A 3.8Ghz channel-select filter using 0.18/spl mu/m CMOS

Abstract

A high gain bandpass filter was designed as a channel-select filter for applications around 3.8GHz. Three stages of 2nd order were cascaded to have a high image rejection filter with an adjustable bandwidth. An experimental filter designed using standard 0.18/spl mu/m CMOS occupies an area of 0.9/spl times/0.9mm/sup 2/. This high performance filter provides a selected center frequency ranging from 3.6GHz to 3.8GHz, an image-rejection of 50dB and a tunable Q from 25 to 50 for bandwidth adjustment. The filter achieves a 15dB gain from a 1.8V supply.