A widely tunable active RF filter topology

Abstract

An active inductor based bandpass radio-frequency (RF) filter circuit topology is presented that achieves a wide tuning range. Based on the proposed structure, a prototype 2 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sup> -order filter is designed, simulated, and laid out in a 0.18mum CMOS process. The center frequency of the filter can be tuned from 880MHz to 3.72GHz. The quality factor of the filter can also be tuned. The filter, including the input and output buffers, consumes between 12 to 26mW from a 1.8V supply and occupies a chip area of 115mum times 70mum