A/D Conversion circuit with carrier frequency removing feature

摘要

The present invention is intended to fully remove a carrier-frequency component despite a compact low-cost configuration. An A/D conversion circuit with a carrier frequency removing feature includes: an A/D converter including a voltage comparator that compares a first signal with a feedback signal and a voltage feedback circuit that produces the feedback signal; a one-input N-output demultiplexer that receives the feedback signal; N integrators that calculate the respective integrals of N output signals of the demultiplexer; an N-input one-output multiplexer that receives the outputs of the N respective integrators; a subtractor that produces a difference between an analog signal and the output signal of the multiplexer; an amplifier that amplifies the output signal of the subtractor to produce the first signal; and a switching control circuit that cyclically switches the input terminals of the multiplexer and the output terminals of the demultiplexer synchronously with a carrier wave.