A new class of very low sensitivity cascade-form digital-filters based on 'passive' second order single-input single-output building blocks

A new type of cascade form structure for digital filtering is proposed, with each building block being a second order section, that satisfies certain passivity properties. This passivity is essentially a "structure-induced" boundedness on the transfer function magnitude, and leads to low passband sensitivity. In addition, the cascade nature ensures low stopband sensitivity, as zeros on the unit circle continue to remain on the unit circle in spite of the quantization. The structure itself is independent of the pole locations and therefore meets a wide range of filtering applications.