AD797, how to make the best of it

[syn08]

Originally posted by Patrik Floding
Can it sound good even if oscillating like mad behind the scene (of my 100MHz 'scope)?

No, you are probably fine. AD797 is not very difficult to handle if good layout principles are employed. To figure out what "difficult" means, you should try something like the OPA847 or AD8056...

[Patrik Floding]

Originally posted by syn08


No, you are probably fine. AD797 is not very difficult to handle if good layout principles are employed. To figure out what "difficult" means, you should try something like the OPA847 or AD8056...

Thanks for the reply!
Layout isn't great, but at least the decoupling is right at the OpA.

[Bonsai]

The advantage of super-shunt regulators is that, if you organize the circuit correctly, the ground return currents are constant. You can see immediately that it there will be a reduction in noise injection between the different circuit s both into the power rail, and into the signal lines (here, because there is always a finite ground return resistance, so Is*Rgnd + Vsig is avoided).

For this to work effectively, th e variuos stages in th e circuit need to be partitioned carefully and local tight loop super shunt regulation applied to these individual stages.

I think if you apply super shunt regulation without partitioning correctly, you will not get the full benefit.

[lineup]

this should be true for shunt regulators
as well as zenerdiode references

[Bonsai]

Line-up, not neccessarily so. If the supply voltage changes, the current through the ground return will change as well. If the shunt is fed from a current source, the ground return current is fixed.

[Hartono]

constant ground return current .......illuminating ^^

also constant power draw IIRC

[lineup]

Originally posted by Bonsai
Line-up, not neccessarily so. If the supply voltage changes, the current through the ground return will change as well. If the shunt is fed from a current source, the ground return current is fixed.

right