Hi all,
Recently I have been testing the two filters that I have designed in the lab however I don't get the same results as the simulation
in TINA and I can't work out why. Below are the two filters and AC responses in TINA.
The first filter is a 2nd order Bandpass filter with cutoffs at 0.005 and 200Hz. I am expecting a roll of 20dB/dec but I am only getting 15dB/dec.
The second filter is a Sallen-Key filter with a bandpass filter attached to it. So in total a third order low pass and first order high pass. The cutoff frequencies are at 0.05 and 200.
In the low pass region I am expecting a roll off of 60dB/dec but I am only getting just less than 40dB/dec.
The only possible explanation I can think of is parasitic components are affecting the roll off, but are there any other more obvious factors that could be causing this difference in the roll off?
Sorry if the question is quite vague as I am quite new to circuit design so would appreciate any help thanks.
Regards,
Bryan Hsieh