Abstract: Apparatus (200) for driving an LCD display. The apparatus (200) comprises a source driver which is operated between a first power supply rail (VDDH) and a second power supply rail (VSSH). The source driver comprises a power buffer (22) being arranged between the first and the second power supply rails (VDDH, VSSH). The power buffer (22) provides at an output (32) a virtual voltage (VV) of about half the voltage between the two power supply rails (VDDH, VSSH). Furthermore, a P-buffer (20) and an N-buffer (21) are provided. The P-buffer (20) is situated between the first power supply rail (VDDH) and the virtual voltage (VV), and the N-buffer (21) is situated between the virtual voltage (VV) and the second power supply rail (VSSH). The P-buffer (20; 31) is driven at its input side (27) by gamma voltages in an upper voltage regime (VinputP) and the N-buffer (21) is at its input side (28) driven by gamma voltages in a lower voltage regime.

Abstract: The present invention relates to a switching circuit and a method of controlling a threshold voltage of a semiconductor switching element of the switching circuit, wherein a bulk voltage of the semiconductor switching element (Mi) is selected in response to a control signal derived from an output signal of the semiconductor switching element (Mi). Thereby, a fast switching circuit with hysteresis, smaller cross current and precisely adjustable threshold voltages can be provided.