Steve Hardy asked:

>Gregg stated a Rds(on) coefficient of +0.6%/K hovever said reference indicated
>only +0.1%/K.

It was only yesterday, but of course I can't find the book I referenced, to
double check.  Anyhow, the figure quoted was per degree Celcius, not Kelvin
which Steves text seems to specify.

>Never mind, but I would be interested in knowing the tempco
>of the threshold voltage since this is not mentioned,

A quick check at some MOSFET devices in a Motorola data book seems to show a
fairly consistent and linear negative 0.6 to 0.7 % /degree C tempco for the
Vgs threshold.

BTW, the bias stability probems I referred to was with an array of Siliconix
VN88/AF devices; many years ago.  Despite many calls to the factory
luminaries, I never did achieve satisfaction.  Bias was near impossible to
stablize, adn current sharing was hap-hazzard.  I concluded that MOSFETS are
fine for switching circuits, but despite the seeming advantages, not for linear.

Hope this helps,
.. Gregg