Combined SPICE-FEM analysis of electrothermal effects in InGaP/GaAs HBT devices and arrays for handset applications

In this paper, an approach based on the combination of a numerical tool supported by an in-house routine and a circuit simulator is used to examine the dc electrothermal behavior of (i) test devices for experimental characterization and (ii) arrays for output stages of power amplifiers in InGaP/GaAs HBT technology. The thermally-induced distortion in I-V curves is explained, and the limits of the safe operating regions are identified in a wide range of biasing conditions.