About ADC and DAC conversions?

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Surender Reddy

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if we convert a analog value into digital value,then again convert it into analog value ,
can we get same analog value? or any data loss?
any data loss! why?
 

certainly,there is data loss.Because in the a to d conversion we use quantization mechanism(where round off is occurring).
 

genboo,547 has said it above. Another important factor is resolution. I'll explain with an example.

Say you're using an 8-bit ADC (for example) and have an input of 2.756V. The ADC reference voltage is 4.096V. So, the ADC reading is 171. Say you're using an 8-bit DAC with reference of 4.096V. So, the DAC output now is 2.747V. Now, it gets worse if you're using a, say, 5-bit DAC. Then, the ADC reading is scaled for 5-bit to 20. Then, you get an output of 2.643V. You just lost 0.113V due to rounding off.

However, this data loss/error can be minimized if you use a high-resolution ADC and DAC. Even 10-bit is good.

Hope this helps.
Tahmid.
 
Another factor that is worth taking into account is the signal to noise ratio of the analogue voltage that you trying to measure, there is no point in having a 16bit A2D converter that can measure a 76uV change of signal over a 5V range if you have a signal with 1mV of noise on it, you would just be quantising noise!
It all depends on the signal that you are trying to measure, A2D and D2A conversion is a very interesting topic in itself with a lot factors having a major effect on the quality of your signal, such as the frequency of the signal you are trying to measure.
 

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