RF Power Amplifier with Cartesian Feedback for TETRA Modulation

The design of a high linearity and high efficiency RF power amplifier with wide bandwidth is presented. Adaptive bias technique is utilized to achieve linearity while preserving good efficiency. Bandwidth analysis and wide bandwidth matching networks of the power amplifier are discussed. Performance data of 34 dBm for the 1 dB power compression point, adjacent channel power ratio (ACPR) of -37 to -38 dBc and PAE (power aided efficiency) of 35 to 37 % for the frequency range 800 to 900 MHz are demonstrated on measurement level. For the closed loop amplifier with Cartesian feedback an ACPR of -65 to -67 dBc has been demonstrated on prototype board. For the prediction of the ACPR performance simulations of the close loop PA based on the Cartesian feedback model are presented. Simulation and measurement results show a good correlation.