A voltage regulator is provided. The voltage regulator includes a shunt transistor and a feedback circuit. The shunt transistor has a first current electrode coupled to a first voltage source terminal, a second current electrode coupled to a second voltage source terminal, a control electrode coupled to receive a reference voltage, and a body electrode. The feedback circuit has an input terminal coupled to the body electrode of the shunt transistor, and an output terminal coupled to the control electrode of the shunt transistor. The voltage regulator is suitable for use in a passive RFID device to protect the device from over-voltage damage. In another embodiment, a method for regulating a voltage is provided.