Modeling and characterization of SiGe HBT low-frequency noise figures-of-merit for RFIC applications

Electr. & Comput. Eng. Dept., Auburn Univ., AL, USA
IEEE Transactions on Microwave Theory and Techniques (Impact Factor: 2.23). 12/2002; DOI: 10.1109/TMTT.2002.804519
Source: IEEE Xplore

ABSTRACT We present the first systematic experimental and modeling results of noise corner frequency (fC) and noise corner frequency to cutoff frequency ratio (fC/fT) for SiGe heterojunction bipolar transistors (HBTs) in a commercial SiGe RF technology. The fC and fC/fT ratio are investigated as a function of operating collector current density, SiGe profile, breakdown voltage, and transistor geometry. We demonstrate that both the fC and fC/fT ratio can be significantly reduced by careful SiGe profile optimization. A comparison of the fC and fC/fT ratio for high breakdown and standard breakdown voltage devices is made. Geometrical scaling data show that the SiGe HBT with AE=0.5×2.5 μm2 has the lowest fC and fC/fT ratio compared to other device geometries. An fC reduction of nearly 50% can be achieved by choosing this device as the unit cell in RF integrated-circuit design.

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