Design And Performance Of A Low-Noise High Dynamic Range WiMAX LNA

Introduction
Mobile WiMAX, based on the IEEE 802.16e standard, is a technology that will play an important role in providing mobility and portability to end users in wireless MANs (metropolitan area networks). This technology will allow non-line-of-sight (NLOS) transmission from the base station over long distances to mobile or portable devices, such as notebook computers and mobile phones. Consequently, the received power strength fluctuates over a wide range, due to the variable transmission path and the signal attenuation caused by metal and concrete obstacles along the NLOS path.

In a WiMAX network, a receiver chain designed with low noise and a high dynamic range ensures reliable performance of the transceiver. This article explains a simple, low-cost, and space-saving approach to address these issues by using a GaAs pHEMT-based low-noise amplifier (LNA) with an integrated bypass switch.

Low-Noise High-Linearity Performance
The Avago MGA-71543 is a single-stage GaAs RFIC amplifier that combines low-noise and high-linearity performance, making it an ideal choice for the RF receiver front-end. Using GaAs pHEMT technologies, the MGA-71543 can achieve noise figures as low as 1.1 dB and 20.7 dBm of OIP3 while operating at a low supply voltage and current of 3 volts, 10 mA. The following diagram shows the implementation circuit of the MGA-71543 with the specified performance.