An improved cascode common-source LNA with inductive source degeneration for RF applications

Abstract

This paper presents a novel structure to enhance the power gain (S21) of the conventional cascode common-source (CS) low-noise amplifier (LNA) with inductive source degeneration. The proposed LNA has an extra transistor and a capacitor in comparison with the conventional structure. The additive transistor significantly increases the S21 of the conventional cascode CS LNA with inductive source degeneration with the same DC power consumption (PDC), third-order input intercept point (IIP3), area, and slightly lower noise figure (NF). The utilized capacitor is used to improve the IIP3 of the proposed LNA. The power gain improvement of the proposed LNA has been validated by both theoretical analysis and extensive post-layout simulation results. The proposed and conventional LNAs have been designed in TSMC 180 nm CMOS technology. The post-layout simulation results of the proposed LNA are 2.42 dB NF, S21 of 15.55 dB, and 0.84 dBm IIP3 while consuming 3.2 mW from 1.2 V power supply. The simulated S21 of the proposed LNA is about 2.55 dB (34.2 %) larger than the conventional cascode LNA with the same other performance parameters. Also, the achieved figure-of-merit (FoM) of the proposed LNA is substantially larger than the conventional cascode CS LNA with inductive source degeneration.