A double binary-tree FIR-filter form and the corresponding low-sensitivity IIR bandpass/bandstop structure

An FIR filter comprising back-to-back binary trees, each using multiple-sample delay blocks, offers advantages; (1) for rate-changing filters, (2) when block delays are especially hardware efficient, and (3) when replacing block delays with allpass sections to create an IIR filter. In the latter case, the peak group delays of the allpass sections approximate the several distinct delays of the blocks replaced. With allpass sections fixed, the combining weights are easily optimized.