Dear reader,
I have a weighing scale board with AD623 and AD7708 as an ADC. After instrumentaion amplifier, I have RC filter. Initially I used 1K and 0.uF. But because of fluctuations, I kept on increeasing RC valuse until I reach 100k and 0.33uF. With this fluctuations seems to be less without ham[ering responce. Now when I kept 1Kg. weight, it drifts by 20 gms in 20 mins .
I suspected capacitor discharge votage, so I checked waveforms on CRO. To my surprise, DC line was pretty clear before RC filter. So I opened ADC pin and knew that noice was introduced by ADC itself. Now stuck up since I have al;ready taken all the care including bypass capacitor, grounding plane, ripple in poer supply, stable refernce volateg etc.
Need a direction!
Could anybody send link for filter calculation for various sensors?
Thanks in advance.
I have a weighing scale board with AD623 and AD7708 as an ADC. After instrumentaion amplifier, I have RC filter. Initially I used 1K and 0.uF. But because of fluctuations, I kept on increeasing RC valuse until I reach 100k and 0.33uF. With this fluctuations seems to be less without ham[ering responce. Now when I kept 1Kg. weight, it drifts by 20 gms in 20 mins .
I suspected capacitor discharge votage, so I checked waveforms on CRO. To my surprise, DC line was pretty clear before RC filter. So I opened ADC pin and knew that noice was introduced by ADC itself. Now stuck up since I have al;ready taken all the care including bypass capacitor, grounding plane, ripple in poer supply, stable refernce volateg etc.
Need a direction!
Could anybody send link for filter calculation for various sensors?
Thanks in advance.