Predicting total harmonic distortion (THD) in ADSL transformers using behavioural modeling

As a design application, the ADSL broadband line transformer offers interesting challenges somewhat different to those in power supply design. The aspect of total harmonic distortion (THD) as affected by the nonlinear behaviour of the magnetic material in a line transformer is analysed using simulation. A mixed technology model of the line transformer is constructed and circuit simulation used to predict the level of THD for a variety of core types and configurations. The simulation results are compared with measured THD figures to demonstrate the accuracy of the models used.