If the VCO frequency is increased, will it influence the phase noise?
if the VCO freq is increased, will it influence the phase noise?
Thanks....
I do think so .
if the frequency is double, basically, the phase noise will be higher about 6dbc/hz
i think yeah
coz the Q of the resonator is changing with frequency , and also the output power of the VCO change with frequency
so the Phase noise will also change
khouly
L{dw}=10log{2FKT/Ps*[1+(w0/2/Q/dw)^2]*(1+dw3/dw)}
w0 increase, then the L{dw} decrease.
while the LO amplitude is increasing if the oscillation frequency increase with other same condition.
yeah in equation , but as w increase the Q will decrease and also the output power
so the phase noise will increase
khouly
One way to think of it is that the resonator has a narrow bandwidth, so for a given available Q (which is a given when you select your media, such as around 30 for microstrip, etc), the bandwidth that the resonator is trying to restrict the oscillator's operation to gets bigger. Q = BW/f0 So, when f0 goes up, your bandwidth goes up, so your oscillator noise bandwidth goes up too.
You can read some of the older papers by Leeson to understand where that phasenoise equation comes from.
If you go higher in frequency, to have the same phase noise you would need a somewhat better resonator Q, or a lot bigger oscillation power.
Do you mean the phase noise of VCO or LO divided by VCO?I think if VCO frequency is double,the divider will double,so the phase noise of LO will improve 6dBc/Hz from Bessel theory.
Thank you very much!
He may means the phase noise of VCO slopes with 20dBc/decade(6dbc/oct). But in fact, it slopes with 30dbc/decade for low frequency and 20dbc/decade for medium frequency. You can refer to Hajimiri?s paper.
Could you send the paper to me because I cann't find it at internet? Many thanks.
This is the link:
https://www.edaboard.com/viewtopic.p...light=hajimiri