US Patent 9438234 Logic circuit and semiconductor device including logic circuit

A logic circuit that can retain a state even without power supply is provided. The logic circuit includes a first circuit, a pair of retention circuits, and a second circuit. The pair of retention circuits includes two switches electrically connected to each other in series and a capacitor electrically connected to a connection portion of the two switches. Each of the two switches is formed using an oxide semiconductor transistor. The first circuit has a function of generating complementary data from a piece of input data. The pair of retention circuits retains the complementary data. The second circuit has a function of amplifying the complementary data retained in the pair of retention circuits.