+ Post New Thread
Results 1 to 20 of 25

23rd December 2005, 01:18 #1
 Join Date
 Jan 2005
 Posts
 111
 Helped
 5 / 5
 Points
 2,625
 Level
 11
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, 01:18

23rd December 2005, 02:04 #2
 Join Date
 Sep 2002
 Location
 Thailand
 Posts
 481
 Helped
 96 / 96
 Points
 6,805
 Level
 19
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
 82 / 82
 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
 7,942
 Helped
 2324 / 2324
 Points
 74,061
 Level
 66
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
4 members found this post helpful.

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/

24th December 2005, 00:10

25th December 2005, 03:50 #7
 Join Date
 Jan 2005
 Posts
 111
 Helped
 5 / 5
 Points
 2,625
 Level
 11
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
 238 / 238
 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
 3,667
 Helped
 1123 / 1123
 Points
 25,958
 Level
 39
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
 5 / 5
 Points
 2,625
 Level
 11
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 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
 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
 56 / 56
 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
 4 / 4
 Points
 2,828
 Level
 12
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
 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 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
 Join Date
 Oct 2005
 Posts
 44
 Helped
 5 / 5
 Points
 1,716
 Level
 9
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
 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_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
+ Post New Thread
Please login