Interleaving Active Feedback in Inverter-Based Optical Receivers for Bandwidth Extension and Linearity Improvement

Main amplifiers are crucial components in the design of optical receivers, amplifying the output voltage of the transimpedance amplifier (TIA). While Cherry-Hooper (CH) amplifiers are widely utilized in optical receivers due to their high bandwidth, they often fall short in linearity, making them less suitable for PAM-4 and higher-order modulation schemes. This study presents a highly linear PAM-4 optical receiver design. The proposed main amplifier employs g
m
/g
m
inverter-based amplifiers known for their superior linearity. We have applied the interleaving active feedback (IAFB) technique to enhance bandwidth while mitigating gain peaking. Notably, our proposed design operates with a 1 V supply, offers a bandwidth of 20 GHz at a gain of 64 V/V, and achieves a total harmonic distortion (THD) of less than 1% for a 600 mV
pp
differential output swing.