A waveform conversion unit (42) of a numerically controlled oscillator has a cosine table (101) and a sine table (102) in which parameters for cosine wave and sine wave signal generation are stored, a correction mechanism (50) for generating correction values according to the phase of an inputted phase signal, an adder (111) for generating a cosine wave signal from a parameter in the cosine table (101) and a correction value, and an adder (112) for generating a sine wave signal from a parameter in the sine table (102) and a correction value. The correction mechanism (50) uses waveform data which is a kind of parabolic data and whose phase interval is more minute than the phase interval of the parameters in each table (101), (102) to generate correction values for correcting cosine wave and sine wave signals to be found by linear interpolation.

A semiconductor device includes an antenna functioning as a coil, a capacitor electrically connected to the antenna in parallel, a passive element forming a resonance circuit with the antenna and the capacitor by being electrically connected to the antenna and the capacitor in parallel, a first field effect transistor controlling whether the passive element is electrically connected to the antenna and the capacitor in parallel or not, and a memory circuit. The memory circuit includes a second field effect transistor which includes an oxide semiconductor layer where a channel is formed and in which a data signal is input to one of a source and a drain. The gate voltage of the first field effect transistor is set depending on the voltage of the other of the source and the drain of the second field effect transistor.