Design of CMOS tunable image-rejection LNA using active inductor

Abstract

A fully integrated CMOS tunable image-rejection low-noise amplifier (IRLNA) has been designed using Silterra's industry standard 0.18 µm RF CMOS process. The notch filter is designed using an active inductor. Measurement results show that the notch filter designed using active inductor contributes additional 1.19 dB to the noise figure of the low-noise amplifier (LNA). A better result is possible if the active inductor is optimized. Since active inductors require less die area, the die area occupied by the IRLNA is not significantly different from a conventional LNA, which was designed for comparison. The proposed IRLNA exhibits S21 of 11.8 dB, S11 of -17.8 dB, S22 of -10.7 dB, and input 1 dB compression point of -12 dBm at 3 GHz.