| 摘要 |
PROBLEM TO BE SOLVED: To provide a signal receiving part for producing an output signal that accurately oscillates between a high level output (HI) and a low level output (LO) in a signal receiving part in a reader/writer, etc., for communicating with a non-contact type data carrier device of a non-contact IC card. SOLUTION: This signal receiving part is provided with an envelope detection circuit 111, a highpass filter 112, a noninverted amplifier circuit 113 and a comparison circuit composed of a Schmitt trigger circuit 114. The envelope detection circuit 111 performs envelope detection of a reception signal, the highpass filter 112 subsequently eliminates a direct current component, the non inverted amplifier circuit 113 using an operational amplifier 113a for amplification performs noninverted amplification of a detection signal that oscillates centering on an obtained ground potential to obtain an amplified signal, the comparison circuit composed of the Schmitt trigger circuit 114 is further used to compare the amplified signal, and a digital output signal composed of a high level output (HI) and a low level output (LO) is produced. |
