N-path filters and mixer-first receivers: A review

To realize a Software Defined Radio covering the mainstream 0.5-6 GHz wireless communication bands, new SAW-less radio receiver architectures are being explored which realize selectivity in a more flexible and programmable fashion. N-path filters and mixer-first receivers can offer high-linearity high-Q RF-filtering around a center frequency defined by a digital clock, which offers the desired flexible programmability. This paper reviews recent research on N-path filters and mixerfirst receivers, identifies advances in performance analysis, circuit performance and applications.