NanoVNA - Inductor Measurements

Starting with a 1.2uH inductor results were immediately satisfying. The measured L and variation with frequency matched the curve shown in the TDK datasheet. And the self resonant frequency was readily measured as 180MHz.

1.2uH Inductor

Let's try an unknown but small 0603 wire-wound chip inductor. Measured as 22nH.

How small can we go? I have some 12nH 0201 chip inductors with factory measurements (sample size, variance etc). Wow. 12nH measured.


Previously I have used a signal generator and test fixture with a measured parallel capacitance
( 112pF from memory ) to measure the resonant LC frequency, then back calculate what L was. This worked very well down to nH sized inductors. With a power detector I was also able to estimate Q by sweeping around the resonant frequency for the -3dB points.

The NanoVNA is now my preferred approach. I prefer the fixture without the 50 ohm resistor. The curves are easier to see and therefore interpret. Either fixture is fast to use and easy to see how L changes with frequency. I can't see how Q can be measured, but A/B comparisons show slight differences. The higher the inductor Q the closer to the edge of the Smith Chart. 

Go on, give it a try.