Region of convergence(Roc) l Fbr any given sequence, the set of values of z for which the z-transform converges is called the region Of Convergence(ROC) z-plane X()=∑” n=0 if some value of Z, say Z=Z1 is in the rocr Re then all values of z on the circle defined by z=z, Will also be in the roc if roc includes unit circle then fourier transform and all its derivatives with respect to w must be continuous functions of w.9 2021/1/31 Zhongguo Liu_Biomedical Engineering_Shandong Univ. z1 Region of convergence (ROC) ◆For any given sequence, the set of values of z for which the z-transform converges is called the Region Of Convergence (ROC). if some value of z, say, z =z1 , is in the ROC, then all values of z on the circle defined by |z|=|z1 | will also be in the ROC. if ROC includes unit circle, then Fourier transform and all its derivatives with respect to w must be continuous functions of w. ( )     = − = n 0 n X z x n z