Patent ID: 8041323

Claim:
A portable electronic unit comprising: transmission-side means for transmitting a signal; and receiving-side means for receiving the signal from the transmission-side means, the receiving-side means comprising gain control amplification means for amplifying and outputting the signal from the transmission-side means, the gain control amplification means including a first amplification circuit that amplifies and outputs the signal from the transmission-side means, a detection circuit that detects and outputs a signal from the first amplification circuit, a reverse gain control amplification circuit that amplifies and outputs the signal from the detection circuit, the reverse gain control amplification circuit having a second amplification circuit that amplifies and outputs the signal from the detection circuit and a feedback circuit for feeding an output from the second amplification circuit back to an input side of the second amplification circuit, and a gain control circuit that controls a gain in the reverse gain control amplification circuit in response to a level of the signal from the detection circuit, the gain control circuit controlling a gain in the reverse gain control amplification circuit by controlling an amount of feedback from the feedback circuit.