Intermodulation Disortion Modelling and Measurement Techniques for GaN HEMT Characterization

Growing demand for higher data rates and ever increasing users on the 3rd generation (3G) network is forcing rapid system enhancements to meet the stringent linearity specifications. The implications of microwave power transistor semiconductor technology and design strategies, implemented in basestation power amplifiers, have become the core focus of research.
Challenges still exists in designing highly linear power amplifier. This has subsequently forced power amplifier designers to rely on complex external linearization techniques for achieving 3G linearity specifications. A new tool for optimising the linearity at the device-level has been developed. Using the Volterra series technique, this work has demonstrated key physical origin of intermodulation distortion (IMD) sources in AlGaN/GaN HEMTs. The disagreement between the model prediction and measured data, in terms of AlGaN/GaN HEMT’s broadband IMD behaviour, is commonly encountered, which restricts dynamic measurements to only narrowband excitation. A new IMD testbench has been established for highly accurate experimental analysis of IMD properties in AlGaN/GaN HEMT. With the new measurement facilities, reliable model verification of the developing AlGaN/GaN HEMT technology can be performed.