2.3-GHz HBT Power Amplifier With Parallel-Segmented On-Chip Autotransformer

A parallel-segmented primary autotransformer is proposed to optimize passive efficiency as well as impedance transformation ratio. In addition, a corresponding equivalent lumped model has been proposed and shows a good agreement with electromagnetic -simulated and measured data. This paper also presents a fully integrated HBT power amplifier with a parallel-segmented primary autotransformer to obtain watt-level output power with low loss. The saturated output power of the power amplifier (PA) is 31 dBm at 2.3 GHz. The PA achieves output power of 24.84 dBm with adjacent channel leakage ratio of less than -40.4 dBc for LTE signal with a 10-MHz bandwidth and 7.3-dB PAPR.