Re: Groundplane in poweramplifier PCB design

On Sunday 16 April 2006 18:25, Ken Smith wrote:

There can also be thermal reasons for putting copper in. You can't ignore
these.

For me, that's not an issue. The driver transistors will be fitted with
internal heatsinks, and the output devices are connected through brackets to
external heatsinks. Everything that needs cooling is taken care of this way.


You want the extra copper as shielding. If you can arrange to effectively
have a thick shorted turn around the whole circuit, this will help to keep
AC magnetic fields from going through the PCB.

Sounds like a good idea. Will do.

Will it matter (much) BTW if that track has a gap in it?

There are other places in the design where you want the trace to be short
and thick. These are the places to look at. It is likely that you will
find that you want those traces so wide that they end up really being a
plane.

I have this for the supply tracks, and speaker output. And, to a lesser degree
also some ground tracks, mainly for those used for decoupling and bypassing.



The speaker returns go directly to the main power supply BTW, so the
groundplane is not necessary for that.


I assume that this amplifier has feedback. Where are you picking off the
two sides of the speaker for feedback? These connections can also be
trouble makers.


What do you mean, the two sides of the speaker? The voltage feedback for the
long tailed pair input stage is taken care of on the PCB, if that's what you
mean.
.