30.3% PAE HBT Doherty power amplifier for 2.5∼2.7 GHz mobile WiMAX

The Doherty power amplifier for mobile WiMAX application is fully integrated in 1.2×1.2 mm² using a 2-μm InGaP/GaAs HBT process. The direct input power dividing technique is employed on a chip. Broadband input and output matching techniques are used for broadband Doherty operation. A 1.5 times larger peaking amplifier than carrier amplifier is used to have high efficiency for IEEE 802.16e m-WiMAX signal, which has 9.6 dB crest factor and 8.75 MHz bandwidth. The PA with a supply voltage of 3.4 V has an EVM of 2.3% and a PAE of 31.5% at an output power of 24.75 dBm and an operating frequency of 2.6 GHz. The PAE of over 30.3% and the output power of over 24.6 dBm with the EVM of lower than 3.15% and the gain variation of 0.2 dB are achieved across 2.5~2.7 GHz without any assistant technique for linearization.