Three independent groups of researc

Three independent groups of researchers have presented experimental examples of the parallel voltage controlled topology with good results [4]–[6]. Reference [4] reports an excellent result of 0.01% THD at 1 kHz from 0.5 to 50 W, and an efficiency
of 90% at 50 W. A custom integrated circuit class D stage with
a separate integrated circuit class B stage also achieves 0.02%
THD up to 30 W with 85% efficiency at 30 W [5]. A full bridge
configuration [6] achieves less than 0.1% THD at 25 W.