I am performing a control loop stability test on my 5V DC-DC Buck Converter with the help of this Keysight App Note
I understand that we are injecting a noise signal on the feedback network of this converter and checking how well our converter is responding.
My questions are :
How much noise voltage should we give while testing? What would be the ideal noise voltage that should be injected at the resistor?
I want to understand intuitively where to give the red and black probes from the injection transformer and where to probe Ch1 and Ch2 in the circuit? Where am I injecting the noise (at the top of the 5ohm resistor or at the bottom of the 5ohm resistor) and where am I taking the output?
On Figure 6, is the 0 degree on the phase plot convey actual -180deg ?
It is not clear from the app note