Analog voltage subtracting circuit and an A/D converter having the subtracting circuit

摘要

An analog voltage subtracting circuit for calculating a difference between an analog input voltage and a voltage drop caused by a load includes an analog voltage generator 7 for generating an analog voltage, a load 3 having one end connected to an output of the analog voltage generator 7 and the other end connected to an output terminal 2, and a D/A converter 6 applying a positive output current Iout for generating a desired voltage drop at said the other end 4 of the load 3 and for applying a complementary output current I(OVS) complementary to the positive output current Iout to said one end of the load 3. By this structure, a constant current of Iout+I(OVS) flows at said one end 4 of the load 3, and therefore linear output can be provided.