Hi all, I'm currently start working with DPLL. One design parameter in the development of narrow bandwidth DPLL is the noise bandwidth. I read that the noise bandwidth could be calculated as the integral over the closed loop response and I did this but I get a huge value for a narrow bandwidth PLL? Could you please help me or give me a hint where I can find a documentation how I can estimate the noise bandwidth of a DPLL using matlab? Thank you, Biel
PLL noise bandwidth
Started by ●April 23, 2009
Reply by ●April 23, 20092009-04-23
On Apr 23, 2:15�pm, "biel_d" <bie...@web.de> wrote:> Hi all, > > I'm currently start working with DPLL. One design parameter in the > development of narrow bandwidth DPLL is the noise bandwidth. I read that > the noise bandwidth could be calculated as the integral over the closed > loop response and I did this but I get a huge value for a narrow bandwidth > PLL? Could you please help me or give me a hint where I can find a > documentation how I can estimate the noise bandwidth of a DPLL using > matlab? > > Thank you, > Biel � �The noise BW for a second order PLL is given in Gardner and also Best. It is (Wn/2)*(Z+1/(4Z)) where Wn is natural freq (rad/sec) and Z is damping factor (unitless). You can see from this eqn that minimum noise BW is half natural freq when Z=0.5. The noise BW blows up fast as Z goes < 0.5 and increases slowly as Z goes > 0.5, so the standard Z=0.707 is fine. John John
Reply by ●April 24, 20092009-04-24
>On Apr 23, 2:15=A0pm, "biel_d" <bie...@web.de> wrote: >> Hi all, >> >> I'm currently start working with DPLL. One design parameter in the >> development of narrow bandwidth DPLL is the noise bandwidth. I readthat>> the noise bandwidth could be calculated as the integral over theclosed>> loop response and I did this but I get a huge value for a narrowbandwidt=>h >> PLL? Could you please help me or give me a hint where I can find a >> documentation how I can estimate the noise bandwidth of a DPLL using >> matlab? >> >> Thank you, >> Biel =A0 =A0 > >The noise BW for a second order PLL is given in Gardner and also Best. >It is (Wn/2)*(Z+1/(4Z)) where Wn is natural freq (rad/sec) and Z is >damping factor (unitless). You can see from this eqn that minimum >noise BW is half natural freq when Z=3D0.5. The noise BW blows up fast >as Z goes < 0.5 and increases slowly as Z goes > 0.5, so the standard >Z=3D0.707 is fine. > >John > >John >Hi John, thank you for your help. I know the table in Gardners book phase lock techniques. But I want to know is, how can I numerical calculate the noise bandwidth for an arbitrary PLL? Thank you for your help again, Biel
Reply by ●April 24, 20092009-04-24
On Apr 24, 7:45�am, "biel_d" <bie...@web.de> wrote:> >On Apr 23, 2:15=A0pm, "biel_d" <bie...@web.de> wrote: > >> Hi all, > > >> I'm currently start working with DPLL. One design parameter in the > >> development of narrow bandwidth DPLL is the noise bandwidth. I read > that > >> the noise bandwidth could be calculated as the integral over the > closed > >> loop response and I did this but I get a huge value for a narrow > bandwidt= > >h > >> PLL? Could you please help me or give me a hint where I can find a > >> documentation how I can estimate the noise bandwidth of a DPLL using > >> matlab? > > >> Thank you, > >> Biel =A0 =A0 > > >The noise BW for a second order PLL is given in Gardner and also Best. > >It is (Wn/2)*(Z+1/(4Z)) where Wn is natural freq (rad/sec) and Z is > >damping factor (unitless). You can see from this eqn that minimum > >noise BW is half natural freq when Z=3D0.5. The noise BW blows up fast > >as Z goes < 0.5 and increases slowly as Z goes > 0.5, so the standard > >Z=3D0.707 is fine. > > >John > > >John > > Hi John, > > thank you for your help. I know the table in Gardners book phase lock > techniques. But I want to know is, how can I numerical calculate the noise > bandwidth for an arbitrary PLL? > > Thank you for your help again, > BielIn the book by Roland Best, the formula I gave is derived. John
Reply by ●April 24, 20092009-04-24
>On Apr 23, 2:15=A0pm, "biel_d" <bie...@web.de> wrote: >> Hi all, >> >> I'm currently start working with DPLL. One design parameter in the >> development of narrow bandwidth DPLL is the noise bandwidth. I readthat>> the noise bandwidth could be calculated as the integral over theclosed>> loop response and I did this but I get a huge value for a narrowbandwidt=>h >> PLL? Could you please help me or give me a hint where I can find a >> documentation how I can estimate the noise bandwidth of a DPLL using >> matlab? >> >> Thank you, >> Biel =A0 =A0 > >The noise BW for a second order PLL is given in Gardner and also Best. >It is (Wn/2)*(Z+1/(4Z)) where Wn is natural freq (rad/sec) and Z is >damping factor (unitless). You can see from this eqn that minimum >noise BW is half natural freq when Z=3D0.5. The noise BW blows up fast >as Z goes < 0.5 and increases slowly as Z goes > 0.5, so the standard >Z=3D0.707 is fine. > >John > >John >Hi John, thank you for your help. I know the table in Gardners book phase lock techniques. But I want to know is, how can I numerical calculate the noise bandwidth for an arbitrary PLL? Thank you for your help again, Biel
