26.8 A 236nW −56.5dBm-sensitivity bluetooth low-energy wakeup receiver with energy harvesting in 65nm CMOS

Batteryless operation and ultra-low-power (ULP) wireless communication will be two key enabling technologies as the IC industry races to keep pace with the IoE projections of 1T-connected sensors by 2025. Bluetooth Low-Energy (BLE) is used in many consumer IoE devices now because it offers the lowest average power for a radio that can communicate directly to a mobile device [1]. The BLE standard requires that the IoE device continuously advertises, which initiates the connection to a mobile device. Sub-1s advertisement intervals are common to minimize latency. However, this continuous advertising results in a typical minimum average power of 10's of μW at low duty-cycles. This leads to the quoted 1-year lifetimes of event-driven IoE devices (e.g. tracking tags, ibeacons) that operate from coin-cell batteries. This minimum power is too high for robust, batteryless operation in a small form-factor.