ANALOG-DIGITAL CONVERTER AND SIGNAL PROCESSING SYSTEM

PROBLEM TO BE SOLVED: To provide an AD converter and a signal processing system that prevent an increase in area and suppress a sampled analog signal error between a coarse ADC and a fine ADC.SOLUTION: An AD converter includes: a coarse AD converter for, in the conversion of an analog input signal to an N-bit digital signal, performing conversion to an upper m-bit digital signal; a fine AD converter for converting the analog input signal to a lower n-bit (n=N-m) digital signal based on the conversion result of the coarse AD converter; and a TH circuit for sampling the analog input signal, supplying a comparison voltage against a coarse reference voltage to the coarse AD converter, and supplying a comparison voltage against a fine reference voltage based on the conversion result of the fine AD converter to the fine AD converter. The TH circuit shares a sampling capacitance in a selective input path for the analog input signal, the coarse reference voltage and the fine reference voltage.