| 摘要 |
<p>PROBLEM TO BE SOLVED: To apply an amplifier circuit, a modulation circuit, a demodulation circuit, a transmitter and a receiver to an IC card that inputs/outputs various data e.g. in a non-contact state and to a reader/writer that communicates with the IC card so that they together with other circuit blocks can simply and easily be made to an integrated circuit and they can efficiently be operated. SOLUTION: This circuit is configured so that 1st and 2nd output signals with a prescribed phase are added to an input signal SC to be outputted, at least the 2nd output signal is gated in responce to input data TX or the result of power amplification is attenuated at the output side of a power amplifier circuit in response to the input data to produce an amplitude modulation signal. Furthermore, the amplitude modulation signal is biased and amplified or clipped and processed. Further, the amplitude modulation signal is clipped and processed, further, the polarity of the amplitude modulation signal is discriminated, the discrimination result is multiplied with the amplitude modulation signal and further, the amplitude modulation signal is selectively outputted based on the polarity discrimination result of the amplitude modulation signal.</p> |
