MAX2831 Power Amplifier (PA) Output Power and Bias-Current Optimization

The MAX2831 is a fully integrated transceiver with power amplifier (PA) for 802.11b/g applications. The bias current and output-matching network for the two-stage PA have been optimized to nominally deliver +18.5dBm while consuming 209mA from a 3.3V supply (at less than 5.6% EVM in 54Mbps (64-QAM) mode) while meeting 802.11g spectral mask requirements. At lower output-power levels, reprogramming the PA Bias Current Registers allows the bias current and overall PA current to be reduced for improved Tx efficiency while still meeting 802.11g requirements. When the PA bias current is optimized for +17dBm transmit power, a current savings of 26mA is achieved as compared with the nominal register setting. When operating at +3dBm transmit power, a current savings of 62mA is achieved as compared with nominal register setting. Further current savings can be achieved for a specific output-power level through optimization of the simple two-capacitor output-matching network.