Bandwidth identifies the number of waveform cycles that have at least 70.7% of the expected current and is displayed on a graph with current on the Y-axis and frequency on the X-axis. The bandwidth will be present when the input waveform is between the upper and lower resonant frequency of an RLC circuit. At resonance, the most current will be allowed through the circuit and the most allowable frequency will be seen at the center of the bandwidth graph. This frequency will also be the resonant frequency. Selectivity identifies the circuit’s ability to allow or reject frequencies outside of the expected current range of 70.7% of maximum and is dependent on the Q-Factor.
Discussion Prompt: Discuss the following prompts
- Research and discuss RLC bandwidth and selectivity and provide the equations for each.
- Research and discuss the upper and lower cut-off frequencies and how they relate to bandwidth.
- How is Q factor related to bandwidth and selectivity?
- What is the shape factor and how does this differ from the bandwidth?
- What happens to frequency signals that are above and below the upper and lower cut-off frequencies of an RLC filter?