Patent ID: 8493254

Claim:
An AD converter comprising: an auto gain control (“AGC”) circuit that changes an input amplitude of an analog signal and outputs the analog signal to an AD converter circuit that converts the analog signal to a digital signal; and a first detection portion that compares an output range of the analog signal output by the AGC circuit with a predetermined voltage range and, based on a comparison result, controls the output range of the analog signal output of the AGC circuit, wherein the first detection portion compares the output range of the analog signal output of the AGC circuit with reference voltages of the AD converter circuit and, based on a comparison result, controls the output range of the analog signal output of the AGC circuit, and wherein, during a period of time in which the output range of the analog signal output of the AGC circuit exceeds a range of the reference voltages, the first detection portion outputs a signal that indicates that the output of the AGC circuit exceeds the range of the reference voltages of the AD converter circuit.