[time-nuts] how to find low noise transistors
Charles Steinmetz
csteinmetz at yandex.com
Sat Jul 25 01:45:50 UTC 2015
Brooke wrote:
>Does hFE (DC) have much relevance to this? Would hfe (AC) be the
>important one?
It depends on whether you are more interested in the 1/f noise, which
causes most of the phase noise in oscillators and the additive
("residual") PN in amplifiers, or the in-band noise. As I said in
the message to which you replied:
>Note that these are static (DC) curves, which are good
>approximations for the 1/f region. The curves in the white noise
>region, even at relatively low frequencies like 1 kHz, generally
>fall off faster than this as current is reduced, so the effect of
>reduced beta on in-band noise figure is greater.
Best regards,
Charles
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