Hi
I often explain it this way:
The power supply must first be kind to itself.
And second, he must be very caring of his connected load.
Even though it seems that way, a linear power supply is not simple.
There are very many mistakes made by amateurs (me too in the past) and professionals, especially regarding the current limitng as Dave showed with the R&S power supply, among others.
Just because R&S designed this power supply does not mean it is good.
The same goes for a number of HP models. I have one here that has a low power rating, below 50Watt, nice and low noise and an output capacitor of 1000u! for less than 2 Amps.
1000uF is way to mutch in this HP Power Supply, to be very caring of his connected load.
For now, I don't know how the voltage loop and current loop are arranged in the R&S power supplies.
But digital is really a NoNo for a linear power supply for now.
If you design an Analog/Linear power supply you should in my opinion make sure that both loops are always stable without switching effects from voltage to current and vice versa.
It's nice that you have lots of options in the menus but loop stability is #1 for a linear power supply.
Also notice the noise or PARD when Dave puts the scope over the output of the power supply, you can sawing wood at the pulses the scope shows, now that's not exactly neat.
Those pulses may be a commonmode problem in Dave's measurement setup, but I have a sneaking suspicion that they are not.
Some opinions from me:Good linear power supplies do not have digital loop control.
To solve this properly in the digital domain, you need very fast and good ADC/DAC and a processor just for this function with a very good "Watch Dog" setup.
This is I think, rather expensive.
The Power section will have been implemented with medium speed transistors of around 5Mhz Ft. (Faster is possible with modern audio power transistors, but it is harder to keep stable.)
If the compensation of your voltage and current loop is set up properly, with good opamps with large phase margin(AD4625), you will achieve 40uF capacitor per Ampere across the output with very good dymamic behavior.
Those were my two cents.
Kind regards,
Bram