| 摘要 |
PROBLEM TO BE SOLVED: To improve response data detection sensitivity in a non-contact ID tag system and to enlarge the operatable area of a non-contact ID tag. SOLUTION: In a response data reception period, switches 21 and 23 are turned OFF and response data outputted from filters 9 and 12 are inputted to reception amplifiers 10 and 13 as they are and amplified. In the other period, the switches 21 and 23 are turned ON and input to the reception amplifiers 10 and 13 is attenuated. Thus, since large amplitude change outputted from the filters 9 and 12 is suppressed at the time of interrogation data transmission, even when the characteristics of the reception amplifiers 10 and 13 are set so as to sufficiently amplify the response data with less amplitude change, the saturation of the amplifier by interrogation data is prevented and the detection sensitivity of the response data is improved. |
