0.13um TSMC RF process 4.8GHz VCO

[eeliuliu]

I'm designing 4.8Ghz VCO with 0.13um TSMC RF process.
The PN of 4.5mA VCO is about -82dBc/Hz@10K，-106dBc/Hz@100KHz, and -126dBc/Hz@1M.
I want to improve PN, but found it's very hard. So, Could you please tell me if I can get better PN no increasing current? thanks a lot and waiting for your reply!

 

[khouly]

and the output power of the oscillator increase the PN decrease ,

but u need to check the flicker noise variation with the bias current , this will give u genraal view if u can get the desired results or not

khouly

 

[n1cm0c]

and the output power of the oscillator increase the PN decrease ,

but u need to check the flicker noise variation with the bias current , this will give u genraal view if u can get the desired results or not

khouly

could you explain more ? 1/f noise from the transistor pair depends mostly on W and L, right ? Increasing the current won't help him, because the VCO amplitude will reach a max value...

I suggest increasing w and l, increasing the current until the oscillator amplitude is max, then looking at the PN. if thermal noise is about equal to 1/f noise, cease and desist...

 

[khouly]

sorry , i have writen a mistake , get the noise as a function in current desnity , not the current only

this will give the indication for noise

khouly

 

[eeliuliu]

hi，khouly, thank you very much!
I don't understand " the flicker noise variation with the bias current "?
Could u pls say more detail ? thanks!

and the output power of the oscillator increase the PN decrease ,

but u need to check the flicker noise variation with the bias current , this will give u genraal view if u can get the desired results or not

khouly

 

[Abhishekabs]

How to improve phase noise of an oscillator in general?

I have heard that flicker noise is frequency dependant. Is it depend on biass current variation also?