2022-11-13 15:47 Status: # Self Resonant Frequency (SRF) Inductor with a Q - series resistance (as it increases, Q decreases) Conditions for SRF: - The [input impedance](Input%20Impedance.md) is at its peak. - The phase angle of the [input impedance](Input%20Impedance.md) is zero, crossing from positive (inductive) to negative (capacitive). - Since the phase angle is zero, the Q is zero. - The effective inductance is zero, since the negative capacitive reactance (Xc = 1 / jωC) just cancels the positive inductive reactance (XL = jωL). - The 2-port [insertion loss](insertion%20loss.md) (e.g. S21 dB) is a maximum, which corresponds to the minimum in the plot of frequency vs. S21 dB. - The 2-port phase (e.g. S21) angle is zero, crossing from negative at lower frequencies to positive at higher frequencies SRF = $\frac{1}{2\pi \sqrt{LC}}$ Hz. [Doc363.pmd (coilcraft.com)](https://www.coilcraft.com/getmedia/8ef1bd18-d092-40e8-a3c8-929bec6adfc9/doc363_measuringsrf.pdf)  At the self-resonant frequency, [Microwaves101 | Self Resonant Frequency](https://www.microwaves101.com/encyclopedias/self-resonant-frequency) [Lab2_ModelingDiscreteComponents.pdf (illinois.edu)](https://courses.engr.illinois.edu/ece453/sp2019/lab_files/Lab2_ModelingDiscreteComponents.pdf) ## Y Parameter Method Using the Y-parameter method, it is clear that only Y12 is needed to find the series inductance and resistance. -3.png#invert) This also means that shunt capacitance does not effect the inductor. -2.png#invert) If you extract the real part of the impedance, you will see that by increasing the width of the inductor tracks, resistance will decrease, which will improve the [insertion loss](insertion%20loss.md) (you can see this in S21 plots).  [^1] --- # References [^1]: [ADS: How to Accurately Extract Inductor’s Inductance and Resistance from S param in ADS - YouTube](https://www.youtube.com/watch?v=JuGXCpwOl5Y)