Digital foreground calibration system and method for successive approximation register analog-to-digital converter based on rram

A digital foreground calibration system for a successive approximation register analog-to-digital converter based on RRAM, comprising:

• a step voltage generating module, a status monitoring module, an information storage module and a data processing module, wherein the step voltage generating module is only effective in a calibration mode and is cut off in an operation mode, the data processing module is cut off in the calibration mode and is effective in the operation mode;
• the step voltage generating module comprises an N+M bit-width counter and a digital-to-analog converter with a resolution of N+M bits, an input terminal of the counter is connected with an external clock, an output terminal is connected with an input terminal of the digital-to-analog converter, and an output terminal of the digital-to-analog converter is connected with an input terminal of the successive approximation register analog-to-digital converter to be calibrated, the counter is provided to generate a continuously self-incrementing digital code, and the digital-to-analog converter is provided to convert the digital code into a continuously rising analog step voltage Vt for output to the successive approximation register analog-to-digital converter to be calibrated, wherein, M and N are both positive integers;
• the status monitoring module comprises a status detection logic unit and a selector, in the calibration mode, an input terminal of the status detection logic unit is connected with an output terminal of the successive approximation register analog-to-digital converter to be calibrated, an output terminal is connected with an input terminal of the selector, and an output terminal of the selector is connected with the information storage module, the status detection logic unit is provided to detect a mode of a digital output code of the successive approximation register analog-to-digital converter to be calibrated, and the selector is provided to respond to different control signals according to the mode of the digital output code;
• in the operation mode, an input terminal of the status monitoring logic unit is connected with the output terminal of the calibrated successive approximation register analog-to-digital converter, the status detection logic unit is provided to detect the mode of the digital output code of the calibrated successive approximation register analog-to-digital converter, and the selector is provided to respond to the different control signals according to the mode of the digital output code;
• the information storage module comprises an address control unit and an RRAM-based storage array unit, in the calibration mode, the storage array unit is connected with the counter, and is provided to store N (N+M)-bit digital calibration codes generated by the step voltage generating module, the address control unit is provided to select different columns in a storage array according to the control signal output by the status monitoring module, and write the digital calibration codes into the storage array;
• in the operation mode, the storage array unit is connected with the data processing module, and the address control unit is provided to select the different columns in the storage array according to the control signal output by the status monitoring module, and read the digital calibration codes from the storage array;
• the data processing module comprises an N+M-bit data accumulator and an N-bit data cutter, an input terminal of the data accumulator is connected with the information storage module, and an output terminal is connected with an input terminal of the data cutter, the data accumulator is provided to accumulate the selected N+M-bit digital calibration codes in the information storage module, and the data cutter is provided to cut data, only retaining the top N bits, serving as an output of the calibrated successive approximation register analog-to-digital converter.