Analysis and Design of Submilliwatt Interference-Tolerant Receivers Leveraging N-Path Filter-Based Translational Positive Feedback

A low-power 2.2-2.4-GHz receiver front end for Internet-of-Things (IoT) applications is presented. The front end consists of a capacitively cross-coupled common-gate low-noise amplifier (CC-CGLNA), with translational positive feedback from baseband to RF through a four-phase switching mixer, providing RF filtering and matching, in conjunction with a 1:4 transformer. A detailed analysis of the architecture is presented, highlighting the design tradeoffs between noise, out-of-band filtering, and power. A prototype integrated circuit, fabricated in 28-nm CMOS, consumes 580 μW of power for the entire receiver front end. With this submilliwatt power consumption, it achieves a noise figure (NF) of 11.9 dB, an in-band IIP3 of -6.5 dBm, and an out-of-band IIP3 of +3.3 dBm.