Heterojunction bipolar transistor technology for analog and digital applications

This paper describes high performance AlGaAs/GaAs heterojunction bipolar transistor (HBT) technologies developed at Rockwell and their applications to digital, analog, microwave and multifunction circuits. The GaAs BBT technology is relatively mature and is being transferred to pilot production at Rockwell. The AIGaAs/GaAs HBT technology provides transistors with high fmax (up to 218 GHz), high f/sub t/ (up to 98 GHz), high Early Voltage (V/sub a/ > 200 V), high breakdown voltage (BV/sub cbo = 15-45 V), a wide range of choice of dc current gain (10-200), and MSI LST integration levels. GaAs HBTs have also demonstrated high power-added efficiency for microwave amplification of both discrete transistors (67.8% at 10 GHz) and MMICs (minimum 43% over 7-11 GHz). Moreover, both digital and analog/microwave GaAs HBT circuits have been successfully fabricated on the same wafer. As a result, a monolithic integration of multifunction circuits becomes feasible and will open a new area for direct digital signal processing at microwave frequencies.