A high-efficiency and high-gain, plastic packaged GaN HEMT for 3.5-GHz-band LTE base stations

A plastic packaged GaN HEMT is presented for 3.5-GHz-band LTE small-cell base-station applications. A pair of GaN HEMT dies and MIM capacitors is assembled in the package for Doherty amplifier use. Optimized drain bonding wire length enhances high efficiency operation. The input prematching with the MIM capacitors suppresses insertion loss and improves power gain. Measurements of a single-chain amplifier using the GaN HEMT show a high drain efficiency of 66.3% and a high power gain of 16.2 dB at 3.5 GHz, regardless of plastic packaging. A Doherty amplifier demonstration with the GaN HEMT shows a drain efficiency as high as 51.2% and an output power of 36.0 dBm at ACLR of -50 dBc. This is the first demonstration of a plastic packaged GaN HEMT Doherty amplifier in the 3.5-GHz band.