Donald J. Kessler Marian K. Kazimierczuk Power losses and efficiency of class E RF power amplifiers at any duty cycle. 533-536 2001 conf/iscas/2001 ISCAS (3) https://doi.org/10.1109/ISCAS.2001.921365 db/conf/iscas/iscas2001-3.html#KesslerK01