there was one "zwischen basis-Schaltung" which has good noise properties
basically the basis and the emitter of a bipolar transistor is connected
to the two ends of a transformer's secondary winding ,a a tap on said
winding is grounded Ulrich Rohde may could tell more about it, I have
seen articles written by him on that subject long time ego perhaps in
German.
73
KJ6UHN
Alex
On 1/13/2020 9:27 AM, Jeffrey Pawlan wrote:
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
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