A/D conversion circuit for use with low-potential and high-potential power supplies
View Patent ↗An A/D conversion circuit including a plurality of resistor elements connected in series between a low-potential power supply and a high-potential power supply. The A/D conversion circuit includes a plurality of comparators that compare a reference voltage divided by each of the resistor elements with an analog input voltage, the comparators having a sample-and-hold function for holding a sampled analog input voltage. The plurality of comparators also include a high-order bit comparator and a low-order bit comparator having different sampling sources. The high-order bit comparator may be configured to compare the analog input voltage and one of the reference voltages to obtain a determination result. The low-order bit comparator may old the analog voltage from the time that the low-order bit comparator retrieves the analog input voltage until the low-order bit comparator performs comparison.
1. A serial and parallel A/D conversion circuit for use with low-potential and high-potential power supplies and for separating a high-order bit and a low-order bit and sequentially performing A/D conversion, the A/D conversion circuit comprising:
a plurality of resistor elements connected in series between the low-potential power supply and the high-potential power supply;
a plurality of comparators for comparing a reference voltage divided by each of the resistor elements with an analog input voltage, the comparators having a sample-and-hold function for holding a sampled analog input voltage, and the plurality of comparators including a high-order bit comparator and a low-order bit comparator having different sampling sources,
wherein the high-order bit comparator is configured to compare the analog input voltage and one of the reference voltages to obtain a determination result; and
selection circuitry configured to select one of the other reference voltages to be input to the low-order bit comparator for comparison with the analog input voltage according to the determination result of the high-order bit comparator.
2. The A/D conversion circuit according to claim 1 , wherein the high-order bit comparator uses the reference voltage as a sampling source, and the low-order bit comparator uses the analog input voltage as the sampling source.
3. The A/D conversion circuit according to claim 2 , wherein the high-order bit comparator uses the analog input voltage as a comparison subject source, and the low-order bit comparator uses the reference voltage as a comparison subject source.
4. The A/D conversion circuit according to claim 3 , wherein the high-order bit comparator completes comparison at substantially the same timing as when the low-order bit comparator completes sampling.
5. The A/D conversion circuit according to claim 3 , wherein the high-order bit comparator and the low-order bit comparator have the same circuit configuration and the same characteristics.
6. A serial and parallel A/D conversion circuit for use with low-potential and high-potential power supplies and for separating a high-order bit and a low-order bit and sequentially performing A/D conversion, the A/D conversion circuit comprising:
a plurality of resistor elements connected in series between the low-potential power supply and the high-potential power supply; and
a plurality of comparators for comparing a reference voltage divided by each of the resistor elements with an analog input voltage, the comparators having a sample-and-hold function for holding a sampled analog input voltage, and the plurality of comparators including a high-order bit comparator and a low-order bit comparator having sampling sources that are the same, wherein the high-order bit comparator remains in a standby state from when comparison is completed to when the low-order bit comparator completes comparison,
wherein the low-order bit comparator holds the analog input voltage from the time that the low-order bit comparator retrieves the analog input voltage until the low-order bit comparator performs comparison.