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chunlee
Joined: 03 Jan 2005
Posts: 114
Helped: 3
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 08 Jul 2008 3:56 Inductance Measurement |
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May I know PNA network analyzer can measure inductance less than 1nH? such as 0.5 nH accurately? Somebody try before?
Thanks.
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vfone
Joined: 10 Oct 2001
Posts: 1720
Helped: 224
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| 08 Jul 2008 10:22 Re: Inductance Measurement |
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No, is not accurate below 1nH.
For greater accuracy try to use a dedicated LCR meter.
http://cp.literature.agilent.com/litweb/pdf/5968-5758E.pdf
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chunlee
Joined: 03 Jan 2005
Posts: 114
Helped: 3
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| 09 Jul 2008 11:16 Re: Inductance Measurement |
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Hi Vfone,
What is the uncertainty if I use PNA to measure sub-nH inductor? below 10%?
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vfone
Joined: 10 Oct 2001
Posts: 1720
Helped: 224
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| 09 Jul 2008 12:39 Re: Inductance Measurement |
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Below 1nH I would go for an accuracy no better than +/-30% (maybe worst).
Inductance measurement in a PNA is an indirect measurement, calculated from an impedance measurement.
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madengr
Joined: 06 Apr 2005
Posts: 369
Helped: 76
Location: Kansas City
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| 09 Jul 2008 14:54 Inductance Measurement |
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You can use a VNA to measure inductance. You just need to measure at a high enough frequency so 1 nH presents a impedance near 50 ohms. That also means you need a good calibration. You can use either 1 port or 2 port measurements, preferably both.
The 4287A is just a 1-port VNA anyway. The bridge type LCR meters are probably too low in frequency to measure 1 nH, however they are very accurate for certain ranges.
You don't have to measure the inductance directly. You can resonant it with a known capacitance and measure the **** out. There are methods using transmission lines too. One method may be better a finding the Q, another better for L or SRF. You need to research the different methods.
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chunlee
Joined: 03 Jan 2005
Posts: 114
Helped: 3
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| 11 Jul 2008 5:54 Re: Inductance Measurement |
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Hi all,
Thanks for your reply.
In this case, I would prefer to measure L and Q over wide frequency band. Hence using LC oscillator is not suitable for my application.
But madengr gives a very good idea: Is it if |Zin| near to 50ohm, measurement accuracy can be greatly improve, assume inductor are measured using 2ports VNA?
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