A voltage regulator includes first and second MOS transistors and a
bipolar transistor. The first MOS transistor has a first conductivity
type and has a drain coupled to a first power supply voltage terminal, a
gate for receiving a first bias voltage, and a source. The second MOS
transistor has a second conductivity type and has a source coupled to the
first power supply voltage terminal, a drain coupled to the source of the
first MOS transistor, and a gate for receiving a second bias voltage. The
bipolar transistor has a collector coupled to the source of the first MOS
transistor, a base for receiving a third bias voltage, and an emitter for
providing an output voltage. The first MOS transistor and the second MOS
transistor control a voltage level at the collector of the bipolar
transistor in response to a varying power supply voltage provided to the
first power supply voltage terminal.