A -104dBm-Sensitivity Receiver with Shared Wireless LO and Envelope-Tracking Mixer Achieving -46dB SIR.

The increased IoT devices have crowded ISM bands, requiring the receiver (RX) with a high tolerance to modulated interferences while maintaining ultra-low-power (ULP) consumption and high sensitivity [1-2]. Among prior ULP RXs that induce critical index compromises [3-5], as shown in Fig. 1 top, mixer-first RXs improve sensitivity and channel selection, and are attractive to long-range and congested networks. Yet, prior mixer-first ULP RXs have low rejection to in-band interferers [6]. Moreover, in applications (e.g. smart warehouse) with a mass of RX nodes, the system power will increase since each prior mixer-first RX requires one integrated LO. To address these issues, based on a shared wireless LO, this paper presents a 915MHz ULP RX with the envelope-tracking (ET) mixer and the intermediate-frequency (IF) calibration to improve sensitivity, in-band interference tolerance, and channel selection, as shown in Fig. 1 middle.