Orthonormal ladder filters

A state-space structure for the realization of arbitrary filter transfer-functions is presented. This structure should prove useful where integrators are the basic building blocks such as in transconductance-C, MOSFET-C, or active-RC filters. The structure is derived from a singly terminated LC ladder and has the characteristics that it is always scaled for optimum dynamic range and its integrator outputs are orthogonal. For this reason, the resulting realizations are called orthonormal ladder filters. Since dynamic range scaling is inherent to the proposed structure, it is felt that this design technique may be most useful in programmable or adaptive filters. The sensitivity and dynamic range properties of an orthonormal ladder filter are shown to be comparable in performance to the equivalent properties obtained from a cascade of biquads.<>