A/D converter and A/D converter calibrating method

摘要

An A/D converter includes an A/D conversion unit, a histogram generation-storage unit, and a control unit. The A/D conversion unit is configured to receive an input voltage, perform an analog-to-digital conversion, and output digital data, and the histogram generation-storage unit is configured to receive the digital data, generate a histogram for a waveform of the input voltage, and store the generated histogram therein. The control unit is configured to control an analog-to-digital conversion characteristics of the A/D conversion unit, based on the histogram stored in the histogram generation-storage unit.

主权项

1. An A/D converter comprising:
an A/D conversion unit configured to receive an input voltage, perform an analog-to-digital conversion, and output digital data; a histogram generation-storage unit configured to receive the digital data, generate a histogram for a waveform of the input voltage, and store the generated histogram therein; and a control unit configured to control analog-to-digital conversion characteristics of the A/D conversion unit, based on the histogram stored in the histogram generation-storage unit, wherein the control unit includes:
a histogram shape determination unit configured to read the histogram stored in the histogram generation-storage unit to perform a shape determination, output an error signal between the histogram and a preset reference histogram, and output a correction signal for correcting the analog-to-digital conversion characteristics of the A/D conversion unit; andan operation control unit configured to receive the error signal to control a calibration operation, the A/D conversion unit includes:
a capacitive D/A conversion unit configured to receive the input voltage and switch over a plurality of capacitors and switches to perform a digital-to-analog conversion;a comparator unit configured to compare voltages of outputs from the capacitive D/A conversion unit; anda successive approximation register type A/D conversion unit configured to output the digital data, based on a comparison result of the comparator unit, and the comparator unit includes:
a plurality of comparators including comparison characteristics different from one another,each of the plurality of comparators receives the voltage of the output from the capacitive D/A conversion unit, andany one of the plurality of comparators is selected in accordance with the correction signal from the histogram shape determination unit, and an output from the selected comparator is output to the successive approximation register type A/D conversion unit.