Micropower active-RC channel filter for a zero-IF Bluetooth receiver

Abstract

A fourth-order low-pass channel filter for a zero-IF Bluetooth receiver is presented. It employs two cascaded multiple feedback biquads and active resistors made by quasi-floating gate MOS transistors in triode region for highly linear continuous tuning. Power consumption is strongly reduced using a gain-enhanced class-AB single-stage opamp together with a filter topology that only requires a single opamp for each biquad. The filter has been fabricated in a 0.18 μm CMOS technology and consumes 290 μW from a 1.2 V supply.