Patent ID: 7554376

Claim:
An offset correcting circuit comprising: an amplifying unit including an offset adjusting unit that adjusts an offset of the amplifying unit; an offset determining unit that detects the offset of the amplifying unit and outputs a signal for correcting the offset of the amplifying unit; and a power-ON detecting unit that detects a power ON signal to output a reset signal which causes the offset determining unit to start correcting the offset, wherein the offset determining unit includes a comparing unit that compares an output of the amplifying unit with a reference value, and a counter that increases or decreases a count value in response to an output of the comparing unit, and the offset adjusting unit includes a bias varying portion having a plurality of transistors connected in parallel with each other and which varies a bias of the amplifying unit by changing on/off states of the plurality of transistors based on the count value of the counter, thereby adjusting the offset.