Numerical performance of non-canonic block state digital filters

Several noncanonic block structures of IIR (infinite impulse response) digital filters are analyzed for numerical performance. Roundoff noise of fixed point noncanonic block structures is compared with that of canonic structures. Proper scaling of nonstate as well as state variables is considered, and explicit expressions for noise gains are derived. It is shown that the output noise due to additional noise sources in these structures cancels out most of the gain obtained from blocking algorithms and may dominate that due to static variables in canonic structures.<>