This paper presents a comparative study of Si, SiGe and InP based Bipolar Junction Transistors (BJT) with reference to their DC, AC, and RF characteristics. Double diffusion doping profile in each case is used to determine the common Figures of Merit (FOM) to assess their potentials for operation at high frequency. A theoretical analysis using Gummel-Poon model has been used to validate the data obtained from simulation using ATLAS module of SILVACO software tool. After validation of models, the three BJT’s DC, AC and RF characteristics are evaluated and thereafter a comparative analysis has been carried out based on the important characteristics such as I–V behavior, frequency response, breakdown, maximum cutoff frequency, and minimum noise figure. It is observed that, with the same physical structure, InP BJT produced a high dc current gain (505) compared to a much lower value of the Si BJT (65). In contrast, the Si BJT provides higher cut-off frequency compared to the others.
