- 23rd December 2005, 01:18 #1

- Join Date
- Jan 2005
- Posts
- 111
- Helped
- 4 / 4
- Points
- 2,097
- Level
- 10

## how to measure inductance

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

- 23rd December 2005, 02:04 #2

- Join Date
- Sep 2002
- Location
- Thailand
- Posts
- 483
- Helped
- 92 / 92
- Points
- 9,590
- Level
- 23

## measuring inductance

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

1 members found this post helpful.

- 23rd December 2005, 05:39 #3

- Join Date
- Aug 2005
- Location
- UE+MIT, Philippines, (14°N , 120°E )
- Posts
- 662
- Helped
- 81 / 81
- Points
- 7,347
- Level
- 20

## how to measure inductance of coil

Hi,

latest technology of Fluke Instruments (the Digital Multi Meter that is)

can measure capacitance, charges (in coulombs) and inductances

Hey, I use Fluke!

1 members found this post helpful.

- 23rd December 2005, 06:13 #4

- Join Date
- Oct 2004
- Location
- West Coast
- Posts
- 7,943
- Helped
- 2303 / 2303
- Points
- 160,151
- Level
- 95

## inductor measurement

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

4 members found this post helpful.

- 23rd December 2005, 06:13

- 23rd December 2005, 07:02 #5

- Join Date
- Nov 2005
- Posts
- 16
- Helped
- 3 / 3
- Points
- 1,324
- Level
- 8

## measure inductance of a coil

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

- 24th December 2005, 00:10 #6
## how to measure inductance of a coil

try this link

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

- 25th December 2005, 03:50 #7

- Join Date
- Jan 2005
- Posts
- 111
- Helped
- 4 / 4
- Points
- 2,097
- Level
- 10

## measure inductance

hi boy,

can u pls tell how to measure inductance and Q using network analyzer?

or send me some document about it?

Thanks.

- 25th December 2005, 09:15 #8

- Join Date
- Apr 2005
- Location
- San Jose, California, USA
- Posts
- 1,209
- Helped
- 237 / 237
- Points
- 12,554
- Level
- 26

## measuring inductance of a coil

You can build an easy microcontroller based L/C meter

here is it..

I hope it helped.

Ahmad

2 members found this post helpful.

- 25th December 2005, 10:54 #9

- Join Date
- Jan 2005
- Location
- Russia SPb
- Posts
- 23
- Helped
- 1 / 1
- Points
- 1,653
- Level
- 9

## inductance measurement method

Originally Posted by**chunlee**

- 28th December 2005, 22:16 #10

- Join Date
- Dec 2003
- Location
- Italy
- Posts
- 468
- Helped
- 68 / 68
- Points
- 5,146
- Level
- 16

## how to measure inductor

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.

- 28th December 2005, 22:16

- 29th December 2005, 02:03 #11

- Join Date
- Nov 2001
- Location
- Earth
- Posts
- 2,498
- Helped
- 718 / 718
- Points
- 18,721
- Level
- 33

## measure inductance coil

Originally Posted by**sergio mariotti**

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.

- 29th December 2005, 03:58 #12

- Join Date
- Jan 2005
- Posts
- 111
- Helped
- 4 / 4
- Points
- 2,097
- Level
- 10

## how to measure an inductor

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.

- 1st January 2006, 19:35 #13

- Join Date
- Dec 2003
- Location
- Italy
- Posts
- 468
- Helped
- 68 / 68
- Points
- 5,146
- Level
- 16

## fluke inductance meter

Originally Posted by**BigBoss**

The accuracy of VNA measurement is set mainly by Standards, that are usually very accurate jewels, and often the residual accuracy is of the order of +/-0.02...0.05 (number! not dB). But, when you try to measure very reactive devices (i.e. near to the boundry of the Smith Chart) , a small uncertainty like +/-0.02 , will became a large uncertainty on Q determination . I don't provide here the formulation, see Agilent AN-95.

Qmeter has a different principle of operation. It read the resonant extravoltage.

But if the practical measurement needs are on wafer, there is no choices. Both VNA and on-wafer Standards are required.

Answering chunlee, set the VNA to display a Smith Chart on the screen. If necessary set marker parameters to display R+jX. I know that is possible on Agilent 87xx and 8510. Q=|X/R|

Since the accuracy on-wafer will be not very high, my suggestion is that the user should propagate the uncertainty equation to give an evaluation of the instrumental uncertainty.

Agilent provide a free and useful MS Excel speadsheet to evaluate uncertainty. look for "VNAUncert"

- 4th January 2006, 10:27 #14

- Join Date
- Jan 2005
- Posts
- 167
- Helped
- 2 / 2
- Points
- 2,765
- Level
- 12

## measuring coil inductance

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

- 4th January 2006, 11:21 #15

- Join Date
- Aug 2004
- Posts
- 227
- Helped
- 53 / 53
- Points
- 5,770
- Level
- 18

## measure coil inductance

Originally Posted by**chunlee**

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,

- 9th January 2006, 14:17 #16

- Join Date
- Oct 2004
- Posts
- 138
- Helped
- 2 / 2
- Points
- 2,472
- Level
- 11

## find inductance

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.

- 10th January 2006, 14:21 #17

- Join Date
- Jan 2005
- Posts
- 167
- Helped
- 2 / 2
- Points
- 2,765
- Level
- 12

## s parameter inductance

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

- 21st February 2006, 07:19 #18

- Join Date
- Jan 2005
- Posts
- 12
- Helped
- 1 / 1
- Points
- 2,748
- Level
- 12

## how to find inductance

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! ^_^

- 1st March 2006, 12:26 #19

- Join Date
- Oct 2005
- Posts
- 44
- Helped
- 5 / 5
- Points
- 1,716
- Level
- 9

## fluke inductance

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

- 3rd March 2006, 14:37 #20

- Join Date
- May 2004
- Posts
- 3
- Helped
- 0 / 0
- Points
- 1,550
- Level
- 8

## coil inductance measurement

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