Designing Frequency-Dependent Impedances?

Feb 19, 2004 1 Replies

Hi, Every one knows, that e.g. a simple RC-parallel circuit has a frequency-dependent impedance-characteristic (Absolute Value) - the impedance (Abs) raises as the Frequency approaches zero. As a formula: Zin = 1/(1/R + i w C) , where i ist the imaginary number and w the frequency.



Now the hard part. How does one create an Impedance, which decreases "slower", for frequencies close to zero but then decreases "faster" for higher frequencies, than the simple parallel RC-Circuit? Is there some kind of procedure like the one for syntesizeing LC-Filters (Butterworth, Chebychev,..)?



Simply increasing C does not really help, because this equals a factoring of the frequency. Increasing R does not help as well, as it seems.


I hope one of you cracks can help me out. So far, thanks for reading. Diego Stutzer


Diego Stutzer schrieb:

It depends on the slope you want to realize. You could use a combination of Rs and Cs to build a more complex frequency response or an active filter. There are many ways. The best would be if you described the task and the characteristics of the filter you're looking for...

- Udo

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