On Sun, Nov 26, 2006 at 10:19:35AM -0500, John Doty wrote: > > On Nov 23, 2006, at 2:17 AM, Karel Kulhavy wrote: > > > > >>> > >>>My application is noise-critical between 1MHz and 10MHz. Would > >>>BC547C be > >>>better than 2N3904? I assume it's not a switching transistor. > >>> > >>Rather use BC549 or BC550, they have tighter spec on noise. > >>Or use BF240 if gain has to be higher. > >>PNP transistors can have lower noise due to lower base resistance. > > > >Does the gold increase only 1/f noise or also the broadband (white) > >noise? > > Broadband. The main effect is to reduce beta by promoting > recombination. That increases base current shot noise: every > additional recombination event is one electron's worth of charge > noise variance.
Is this base current shot noise amplified by the transistor like any other current that is applied to the base? CL< > > This isn't a huge effect: an expert can usually get better results > from things like 2N3904 than a non-expert can get from anything. > Noise performance depends less on the parts than on how you use them. > For a good start here, study the part of Horowitz and Hill's "The Art > of Electronics" that describes low noise design. > > John Doty Noqsi Aerospace, Ltd. > [EMAIL PROTECTED] > > > > > _______________________________________________ > geda-user mailing list > [email protected] > http://www.seul.org/cgi-bin/mailman/listinfo/geda-user _______________________________________________ geda-user mailing list [email protected] http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
