1. ADC

2. ADC types
Flash ADC
SAR ADC
Flash

3. Notations/Interface
REF+, REF-
AGND, DGND
EOC

4. The Comparator: A 1-Bit ADC
INL=DNL=0
Widely used as a building block in many higher resolution ADCs
Comparator’s resolution needs to be able to support overall high resolution ADC
Without hysteresis, a 1-bit ADC is inherently linear, but with hysteresis, it is not
Hysteresis size should be less than required resolution
Constant offset does not harm linearity by itself, but may cause internal signals to go out of range, thus causing errors

5. Flash ADC

6. Flash ADC Very fast: just one clock cycle Flash ADC N bit string DAC
2N – 1 comparators
Thermometer to binary encoder
Logic latch
Clock signal
Vref to the DAC
Very fast: just one clock cycle

7. Chapter 17 Figure 24 1 1 1 1 1 1 1 1 1 1

8. Chapter 17 Figure 24
Bubbles 1 1 1 1 1 1 1 1 1 1

9. Bubble/sparckle removal
Chapter 17 Figure 26
Single bubble correction
J. G. Peterson, “A monolithic video A/D converter,” IEEE Journal of Solid-State Circuits, vol. 14, pp , issue 6, 1979.

10. Error Sources Comparator offset R-string mismatch Input capacitance
Feedthrough of input signal to reference ladder …

11. SAR ADC

12. SAR ADC
Chapter 17 Figure 05

13. Binary Search