Orthonormal Ladder Structure Log-Domain Filter

A novel method for the design of log-domain filters is presented which is based on the operational simulation of orthonormal ladder networks. The approach permits the realization of a given arbitrary filter transfer functions. By using the method, a third-order log-domain elliptic lowpass filter with 1 dB ripples is designed. PSPICE simulations show the proposed filter possesses almost ideal frequency responses, simple circuit topology, low sensitivity and optimum dynamic range, etc.