Process Variation Compensation of a 2.4GHz LNA in 0.18um CMOS Using Digitally Switchable Capacitance

A 0.18um CMOS 2.4GHz LNA (Low Noise Amplifier) with digitally switchable capacitance has been designed to investigate its ability to compensate for performance variation across worst case process conditions. The effects of transistor model and passive component variation are first simulated to quantify the range of performance uncertainty. The use of various methods of switchable capacitance is then investigated at multiple LNA nodes to observe the effect on S11, S21, and NF. After calibration, the new design allows for 300MHz of frequency tuning and improvements in S11 by 7.2dB, S21 by 2.4dB, and NF by 0.6dB.