About ADC

Check out the following link: I found it by typing in 'adc enob' into the google search bar. Anyway they discuss lots of stuff about adc's.

-Kevin

Interestig, but there is only enob definition and not its pratical menaning; also there ins't any definition of noise free resolution. For example, what means:"enob of an adc 12 converter is equal to 11 bit"? and "noise free resolution of a 12bit adc is 10 bit"? Thanks

The least significant bits of an A-D converter have some level of uncertainty because an analog level may fall between two steps of the digital output - the A-D converter may hunt between the two levels, thus there is "noise" in the output. When measuring with a 12 bit ADC, even the circuit layout and the wiring can affect the reading and the accuracy of the lowest bits of the measurement.

Very simplified examples: A-D converter measures in 0.1 volt steps. Analog input varies by 0.05 volt. Which step does the A-D converter put out? The 0.1 volt step below the actual value? The 0.1 volt step above the actual value?

The circuit is exposed to outside interference (RF or AC). How much does the output change in response to the interference?

The input of the ADC is high impedance and the conductance of the circuit board is affected by moisture. How much does the output change when the humidity is 95% ?

John