Coupling effects of dual SiGe power amplifiers for 802.11n MIMO applications

The large-signal and small-signal coupling effects of dual SiGe power amplifiers (PAs) on a single chip for 802.11n multiple input multiple output (MIMO) applications are demonstrated for the first time. Deep trench isolation and grounded guard ring are used for crosstalk isolation at both transistor and circuit levels. The equivalent small-signal coupling at 2.45 GHz between two PAs is -30 dB. The PA delivers 18.1 dBm and 16.6 dBm with 3% EVM (OFDM, 64-QAM) in single and dual PA operation modes, respectively. The EVM degradation becomes severe as the relative interfering power level increases.