6 GHz SiGe power amplifier with on-chip transformer combining

The design synthesis of an innovative power amplifier topology is presented. It consists of two efficient push- pull stages whose output powers are combined by a monolithic three-port transformer. The design and optimization of the on- chip transformers have been performed within a 2.5-D electromagnetic simulation environment. The integrated power amplifier is targeted for a SiGe HBT technology. It achieves a power added efficiency of 43.5% and an output power of 28.3 dBm at a frequency of 6 GHz. The comparison of the proposed amplifier to a conventional push-pull amplifier has been carried out and the advantages of the new architecture over the conventional power amplifier are shown.