ADC Basics and resolution??

[Sarav.thegreat]

Hi,

Just i want to few terms in ADC.

1) What is ADC
2) Accuracy in ADC
3) Resolution in ADC
4) Linearity
5) How number of bits is helping in increasing accuracy.

Regards,
Saravanan.K

 

[crutschow]

Sounds like homework, which should be in the "Homework Help" forum.

 

[Pommie]

Sounds like homework, which should be in the "Homework Help" forum.

It is!

Edit, nearly forgot a link for the original poster.

Mike.

 

[crutschow]

Yes, I forgot what forum I was in.

 

[ericgibbs]

Yes, I forgot what forum I was in.

hi Carl,
Your memory is still intact, I moved the Thread as suggested in post #2.

 

[crutschow]

hi Carl,
Your memory is still intact, I moved the Thread as suggested in post #2.

Thanks. I know I get a case of "old timers" disease now and then, but it's good to know this wasn't one of them.

 

[ronsimpson]

Soon I will not remember I have "old timers disease".

 

[MrAl]

Hi,

This is interesting, six additional posts and not one of them gives any clue as to what the answers to the original questions might be

I'll start:

1. What is ADC?
ADC usually stands for Analog to Digital Converter.
These take an analog signal (a continuously variable signal) and quantize it into a digital word or words.
There is also DAC, which stands for Digital to Analog Converter.
Those take the digital word or words and convert it to an analog signal, but the analog signal could possibly be discrete steps rather than the original continuously variable signal.

Ok guys, take it from here. I did #1 so you can follow with #2, etc. if you like

 

[ronsimpson]

ADC example
1 bit: output=0 if the in put is near 0 volts, output=1 if the input is near 1 volts.
2 bit: output=0,1,2, or 3 if the input is 0, 0.25, 0.5, or 0.75
3 bit: output=0,1,2,3,4,5,6,7 0 to 1 volts in 1/8 volt steps
4 bit: output=0 through 15 0 to 1 volt in 1/16 volt steps
8 bit 0 to 255 in 3.9mV steps
16 bit 0 to 64535 in 16uV steps

 

[ronsimpson]

Resolution has to do with how small a change the ADC can see. Example 16uV is a very small amount. High Resolution.
Accuracy: No matter how good the resolution is, if the ADC input is 3 volts but it reads 4.0000001 volts, it is not good.
Linearity:
There is a "0" error and a "full scale" error. If the input range is 0 to 1 volt then the data sheet will give a accuracy measurement at these two points. All other points should be a strait line between 0 and 1. Example 0.5 volts should give a number exactly 1/2 full scale. The problem the line is not strait.

Now back to unrelated noise.

 

[Pommie]

I thought my link answered most of the questions.

Mike.

 

[MrAl]

Hi Mike,

Yes if the monitor of the reader can show good enough that the word 'link' is actually written in blue rather than the regular black. Some monitors dont show thin text colors as well as others, so it might be better to indicate a little better where the link actually is.

Also, if you want readers to Google everything why dont you just ask Electromaster to provide a direct link to Google so that when readers click on ElectroTech they get transferred to Google instead. Save you not much, but a little typing there (ha ha)

 

[Pommie]

MrAl, I only use lmgtfy when the OP asks questions that are easily answered by google and I consider that they are just being lazy.

Mike.