60-GHz GaAs MMIC low-noise amplifiers

GaAs monolithic MESFET low-noise amplifiers (LNAs) developed for operation in the 60-GHz band are described. A device/circuit computer-aided design (CAD) program developed at COMSAT Laboratories permitted a parametric study of circuit performance, with variation of the device structure and material parameters prior to monolithic microwave integrated circuit (MMIC) fabrication. Single-stage and dual-stage LNA modules with DC-blocking capacitors and bias networks were developed from the first design iteration. A cascaded multistage monolithic amplifier having stable operation was also achieved. The radio-frequency results obtained demonstrated the application of MESFETs in single-stage and multi-stage MESFET MIC LNAs, with good noise performance and usable gain for this frequency range. The single-stage MMIC achieved a 6.4-dB noise figure and 3.5-dB gain at 59 GHz; the cascaded six-stage amplifier exhibited 9.5-dB minimum noise figure and 26-dB gain from 56 to 60 GHz.<>