In this episode Shahriar takes a look at a high-speed driver module intended for coherent applications. The Mach-Zehnder driver circuit can reach speeds of 43Gb/s and provide up to 8Vpp into a differential modulator. The ASIC is realized in an InP HBT process and manufactured more than 21 years ago! The teardown shows the interface design as well as detailed circuit analysis & ASIC architecture.