In this article, the equivalent circuit model of an electro‐absorption modulator (EAM) with planar isolated pedestal GSG contact is built to investigate the high‐speed performances. A novel broadband impedance matching method for the microwave packaging of the EAM is presented. With this matching network, RF return loss can be great suppressed in a wide frequency range up to 40 GHz, along with an extended 3‐dB bandwidth to 38.8 GHz. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2026–2032, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27040