Design and Analysis of a Programmable Receiver Front End With Time-Interleaved Baseband Analog-FIR Filtering

This paper presents time interleaving as an approach to improve the performance of programmable receiver front ends based on filtering-by-aliasing. Using two parallel periodically time-varying paths, a sharp programmable filtering response is produced at RF, while achieving a good wideband <inline-formula> <tex-math notation="LaTeX">$S_{11}$ </tex-math></inline-formula>. The implemented receiver achieved a filter stopband suppression of 70 dB with a transition band of only 4<inline-formula> <tex-math notation="LaTeX">$\times$ </tex-math></inline-formula> RF bandwidth, while <inline-formula> <tex-math notation="LaTeX">$S_{11}$ </tex-math></inline-formula> is better than −10 dB throughout most of the receiver local oscillator range. Analysis for achieved <inline-formula> <tex-math notation="LaTeX">$S_{11}$ </tex-math></inline-formula> and noise figure are shown, while detailing methods to improve filtering performance in the presence of important circuit parasitics. The effects of mismatches between time-interleaved paths are also analyzed and quantified.