A 57.2-Gb/s PAM4 Driver for a Segmented Silicon-Photonics Mach-Zehnder Modulator with Extinction Ratio >9-dB in 45-nm RF-SOI CMOS Technology

A 57.2-Gb/s four-level pulse-amplitude modulation (PAM4) driver for silicon photonic Mach-Zehnder modulator (MZM) is presented. The driver is designed in a 45-nm RF-SOI CMOS technology and consists of a pre-driver and an outputdriver. The pre-driver is made up with scaled, cascaded single- ended CMOS inverter transimpedance amplifiers with inductive and resistive feedback and interstage series inductive peaking. The output-driver adapts the structure of series-stacked cascoded CMOS inverter to overcome the breakdown voltage (BV) limit of transistors in advance technologies while getting high differential voltage swing >4 Vpp for MZM. The MZM is configured as an optical digital-analog converter (ODAC) and consists of a 1.1 mm LSB segment and a 1.9 mm MSB segment. The post-layout simulation results show that 5.6-Vpp differential swing, 9.1 dB extinction ratio (ER) and 95.2% ratio of level mismatch (RLM) at 28.6-GBaud (57.2-Gb/s) with a total power consumption of 750 mW are realized. Furthermore, a larger ER can be obtained by increasing the supply voltage. This work achieves an optimized tradeoff between power consumption, data rate, output swing, chip area and extinction ratio.