A/D conversion apparatus

1. An A/D conversion apparatus for converting an analog signal into a digital signal, comprising:

a successive approximation A/D converter receiving the analog signal and outputting high-order data of the digital signal;

a flash A/D converter receiving the analog signal and outputting low-order data of the digital signal; and

a coupling circuit coupling the high-order data and the low-order data and outputting the digital signal.

2. The A/D conversion apparatus of claim 1 , wherein the flash A/D converter outputs a correction bit for correcting the high-order data together with the low-order data.

3. The A/D conversion apparatus of claim 2 , further comprising a correction circuit correcting the high-order data based on the correction bit.

4. The conversion apparatus of claim 1 , wherein the flash A/D converter comprises:

a voltage dividing resistor including a plurality of resistors connected in series and receiving a reference voltage; and

a plurality of comparators comparing a divided fraction of the reference voltage divided by the voltage dividing resistor with the analog signal, wherein the reference voltage is determined based on the high-order data.

5. The A/D conversion apparatus of claim 2 , wherein the flash A/D converter comprises:

a voltage dividing resistor including a plurality of resistors connected in series and receiving a reference voltage; and

a plurality of comparators comparing a divided fraction of the reference voltage divided by the voltage dividing resistor with the analog signal,

wherein the reference voltage is determined based on the high-order data.

6. The A/D conversion apparatus of claim 3 , wherein the flash A/D converter comprises:

a voltage dividing resistor including a plurality of resistors connected in series and receiving a reference voltage; and

a plurality of comparators comparing a divided fraction of the reference voltage divided by the voltage dividing resistor with the analog signal,

wherein the reference voltage is determined based on the high-order data.

7. The A/D conversion apparatus of claim 4 , wherein the flash A/D converter creates the correction bit based on a comparison result of the plurality of comparators.

8. The A/D conversion apparatus of claim 1 , wherein the successive approximation A/D converter includes a comparator implemented by a single-stage amplifier.

9. The A/D conversion apparatus of claim 2 , wherein the successive approximation A/D converter includes a comparator implemented by a single-stage amplifier.

10. The A/D conversion apparatus of claim 3 , wherein the successive approximation A/D converter includes a comparator implemented by a single-stage amplifier.

11. The A/D conversion apparatus of claim 4 , wherein the successive approximation A/D converter includes a comparator implemented by a single-stage amplifier.

12. An A/D conversion method comprising:

generating high-order data as a result of converting an input analog signal into a digital signal of a first predetermined number of bits by performing successive approximation a plurality of times;

generating low-order data as a result of converting the input analog signal into a digital signal of a second predetermined number of bits by comparing in parallel the analog signal with a reference voltage set based on the high-order data; and

converting the input analog signal into a digital output signal by coupling the high-order data and the low-order data.

13. The A/D conversion method of claim 12 , wherein generating low-order data further comprises outputting a correction bit for correcting the high-order data together with the low-order data.

14. An A/D conversion apparatus for converting an analog signal into a digital signal, comprising:

means for successive approximation A/D conversion receiving the analog signal and outputting high-order data of the digital signal;

means for flash A/D conversion receiving the analog signal and outputting low-order data of the digital signal; and

means for coupling the high-order data and the low-order data and outputting the digital signal.

15. The A/D conversion apparatus of claim 14 , wherein the means for flash A/D conversion outputs a correction bit for correcting the high-order data together with the low-order data.

16. The A/D conversion apparatus of claim 15 , further comprising means for correcting the high-order data based on the correction bit.

17. The conversion apparatus of claim 14 , wherein the means for flash A/D conversion comprises:

means for voltage dividing receiving a reference voltage; and

a plurality of means for comparing a divided fraction of the reference voltage divided by the means for voltage dividing with the analog signal, wherein the reference voltage is determined based on the high-order data.

18. The A/D conversion apparatus of claim 15 , wherein the means for flash A/D conversion comprises:

a means for voltage dividing receiving a reference voltage; and

a plurality of means for comparing a divided fraction of the reference voltage divided by the means for voltage dividing with the analog signal, wherein the reference voltage is determined based on the high-order data.

19. The A/D conversion apparatus of claim 16 , wherein the means for flash A/D conversion comprises:

means for voltage dividing receiving a reference voltage; and

a plurality of means for comparing a divided fraction of the reference voltage divided by the means for voltage dividing with the analog signal,

wherein the reference voltage is determined based on the high-order data.

20. The A/D conversion apparatus of claim 17 , wherein the means for flash A/D conversion creates the correction bit based on a comparison result of the plurality of means for comparing.