On Fri, 7 Apr 2017 04:09:38 -0400, you wrote: >David wrote: > >>> what doping is used for PNP RF transistors and saturated switches >>> if it is not gold? Does it also increase leakage? > >I replied: > >> Gold doping doesn't affect the speed of BJTs in the active region very >> much -- its purpose is to reduce minority carrier lifetime and, thereby, >> to reduce storage time when a transistor recovers from saturation. I'm >> not sure how manufacturers deal with this in the case of PNPs. > >After I posted, I recalled learning in a long-ago device physics course >that both Gold and Platinum doping were used to reduce minority carrier >lifetime in PNP saturated switches. According to Motorola, the >MPS3639/3640, 2N4209, and 2N5771 were gold-doped PNP saturated switches >(all are now obsolete, although SMD versions of the 3640 and 5771 appear >to still be available). > >And yes, doping PNPs with either Gold or Platinum does increase reverse >leakage current (Platinum less so than Gold). > >Best regards, > >Charles
So gold doping does work with PNP devices. Previously when I brought it up, I was told gold doping only applied to NPN devices leading to my confusion. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
