A semiconductor device includes a first transistor having a first gate oxide layer with a first thickness; a second transistor having a second gate oxide layer with a second thickness different from the first thickness; and at least one of a capacitor and a variable capacitance diode. One of the capacitor and the variable capacitance diode includes a first electrode having a first area and a second area; a second electrode formed in the first area with the first gate oxide layer in between; and a third electrode formed in the second area with the second gate oxide layer in between. The second electrode and third electrode have comb shapes nested inside one another.