The invention discloses an analog-digital converter. The analog-digital converter comprises a hardware adder and a proportional amplifier; the hardware adder comprises two DAC chips; a digital signalis converted into a current signal through the DAC chips, the current signal is introduced to be externally connected with a linear operational amplifier and then is converted into a corresponding analog voltage signal, and the analog voltage signal is converted into a voltage required for actual control after passing through the proportional amplifier; and the proportional amplifier is used for carrying out proportional amplification on the voltage generated by the hardware adder to achieve the voltage required for actual control. The analog-digital converter has the following beneficial effects: 1, the system noise is reduced to a certain extent, the effective digit number of measurement is increased, and the effective digit number of the DAC is increased to 32 bits in reality; and 2, the new 32-bit high-resolution DAC is relatively easy in the wiring aspect of a PCB.