HEMT circuits for signal/data processing

HEMT devices exhibit excellent figures of merit for high frequency operation. Therefore they are strong candidates for high speed signal and data processing. This article presents an overview of recent results of a broad range of applications and dedicated monolithic integrated circuits based on HEMT devices. Based on a 0.3 mu m AlGaAs/GaAs/AlGaAs HEMT technology with two threshold voltages for enhancement and depletion transistors complex analog and digital functions can be integrated on a single chip with low power dissipation. For the interface to the analog environment analog-to-digital and digital-to-analog converters are required for signal processing with sampling rates well above 1 Gsample s (exp -1). The GHz clock rates of digital GaAs circuits deliver maximum operating speed for data processing. The high speed digital logic cells combined with optoelectronic components are also advantageous for optical links with data rates up to 40 Gbit s (exp -1). These logic cells in combi nation with microwave and millimeter wave analog circuits enable monolithic integrated transmit and receive chips for advanced communication and radar systems.