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 S
₁₁
. The implemented receiver achieved a filter stopband suppression of 70 dB with a transition band of only 4× RF bandwidth, while S
₁₁
is better than -10 dB throughout most of the receiver local oscillator range. Analysis for achieved S
₁₁
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.