| 摘要 |
PROBLEM TO BE SOLVED: To precisely read out transmission data from a non-contact IC card by mutually adding positive and negative rectified signals and outputting the added result as a threshold signal. SOLUTION: An inputted carrier (a) is turned to positive and negative rectified signals (b) through a rectifying means consisting of a preamplifier 51, an operational amplifier 53, diodes 57, 59, and resistors 52, 54, 58, 60. Then, the positive rectified signal is averaged through a threshold signal generating means consisting of a resistor 61 and a capacitor 62 and the negative rectified signal is averaged through a threshold signal generating means consisting of a resistor 64 and a capacitor 65. The positive and negative rectified signals are mutually added through a threshold signal generating means consisting of resistors 63, 66. A comparator 56 to be a comparing means compares an wave (e) to be a threshod with the carrier (a) and outputs a waveform corresponding to a compared result. Thereby, the comparator 56 outputs an accurate digital signal to a demodulation circuit. |
