Hi..
It's the first post on this excellent forum!! I hope to get help from you proffessionals!
In PLL VCO specs, noise is represented by the unit: dBc/Hz..
What does it mean?? Where did it come from, i.e. its origin??
Any tutorials about PLL blocks intrensic noise?? My big dream now is to get clear detailed explaination for it!
Any tutorials about noise in general??
It is the power at a given frequency compared (by taking ratio) with the power at the 'carrier' frequency. In PLL applications carrier means the frequency at which you 'want' the VCO to run.
It is the power at a given frequency compared (by taking ratio) with the power at the 'carrier' frequency. In PLL applications carrier means the frequency at which you 'want' the VCO to run.
It is any frequency in the spectrum *except* for the carrier frequency. Usually you will get a gaussian looking waveform centered on the carrier, that means that most of the power of the signal is concentrated around the VCO frequency. You get the dBc/Hz figure by taking the value at adjacent frequencies and dividing by value at VCO frequency.
to check ma self, is dBc= VCO power(in dBm) - Adjacent freq or 1st harmonic power (in dBm) ??
If so, this's easy to calculate, but how to calculate for it to be dBc/Hz ??
e.g. assume center freq. power=20dBm, and the first adjacent component power=-50dBm, then do I have -70dBc difference between them?? and/or I have -70dBc/Hz ........ (don't know what to say about it?).
u have -70dBc/Hz as u have center freq,. power 20dbm/Hz and 1st comp @ -50dBm/Hz , i.e,. the hole graph is dBm/Hz or dBm/Hz but if u subtract two powers then the result is in dB/Hz and if u refered any result to the carrier then the result will be dBc/Hz