A-D converter and A-D convert method

An A/D converter that outputs a digital output signal obtained by digitalizing an analog input signal, comprising:

• a plurality of comparators of which each compares the analog input signal and an analog threshold value according to a specified digital threshold data;
• a high-order field determining section that narrows down a data value corresponding to a high-order field for a predetermined bit number in the digital output signal on the basis of a plurality of comparison results obtained by supplying different threshold data to the plurality of comparators;
• a low-order field computing section that computes a plurality of candidate values for a data value corresponding to a low-order field for a predetermined number of bits located at a side lower than the high-order field by means of the plurality of comparators;
• a low-order field determining section that determines the data value corresponding to the low-order field on the basis of the plurality of candidate values;
• and
• a timing controlling section that causes, when computing the plurality of candidate values of the data value corresponding to the low-order field, a first comparator among the plurality of comparators to compare the analog input signal and the analog threshold value at a first timing in a conversion time interval determining a value for one bit and causes a second comparator among the plurality of comparators to compare the analog input signal and the analog threshold value at a second timing different from the first timing in the conversion time interval.

An A/D convert method for outputting a digital output signal obtained by digitalizing an analog input signal, comprising:

• selecting a conversion object bit from a high-order bit to a low-order bit of the digital output signal in order;
• determining a threshold data expressing a boundary value between zero and one of the conversion object bit on the basis of an already-determined value of a higher-order bit than the conversion object bit;
• digital-to-analog converting the threshold data and generating an analog threshold value;
• comparing, at a plurality of different timings in a conversion time interval determining a value of the conversion object bit, the analog input signal and the analog threshold value and outputting a plurality of comparison results at the timings;
• and
• determining the value of the conversion object bit on the basis of the plurality of comparison results.

An A/D convert method for outputting a digital output signal obtained by digitalizing an analog input signal, comprising:

• narrowing down a data value corresponding to a high-order field for a predetermined bit number in the digital output signal on the basis of a plurality of comparison results obtained by supplying different threshold data to a plurality of comparators of which each compares the analog input signal and an analog threshold value according to a specified digital threshold data;
• computing a plurality of candidate values for a data value corresponding to a low-order field for a predetermined number of bits located at a side lower than the high-order field by means of the plurality of comparators;
• determining the data value corresponding to the low-order field on the basis of the plurality of candidate values;
• and
• causing, when computing the plurality of candidate values of the data value corresponding to the low-order field, a first comparator among the plurality of comparators to compare the analog input signal and the analog threshold value at a first timing in a conversion time interval determining a value for one bit and causing a second comparator among the plurality of comparators to compare the analog input signal and the analog threshold value at a second timing different from the first timing in the conversion time interval.