Lee,
You asked, so let me explain.
When I was developing my Dynamic load I was trying to get high bandwidth for doing transient load tests. I did my control loop without considering the characteristics of the test leads that are used to connect the power supply to the load.
When I tried the load I found the current oscillated at around 200kHz.
So I thought may be the inductance of the leads going between the power supply and the load were causing problems.
I estimate that the inductance is between 1 and 5uH.
I can make a small signal model:
![](https://www.eevblog.com/forum/projects/yes-another-dummy-load-)/?action=dlattach;attach=60221;image)
These are the results, the current splits between the source and the damping network depending on the frequency.
![](https://www.eevblog.com/forum/projects/yes-another-dummy-load-)/?action=dlattach;attach=60223;image)
Without the damping network, the source impedance rises.
Adding the damping network let me get a high bandwidth dynamic load. The damping network is really a function of the lead inductance and resistance.
Jay_Diddy_B