Analog-digital converter circuit and calibration method

An analog-digital converter circuit having a normal mode for converting a received analog signal into a digital signal, and a calibration mode for adjusting an offset voltage of a comparator, the analog-digital converter circuit comprising:

• a first comparator having a first analog signal input terminal supplied with an analog signal, and a first reference signal input terminal supplied with a first reference signal, in the normal mode;
• and
• a first calibration circuit that adjusts an offset voltage of the first comparator,
• wherein the first calibration circuit comprises:
• a first main calibration unit that adjusts an offset adjustment amount so that an adjusted offset voltage has a value in a range of 0 to Δ1 (where Δ1 is a calibration resolution of the first calibration circuit);
• and
• a first fine adjustment unit that shifts the offset adjustment amount by Δ1/2.

A calibration method that adjusts an offset voltage of a comparator by a calibration circuit having a calibration resolution A, the calibration method comprising:

• fixing a potential difference applied to two input terminals of the comparator to nΔ+Δ/2 (where n is an integer);
• changing a calibration signal supplied to the comparator from the calibration circuit;
• and
• determining an offset adjustment amount based on an output signal output from the comparator.

A calibration method that adjusts an offset voltage of a comparator by a calibration circuit having a calibration resolution A, the calibration method comprising:

• causing two input terminals of the comparator to be short-circuited;
• changing a calibration signal supplied to the comparator from the calibration circuit;
• determining an offset adjustment amount based on an output signal output from the comparator;
• and
• shifting the determined offset adjustment amount by Δ/2.