A -121dBm Sensitivity, 2.8μJ/bit Rx, 47.5% Efficient Tx, Narrowband IoT Transceiver

This work demonstrates a low power narrowband transceiver exhibiting extremely low sensitivity and large interference tolerance so that it can satisfy the IoT deployment demand with larger cell size and a large number of nodes. The circuit techniques in the transceiver include an injection locked IQ-divider that does not require any power hungry high speed logic gates or flip-flops to generate 25% duty cycle LO, and a simultaneously matched g
_m
-boosted LNA to ensure low-NF, high-gain, less power consumption. An automatic frequency correction (AFC) technique is used to adjust the LO frequency in the analog domain. Thus, the IF is independent of the crystal frequency offset, allowing the detector in baseband to operate at the lowest noise bandwidth with optimal SNR. Moreover, the IF signal is at the center of the pass band of the high-Q IF chain, thus the SNR is not impaired by the phase distortions in the 3 dB transition region. The measured Rx sensitivity is -121dBm, power consumption is 13.5 mW, energy efficiency is 2.8 $\mu$J/bit, adjacent channel rejection of 44 dB, and a negligible LO leakage of-100 dBm. Transmitter power consumption is 42.1mW, and the global Tx efficiency is 47.5%.