Arithmetic circuit, control circuit, and display orientation detecting system

An arithmetic circuit comprising:

• an auto-zero amplification circuit that compensates an offset of an entered differential signal;
• a comparator circuit that converts an output signal from the auto-zero amplification circuit to a digital signal;
• a clock supply circuit that supplies an operation clock, which is a periodic pulse signal;
• and
• a logical operation circuit that operates according to the clock supply circuit;
• wherein
• the auto-zero amplification circuit and the comparator circuit are provided in a same package;
• the auto-zero amplification circuit includes a first operational amplifier that amplifies the differential signal and produces the output signal and a second operational amplifier that adjusts an offset voltage of the first operational amplifier;
• the auto-zero amplification circuit includes two states including are a first state in which an offset voltage of the second operational amplifier is adjusted and a second state in which the offset voltage of the first operational amplifier is adjusted by using an output from the second operational amplifier having the offset voltage that has been adjusted in the first state;
• and
• the operation clock supplied by the clock supply circuit is used to select a switching timing signal for use in switching between the first state and the second state.