3-dB bandwidth enhanced InGaAs PIN photodiode by inductive CPW electrode for datacenter applications

We report on a 3-dB bandwidth extension technique achieved through a coplanar waveguide (CPW) electrode design that imposes inductive gains in a backside-lens-integrated InGaAs positive-intrinsic-negative (PIN) photodiode. The inductive CPW electrodes are analyzed in detail using an equivalent circuit model in which the transit time of the photo-generated carriers has been included. The transit times for the electrons and holes have been analyzed numerically. By including the transit time effect in the equivalent circuit model, the extracted RLC parameters show a good consistency with measured frequency response data. As a result, the 3-dB bandwidth has been extended from 48 GHz to over 67 GHz at a -2.5 V bias voltage simply by reconfiguring the CPW electrode design.