These look like very low Rb transistors based on the Vbe curves and max pulse current:
ZTX869 - high minimum Hfe of 300
ZTX855
If you wanted to try and find lower noise than the ZTX851 I would look there.
ZTX869 - high minimum Hfe of 300
ZTX855
If you wanted to try and find lower noise than the ZTX851 I would look there.
To make good use of the new found Zetex i made a high speed circuit.
It is a kind of PIP but parallel symmetric.
The circuit has a 3dB noise disadvantage over the Paradise. This does not matter much because the Zetex are ultra low noise.
The circuit is much simpler then the Paradise and has the advantage of DC coupling.
Unfortunately i have a problem with my scanner so you have to wait somewhat.
It is a kind of PIP but parallel symmetric.
The circuit has a 3dB noise disadvantage over the Paradise. This does not matter much because the Zetex are ultra low noise.
The circuit is much simpler then the Paradise and has the advantage of DC coupling.
Unfortunately i have a problem with my scanner so you have to wait somewhat.
With the same input stage the Hawksford version could have more output or lower output impedance. Not sure how that would affect noise though.
The Hawksford is inverting i think but that is not a big deal.
The input stage of that one could have CCSs too for more open loop gain.
The input stage of that one could have CCSs too for more open loop gain.
Here is an older folded cascode circuit that could be modified for BJT´s.
It is simple and performs very well.
I designed and build this circuit with good results but i did not show it because i wanted to use it commercial.
This is not the case any more so here we go.
It is simple and performs very well.
I designed and build this circuit with good results but i did not show it because i wanted to use it commercial.
This is not the case any more so here we go.
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