A universal method of ADC emulation based on FPGA is presented.By this method

testing of system design can be done before the development board of ADC of high precision is completed.It can reduce the developing and debugging time of system design effectively.The method is implemented by RTL level code of VHDL.It is validated on LM98640

which is a ADC chip containing SPI configuration interface.The outputs of test mode and their timing specifications of the chip

is emulated.The design is validated on FPGA development board of the project.Results indicate that outputs of test mode and their timing specifications of LM 98640 are consistent with those in datasheet.The method can also apply to other system designs containing ADC which is similar with LM98640.