Monolithic Integration of HEMT-Based Common Gate Oscillator with Active Integrated Antenna in the GaN Material System

and Introduction: This project focused on the preparation of high electron mobility transistors (HEMTs) and the design of a HEMTbased, single-lithography-layer oscillator with active integrated antenna circuit with target oscillation frequencies up to 100 GHz. HEMT devices are well known for their suitability in high frequency microwave circuits, possibly for two reasons. Firstly, HEMTs offer high electron densities, high breakdown voltages and superior drain currents as well as transconductance, making the devices suitable for high power, high frequency application. Secondly, because of reduction in columbic scattering and collisions, HEMT devices are known to display low-noise characteristics. These two factors combine make HEMTs amenable to nano-scale microwave oscillator design. Focus on reduction in device size is a growing demand and the prevalence of cellular phones, WiFi and other radio devices is increasing. Thus, the design of a low-cost, nano-scale microwave oscillating circuit is desirable. In this project, AlGaN/GaN HEMTs were fabricated with recessed gates in order to enhance aspect ratio, transconductance, cutoff frequency and maximum frequency of oscillation [1].