Sorry, I have almost no experience in using dual-gate MOSFETS, for the
reasons I mentioned. Beginning somewhere around the mid-80s, when
manufacturing became highly automated, my employers strongly discouraged
designs which included any adjustments. Besides the labor required to
make the adjustment, the variable component lowered the product's
reliability, so we'd often design in a lot of parts to get around having
any tweaks. But individual adjustment is still a viable option for some
products. What I don't know is whether you'd get satisfactory
performance with widely differing devices all running at the same drain
current. That would depend on your design and application.

If you're considering making a product, I'd certainly do some modeling
with extreme component parameters to see what happens. And you might
consider some sort of device selection and/or incoming inspection or
sorting to make sure you don't get any truly extreme parts. One thing to
be careful about is that when a part is so poorly specified, other
companies might be buying large numbers of selected parts. That leaves
you with the leftovers. I've seen some really strange distributions
resulting from this -- parts with extreme characteristics on both ends,
but nothing anywhere near the "typical" values. It used to be common
with zeners, until they got better at making -- 10% tolerance zeners
would all be between 5 and 10% from nominal, in both directions, with
none closer than 5%. Those had been selected out and sold as 5%
tolerance parts.

Just a few of the things I've picked up in 30 or so years as a design
engineer.

Roy Lewallen, W7EL

David wrote:
Roy,

So if I had an adjustment on VG2 for each circuit and adjust for
required Drain current on each product ?

What's the consensus regarding Common Base BJT as LNA ?

Thanks

Regards

David