An apparatus is provided which comprises: a first device coupled to a first power supply rail; a second device coupled in series with the first device, wherein the second device is coupled to a second power supply rail; and a third device coupled to the first and second power supply rails, wherein the first device is controllable by a first input, wherein the second device is controllable by a second input, wherein the third device is controllable by a third input, and wherein the first input is an analog bias between a high power supply level and a ground supply level.