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I am getting 100mv noise at my ADC input channel, how can I remove it using DSP filter in micro-controller.
I am using PIC18f.
I am using PIC18f.
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I am getting 100mv noise at my ADC input channel, how can I remove it
I need low pass filter with range 0 to 50Hz , 0 to 500 Hz and 0 to 1KHz
...as well the layout and a picture of the noise.If you need help in this, then show us your circuit
Hi,
as far as i can see it is not "random noise". I expect it is 50kHz ripple (of course with it´s overtones).
The ripple is caused by the half wave recitier you use.
The 50kHz are not filtered out carefully.
There is only a fiter first order. the vaues are 1k+1k to 10n parallel to 10n.
this gives 2k to 20nF. Cutoff frequency of 4kHz, but only on discarging the capacitor. During charge the impedance of the diode is low, and thus the filtering is worse.
Even with a clean 4kHz filter first orde will leave a ripple of about 8% of 50 kHz input amplitude.
My hint:
Connect a 10nF capacitor in parallel to R2 (I´m not sure is it 30k?).
This gives another first order lowpass with 1kHz cutoff frequency.
Lowering the remaining ripple from 100mV to about 2mV.
If you need even better quality then we need more information...
(or you could play with bigger capacitors, but this possibly makes your regulation loop slow and therefore unstable)
Klaus
Ya I try bigger capacitor It make my system response too much slow, which is not acceptable.
Hello Klaus I use 100uf capacitor to filter out ripples from output amplifier, but ...
Your circuit is something inbetween peak measurement and average measurement. You shoud decide what you need. It seems your circuit is a voltage regulation circuit.new problem is that DC output which i get it's moving up and down around 200mV