Mixed Signal: Systematic Characterization and Profile Design of SiGe HBTs for Mixed Signal Wired and Wireless Telecommunications

Auburn University, Auburn AL

Investigators

Abstract

Because of its high performance, low cost, and compatibility with silicon CMOS, SiGe HBT technology has recently emerged as a contender for both mobile and optical networking applications. Current SiGe HBTs designs are focused on improving the speed of these devices, while our recent experiments have shown that the optimum device structure for wireless applications are considerably different. Issues important for mobile and optical networking, such as 1/f noise, phase noise (frequency domain sideband and time domain jitter), and linearity, have not been researched as a function of the device structure, or optimized for these performance targets. This proposal is aimed at systematically examining the impact of bandgap engineering and scaling on all of the device figures-of-merit that are of interest to both wireless and optical communication IC's, and use of these results to optimize the SiGe profiles and geometries for next generation SiGe HBTs. We expect the design tradeoffs to be much more complicated than in first generation SiGe HBTs, because of aggressive vertical and horizontal scaling to achieve high speed operation (as high as 200GHz cutoff frequency and maximum oscillation frequency). In the process, we will answer scientifically intriguing and technologically important questions, such as why SiGe HBTs with a nonlinear I-V can have excellent linearity. This is a brand new area of SiGe device research, and has a high potential payoff given the exploding industry interest in applying SiGe technology to wireless and optical networking systems. The outcome will include a scientific understanding of important open questions on SiGe HBTs, a modification of the design approach and methodology, as well as data of the key device figures-of-merit as a function of SiGe profile. Given the enormous amount of interest in applying SiGe technology to both wireless and optical networking applications, we will develop an advanced course on SiGe HBTs, so that the outcome of the proposed research can be remotely accessed by graduate students and practicing engineers in industry.