A circuit includes a first power node configured to carry a voltage K·VDD, a second power node configured to carry a zero reference level, an output node, K P-type transistors serially coupled between the first power node and the output node, and K N-type transistors serially coupled between the second power node and the output node. Gates of the K P-type transistors are configured to receive biasing signals set at one or more voltage levels in a manner that one or more absolute values of source-gate voltages or absolute values of drain-gate voltages are equal to or less than VDD. Gates of the K N-type transistors are configured to receive biasing signals set at one or more voltage levels in a manner that one or more absolute values of gate-source voltages or gate-drain voltages are equal to or less than VDD.