Noiseless MOSFET boosters: ZAZEN and QIGONG

[Rob Strand]

I may just bother one my uni professors with that question when we're back in class in January hahah

I'd be surprised if they know.  Once you past textbook theory MOSFET noise is very hard to pin down theoretically since the actual noise (at least at low frequencies) is from other causes.

Here's an old Depletion MOSFET datasheet,  RCA 40841, 
https://www.box73.de/file_dl/bauelemente/40841.pdf

At the end of the datasheet it has a plot of noise voltage,  very rare to have that spec'd in a datasheet,

100Hz: 100nV/rtHz
1kHz:  33nV/rtHz  to 40nV/rtHz
10kHz: 15nV/rtHz to 17nV/rtHz


The LND150 is likely to be something in that order.  So better 100's nV/rtHz but definitely not better than 1nV/rtHz.  Kind of in the acceptable zone of generic opamps.

Since this stuff is rare gold I extracted the plots:





The databook was 1978 but the datasheet could be 1971.
I manually thumbed through an old Motorola transistor databook and this was the only
other info I found.   Not great for noise and in the same ball-park as 2N7000s.