Design and Analysis of 2.4 GHz 30~\mu \text CMOS LNAs for Wearable WSN Applications

To meet the requirements of wearable wireless sensor networks, the power dissipation of the RF transceiver has to be drastically reduced. This paper presents two ultra-low power low noise amplifiers (LNAs) with RF performance exceeding the requirement of the intended application. In the first LNA, by reusing the current several times and employing passive gm boosting, the LNA input impedance is reduced by a factor of 24 compared with a single transistor using the same current. The feasibility of passive gm boosting for designing an ultra-low supply voltage LNA is also investigated. Limitations of both LNAs, including NF, non-linearity, and stability in a 40-nm CMOS technology are also investigated. The proposed LNAs consume only 30~\mu \text{W} of power, operate with 0.8 V and 0.18 V and show NF of 3.3 and 5.2 dB, respectively. Using a widely accepted figure-of-merit for LNAs, the proposed circuit is almost three times better than the best previously reported sub-mW LNA.