Realisation of lattice wave digital filters using three-port adaptors

The second-order allpass section is the main building block of the lattice wave digital filter (LTWDF). This is conventionally realised using two-port adaptors. The authors present comparison between the two-port realisation of the second-order allpass section and another based on the three-port series adaptor. It is shown that the sample rate of LTWDFs can be increased by up to 90% with the three-port realisation