Bode Plot help
in [Design]
|
Prev: Which type of volatile RAM has the least duration of data remanencewhen power-offed?
Next: PSU help understanding this circuit
From: Harry D on 14 May 2010 21:01 How do I attach a PDF (Bode plot) to this message so I can ask questions. I am using Google groups and they do not have alt.binares.electronic.design. I know I am asking to be totally harassed and Joerg will tell me how much smarter he is but I would like some help. Cheers, Harry
From: John Larkin on 14 May 2010 21:17 On Fri, 14 May 2010 18:01:08 -0700 (PDT), Harry D <harryd(a)tdsystems.org> wrote: > How do I attach a PDF (Bode plot) to this message so I can ask >questions. I am using Google groups and they do not have >alt.binares.electronic.design. I know I am asking to be totally >harassed and Joerg will tell me how much smarter he is but I would >like some help. > Cheers, Harry Park it in one of those free photo hosting sites, photobucket, imageshack, like that. Joerg can provide the sound effects. John
From: a7yvm109gf5d1 on 14 May 2010 22:08 On May 14, 8:01 pm, Harry D <har...(a)tdsystems.org> wrote: > How do I attach a PDF (Bode plot) to this message so I can ask > questions. I am using Google groups and they do not have > alt.binares.electronic.design. I know I am asking to be totally > harassed and Joerg will tell me how much smarter he is but I would > like some help. > Cheers, Harry Maybe try a Google Docs thing.
From: Harry D on 14 May 2010 23:38 On May 14, 6:17 pm, John Larkin <jjlar...(a)highNOTlandTHIStechnologyPART.com> wrote: > On Fri, 14 May 2010 18:01:08 -0700 (PDT), Harry D > > <har...(a)tdsystems.org> wrote: > > How do I attach a PDF (Bode plot) to this message so I can ask > >questions. I am using Google groups and they do not have > >alt.binares.electronic.design. I know I am asking to be totally > >harassed and Joerg will tell me how much smarter he is but I would > >like some help. > > Cheers, Harry > > Park it in one of those free photo hosting sites, photobucket, > imageshack, like that. > > Joerg can provide the sound effects. > > John Ok JL, let's give this a try. Attached Bode Plot PDF. http://www.keepandshare.com/doc/1913125/bode-plot-gp-30k?da=y (Google groups not like links) This is an open loop SPICE plot of a multi stage system. The gain crosses 0 at 26.3MHz with the phase at -675 degrees and the phase = -720d at 45.2MHz with the gain at -3.2dBv. Looking at the gain crossing zero at a low slope makes the system appear stable but the phase crossing is at -675d, not near -360d. But how does the system know how many spins the phase vector has rotated greater than 360d? Is the system not just comparing the feedback phase to the reference phase on an instantaneous basis? If true, I can then subtract N*360 (N= integer) from -675 and get -315d which gives, 360 - 315 = 45d phase margin. This collaborates the low slope of the gain crossing zero and the (Low) 3.2dBv gain margin. Just a chicken farmer trying to be a electronic consultant, Harry
From: miso on 15 May 2010 00:04
On May 14, 8:38 pm, Harry D <har...(a)tdsystems.org> wrote: > On May 14, 6:17 pm, John Larkin > > > > <jjlar...(a)highNOTlandTHIStechnologyPART.com> wrote: > > On Fri, 14 May 2010 18:01:08 -0700 (PDT), Harry D > > > <har...(a)tdsystems.org> wrote: > > > How do I attach a PDF (Bode plot) to this message so I can ask > > >questions. I am using Google groups and they do not have > > >alt.binares.electronic.design. I know I am asking to be totally > > >harassed and Joerg will tell me how much smarter he is but I would > > >like some help. > > > Cheers, Harry > > > Park it in one of those free photo hosting sites, photobucket, > > imageshack, like that. > > > Joerg can provide the sound effects. > > > John > > Ok JL, let's give this a try. Attached Bode Plot PDF. > http://www.keepandshare.com/doc/1913125/bode-plot-gp-30k?da=y > (Google groups not like links) > This is an open loop SPICE plot of a multi stage system. The gain > crosses 0 at 26.3MHz with the phase at -675 degrees and the phase = > -720d at 45.2MHz with the gain at -3.2dBv. Looking at the gain > crossing zero at a low slope makes the system appear stable but the > phase crossing is at -675d, not near -360d. But how does the system > know how many spins the phase vector has rotated greater than 360d? Is > the system not just comparing the feedback phase to the reference > phase on an instantaneous basis? If true, I can then subtract N*360 > (N= integer) from -675 and get -315d which gives, 360 - 315 = 45d > phase margin. This collaborates the low slope of the gain crossing > zero and the (Low) 3.2dBv gain margin. > Just a chicken farmer trying to be a electronic consultant, > Harry It says EMI active filter as the title, so you are showing the response of a filter, right? Unless you are going to close a loop around this filter, why do you think it is necessary to do Bode analysis (gain/phase margin)? |