A 56-Gb/s Reconfigurable Silicon-Photonics Transmitter Using High-Swing Distributed Driver and 2-Tap In-Segment Feed-Forward Equalizer in 65-nm CMOS

This article presents a reconfigurable silicon- photonics transmitter (TX) for short-reach optical interconnects. The proposed hybrid-integrated TX combines a 65-nm CMOS driver with a 180-nm SOI-CMOS silicon-photonic Mach-Zehnder Modulator (MZM). The driver integrated with in-segment fractional-UI spaced feed-forward equalizer (FFE) is proposed to support the non-return-zero (NRZ) signaling, electrical- and optical-domain 4-level pulse-amplitude modulation (PAM-4) signaling. The driver employs a reconfigurable distributed topology to achieve high swing, wide bandwidth and flexible operation. The MZM is driven differentially in a push-pull configuration for high modulation efficiency. Measurement results show that the proposed TX operates up to 50-Gb/s NRZ data rate with 4-Vppd swing and 1.92-ps RMS jitter. In the optical PAM-4 mode, it reaches 56-Gb/s data rate and achieves >5-dB extinction ratio (ER) at the cost of 10.9-pJ/bit power efficiency.