A driver circuit for a semiconductor test system significantly reduces power consumption and limits current flowing from a power-supply. The driver circuit provides a test signal having predetermined voltage levels to a semiconductor test under test by switching diode bridges connected with high and low reference voltages. When receiving a switching signal, transistor circuits drive the diode bridge so that a test signal having the reference voltage is supplied to an output driver through the selected diode bridge. The output driver then supplies the test signal to the semiconductor device under test. The transistor circuits drive the diode bridge by supplying bridge current to ON/OFF control the diode bridges. Each of the diode bridges has a plurality of diodes connected symmetrically and an output of the diode bridge is taken from a point shifted by one diode from a center the diode bridge. The output driver is formed of a first and second pairs of transistors each pair of transistors are connected in a current Miller fashion, and the first pair of transistors are NPN transistors and the second pair of transistors are PNP transistors.