Linearity study of path imbalances in multi-level LINC transmitter for wideband LTE application

This paper analyses the linearity of a multi-level linear amplifier with nonlinear components (LINC) transmitter with the existence of path imbalance. The study relies on the fact that the mismatch between two paths in a LINC system always exist nomatter if it is an integrated circuit (IC) or hybrid design. Based upon the built system model, path imbalance, such as gain, phase and delay mismatch effect can be simulated. The influences of path imbalances on the linearity in terms of error vector magnitude (EVM) and adjacent channel leakage ratio (ACLR) is analysed as well. The work also shows the difference in linearity degradation for different bandwidths and number of applied levels. An ML-LINC transmitter is built to verify the analysis, and the measured results show good agreement with the simulation results.

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