26.6 A Programmable Receiver Front-End Achieving >17dBm IIP3 at <1.25×BW Frequency Offset

Abstract

This paper proposes a programmable receiver front-end that achieves sharp filtering, while maintaining linearity in the presence of large close-in blockers. It uses the recent concept of Filtering by Aliasing (FA). Suppose we have a simple filter, h(τ), whose output is sampled at a sampling period, Ts. It can be shown that if the input, x(t), to the filter is first multiplied with a periodic signal d(t) whose period is Ts, then the system is equivalent to the input being passed through an apparent LTI filter, g(τ)= h(τ)d(-τ), before sampling. Furthermore, if d(t) is designed appropriately, g(τ) will be a far more selective filter than h(τ).