Enhancing the Speed of SiGe HBTs Using fT-Doubler Techniques

Abstract

A peak f_T of 325 GHz is achieved, for the first time, in a 130 nm, 200 GHz, 3^rd-generation SiGe HBT technology at 300 K, by utilizing f_T-doubler techniques. This speed enhancement is equivalent to gaining an additional generational node (from 3^rd to 4^th), with no underlying change to the transistor profile or lithography. The f_T-doubler can be treated as a single transistor unit cell during circuit design, which is verified by the investigation of its small-signal equivalent circuit. Reduced C_pi is demonstrated to be the root origin of the f_T-enhancement. The impact of emitter geometry on performance is investigated. A record f_T of 438 GHz is achieved at 93 K.