Design of current-mode ladder filters using coupled-biquads

Abstract

A new design approach for current-mode (CM) filters is presented. The proposed method is based on simulating RLC ladder networks using coupled-biquad structures. The loop-and branch-currents are used as variables to generate transfer functions. These functions are realized by CM circuits implementing multiple output CMOS OTA's. The resulting CM structures use only grounded capacitors making them suitable for VLSI. To demonstrate the proposed approach, a low-pass and a band-pass ladder filter were designed and simulated using HSPICE.