A circuit provides a voltage reference using very low power. It can also be used as a shut regulator for a quiescent current as low as 1.5 .mu.A. It includes a transconductance amplifier, a gain stage, and a power transistor. One embodiment of this invention utilizes a work function difference between p.sup.+ gate and n.sup.+ gate to generate a predetermined reference voltage. In another embodiment of this invention, the predetermined reference voltage can be pre-adjusted using gate materials with different work functions.