RF characterisation and modelling of AlGaAs/GaAs HBT for 1.8 GHz applications

Laboratoire d'Analyse et d'Architecture des Systèmes du CNRS, 7 avenue du Colonel Roche, 31077 Toulouse Cedex 4, France

Corresponding author: cazarre@laas.fr

Received: 22 January 1999
Revised: 8 June 1999
Accepted: 8 June 1999
Published online: 15 September 1999

Abstract

For power applications, AlGaAs/GaAs heterojunction bipolar transistors (HBT's) were found to present high efficiency and linearity at high density RF power. We report power performances in S-band of a 6 × 60 µm² one emitter finger HBT fabricated in our laboratory. At 1.8 GHz, when tuned for maximum efficiency, each transistor delivered a CW output power of 0.5 W (150 kW/cm²) and a power-added efficiency of 62% and 80% in class AB and C operation respectively. The physical model based on technological and measured parameters incorporates temperature dependence for most of its parameters. It has been easily used to analyse DC and RF power characteristics in class AB mode and to determine input and output optimum matching cells. Good agreement between simulated and experimental results support the validity of the model.