Dynamic Comparators

Dynamic Comparators - Dynamic Comparators Comparator A...

Info iconThis preview shows pages 1–12. Sign up to view the full content.

View Full Document Right Arrow Icon
Dynamic Comparators
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Comparator A comparator is a circuit that provides a high Boolean output if the differential input is positive and a low Boolean output if the differential input is negative IN THR o X K IN THR o X K
Background image of page 2
Comparator IN THR o X K High gain amplifiers are often used as comparators since the outputs of most amplifiers naturally clip at high and low levels when overdriven Since comparators are usually not used with feedback, there is not a need for compensation so neither the area reduction or speed reduction penalty is incurred Since feedback is not used, higher-order amplifiers such as cascades can be used to increase the gain of a comparator to arbitrarily high levels If over-driven amplifiers are used for comparators, the power dissipation of these types of comparators is often high
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Comparator Some comparators are clocked and only provide an output after the transition of the clock The value of the input to a clocked comparator is only of concern in a short time interval around the clock transition The speed of clocked comparators can be very high and the power dissipation of clocked comparators can be very low Clocked comparators are often called Dynamic Comparators IN THR o X K CLK Dynamic comparators are widely used in the design of high-speed ADCs Regenerative feedback is often used in dynamic comparators and occasionally in non-clocked comparators
Background image of page 4
Comparator IN THR o X K OUT + V OUT V d 2 V d 2 Amplifier-Based Comparator
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Comparator IN THR o X K Amplifier-Based Comparator o V + K o V K Note symmetry in the comparator
Background image of page 6
Comparator IN THR o X K Amplifier-Based Comparator At the start of the comparison process, an amplifier-based comparator behaves as a linear amplifier () out d 1 2 m1 Lo 1 o 2 g As sC +g +g == V V d - in in =− + VV V
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Comparator o X K Lower-gain Amplifier-Based Comparator At the start of the comparison process, an amplifier-based comparator behaves as a linear amplifier () out d 1 2 m1 Lo 1 o 2 m 3 g As sC +g +g g == + V V d - in in =− + VV V V DD V B1 M 1 M 2 V B2 M 3 M 4 V IN V IN M 9 C L C L V OUT V OUT d 2 V 3o 1 m 1 m 3 OUT OUT sC g g g g 0 d 2 −− + ++ + = V
Background image of page 8
Comparator o X K Lower-gain Amplifier-Based Comparator V DD V B1 M 1 M 2 V B2 M 3 M 4 V IN V IN M 9 C L C L V OUT V OUT Amplifier-Based Comparator with Regenerative Feedback
Background image of page 9

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Amplifier-Based Comparator with Regenerative Feedback At the start of the comparison process, an amplifier-based comparator behaves as a linear amplifier
Background image of page 10
Amplifier-Based Comparator with Regenerative Feedback At the start of the comparison process, an amplifier-based comparator behaves as a linear amplifier g m1 V GS1 V GS1 g 01 g m3 V GS3 V GS3 g 03 d 2 V OUT L OUT () Lo 3o 1 m 1 m 3 OUT OUT sC g g g g 0 d 2 −− ++ + + = V VV m1 OUT 1m 3 g sC g g
Background image of page 11

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 12
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 49

Dynamic Comparators - Dynamic Comparators Comparator A...

This preview shows document pages 1 - 12. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online