AD converter and AD conversion method
View Patent ↗An exemplary object of the present invention is to achieve both of high-speed operation by parallel processing and a simple configuration by sequential comparison processing, so as to realize high accuracy of AD conversion processing. An AD converter according to the present invention includes a parallel-type AD converting unit that generates an upper bit digital signal composed of a plurality of bits by parallel processing based on an input analog signal input from a predetermined input circuit, a sequential comparison type AD converting unit that generates a digital signal by sequential comparison processing based on a converted analog signal that is generated by converting the upper bit digital signal into an analog signal, and a reconversion controller that detects an indefinite bit included in the upper bit digital signal and reconverts the indefinite bit by the sequential comparison type AD converting unit.
1. An AD converter comprising:
a parallel-type AD converting unit that generates an upper bit digital signal composed of a plurality of bits by parallel processing based on an input analog signal input from a predetermined input circuit;
a sequential comparison type AD converting unit that generates a digital signal by sequential comparison processing based on a converted analog signal that is generated by converting the upper bit digital signal into an analog signal; and
a reconversion controller that detects an indefinite bit included in the upper bit digital signal and reconverts the indefinite bit by the sequential comparison type AD converting unit.
2. The AD converter according to claim 1 , wherein the reconversion controller comprises an indefinite bit detecting unit that sets a comparison digit string based on the upper bit digital signal and compares the upper bit digital signal with the comparison digit string for each bit, so as to detect the indefinite bit.
3. The AD converter according to claim 2 , wherein the indefinite bit detecting unit judges a bit position as the indefinite bit when at least one of a plurality of values of the upper bit digital signal and the comparison digit string that correspond to the same bit position is different.
4. The AD converter according to claim 2 , wherein the comparison digit string is set by subtracting a compared correction value composed of any integer from the upper bit digital signal or by adding the compared correction value to the upper bit digital signal.
5. The AD converter according to claim 4 , wherein the compared correction value is 1.
6. An AD conversion method comprising:
generating an upper bit digital signal composed of a plurality of bits by parallel processing based on an input analog signal input from a predetermined input circuit;
generating a digital signal by sequential comparison processing based on a converted analog signal that is generated by converting the upper bit digital signal into an analog signal;
detecting an indefinite bit included in the upper bit digital signal; and
reconverting the indefinite bit by the sequential comparison processing.
7. The AD conversion method according to claim 6 , further comprising
setting a comparison digit string based on the upper bit digital signal and comparing the upper bit digital signal with the comparison digit string for each bit.
8. The AD conversion method according to claim 7 , further comprising
judging whether a plurality of values of the upper bit digital signal and the comparison digit string that correspond to the same bit position match, and judging the bit position as the indefinite bit when at least one of the values is different.
9. The AD conversion method according to claim 7 , further comprising setting the comparison digit string by subtracting a compared correction value composed of any integer from the upper bit digital signal or by adding the compared correction value to the upper bit digital signal.
10. The AD conversion method according to claim 9 , wherein the compared correction value is 1.