Moving the PAR reduction criterion into the line driver

Traditionally, Peak to Average Ratio (PAR) reduction in digital subscriber line (DSL) transmitters focuses on a digital-domain signal, either at the output of the baseband processing block or at the input of the digital-to-analogue converter (DAC). However, analysis of a DSL transceiver shows that the power dissipation is highly dependent on the PAR at a certain node inside the line driver. Thus, in order to be fully effective, the algorithm design should include the power amplifier dynamics. A typical, actively terminated, line driver is analysed and a model is constructed for PAR reduction purposes. The PAR reduction algorithm is then extended to take advantage of the model. Simulations show that algorithms which are designed to reduce PAR at the new, physically motivated, node obtain about 0.5 dB lower PAR evaluated at this node compared to methods that focus on the PAR of the DAC input.