Filter Basics Part 7: Different Approaches To Q Factor
![KPD7 KPD7](https://vertassets.blob.core.windows.net/image/f38104fd/f38104fd-b074-412e-b3df-4c6b2dc3e0e1/375_250-kpd7.jpg)
As an RF engineer, you likely frequently hear the term “quality factor”, or Q factor, used as shorthand figure of merit (FOM) for RF filters. In short, Q factor is expressed as the ratio of stored versus lost energy per oscillation cycle.
More specifically, Q factor generally describes specifications such as the steepness of skirts, or the selectivity, and how low the insertion loss is. Overall losses through a resonator increase as Q factor drops and will increase more rapidly with frequency for lower values of resonator Q. However, truly understanding how Q factor is determined is a bit more intricate. Let’s start by looking back to the example bandpass filter specification we showed in Part 3.
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