I just got a KGSS (not the HV variant) up and running recently. It is based on my own PCB layouts for the amps and the PSU.
The first amp board I assembled I fitted with the current sources based on the IXTP01H100D. The temperature drift seemed to be fairly large, so for the second board I went back to the original KGSS configuration using resistors. I expected this to have much less temperature drift and that also seems to be the case. So at the moment I am running both boards with the resistors instead of the current sources for the third stage.
Looking at the data sheet for the IXTP01H100D I guess quite a lot of temperature drift is to be expected, since the drain current, for a given VGS, changes a lot from 25 degrees to 100 degrees.
I would expect a current source based on the 2SA1968 to be less temperature dependent. Unfortunately I don’t have any 2SA1968, so I am not able to test that at the moment. Has anyone here compared the two solutions and have an opinion on this?
My amp PCB is actually prepared for mounting either resistors or a current source, based on the 2SA1968 (which I don’t have!), but not the current source based on the IXTP01H100D (which I have!), so I had to mount it in a less than optimum way.
I used 1.2k resistors for the IXYS current sources.