[time-nuts] Norton amplifiers

[Alex Pummer]

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 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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