Improved modeling and parameter-extraction procedure emphasizing on extrinsic inductances and base-collector capacitances of collector-up HBTs

In this paper, an improved modeling and parameter-extraction procedure requiring no special de-embedding test structures, reverse/high-forward-biased measurements, or the use of numerical optimization process has been successfully developed to efficiently determine the equivalent-circuit parameters of collector-up heterojunction bipolar transistors. This new approach, modified from a previous work by our group, emphasizes the ad hoc analytical extraction of extrinsic inductances (Lb, Lc, Le) and base-collector capacitances (Cex, Cbc), which are crucial parameters for characterizing RF performances in device modeling. A comprehensive set of practical modeling equations is derived from systematically formulating two-port-network matrices on the basis of measured S-parameters. Physically realistic results are demonstrated under various biasing conditions for the p-n-p InGaAs collector-up heterojunction bipolar transistor with a graded base of 25 nm. The superiority of the improved technique is verified by observing the consistency between calculated and measured S-parameters.