A Wideband Variable Gain LNA With High OIP3 for 5G Using 40-nm Bulk CMOS

This letter presents a CMOS wideband variable gain LNA for 28-GHz 5G integrated phased-array transceivers preserving high third-order intercept point (OIP3) at all gain settings. The prototype LNA has three stages providing digitally controlled gain optimized for higher IIP3 at lower gain. The stages are coupled together using double-tuned transformers for maximum group delay flatness. Fabricated in a 40-nm CMOS process, it achieves 18-26 dB gain at 1-dB gain step with 12-14.5 dBm OIP3 and 3.3-4.3 dB noise figure, while consuming 21.5-31.4 mW across 26-33 GHz frequency range. The root-mean-square error of the gain steps is less than 0.38 dB.