21.5 An Integrated 2.4GHz -91.5dBm-Sensitivity Within-Packet Duty-Cycled Wake-Up Receiver Achieving 2μ W at 100ms Latency

The Internet-of-Things (IoT) requires dense sensor networks with low-latency response from wireless devices that operate on severely limited power budgets. Integrated wakeup receivers (WuRX) contribute to this vision by enabling event-driven, energy-efficient connectivity, but they must provide similar sensitivity and interferer tolerance as the main receiver at much lower power. Recent WuRX work has pushed operation into the multi-GHz range, including the 2.4GHz ISM band, but it shows the challenge of simultaneously realizing high sensitivity, high selectivity, and near-$\mu$ W average power (P avg ) at average latency (L avg ) of milliseconds. A 2.4GHz Envelope-Detector (ED)-first topology WuRX [1] achieved 236nW at a limited sensitivity of -56.5dBm. A -99dBm Tuned-RF WuRX achieved 2.17$\mu$ W with duty-cycled 61dB RF gain at 434MHz [2], but high gain can lead to instability and limited interference tolerance at multi-GHz. An Uncertain-IF (U-IF) WuRX achieved sensitivity of -97dBm and signal-to-interference ratio (SIR) of -31dB at 99$\mu$ W [3] by adopting off-chip inductors, which increases integration volume. A duty-cycled heterodyne WuRX demonstrated -92dBm sensitivity at 4.4$\mu$ W [4], but at 1s latency which can be undesirable for large-scale networks.