Monolithically Integrated Si Photonics Transmitters in 0.25µm BiCMOS Platform for High-Speed Optical Communications
Monolithically integrated electro-optical transmitters fabricated in a 0.25 µm SiGe:C BiCMOS electronic-photonic integrated circuit (EPIC) technology with fT =190 GHz are presented. The modules are based on the co-design and integration of a segmented depletion-type Si Mach-Zehnder modulator and multichannel driver amplifiers. Two driving approaches and their performance trade-offs are discussed: a linear one, with direct interface to an external digital-to-analog converter (DAC), as well as a more power efficient implementation featuring integrated 4-bit DAC functionality. High extinction ratios at high speed are demonstrated, enabled by the high breakdown voltages of the HBT transistors. The modules support several modulation formats among which pulse-amplitude-modulation (PAM)-4 eye diagrams up to 37 GBd are shown, for the first time.