z-2-0.2z note the discontinuity by the amount of 2t in the phase e(o) Principal value of phase -2 0.8 o/π Copyright C 2001, S K Mitra9 Copyright © 2001, S. K. Mitra Allpass Transfer Function • Figure below shows the principal value of the phase of the 3rd-order allpass function • Note the discontinuity by the amount of 2p in the phase q() 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 0 0.2 0.4 0.6 0.8 1 -4 -2 0 2 4 /p Phase, degrees Principal value of phase