My version of the G = 1000 low noise measurement amp (for Ikoflexer).
That and the few surounding posts have some info on Sanyo/Fairchild/Onsemi/? jfet parts
That and the few surounding posts have some info on Sanyo/Fairchild/Onsemi/? jfet parts
You can still get the 2SK209, which is the SMD version of the 2SK117. It has only slightly higher en than a 2SK170 but about a third of the capacitance.
Apparently 3nV/sqrtHz :
http://www.linearsystems.com/lsdata/datasheets/201181 - 4391DFN SERIES Rev A7 dated 2018 01 31.pdf
Cheers,
Patrick
http://www.linearsystems.com/lsdata/datasheets/201181 - 4391DFN SERIES Rev A7 dated 2018 01 31.pdf
Cheers,
Patrick
can you use a low capacitance device for the cascode ?
the cascode device doesn't contribute much noise, so you can choose based on capacitance
with the cascode, the ccs device underneath doesn't have dynamic voltages, so the capacitance is much less important
or am i missing something??
"with the cascode, the ccs device underneath doesn't have dynamic voltages, so the capacitance is much less important"
What's more is those cascode devices present a low impedance to the capacitance underneath it. The designer doesn't have to care about the capacitance of large die matched transistors.
What's more is those cascode devices present a low impedance to the capacitance underneath it. The designer doesn't have to care about the capacitance of large die matched transistors.
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