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23rd December 2005, 01:18 #1
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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
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measuring inductance
you can use a network analyzer. You can determine the Q value from group delay obtained from the network analyzer.
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23rd December 2005, 05:39 #3
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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!
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23rd December 2005, 05:39

23rd December 2005, 06:13 #4
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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 LCtank equation: ω=1/√LC > L=1/ω²C, where ω=2Πf ..
See circuit below ..
Regards,
IanP
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23rd December 2005, 07:02 #5
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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/

24th December 2005, 00:10

25th December 2005, 03:50 #7
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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
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measuring inductance of a coil
You can build an easy microcontroller based L/C meter
here is it..
I hope it helped.
Ahmad
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25th December 2005, 10:54 #9
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inductance measurement method
Originally Posted by chunlee

25th December 2005, 10:54

28th December 2005, 22:16 #10
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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.

29th December 2005, 02:03 #11
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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
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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
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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 AN95.
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 onwafer 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 onwafer 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
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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
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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
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find inductance
Treat the inductance as a twoport network, and you can measure the s parameter,
and you can deduce the L from the S parameters.
Perhaps not accurate.

9th January 2006, 14:17

10th January 2006, 14:21 #17
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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
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how to find inductance
Hi all,
I got a problem when redraw Sparameters after deembedding procedure.
I used ADS to redraw 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 testfixture only (open standard). Here I got Sopen values.
Since I got the Sparameters 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 Sparameters 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
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fluke inductance
Can you connect the same to a connector directlyboth ends of the inductor and measure S11 to find L?

3rd March 2006, 14:37 #20
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coil inductance measurement
The problem is lying at that you Ymo=Y_measY_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
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