Enhanced Interference Rejection Bluetooth Low-Energy Back-Channel Receiver With LO Frequency Hopping
Abdullah Alghaihab, Yao Hong Shi, Jacob Breiholz, Hun-Seok Kim, Benton Highsmith Calhoun, David D. Wentzloff · IEEE Journal of Solid-State Circuits · 2019
Two prototypes of low-power back-channel (BC) Bluetooth low-energy (BLE) wake-up receivers are presented. The receivers scan the BLE advertising channels for modulated advertising channel patterns by hopping the local oscillator (LO) frequency. The BC message is modulated in the sequence of the three advertising channels in each advertising event. This makes the wake-up via BC messaging compatible with the BLE standard, so it can be generated by a commercial offthe-shelf device. The first proposed receiver uses a dual mixer to downconvert the RF input to reduce the ring-based LO power consumption by operating it at half the RF frequency. The second prototype aims to achieve faster channel hopping using a more stable and lower noise LC-based oscillator. The receivers have -57.5-dBm/-82.2-dBm sensitivity while consuming 150 μW/1.2 mW.