HOW MULTI-VCO UNIT will work?

[sathi.ec]

multi-vco

Hi, all

I am designing a 2nd order PLL (10MHz input and 1GHz output), my VCO is working fine for tuning range(950MHz-1.01GHz). In one pdf file they told we can increase the tuning range of the VCO without increasing the CHIP-AREA, by using MULTI-VCO unit. I didn't get the logic of MULTI-VCO UNIT, please help me to understand this one.

Thanks :|

 

[pi331133]

Multi-VCO may have the proble of injection locking and pushing, It also increase the cost. If it is possiable, I think redesign the VCO to achieve the tuning range may be helpful, since you already has a working VCO.

Regards.

 

[rjshmadala]

which type of varactors r u using. now u have only approx.50 MHz tuning range.u can get more tuing range by desigining of accumalation or inversion mode varactors properly.if u want more tuning range design wide band VCO by using switched capacitor array.power consumption is very low for this.

 

[sathi.ec]

Hi rjshmadala
I am using nmos type varactors. what u have told is OK.

But the reason for going to MULTI-VCO is to partition output frequency range into sections, one VCO is responding to one section. A multiplexer unit is used to direct the valid VCO output to the synthesizer output. in one pdf file they told this much only. It is not clear to me, so i want details of this one.