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problem with comparator selection

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kickbeer

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comparator selection

Hallo,

which comparator should i use to design folding ADC? I'm very confused since there are many types of comparator are available..
 

it depends to your requiremnts, for example bit resolution, sampling frequency.if frequeny is high you must use of latched comparator but if frequency is not so high, you can use of static comparators.
Good Luck
 

    kickbeer

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Hi monady,

The A/D converter which i'm going to design is high speed ADC that is folding ADC. Its resolution must be 8-bit. So latched comparator should be ok for this type of ADC? I heard also that auto-zeroing comparator is widely used in high speed ADC design..
 

i think you must use of latched comparator.i did not use of auto-zeroing or ... .if you choose proper comparator, be sure that it will work properly with low offset.you must read some papers about low offset comparator that used in Flash or another ADCs.
 

    kickbeer

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hi monady,

i found in the book and internet that there are lot of latched comparators available. Besides low offset comparator, what are the other requirements to select a suitable latched comparator for flash or folding ADC? Practically can i used all latched comparator?
 

it depends to many things for example power consumption, input common mode range,...
if your ADC if flash thus you must select comparator with low kickback noise.you can read some paper about folding ADCs, be sure you'll find proper comparator(because in the most papers, this block described).
 

    kickbeer

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hi,

but i think the comparator in flash architecture can be used in folding as well. because the folding technique using a fine flash adc and a coarse flash adc and a folding amplifier. what do you think?
 

in fact i didn't design folding ADC but i think in flash ADC always speed is so high and resolution is moderate, thus in flash ADC comparator can have large offset(e.g. 15mV for 6bit&Vref=1 )but if you want design 10bit ADC, your comparator must have at most 0.97mV offset.thus you should select accurate and low offset comparator for high resolution ADCs.
 

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