[time-nuts] Norton amplifiers

[Jeffrey Pawlan]

Many years ago I did a study of Norton amplifiers and optimized for IP3 
using non-linear circuit simulation tools. I published a two part 
article in RF Design Magazine which covered the amplifier itself as well 
as the non-linear model for the BJT. My use for the Norton amplifier did 
not require high isolation so I spent little tile on that aspect. I am 
friends with the co-inventor of the original and the author of the 
subsequent patents. His name is Allen Podell.  The webpage you included 
speculated that the reverse isolation degradation at high frequencies 
was owing to the layout or the transformer. Although those are 
contributors, the simulation showed high frequencies had poorer s12 so 
it is expected.

If high isolation is what you need, then as written on this list, there 
are ICs which can provide this much better than a single stage 
amplifier. They do suffer from more residual noise however.

Jeffrey Pawlan