The application relates to a dual-mode FLASH-SAR ADC conversion circuit and method, the circuit comprising a
FLASH ADC module, a SAR ADC module, a
clock control module and an encoding module. In reference mode one, the
FLASH ADC module is a single-end structure, the
FLASH ADC module samples the
voltage division of a first reference
voltage in a conversion stage, the positive and negative ends of the FLASH ADC module are connected with the
voltage division of the first reference voltage and an input
signal respectively in a sampling stage, and all the sampling capacitors in the SAR ADC module sample the input
signal. In reference mode two, the FLASH ADC module is a differential
capacitor structure, the FLASH ADC module samples the voltage division of a second reference voltage in a conversion stage, the positive and negative ends of the FLASH ADC module are connected with the second reference voltage and the input
signal respectively in a sampling stage, and half of the sampling capacitors in the SAR ADC module sample the input signal. The ADC circuit resources are greatly saved, and the application cost is saved.