Patent ID: 8373501
Filing Date: 2013-02-12
Classification: G05F

Abstract:
1. A reference voltage circuit, comprising: a reference voltage section comprising a depletion mode MOS transistor and a first enhancement mode MOS transistor; and a soft start circuit, wherein the soft start circuit comprises: a second enhancement mode MOS transistor having a gate connected to a gate and a drain of the first enhancement mode MOS transistor, and a drain connected to an output terminal of the reference voltage circuit; a MOS switch having one terminal connected to an output terminal of the reference voltage section, and another terminal connected to the drain of the second enhancement mode MOS transistor; and a constant current source and a capacitor connected in series between a power supply and a ground, and wherein the MOS switch is gradually turned ON by a voltage supplied when the capacitor is charged with a current of the constant current source, to thereby gradually raise a reference voltage.