Patent ID: 7469127

Claim:
A noncontact information carrier reader for transmitting a carrier wave to a noncontact information carrier, the noncontact information carrier reader comprising: a receiving unit configured to receive a response wave transmitted from the noncontact information carrier, the response wave being generated by modulating the carrier wave based on a response signal in the noncontact information carrier; an amplifying unit configured to amplify carrier wave components contained in the received response wave based on a first gain and to amplify response signal components contained in the received response wave based on a second gain, thereby outputting the amplified response wave, the second gain being higher than the first gain; and a synchronized-detection demodulator configured to demodulate the response signal components contained in the amplified response wave outputted from the amplifying unit by mixing the transmitted carrier wave and the amplified response wave outputted therefrom, wherein the amplifying unit comprises: a first diode series circuit composed of a first diode and a first zener diode, one of cathode and anode of the first diode is connected to corresponding one of cathode and anode of the first zener diode in series; and a second diode series circuit composed of a second diode and a second zener diode, one of cathode and anode of the second diode is connected to corresponding one of cathode and anode of the second zener diode in series, wherein the first diode series circuit and the second diode series circuit are connected in parallel to each other such that the other of the cathode and anode of the first diode of the first diode series circuit is connected to the other of the cathode and anode of the second zener diode of the second diode series circuit, and the other of the cathode and anode of the second diode of the second diode series circuit is connected to the other of the cathode and anode of the first zener diode of the first diode series circuit.