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High Frequency VCO -- Capacitor bank

gkini19

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Why do we use capacitor bank in VCOs? is it for tuning ?
 

KlausST

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Hi,

good question.
Where is this "capacitor bank"? (We don´t see your schematic) In the tuning circuit?
* Yes: Then it is for tuning.
* No: Then it is not for tuning.

Klaus
 

gkini19

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Hi Klaus,

I was referring to many designs and I had some doubts.
if we are using a cap bank for tuning and then why do we use varactors.

Is it like fine-tuning is done by cap bank and coarse tuning is done by varactors?

Please let me know
 

gkini19

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1626964634881.png


Please take just as reference
 

KlausST

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Hi,

use the same document, read the next few lines and have a look at
Figure 8 Voltage Controlled Oscillator (VCO) output frequency as a function of the capacitor bank
control word



Klaus
 
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vfone

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The 3-bits capacitor bank is used for coarse tuning, when the varactor bank is used for fine tuning.
 

BigBoss

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Coarse Tuning and Calibration.Every RFIC circuit has process variations and in order to compensate these process variations, a calibartion routine runs while initializing to maintain the VCO standard.
 

biff44

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inductors are hard to fabricate in ICs.
Capacitors are easy to fabricate, and you can change their total capacitance by adding a varactor diode, or switching in other fixed capacitor values
 

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