Design and implementation of an MRC-C TQE filter with on-chip automatic tuning

Abstract

This work describes the design and implementation of the tuning loops (both central frequency and quality factor control loops) for a bandpass continuous-time fully-balanced filter based on a modification of the Transimpedance Q-Enhancement (TQE) structure, intended for audio-band applications. The circuit has been designed and fabricated in a CMOS 0.8 /spl mu/m technology, and MRC (MOS Resistive Circuit) cells have been used to implement electronically tunable active resistors. Both post-layout transistor-level simulation results and experimental results validate the functionality of the tuning system.