Semiconductor device and physical quantity measuring device

A semiconductor device comprising:

• a transmission device radiating, from an antenna to a measuring object, a first transmission signal generated by modulating a carrier wave with a first modulating signal, a carrier frequency of the carrier wave being a first frequency, and a second transmission signal generated by modulating the carrier wave with a second modulating signal, the carrier frequency of the carrier wave being a second frequency;
• and
• a reception device generating a first demodulating signal by demodulating the first transmission signal, the first transmission signal receiving, with the antenna, a first reception signal via the measuring object, generating a second demodulating signal by demodulating the second transmission signal, the second transmission signal receiving, with the antenna, a second reception signal via the measuring object, and performing a processing to the first demodulating signal and the second demodulating signal,
• wherein the transmission device is configured to switch starting and stopping modulation at a first phase of the carrier wave, the carrier frequency of the carrier wave being the first frequency, and switch starting and stopping the modulation at a second phase of the carrier wave, the carrier frequency of the carrier wave being the second frequency, and
• wherein the reception device is configured to:
• store a difference between the first phase and the second phase and a physical quantity corresponding to a phase change amount in advance;
• estimate, based on a waveform of the demodulating signal, first modulation switch timing at which the first reception signal switches between a non-modulation period and a modulation period, and second modulation switch timing at which the second reception signal switches between the non-modulation period and the modulation period;
• calculate a third phase that is a phase at the first modulation start timing;
• calculate a fourth phase that is a phase at the second modulation start timing;
• calculate a variation to a difference between the third phase and the fourth phase based on the difference between the first phase and the second phase that are stored;
• and
• determine the physical quantity corresponding to the variation based on the physical quantity corresponding to the stored phase change amount.