Power supply with forced symmetry

[enaB]

Hi!

Is it better to have independently regulated positive and negative voltage rails, or something like this schematic, to always keep voltage symmetric by decreasing voltage on less loaded side?
I am trying to design custom voltage regulator and protection for power amplifier (this is a extracted and simplified part of regulator circuit), and this looks interesting but I'm not sure is this concept actualy a good idea for audio amplifier?



P.S. Sorry for my bad English

[twest820]

When I looked at servoing ground in an amp I was fooling around with a while back I concluded it wasn't worth the hassle; no real gain to forcing symmetry in a linear supply as most amplifiers have no signifiant error terms which would benefit from cancellation by symmetric movement of the rails.

For switchmode I found there may be some benefit depending on the control loop gain, supply structure, switching frequency, SMPS topology, and noise injection points. But that's a separate discussion.

[simon7000]

There may be an advantage to not having matching rail voltages. Depends on the circuitry and how it handles zero crossings.

[twest820]

True. Though, personally, I've yet to find an application where class XD operation is compelling.

[sreten]

Hi, Generally forced symmetry has no advantages whatsoever, rgds, sreten.

In some cases you make the ripple on one rail lower (asymmetrical) to match
the assymetrical PSRR of the power amplifier circuit, depends on the circuit,
and for what stage you are manipulating the intrinsic ripple.

[enaB]

Thanks!