A Subthreshold Low-Noise Amplifier Optimized for Ultra-Low-Power Applications in the ISM Band

The IEEE 802.15.4 standard relaxes the requirements on the receiver front-end making subthreshold operation a viable solution. The specification is discussed and guidelines are presented for a small area ultra-low-power design. A subthreshold biased low-noise amplifier (LNA) has been designed and fabricated for the 2.4-GHz IEEE 802.15.4 standard using a standard low-cost 0.18-mum RF CMOS process. The single-stage LNA saves on chip area by using only one inductor. The measured gain is more than 20 dB with an S11of -19 dB while using 630 muA of dc current. The measured noise figure is 5.2 dB.