Ultra Linear 3.5GHz RF Front-End for OFDM System

Abstract

This paper presents the design and performance of chips suitable for an RF front-end module, for WiMAX applications. The chips include a low cost single pole double throw (SPDT) switch and low noise amplifier as well as a 10-Watt 3.5GHz power amplifier MMIC implemented in a plastic air cavity QFN 8times6 mm2 package. Plastic packaging is used for the switch and the low noise amplifier. The broadband performance of these parts allow coverage from 3.3 GHz up to 3.8 GHz, over temperature range and process spread. The transmit path exhibits over 15dB of gain, thanks to very low insertion loss on the switch, manufactured on a high yield and reliable process. The error vector magnitude (EVM) is maintained below 2.5% up to 30dBm transmit power, for OFDM signal with PAR=10dB. On the receive path, the LNA provides 2 modes: a low noise operation with NF of 2.5dB and a bypass mode with 28dBm output PldB