Trans-impedance amplifier of source follower topology using an active device for bandwidth extension in optical communication systems

Abstract

This paper presents a trans-impedance amplifier (TLA) of a source follower topology for bandwidth extension. An analytical model for designing a TIA with a source follower stage has been derived. Based on this approach, we have designed two TIAs, which are a conventional common source TIA (CS-TIA) and a proposed source follower TIA (SF-TIA) for bandwidth extension. They were implemented for a 2.5-Gbps optical receiver using commercial 0.5 mum metal semiconductor field-effect transistor (MESFET) technologies. The trans-impedance gain (TIG) of the two fabricated amplifiers is the same, at 59 dBOmega. The measured bandwidth of the CS-TIA is 2.35 GHz, and that of the proposed SF-TIA is 4.05 GHz, enhanced by 1.7 GHz.