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Measurement of VCO phase noise

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OMEsystem

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open loop vco phase noise measurement

I have a VCO, I would like to measure its phase noise in open loop.
But it looks like not to be measured easily because noise in Vtune.
Do I need to the help of PLL to stabilize the Vtune?
Is it a general way to measure VCO phase noise with a constant voltgae giving
to Vtune?
I would like to know how you guys perform this measurement.
Thank you,
 

Traditionally, you take a big lantern battery and a 50K potentiometer set up like a voltage divider to generate the tune voltage. A 10 uF cap across the tune line helps also.

Then you put a big sheet of cardboard over VCO to keep it from drifting with air currents.

If you are lucky, you can make your measurement.

If it is drifting too far, you will have to use a more forgiving way to measure, like a delay line discriminator.
 

biff44 said:
Traditionally, you take a big lantern battery and a 50K potentiometer set up like a voltage divider to generate the tune voltage. A 10 uF cap across the tune line helps also.

Then you put a big sheet of cardboard over VCO to keep it from drifting with air currents.

If you are lucky, you can make your measurement.

If it is drifting too far, you will have to use a more forgiving way to measure, like a delay line discriminator.
Click to expand...

So, it's not an usual case that measure a free running VCO?
 

OMEsystem

the free running VCO phase noise measurement is not very simple. You can look the VCO in a PLL with a very narrow bandwidth (1 kHz for example) and see the VCO curve from 10 kHz. Or you can use the delay line method. You can see in the Europtest site: there are some application note can help you.

By
 

dinone said:
OMEsystem

the free running VCO phase noise measurement is not very simple. You can look the VCO in a PLL with a very narrow bandwidth (1 kHz for example) and see the VCO curve from 10 kHz. Or you can use the delay line method. You can see in the Europtest site: there are some application note can help you.

By
Click to expand...

Thanks for your help, by the way, what is the dely line method?
 

This application note can help you
 

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