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Simulators >> RF Simulators >> VCO / VCXO Modulation bandwidth
https://designers-guide.org/forum/YaBB.pl?num=1314062842

Message started by ppg on Aug 22^nd, 2011, 6:27pm

Title: VCO / VCXO Modulation bandwidth
Post by ppg on Aug 22^nd, 2011, 6:27pm

Dear All,

Can someone explain how one shall use Spectre-RF tool to calculate VCO / VCXO FM Modulation Bandwith. Using PAC after PSS applying a small PAC signal at V Ctrl pin (say VCON) and observing ...? I believe PAC assume fosc=constant so it does not work this way.

Indeed Transient Analysis can always be used with long simulation time and freq measured in the time domain as 1/Tperiod, Tperiod the time between two output clock rising edges (for instance).

Thank you.

Best Regards,
ppg

Title: Re: VCO / VCXO Modulation bandwidth
Post by raja.cedt on Aug 23^rd, 2011, 2:45am

hello what do you mean by VCO / VCXO FM Modulation Bandwith?

Thanks.

Title: Re: VCO / VCXO Modulation bandwidth
Post by ppg on Aug 23^rd, 2011, 9:15am

VCO / VCXO oscillation frequency varies with voltage applied at VC pin (see 'VC'O and 'VC'XO) ... but not for arbitrarily high speed signal through VC pin. VCO / VCXO includes low-pass in VC pin path to limit the signal bandwidth through VC pin or the (FM) "VCO / VCXO Modulation bandwith".

Accurate estimations of Modulation bandwith requires one to include circuit parasitics, Q of resonator used, ... . Final validation needs to be done using RF circuit simulators. But HOW this is precisely my question?

Regards,
ppg