Toru Ezawa Hiroo Sekiya Takashi Yahagi Design of class DE amplifier with nonlinear shunt capacitances for any output Q. 2190-2193 2008 ISCAS http://dx.doi.org/10.1109/ISCAS.2008.4541886 conf/iscas/2008 db/conf/iscas/iscas2008.html#EzawaSY08