Fundamentals on ADCs Jose Silva- Martinez Fundamentals of ...

Universidad Politecnica de Catalunya 1 May 25, 2010

Fundamentals on ADCs Jose Silva-Martinez

Jose Silva-MartinezAmesp02.tamu.edu/~jsilva

Many of these slides were provided by

Dr. Sebastian Hoyos

Amesp02.tamu.edu/~hoyos

Fundamentals of Flash ADCs



Issues in this architecture:Accuracy, area and power consumption trade-offs due to the string of resistorsInput impedance at Vin terminalGlitches produce by the dirty comparatorsArea and power































Fundamentals of Comparators































Effects of CGD. The capacitors are differentiators: good friends of the fast transitions, glitches, speaks, etc.











































If you can measure it (If you can measure it (correctlycorrectly) you can correct it) you can correct it





















Be careful with the effects of kickback noiseBe careful with the effects of kickback noise











There are always trade-offs! Check the drawbacks!There are always trade-offs! Check the drawbacks!



Sure, but can you replace the P-Network by a simple current source?Sure, but can you replace the P-Network by a simple current source?

Is this the only Is this the only possible possible solution?solution?





This looks much better than the previous one!This looks much better than the previous one!

Nice Nice properties:properties:

Embedded Embedded CMFBCMFB

Large gainLarge gain

Good common-Good common-mode control for mode control for next stagenext stage













Double check performance (worst case) for all cornersDouble check performance (worst case) for all corners





Again: double check system performanceAgain: double check system performance

Good ideas, Good ideas, but..but..

Input Input impedanceimpedance

Glitches due to Glitches due to clocksclocks

Power Power consumptionconsumption

Resolution?Resolution?









Many other techniques have been Many other techniques have been recently reported since the recently reported since the comparators are essential part of comparators are essential part of pipelines and SD ADCspipelines and SD ADCs

We will discuss some of these We will discuss some of these topologies in the following topologies in the following lectureslectures

End of Flash ADCsEnd of Flash ADCs

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Fundamentals on ADCs Jose Silva- Martinez Fundamentals of ...

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