30.6 A Low-Power BLE Transceiver with Support for Phase-Based Ranging, Featuring 5µs PLL Locking Time and 5.3ms Ranging Time, Enabled by Staircase-Chirp PLL with Sticky-Lock Channel-Switching

Nowadays, almost every mobile device features Bluetooth Low Energy (BLE) connectivity. Accurate RF-based ranging is of major importance to enable rapidly emerging applications such as indoor localization and navigation, asset tracking as well as secure access control. Phase-based ranging has many advantages over other methods such as Time-of-Flight or signal-strength-based approaches [1]. Phase-based ranging is based on the phase difference between the two nodes, which depends on the RF frequency. To mitigate multipath problems and deal with the 2n ambiguity in phase measurements, the phase difference is measured on multiple frequencies, i.e. Multi-Carrier Phase Difference (MCPD) [1].