The THD measurements at voltage levels 1.41 - 2.83 V were carried out with High Pass Filter "on" (2nd order Buttreworth type, 2000 Hz cutoff, HPF2-2k).
The THD measurements at voltage levels 4 - 8 V were carried out with High Pass Filter "on" (2nd order Buttreworth type, 3000 Hz cutoff, HPF2-3k).