Low-Noise Amplifier Design: An Open-Source Perspective

Abstract

LNA stands for Low-Noise Amplifier.It is an integral part of the receiver chain in any RF system. The LNA is the first in a long chain of devices in the receiver chain however it also has the most impact on the sensitivity as well as the overall performance of the subsequent stages of the receiver. LNA design for RFIC has a lot of trade-offs that need to be made in order to achieve good performance both in terms of noise Figure and gain. The cascode topology is selected as the main focus for this brief. It is basically a two-stage amplifier that is built around a Commongate and Common-Source stages. The cascode LNA topology with inductive degeneration is best able to circumnavigate the hurdles posed in 5G or other wide-band RF technologies. It is able to balance good gain flatness with respectable noise Figure over a wide range of frequency spectrum while providing good impedance matching and reverse isolation. A three-stage Cascode LNA built using Advanced Spice Model for High Electron Mobility Transistor (ASM-HEMT) using Cadence Virtuoso is initially implemented. Its performance analysis using simulation results is done. This work also discusses the design of a cascode low-noise amplifier (LNA) using completely open-source tools namely Xschem and Magic among others. The design environment setup is also discussed in detail. The technology used to realize the circuitry is Google Skywater130.