MOSFET as switch

When the MOSFET is used as a switch, it it operated at the extreme points of the transfer curve. Specifically, the device is turned off by keeping Vi<Vt resulting in operation with [blank_start]Vo = Vdd[blank_end]. The switch is turned on by applying a voltage close to Vdd, resulting in operation with [blank_start]Vo = 0[blank_end]. At this juncture, the common-source MOS circuit can be used as a logic inverter with the '[blank_start]low[blank_end]' voltage level close to 0V and the '[blank_start]high[blank_end]' level close to Vdd.