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FilterPro 2.0 vs 3.1 show different component values
Made design at home using FP2 and FP3 at work to find very different component values for filter at output of RTD temp sensor. Filter is 1 Hz, 2 pole LPF, Gain = 1 (0 dB), MFB Single end, Butterworth, using E96 resistors/ E12 caps. FP3 Gain plot shows -30 dB in pass band though header shows G = 1. Can not edit FP3 values to FP2 values. Discrepancy between FP2 and FP3 seem to start below 10 Hz. Which is correct?
Thank you for reporting this issue. This is a resolution problem in FP3. Since Lowpass filters at such low cutoff frequencies are impractical, the support in the FP3 plots is limited and any frequencies under 10 Hz will most likely demonstrate the same behavior. The real issue is that there are not a whole lot of points available to be plotted at such low frequencies and, therefore, it is hard to see the actual cutoff at 1 Hz. If you use a simulation software e.g. TINA-TI and build the circuit that FP3 has generated, you will see that the resulting circuit is accutate and waveforms display the cutoff accurately.
This issue is already known and will be addressed in the upcoming releases.
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