A 56Gbaud PAM-4 Linear Driver for Mach-Zehnder Modulators in 90-nm SiGe BICMOS Technology

This paper presents a 4-level pulse amplitude modulation (PAM-4) linear driver for Mach-Zehnder Modulators (MZM) in 90-nm SiGe BiCMOS technology. The transmission line was employed in the input and output wiring to reduce the transmission loss of the high-speed signal. In addition, by adopting coupled inductor peaking technology and continuous time linear equalizer (CLTE), the bandwidth of system reaches 42.1 GHz. The drive output stage of the system uses single emitter follower push pull (SEFPP) structure to achieve large output swing. Post-simulation results show that the MZM-driver can deliver a differential output signal of 3.6 V
pp
when inputting 56Gbaud PAM-4 signal of 300-900 mV
ppd
, and the total harmonic distortion (THD) is 2.7%. The driver works under a 5 V supply with a power consumption equal to 905 mW. The physical layout occupies an area of 0.96×1.1 mm
²
.