A level shifter includes an input node, an output node, a pull-up transistor, a pull-down transistor, and at least one diode-connected device coupled between the pull-up transistor and the pull-down transistor. The level shifter is arranged to be coupled to a high power supply voltage, to receive an input signal having a first voltage level at the input node, and to supply an output signal having a second voltage level at the output node. The high power supply voltage is higher than the first voltage level. The at least one diode-connected device allows the output signal to be pulled up to about a first diode voltage drop below the high power supply voltage and/or to be pulled down to about a second diode voltage drop above ground. The first diode voltage drop and the second diode voltage drop are from the at least one diode-connected device.