A 50 Gbit/s PAM-4 Linear Burst-Mode Transimpedance Amplifier

This letter presents a linear burst-mode transimpedance amplifier (LBMTIA) capable of receiving 50 Gbit/s 4-level pulse amplitude modulation (PAM-4), targeting upstream transmission in high-rate time division multiplexed passive optical networks (TDM-PONs). Using a digitally controlled high-speed datapath, where offset- and gain are corrected using a fast lookup from on-chip stored settings, the receiver achieves a settling time of 48 ns and has an input dynamic range of at least 17.7 dB for 25 Gbit/s non-return-to-zero (NRZ) and 10.9 dB for 50 Gbit/s PAM-4 at the low-density-parity-check (LDPC) forward-error-control (FEC) threshold of $1\times 10^{-2}$ (as now standardized for 25 and 50G TDM-PONs). The LBMTIA is fabricated in the 0.25 um SiGe:C BiCMOS-technology from NXP and consumes 375 mW.