1. Chapter 10 Figure 07

4. Chapter 10 Figure 10

8. Input Noise on the Comparator
Problem:
Solution:
Introduce
Hysteresis

9. External Positive Feedback
Homework

10. Internal Positive Feedback

11. Latched comparators Pre-amplification followed by a track-and-latch.
Pre-amplification is used to obtain high resolution and to minimize “kickback” effects.
Kickback: charge transfer in or out of the input side when the track-and-latch goes from track mode to latch mode.
Pre-amplification has moderate gains, or small gains for higher speed
Output of pre-amp is too small to drive digital.
It is amplified during track-and-latch modes by positive feedback which regenerates the analog signal into a full-scalar digital signal.

12. The inputs are initially applied to the outputs of the latch.
Vo1’ = initial input applied to vo1
Vo2’ = initial input applied to vo2
Then positive feedback drives the higher of the two to digital 1 and the lower of the two to digital 0

13. CMOS Latch

14. Chapter 10 Figure 14

16. There are several comparator circuit in the book, here is one from a paper by
T.B. Cho and P.R. Gray, “A 10b, 20Msamples/s, 35mW pipeline A/D Converter,” IEEE J. Solid-State Circuits, vol. 30, no. 3, pp , March 1995.

17. When phi_1 is low:

18. When phi_1 is high:

19. Chapter 10 Figure 20

20. Chapter 10 Figure 21