Patent ID: 8811901

Claim:
A semiconductor device comprising: an antenna circuit; a rectifier circuit; a demodulation circuit; a signal processing circuit portion; an oscillator circuit; a divider circuit; a switch; a mixer; and a secondary battery, wherein the antenna circuit is configured to receive an electromagnetic wave from a power feeding device and output an electrical signal, wherein the rectifier circuit is configured to rectify the electrical signal and generate a rectified signal, wherein the demodulation circuit is configured to demodulate the rectified signal and transmit a demodulated signal to the signal processing circuit portion, wherein the signal processing circuit portion is configured to receive the demodulated signal and generate a transmission signal, wherein the oscillator circuit is configured to operate in response to the transmission signal and input a base carrier to the divider circuit and the mixer via the switch, wherein the divider circuit is configured to divide a frequency of the base carrier, thereby generating signals having a plurality of frequencies which are lower than the frequency of the base carrier generated in the oscillator circuit, wherein the switch is configured to select one of the signals having the plurality of frequencies and transmit a selected signal to the mixer, wherein the mixer is configured to mix the base carrier with the selected signal, and is configured to transmit a mixed signal to the antenna circuit, wherein the secondary battery is configured to store first power transmitted from the power feeding device and supply second power to a power load portion, and wherein the switch is provided between the mixer and the divider circuit.