An A/D converter adopting mixed type dual-layer folding circuit

The invention belongs to the integrated circuit technical field, in particular to a mixed type double-layer folding circuit analog-to-digital converter. The invention consists of a single sample-hold circuit, a reference resistance string, premagnification, resistance offset averaging and twice interpolating circuit, a rough analog-to-digital converter, a folding circuit, an resistance eight-time interpolating circuit, a comparator and a code circuit, etc.; wherein, the folding circuit consists of an amplifying circuit and an outputting circuit and makes improvement of high-speed and low-dissipation to the amplifying circuit which comprises double-layer amplifying units which are same with the number being M and leads 3 multiplied by M pairs of differential input voltage to be amplified. In the invention, the consumption of the circuit is reduced greatly and the speed is raised greatly.