PURPOSE: An analog/digital conversion circuit is provided to reduce the power consumption by using a metal-to-metal capacitor and a capacitor tuning circuit. CONSTITUTION: The first sample/hold amplifier(201) is used for sampling or holding an analog input signal(Vi). A switch(202) is used for selecting one of a feedback signal and an output signal of the first sample/hold amplifier(201). An analog/digital sub-converter(206) is used for converting the analog signal of the switch(202) to a digital signal. A digital/analog sub-converter(207) is used for converting the digital signal of the analog/digital sub-converter(206) to the analog signal. A subtracter(203) is used for calculating a difference between the analog signal of the switch(202) and an output signal of the digital/analog sub-converter(207). A voltage amplifier(204) is used for amplifying the output signal of the subtracter(203). The second sample/hold amplifier(205) is used for sampling or holding an output signal of the voltage amplifier(204). A digital correction portion(208) is used for overlapping the output signal of the analog/digital sub-converter(206). A timing control portion(209) is used for generating a timing clock.
