HEXFETs and lateral mosfets-what's the difference?

[darkfenriz]

Do they differ something important, i.e. I con replace IRFs with IRFs only?

[peranders]

Yes they differ rather much. The thing you can do is to download datasheets for both types. The main difference is Vgs and transfer characteristics.
Below you have datasheets of good old 2SK135/2SJ50 from Hitachi/Renesas
http://www.sjostromaudio.com/datashe..._datasheet.pdf
http://www.sjostromaudio.com/datashe..._datasheet.pdf

If you have lateral fet's and want to replace them you should be aware of that you must consider much larger capacitances' (less bandwidth if you don't do anything about it), much higher bias voltage (may need some redesigning), have different temp characteristics (may need some redesigning).

[darkfenriz]

thx