The THD measurements at voltage levels 2.83 - 4 V were carried out with High Pass Filter "on" (2nd order Buttreworth type, 300 Hz cutoff, HPF2-300)
The THD measurements at voltage level 5.6 V were carried out with High Pass Filter "on" (2nd order Buttreworth type, 500 Hz cutoff, HPF2-500)
The THD measurements at voltage level 8 V were carried out with High Pass Filter "on" (4th order Buttreworth type, 700 Hz cutoff, HPF4-700)