Temperature And Frequency Dependence Of Thermal Impedance In Dielectrically Isolated SiGe HBTs

Abstract

Silicon Germanium (SiGe) heterojunction bipolar transistors (HBTs) have been designed to cater the demand of high speed circuits having applications in wireless and optical communication. Due to higher cut-off frequencies and high speed applications, self heating plays a significant role in the performance of SiGe HBTs. This thesis paper does an extensive analysis on the effect of self heating and used different DC, time domain and frequency domain methods to extract the self heating parameters thermal resistance (Rth) and thermal capacitance (Cth). The VBIC (Vertical Bipolar Inter Company) model is used for all the simulations. Simulations are performed using ICCAP (Integrated Circuit Characterization and Analysis Program) tool. Measurements are done using HP 4142 DC source module, Agilent 6000 series oscilloscope and Agilent 8753 ES s-parameter network analyzer. National Semiconductor Corporation's SiGe LV (low voltage) NPN HBT with emitter dimensions 10um×0.25um from their CBC8 process is used for getting real data.