Considerations on the Design of Transceivers for Ambient Internet of Things
Yuxiao Zhao, Zhen Shen, Shiyu Li, Jing Feng, Hao Min
TL;DR
This paper tackles the challenge of designing battery-free, ultra-low-power transceivers for Ambient IoT by proposing a crystal-less, approximate low-IF receiver architecture paired with a carrier-auxiliary IF feedback LO synthesizer. Implemented in 55 nm CMOS, the design achieves sub-mW receiver operation and eliminates external crystals, with measured receiver sensitivity better than $-88\,\mathrm{dBm}$. The approach uses a 4-path mixer-first RF front-end, a SAW-less image-rejection scheme, and a crystal-less LO calibration loop to maintain carrier alignment while keeping power consumption minimal. The work demonstrates a viable route to scalable zero-power IoT connectivity, bridging digital and physical worlds and enabling dense, maintenance-free sensor networks with long lifetimes.
Abstract
The Ambient IoT (A-IoT) will introduce trillions of connections and enable low-cost battery-less devices. The A-IoT nodes can achieve low cost ($\sim\$ 0.1$ like RFID tag), sub-1mW average power consumption, $\leq 10$ kbps data rates, maintenance-free working for decades, cm-scale size, and support applications like supply chain and smart agriculture. The transceiver challenges in A-IoT focus on sub-mW receivers and crystal-less clock generation. The paper proposes an approximate low-IF receiver and carrier-auxiliary IF feedback LO synthesizer architecture for Type-B/C A-IoT devices, which tracks the RF carrier frequency and eliminates external crystals. The proposed receiver and LO generator are implemented using 55nm CMOS technology. After locking the LO calibration loop, the receiver sensitivity is better than -88 dBm. The proposed receiver architecture will promote zero-power devices for ubiquitous IoT connectivity, bridging digital and physical worlds.