F4 Beast Builders

[aspringv]

You can split the rails with an active ground and get the firstwatt standard 23v rails.

Ground is just a state of mind.

[generg]

The pucks have lower capacities with higher voltage.

[lae2]

Originally Posted by generg

The pucks have lower capacities with higher voltage.

Thank you. Ciss? I have looked at the curves for many of the SOT227 (pucks). The Ciss appears fairly asymptotic beyond 25 V?
What decision making applies to SOT227 versus PLUS247 for the same device?

[lae2]

Originally Posted by needtubes

How about the IXFN40N90P as a match for the IXTN40P50P? Problem is, it seems to be hard to find here in the US. No one has it in stock.

When looking at device datasheets, what are the most important characteristics for choosing a P and N pair? Low/similar Ciss? Similar Transconductance?
The strategy for deciding upon a pair is to optimize "perfect “square law” cancellation of distortion?"

[generg]

I was told that with source followers the Crss is the more important value to look at.

And this one declines with certain types at 25V considerably. Look at Pa´s Burning Amp speech 2016 and there was besides other this interesting picture....
So you must look for Ixys that go down in this way for Crss.

It is a pleasure to hear his explanations.

[lae2]

Wow! What a great resource. Thank you so much. I almost missed that your screenshot was at 13 min. I thought the discussion about capacitance was over at 4m into part two. This talk answers a bunch of questions for me. I usually do not study videos. I don't have the patience. I must rethink. Thank you for alerting me to this talk. I imagine that if I was going to play with "pucks" using a typical FW PS; this P channel having asymptotic capacitance changes at a low voltage would be a candidate if I could match it up with an N channel.
http://ixapps.ixys.com/DataSheet/93001.pdf

[lae2]

A candidate if I could match it with a P channel.

[Zen Mod]

I have great difficulties watching Papavideos ........ I'm laughing at least half of time , so must watch it several times to get everything

[Zen Mod]

Originally Posted by lae2

A candidate if I could match it with a P channel.

I believe answers are already there .......

[lae2]

I got itchy and ordered a few pairs of IXTH20P50P and IXTH30N60P. The capacitance and transconductance appear comparable relative to other documented push/pull pairs.