| 摘要 |
PROBLEM TO BE SOLVED: To provide a data writing device or the like which can hold a sufficient communication distance even when a power source of a low voltage such as a battery is used in a non-contact type IC card system. SOLUTION: A transmission circuit of a data writing device has a battery and a transmission side amplifying circuit 32 which is supplied with voltage from this battery and drives a loop antenna. The transmission side amplifying circuit 32 is equipped with a boosting circuit 42 consisting of a frequency division circuit 41 for frequency dividing a modulation signal (CLK) modulating transmission data by using a clock, a voltage shifter 43 for shifting a level of the frequency divided modulation signal in a direct-current manner and a maximum value holding circuit 44 for holding a peak value of the level shifted modulation signal. This transmission side amplifying circuit 32 generates a DC voltage higher than a power source voltage by the boosting circuit and amplifies the modulation signal by using this DC voltage. |
