Comparison between latest Si-LDMOS and GaN technology for RF-Power base station transistors

Microwave power transistors are continuously optimized towards increased power densities. This paper investigates the boundaries of a further improved integration in laterally-diffused metal-oxide semiconductor transistors (LDMOS) and compares it to latest generation gallium-nitride high-electron mobility (GaN-HEMT) transistor results for mobile communication RF power base station applications. Baseline LDMOS device designs were further improved in technology (higher breakdown voltage, layout optimizations) to achieve higher power densities (HD) per bare die area. Four GaN and LDMOS carriers have been designed and evaluated for 2.1 GHz targeting 500W output power. It has been found that the power density per bare die area can be improved by a factor of 1.5 compared to the latest generation LDMOS designs while maintaining efficiency. This improved HD-LDMOS comes within 1 dB P3dB close to the output power of the GaN carrier, being designed in the same package footprint.