Modeling and Characterization of SiGe HBT Low-Frequency Noise Figures-of-Merit for RFIC Applications

We present the first systematic experimental and modeling results of noise corner frequency ( ) and noise corner frequency to cutoff frequency ratio ( ) for SiGe heterojunction bipolar transistors (HBTs) in a commercial SiGe RF technology. The and ratio are investigated as a function of operating collector current density, SiGe profile, breakdown voltage, and transistor geometry. We demonstrate that both the and ratio can be significantly reduced by careful SiGe profile optimization. A comparison of the and ratio for high breakdown and standard breakdown voltage devices is made. Geometrical scaling data show that the SiGe HBT with = 0 5 2 5 m has the lowest and ratio compared to other device geometries. An reduction of nearly 50% can be achieved by choosing this device as the unit cell in RF integrated-circuit design.