A Blocker-Resilient Receiver with Second-order Impedance Mapping for NB-IoT Applications

Abstract

Wideband receiver used in IoT applications operating at sub-GHz suffers from strong interferes. This paper presents a blocker-resilient wideband receiver architecture for NB-IoT applications. By exploiting the impedance mapping characteristic of N-Path filter and a low noise amplifier with negative feedback, a high-order filtering characteristics of baseband is mapped to RF input so as to implement wideband impedance matching and blocker suppression. To further improve the out-of-band linearity, a dual mixer structure is employed to cancel the out-of-band blockers before the TIA. Measurements show the RX out-of-band IIP3 is +17.6 dBm, while in-band IIP3 is -13 dBm.