Calibration circuit for reference voltage in chip and reference voltage calibration chip

The utility model is suitable for the field of reference voltage calibration, and particularly relates to a calibration circuit for reference voltage in a chip and a reference voltage calibration chip. The calibration circuit comprises a comparator, an adjustable voltage division branch and a successive approximation logic branch, the comparator comprises a first input end, a second input end and a comparator output end, and the second input end is connected with an external reference voltage; the adjustable voltage division circuit comprises a voltage division device, the voltage input end of the voltage division device is connected with reference voltage in the chip, and the voltage output end is connected with the first input end; the adjusting input end of the successive approximation logic branch is connected with the output end of the comparator, the adjusting output end of the successive approximation logic branch is connected with the voltage division control end of the voltage division device, the co