Abstract

Today's telecommunications involves ever-increasing amounts of optical communication. Besides being an important component of the long-haul network, optical communications are also being used in data centers, circuit boards, integrated circuits, and the next generation of mobile networks. This thesis proposes an optical receiver in which the damping factor of both the transimpedance and post amplifiers is modulated synchronously with incoming data. Modulation of the damping factor allows the fast response of the low-damping factor while mitigating the intersymbol interference (ISI) associated with underdamped systems.
To investigate the modulated damping shunt-feedback transimpedance amplifier (SF-TIA), some methods, including switching the feedback resistor and modulating the damping factor by a sine wave, are used. Due to damping factor value limitation by changing the shunt-feedback and complexity of producing appropriate value of the sine wave with proper DC offset, amplitude and phase, damping factor modulation by a rail-to-rail square wave signal is presented where only phase adjustment is necessary and has better noise performance, Vertical Eye Opening (VEO) gain and gain to power ratio.
The extension of dynamic damping to the post amplifier is investigated through simulation at 10 Gb/s. A shunt-feedback TIA with cross-coupled inverters at the output, optimized to reach minimum input-referred noise is used as a reference for creating SF-TIA and Cherry-Hooper post-amplifier (CH-PA) blocks. By modulating the damping factor in both blocks, the proposed system achieves more than three times the VEO and lower input-referred noise compared to the optimized reference. Alternatively, an equal-gain modulated system has 40 % lower power consumption compared to the reference design.