High Frequency VCO -- Capacitor bank

[gkini19]

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

 

[KlausST]

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]

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

 

[KlausST]

Hi,

is it asking too much to upload a schematic?

Klaus

 

[gkini19]

Please take just as reference

 

[KlausST]

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

(PDF) A Bandwidth-Enhanced Differential LC-Voltage Controlled Oscillator (LC-VCO) and Superharmonic Coupled Quadrature VCO for K-Band Applications

PDF | A novel varactor circuit exhibiting a wider tuning range and a new technique for quadrature coupling of LC-Voltage Controlled Oscillator (LC-VCO)... | Find, read and cite all the research you need on ResearchGate

www.researchgate.net

Klaus

 

[vfone]

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

 

[BigBoss]

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]

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