A 90-Gb/s Modulator Driver IC Based on Functional Distributed Circuits for Optical Transmission Systems

Abstract

A monolithic modulator driver IC based on InP HBTs with a new circuit topology — called a functional distributed circuit (FDC) — for over 80-Gb/s optical transmission systems has been developed. The FDC topology includes a wide-band amplifier designed using a distributed circuit, a digital function designed using a lumped circuit, and broadband impedance matching between the lumped circuit and distributed circuit to enable both wider bandwidth and digital functions. The driver IC integrated with a 2: 1 multiplexing function produces 2.6-Vp-p (differential output: 5.2Vp-p) and 2.4-Vp-p (differential output: 4.8Vp-p) output-voltage swings with less than 450-fs and 530-fs rms jitter at 80Gb/s and 90Gb/s, respectively. To the best of our knowledge, this is equivalent to the highest data rate operation yet reported for monolithic modulator drivers. When it was mounted in a module, the driver IC successfully achieved electro-optical modulation using a dual-drive LiNbO3 Mach-Zehnder modulator up to 90Gb/s. These results indicate that the FDC has the potential to realize high-speed and functional ICs for over-80-Gb/s transmission systems.