Thus far, we have dealt with principle of operation of an nMOS transistor. A p-channel transistor can be realized by interchanging the n-type and the p-type regions, as shown in Figure 2.6. In case of an pMOS enhancement-mode transistor, the threshold voltage V_th is negative. As the gate is made negative with respect to the source by at least |V_th|, the holes are attracted into the thin region below the gate, crating an inverted p-channel. Thus, a conduction path is created for the majority carriers (holes) between the source and the drain. Moreover, a negative drain voltage V_DS draws the holes through the channel from the source to the drain.