A 100kHz – 20MHz reconfigurable nauta g<inf>m</inf>-C biquad low-pass filter in 0.13µm CMOS

Abstract

A fully reconfigurable g <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">m</sub> -C biquadratic low-pass filter is presented with a bandwidth tunable over more than two orders of magnitude starting from 100 kHz up to 20 MHz able to cover all common wireless standards. Furthermore, power and performance can be traded thanks to a new switching technique inside Nauta's transconductor that allows changing its transconductance and input capacitance independently. Bandwidth, quality factor, noise level, linearity and common mode suppression arc all programmable over a very wide range. The circuit is realized in a 0.13 mum CMOS technology and consumes between 103 muA (100 kHz) and 11.85 mA (20 MHz) from a 1.2 V supply for a low integrated noise setting around 25 to 35 muV <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">rms</sub> and an IIP3 of 10 dBV <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">p</sub> giving an SFDR of 68 dB. Extra power can be saved when higher noise levels are allowed. Measurement results confirm flexibility, noise-power scaling and linearity behavior of the biquad architecture.