AMZ Mosfet Boost Clarification

[Khas Evets]

Jack mentions in his mosfet boost ariticle that the mosfet is a depletion mode device and the schematic also draws it this way. Isn't the BS170 an enhancement mode mosfet?

Also, are depletion mosfets biased the same way as jfets? Can they be interchanged?

[spudulike]

Depletion Mode
Enhancement Mode

Fairchild BS170's are enhancement mode according to the datasheet.

[amz-fx]

That's a typo... the BS170 is an enhancement mode device.  There are depletion mode mosfets for small signal use.  Supertex makes some that are available...  I have used the LN150, for example.

-Jack