An analysis of self-heating and collector-current-collapse on RF power transistor

This paper examines the influences of the self-heating behavior of Silicon-on-Insulator (SOI) MOSFET transistors and multi-finger Hetero-junction Bipolar Transistors (HBT) on a range of primitive Radio Frequency Integrated Circuits (RFIC) cells. In addition to the more well-known self-heating effect (SHE), Collector Current Collapse effects (CCCE) are examined. Particular emphasis is given to the impact of these effects on drain current mismatch due to localized temperature differences. Simulations and analyses are presented for a simple cascode amplifier stage. Anomalies due to self-heating are also clearly visible in the small-signal characteristics of the cascode stage. The paper demonstrates how circuit-level simulations can be used to predict undesirable nonisothermal operating condition during the design stage.