A $300\mu \mathrm{W}$ Bluetooth-Low-Energy Backchannel Receiver Employing a Discrete-Time Differentiator-Based Coherent GFSK Demodulation

This paper presents a $300\mu \mathrm{W}$ backchannel receiver (RX) compatible with the Bluetooth-Low-Energy (BLE) standard for ultra-low power Internet-of-Things (IoT) applications. A PLL-less, mixer-first zero-IF architecture is proposed to achieve the low power operation featuring an antenna-chip co-design for lossless quadrature (I/Q) generation in the RF path. A novel $10\mu \mathrm{W}$ switched-capacitor differentiator-based GFSK demodulator is presented. The demodulator exhibits a robust operation under I/Q phase and amplitude imbalances and operates at a 1MHz baseband clock frequency. The proposed backchannel communication within the packet's payload is achieved through 2× data repetition. The chip is designed and fabricated in CMOS 40nm technology. The RX achieves −69dBm sensitivity for 0.1% BER at 0.5Mbps effective data rate.