Iterative characterisation approach using realistic excitation signals for linearisation of transmitters

This paper presents a new approach to improve the accuracy of power amplifier or transmitter characterisation. Compared to traditional characterisation, an iterative characterisation approach using realistic excitation signals is introduced. Based upon this approach, more accurate nonlinear behaviour for AM/AM and AM/PM can be measured. A memoryless piecewise digital predistortion (DPD) model using iterative characterisation is built to linearise a power amplifier (PA). The linearity improvement by using the iterative characterisation approach is verified in measurements with LTE excitation signals on a PA at 2.05 GHz. For a 10 MHz 64-QAM LTE signal with a PAPR of 8.1 dB measured ACLR1 could be reduced with two additional steps from -41.6 dBc to -47.6 dBc. At the same time measured EVM was better than 4.2% for an average drain efficiency of 51%. Only few steps are required with the proposed linearisation approach to improve the linearity of components without extra complexity to the DPD.