A Highly Linear Low-Noise Transimpedance Amplifier for Indoor Fiber-Wireless Remote Antenna Units

Abstract

This article presents an optimized design of a low-noise transimpedance amplifier (TIA) with high linearity for use in the downlink receiver of a remote antenna unit (RAU). The aim of this design is to be used in a cost-effective indoor distributed antenna system (DAS) for WLAN transmission using a mixed fiber-wireless system. The circuit topology consists of a fully differential shunt–shunt feedback TIA with digitally programmable transimpedance. An open-loop gain compensation technique is used to maintain stability and constant bandwidth (BW). The TIA has been fabricated in 65 nm CMOS technology with a 1.2 V voltage supply. The total power consumption of the TIA is 6 mW. A complete electrical and optical characterization with a 1550 nm PIN photodiode has been performed to demonstrate the reliable 54 Mb/s 802.11a WLAN transmission achieved with an error vector magnitude (EVM) lower than 3% for a 20 dB optical input range.