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reference resistance in adc design

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tuza2000

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which kind of resistance in 6bit flash adc can i use ,in tsmc 0.18 technology？

rnploy/rnlploy /rnplus?

why?

i want to parallel resistance to gain a little and accurate one,

is it avilable?
 

Use the one that offers you the best tradeoff matching-low power consumption. If power consumption is lees than an issue, the use the one that gives you the best matching.
 

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    tuza2000

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poly res is better than rnplus for better match and voltage char.
rnploly is maybe better
 

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    tuza2000

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non-salicide p-poly in n-nwell is a low noise resistor, but large resistor value. in flash adc, metal resistor can also consider.
 

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    tuza2000

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" want to parallel resistance to gain a little and accurate one" If u dont concider the area of the circuit.
 

my resistance valule is 20-40 ohm,
is it better that i use parrel rnploy resistance that the area are acceptable?
 

6 bit flash uses metal resistors most of the time. I see you don't want speed (20-40 ohms means a "slow" ADC), in this case rnpoly (high resistance, 160-180 oh./sq.) has the best matching.
 

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    tuza2000

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The criterial aspects are as below:

1. sheet value percent square;

2. temperature coeffecient;

3. voltage coeffecient;

4. the offect of comparator;

5. the speed of adc;

6. area or matching;
 

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    tuza2000

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i use the 20-40 ohm resistance because of the kickback noise .
 

This makes it worse, isn't it? You don't have preamps? Is the middle of the ladder decoupled?
 

Hi Tuza2000,

Can you explain to me what is that "kickback noise"?

regards,
suria3
 

take care of the vdd and grounding routing
regards
 

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    tuza2000

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