Millimeter-wave and mixed-signal integrated circuits based on advanced metamorphic HEMT technology

Integrated circuits based on metamorphic HEMT (MHEMT) technologies on 4" GaAs substrates for both millimeter-wave and mixed-signal applications are discussed in this paper. Extrinsic cut-off frequencies of f_t= 293 GHz and f_max = 337 GHz were achieved for the 70 nm gate length depletion type MHEMT technology. The MMIC process features high yield on transistor and circuit levels. Single-stage low-noise amplifiers demonstrate a small signal gain of 12 dB and a noise figure of 2.2 dB at 94 GHz. An amplifier MMIC developed for D-band operation exhibits a gain of 15 dB from 155 to 160 GHz. The achieved results are equivalent to state-of-the-art InP-based HEMT technologies. In order to realize 80 Gbit/s mixed-signal circuits, a 100 nm gate length enhancement type HEMT process with a transit frequency of 200 GHz is applied. Three metalization layers are available for interconnects. The parasitic capacitance of the interconnects is kept low by using BCB and plated air bridge technology. Based on this process, static and dynamic frequency dividers are realized which achieve a maximum toggle frequency of 70 GHz and 108 GHz, respectively. Furthermore, 2:1 multiplexer and 1:2 demultiplexer ICs were developed and successfully tested at 80 Gbit/s data rate.