Abstract: A low voltage regulator integrated circuit for high speed/high frequency circuits incorporates a field effect transistor switch with a heterojunction bipolar transistor in order to reduce voltage requirements of the circuit and allow lower power voltages to be regulated. A first field effect transistor connects an unregulated power input terminal to a regulated power output terminal with a bias circuit including the heterojunction bipolar transistor provided to maintain conductance of the field effect transistor in regulating a voltage on the output terminal. A second field effect transistor can be included in the circuit to provide a power down or power saving mode of operation. An input voltage range of the voltage regulator is reduced from 3-3.5 V to 2-2.3 V using the integrated field effect transistor/heterojunction bipolar transistor device structure.