A 2.5 Vppd broadband 32 GHz BiCMOS linear driver with tunable delay line for InP segmented Mach-Zehnder modulators

Abstract

In this paper a linear optical modulator driver fabricated in a 0.13 μm BiCMOS SiGe:C technology is presented. The prototype is to be used in hybrid configuration with an InP segmented Mach-Zehnder modulator (SE-MZM), forming a transmitter sub-system with direct interface to the digital to analog converter (DAC), which is suitable for high order modulation formats. A tunable broadband delay line that provides for better optical and electrical delay synchronization was also implemented. The driver, designed for a 16-segments modulator, features 8 dB of gain, 32 GHz of 3-dB bandwidth and delivers a differential output swing of 2.5 Vpp, dissipating 1.65 W of DC power. The measured total harmonic distortion (THD) at 1 GHz is lower than 3.7%. The delay line allows for a ±15% of delay tuning from the nominal value of 3.68 ps per segment. To the best knowledge of the authors, this is the first time a linear driver for a SE-MZM is presented.