Sigma-delta digital drive signals for switchmode power amplifiers

A novel all-digital approach to generate a pulse train to drive switch-mode power amplifiers is proposed. Sigma-delta (ΣΔ) techniques are used to shape time quantisation noise away from the band of interest. The proposed architecture promises greater than 10-dB improvement in adjacent channel power over an existing scheme. The key contribution is to quantise in the polar domain while performing the ΣΔ filtering in the Cartesian domain.