On Thu, Mar 23, 2006 at 10:43:45PM -0800, Steve Meier wrote: > Digital ground and analog ground have to get tied together some where. > Think of the ground path being the return of an electrical circuit. All > seperating the grounds out does is to have the single ended analog > signals return signals not getting mixed in with the digital return > signals. Yes noise on one side will propigate through to the other > but.... an inductor along with the capacitance between the planes will
As the ground is thought as a zero point, nothing can propagate through it. Unless the ground has resistance or inductance, but then it's not a ground. CL< > significantly lower the short term amplitude. > > So the operative word is immediately... remember the idea of an inductor > is that the current flowing through it can not change instantly. > > Steve Meier > > Phil Taylor wrote: > >Steve Meier <[EMAIL PROTECTED]> wrote: > > > > > >>I also use seperate > >>ground plains (the return path) and tie the analog ground to the digital > >>ground with a power inductor. > >> > > > >Steve, how does this work? It'd seem like any spikes getting into the analog > >side (or even an analog signal transient) would return thru this inductor > >(that ties gnda to gndd) and immediately cause the entire analog ground to go > >high? This seems contradictory. > > > >pt > > > > > > > >
