A 720-mVpp 224-Gb/s PAM4 Optical Receiver with Multiple Peaking Techniques in 130-nm SiGe BiCMOS

In this work, an optical receiver (RX) with multiple peaking techniques is presented. The RX consists of a trans-impedance amplifier (TIA), a continuous-time linear equalizer (CTLE), and a 2-stage single-to-differential converter (S2D). Adopting the proposed RC parallel structure, the TIA's bandwidth and transition speed get improved. Moreover, multiple peaking techniques, including RC emitter degeneration, shunt-inductive peaking and T-coil peaking, are implemented for bandwidth extension. With the asymmetrical T-coil, the S2D's output imbalances in amplitude and phase are limited to 0.2 dB and 1.6°. Designed in 130-nm SiGe BiCMOS, the system achieves a differential of
$58\ \text{dB}\Omega$
and a bandwidth of 61 GHz. In general, the RX handles the 224-Gbit/s PAM4 input data with a
$\text{THD} < 7\%$
. The total power-efficiency is 0.43 pJ/bit.