M.Sc. Binh Pham

The amount of global data traffic continues to increase due to the rapid growth in data volumes, leading to higher technical requirements for optical communication transceivers. One of the key challenges in these systems, particularly in passive optical networks (PON), is the significant variation in signal amplitude. At the central office, the level variation can reach up to 30 dB. When such a large signal is received by a transimpedance amplifier (TIA) with fixed transimpedance, the output becomes distorted, potentially causing information loss. To mitigate this, a
feedback automatic gain control (AGC) loop can dynamically adjust the gain setting of the TIA.
A systematic analysis of the loop must first be conducted to derive the requirements for the AGC. A short settling time and a large input signal dynamic range are targeted to ensure stable operation of the subsequent data processing
stages are targeted. In addition to the classical implementation that employs an operational amplifier (op-amp) to drive the gain control voltage, alternative approaches, such as comparator-based solutions, should also be investigated.

Tasks: 

- Analyze the loop and derive the requirements for the AGC block
- Evaluate the feasibility of an op-amp approach and design an op-amp
- Investigate other approaches if necessary

Prerequisites:

- Understanding of circuits (e.g. ES, MCS, ...)
- Exposure with Cadence is a big plus

Description.pdf