On Tue, Nov 21, 2006 at 11:02:51AM +0100, Wojciech Kazubski wrote: > > > > What happens when there are gold atoms? The electrons bouce against these > > atoms and they produce noise in the process? Does these gold increase > > only 1/f noise or also the broadband (white) noise? > Gold reduces lifetime of carriers and thus increase switching speed of the > device. If the junction is forward biased then it is filled with free > minority carriers (electrons or holes). If the junction is rebiased to > reverse bias, carries from deleption layer have to be removed. Without gold > doping they have to be removed trough external circuit and the diode conducts > for a moment (up to miliseconds for sislicon - see switching characteristis > of the diode). Gold makes minority carriers to recombine fast and less charge > is stored during forward bias. Such diode recovers quickly at turn off. > In saturated transistor B-C get forward biased and charge is stored here. > > > > 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? CL< > > Wojciech Kazubski > > > _______________________________________________ > geda-user mailing list > geda-user@moria.seul.org > http://www.seul.org/cgi-bin/mailman/listinfo/geda-user _______________________________________________ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user