1. I know that this formula is only valid when L(fm) is in dBc/Hz. In SPICE simulation such as LTSPICE, the phase noise generated is always in in nV/Hz unit. Let say if the noise generated is 2.3505nV/Hz, how to convert this phase value to dBc/Hz? . I only managed to convert nV/Hz to dBm/Hz but I'm not satisfy with my calculation.
2. If my local oscillator is a 2.4-GHz oscillator, does it suitable to be use with GSM800 and GSM900? Do I need a new GSM with higher frequency to make it compatible with the 2.4-GHz oscillator?
... Let say if the noise generated is 2.3505nV/Hz, how to convert this phase value to dBc/Hz? . I only managed to convert nV/Hz to dBm/Hz but I'm not satisfy with my calculation.
I knew that dBc and dBm is two different things. Thats why I guess there is something wrong with my calculation. Do you have any reference on how to do the conversion of nV/Hz to dBc?
Thanks, ok now I'm more understand. But what do you meant by 'peak spectral voltage of carrier signal'?. If I measure at frequency of 2.4-GHz, so I will get the value of Vn. But how I determine the value of Vc?
... what do you mean by 'peak spectral voltage of carrier signal'?.
If I measure at frequency of 2.4 GHz, so I will get the value of Vn. But how I determine the value of Vc?
I'd think fo is your oscillator frequency (2.4GHz), fm the measurement frequency (e.g. 2.0 GHz) where you measure the spectral noise voltage Vn = L (in units of V/√Hz).
So I think Vc is the 'peak spectral voltage of your carrier signal' (@ 2.4 GHz), whereas Vn is the spectral noise voltage at a certain measurement frequency of interest fm, where you want to diagnose the frequency-dependent FoM.
But I don't know your above equation, so perhaps I'm wrong.
I'd think fo is your oscillator frequency (2.4GHz), fm the measurement frequency (e.g. 2.0 GHz) where you measure the spectral noise voltage Vn = L (in units of V/√Hz).
So I think Vc is the 'peak spectral voltage of your carrier signal' (@ 2.4 GHz), whereas Vn is the spectral noise voltage at a certain measurement frequency of interest fm, where you want to diagnose the frequency-dependent FoM.
But I don't know your above equation, so perhaps I'm wrong.
Yes you are correct. 85.3808pv/Hz is the value that I obtain for Vnoise at 2.4-GHz. Is that correct? If not,so how do we calculate or get the Vc? At 10-MHz offset frequency, the value is 85.6531pV/Hz.
Thanks erikl for reminding me about the spectral voltage. My peak spectral voltage for 2.4-GHz is 180mV/Hz. Therefore the phase noise is around -185 @ 1-MHz. I really appreciate your help. Thank you.