how to measure inductance

时间：04-07 整理：3721RD 点击：

Can somebody tell which instruments are needed to measure the inductance and Q of a spiral inductor and active inductor? how to measure it?

Thanks.

Best regards,
chunlee

you can use a network analyzer. You can determine the Q value from group delay obtained from the network analyzer.

Hi,

latest technology of Fluke Instruments (the Digital Multi Meter that is)
can measure capacitance, charges (in coulombs) and inductances

Hey, I use Fluke!

One of the easiest ways of measuring L is to build an LC oscillator with known capacitance, measure frequency and calculate the inductance from the common LC-tank equation: ω=1/√LC --> L=1/ω2C, where ω=2Πf ..
See circuit below ..
Regards,
IanP

Q meter is mostly used for the measurement of inductance and Q of circuit

try this link

http://ironbark.bendigo.latrobe.edu.au/~rice/lc/

hi boy,

can u pls tell how to measure inductance and Q using network analyzer?
or send me some document about it?

Thanks.

You can build an easy microcontroller based L/C meter
here is it..

I hope it helped.
Ahmad

The NA is a rather expencive & very rare instrument. You'd better try some LC-Q meter which are much easier to find.

VNA may measure L (and or C) but it's poorly accurate, especially on the Q determination.

Qmeter, when used in conjunction with Standard inductances is the most accurate instrument.
Qmeter give L, Q, SRF.

Why did you comment so ? When you short circuit of an inductance, you'll get "very accurately" R and X so then to find inductance value and its associated Q factor are not difficult.

Because in RF region, inductances and capacitances are not flat responded and in my opinion an inductance or capacitance should be measured at the frequency of operation (or closer to )

But essentially, Q factor measurement equipments can not reach very high frequencies and their results are therefore not indicative.

hi everyone,

I'm intend to measure my inductor on wafer at frequency around 2.4GHz. So i think the VNA is suitable for me. Can someone pls briefly tell me the procedure to characterize the inductor? (spiral and active inductor)

Thanks.

What is the best way for measuring the inductance of a small planar coil inductor (i.e. RFID tag) ?

Would it be OK to use the VNA method for this? i.e. connect both terminals of the coil to a 50 Ohm bnc connector and measure it that way?

OR

Is there a better suited method? i.e. involving a signal/function generator?

Regards

Cat

After doing two ports S-parameter measurement, transform S-matrix into admittance (Y) matrix, you can calculate Q and L using:

Q=-Im[Y(1,)]/Re[Y(1,1)]

L=Im[1/Y(1,1)]/ω

I am not sure whether there is difference between the calibration procedure of passive inductors and active inductors.

Regards,

Treat the inductance as a two-port network, and you can measure the s parameter,
and you can deduce the L from the S parameters.
Perhaps not accurate.

Hi,

To measure the inductance of a coil is the following method reasonable?

1. Connect coil to DC voltage supply and measure the current
2. Calculate the DC resistance
3. Connect coil to an AC voltage suuply with known voltage and frequency, measure the current.
4. Calculate the Impedance
5. Calculate Inductive Reactance using results from steps 2 and 4.
6. Calculate the Inductance using the result from step 5.

Would this be accurate?

Regards

Cat

Hi all,
I got a problem when re-draw S-parameters after de-embedding procedure.
I used ADS to re-draw Smith chart of an on chip spiral inductor.

- 1st, I used GSG probe tip to measure spiral (DUT) not very high frequency (50MHz --> 10GHz). Here I got S_measured values.
- 2nd, I measured inductor test-fixture only (open standard). Here I got S-open values.

Since I got the S-parameters data, I used ADS to convert S into Y data (S_measured ==> Y_measured & S_open ==> Y_open).
Then, took: Y_mo = Y_measured - Y_open
Finally, Y_mo data were reconverted into S-parameters and plotted in Smith chart.
But in here, the Smith chart was not as I expected.
Please take a look at 2 pictures following:

Is there any body give me an advice? I really appreciate any your help.
Thank in advanced! ^_^

Can you connect the same to a connector directly-both ends of the inductor and measure S11 to find L?

The problem is lying at that you Ymo=Y_meas-Y_Open, after that, the Y you got still include 50 ohm (system impedance) in series. That is why it looks so strange.

Hope it help!

Laipi