Patent ID: 8692610

Claim:
A reference voltage supply circuit comprising: a current supply; a first transistor; and a second transistor; which are sequentially coupled in series, wherein the first transistor is provided in a first well, which is a shallow well located in a deep well of a first conductivity type provided in a semiconductor layer, and includes a first gate insulating film and a first gate electrode containing first gate impurities, the shallow well has a second conductivity type, the second transistor is provided in a second well of the second conductivity type provided in the semiconductor layer, and includes a second gate insulating film and a second gate electrode containing second gate impurities, the first gate electrode, a drain of the first transistor, and the second gate electrode are electrically coupled to the current supply, a source of the first transistor, a drain of the second transistor, and the first well are electrically coupled together, a source of the second transistor and the second well are coupled to ground, the first gate insulating film and the second gate insulating film are made of a same type of film with a same thickness, the first gate impurities contained in the first gate electrode and the second gate impurities contained in the second gate electrode have different conductivity types, or have a same conductivity type and different concentrations, the first transistor has a greater gate width than the second transistor, and the first transistor and the second transistor operate in a subthreshold region when potential of the source of the first transistor is output outside as a reference voltage.