Optimized analog filter designs with flat responses by semi-definite programming

Abstract—Analog filters constitute indispensable components of analog circuits. Inspired by recent advances in digital filter design, this paper provides a flexible design for analog filters. All-pole fil-ters have maximally flat passband, so our design minimizes their passband distortion. Analogously, maximally flat filters have max-imally flat passband, so our design maximizes their stopband at-tenuation. Its particular cases provide flexible alternatives to the classical counterparts. Semidefinite program (SDP) formulations for the posed filter design problems are presented, which are ef-ficiently solved by existing optimization software. Several exam-ples and comparisons are provided to validate the viability of our design. Index Terms—Analog filter, convex analysis, global optimization, semidefinite programming (SDP). I