Carry chain TDC code width monitoring and adjusting method

The invention relates to a carry chain TDC code width monitoring and adjusting method, and mainly solves the technical problems that in the prior art, the real-time change of the carry chain TDC code width is realized on an FPGA platform, the accurate calibration of the TDC code width is difficult, and the code width linearity is poor. Based on a coherent sampling theory and a code density calibration method, sequential logic is used, an output holding circuit is combined, a random calibration signal is generated, the calibration signal is strictly coherent with a TDC main clock, the calibration signal is input into a carry chain TDC, and the purpose of accurately calibrating the code width of the carry chain TDC is achieved. According to a calibration result, through sequential combination, a proper tap position is manually selected, and the tap code width of the TDC is optimized, so that the linearity of the carry chain TDC can be effectively improved. A delay change monitoring part is added in a carry chai