16 bit adc interface , 5v reference

[jit_singh_tara]

ph meter +resolution +adc

hello friends , i am interfacing a 16 bit adc with 5 v reference i.e , 5V / 65536 = 76 micro volts , now how do i maintain such a precision in giving analog input of microvolts , my application is a ph meter which reads electrode potential which is then fed to a to d converter 16 bit , how the hardware is to be designed keeping all this in mind.

 

[artem]

5v reférence

I am not expert in the field but what comes to my mind is :
- choosing right components for signal conditioning (16 adc AN from manufacturers is good start point )
- filtering input signal (LPF and bandgap filter)
- averaging results on duration of noise frequency period (50 Hz)
- right layout
- clean power
- calibration
- in circuit bias measurement for self calibration
- ... ?

And do you need precision or just resolution ?

 

[rikie_rizza]

adc 16 bit

I've design a Ph meter before and 16 bit is more than enough. I prefere 12bit instead because of the low INL.
Using 16bit and above ADC... what ADC will you use?...are a designer nightmare especialy beginners. You must calculate all the error, PCB design must be perfect according the rules that the datasheet usually provide. And... stabilizing the signal needs more than just an averaging technique. A DSP would be necesary. Ph meter is one hard thing to handle, mostly the probe.