Channelized front-ends for broadband signal processing with relaxed anti-aliasing filtering

Abstract

A digital post-processing approach for reducing the anti-aliasing requirement in a frequency-folding channelizer architecture is described. The channelizer decomposes a broadband spectrum into multiple sub-bands. A signal of bandwidth N/2fLO is downconverted into N paths that are clocked using rectangular, non-overlapping pulse waveforms at a fundamental frequency of fLO with a duty-cycle of 1/N. All portions of the input are aliased onto a baseband signal of bandwidth fLO/2, which is low-pass filtered and applied to N sub-ADCs with identical sampling clocks. Individual sub-bands are selected in the digital domain. Aliasing between sub-bands is also removed after digitization. This is used to reduce the order of the anti-aliasing filters in the analog signal paths, which can potentially reduce power and design complexity. It is shown that a filter-order of at least one is necessary in the analog-domain to apply digital post-processing. The approach is verified in simulation.