Synthesis of log-domain filter with well-defined operating point

Abstract

A new systematic approach for the design of nth order log-domain filters is presented. By eliminating the bias uncertainty, proper working condition is guaranteed for log-domain CMOS realization. This approach is based on the inverse-follow-the-leader-feedback (IFLF) topology and DC negative feedbacks are introduced to define the bias condition. To illustrate the proposed approach, a fourth order low-pass filter is designed and simulated in HSPICE.