High-Performance High-Gain Amplifiers
Based on Metamorphic GaAs HRMT's
K. van der Zanden, D. Schreurs, R. Vandersmissen, G. Borghs
IMec, MCP/NMC, Kapeldreef 75, B-3001 Leuven, Belgium
For almost a decade InP based HEMT's have shown to be the best performing three-terminal devices . It combines high gain with low noise levels, resulting in excellent performance in the microwave and millimeter wave range. MMIC's with operating frequencies up to 100 GHz and beyond [2,3] have been realized and demonstrate the applicability of this technology.
Despite its convincing performance level, InP is unlikely to break through in mass-market applications such as automotive radar and LAN's because of several practical reasons. First of all, there is the availability of only 2" and 3" substrates at a high cost per square inch. In combination with its brittleness, this strongly limits the manufacturability of InP, resulting in a significant higher cost level compared to GaAs.
Over the last years, the technology of metamorphic GaAs based HEMT's has matured, demonstrating performance levels close to InP with fT values of typically 200 GHz . In these heterostructures, yielding way for production for consumer applications.
Until now, research efforts were mainly on device level. In this paper, we first will present the results of metamorphic devices based on a double delta-doped heterostructure, grown by MBE on GaAs with a ternary graded InAlAs buffer. Secondly, we integrate these devices monolithically into high-gain amplifiers in the Q- and W-band. These coplanar M4IC's (metamorphic MMIC's) have been fabricated with a mask set, originally designed for InP based devices. A performance comparison between MMIC's on LM InP and MM GaAs is made.