Home
Back
Self Resonant Frequency Formula:
| From: | To: |
Self Resonant Frequency (SRF) is the frequency at which a capacitor's parasitic inductance resonates with its capacitance. At this frequency, the capacitor behaves like a pure resistor and loses its capacitive characteristics.
The calculator uses the SRF formula:
Where:
Explanation: The formula calculates the frequency at which the inductive and capacitive reactances are equal in magnitude, causing resonance.
Details: Knowing a capacitor's SRF is crucial for high-frequency circuit design. Operating above the SRF can cause unexpected behavior as the capacitor becomes inductive.
Tips: Enter the parasitic inductance in Henries (H) and capacitance in Farads (F). Both values must be positive numbers greater than zero.
Q1: Why is SRF important in capacitor selection?
A: SRF determines the useful frequency range of a capacitor. Beyond this frequency, the capacitor loses its effectiveness as a capacitive element.
Q2: What factors affect a capacitor's parasitic inductance?
A: Lead length, package size, internal construction, and mounting technique all contribute to a capacitor's parasitic inductance.
Q3: How does SRF vary with different capacitor types?
A: Ceramic capacitors typically have higher SRF than electrolytic capacitors due to their smaller physical size and lower parasitic inductance.
Q4: Can I use a capacitor above its SRF?
A: While possible, it's generally not recommended as the capacitor will exhibit inductive behavior above its SRF, which may cause unexpected circuit performance.
Q5: How can I measure a capacitor's actual SRF?
A: SRF can be measured using a network analyzer by finding the frequency where the capacitor's impedance is at its minimum (series resonance) or maximum (parallel resonance).