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VCO tuning range between 80-90%

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AdvaRes

AdvaRes

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Hi members,

I noticed that always the VCO tuning range is between 40 and 80 % of the nominal voltage.
What about VCOs in which the Tuning range is between 80 % and 90 % ?
 

VCO tuning range

the tuning range of the VCO depends on the CV curve of the varactor , so to get high tuning range u need the vacattor to have wide tuning volateg

khouly
 

    AdvaRes

    AdvaRes

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Re: VCO tuning range

You could do this with the control voltage of VCO in the related range.
 

    AdvaRes

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Re: VCO tuning range

AdvaRes said:
Hi members,

I noticed that always the VCO tuning range is between 40 and 80 % of the nominal voltage.
What about VCOs in which the Tuning range is between 80 % and 90 % ?
Click to expand...

It is up to the CP output voltage range.
When the Vtune larger than 80% or lower than 20%, CP will be mismatch.
But if you use ADPLL, there is no problem.
 

Re: VCO tuning range

If the VCO could use only 10% of the supply as voltage tuning range it will be more sensitive to noise and tolerances. Typical designs try to maximize the range ro 20-80% which could be covered by either a chargepump or an opamp in an active loop filter.
 

    AdvaRes

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Re: VCO tuning range

As mentioned, if VCO tuning range is covered by 10% of supply then Kvco is very high, making it very sensitive to noise in the tuning voltage.

One designs for a tuning voltage between 20% to 80% of supply rail because that's about the max useful output range of the CP.

This way one can lower the Kvco and reduce sensitivity to noise in the tuning control line.
 

    AdvaRes

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VCO tuning range

Hi

Tuning range is depended on varactor network. You can have a tuning range from 2% to 100%.
 

    AdvaRes

    AdvaRes

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