> Does driving the transistor into cutoff but not saturation also count > as saturation switching? > > CL< > No, saturation is when collector voltage drops below base level and the collector junction becomes forward biased. Charge stored in this junction is the cause of swithing delays. Swiching transistors have special doping that reduces carrier lifetime and speeds up the transistor. Transistors can be operated into cutoff on high frequency, this happens for example in B or C class RF amplifiers. Their parameters (hfe, fT) degrade a bit when the transistor approaches cutoff, so C class amplifiers cannot be operated on the frequences as high as in linear mode (class A) with higher DC current. But I think that this may be a problem above VHF band.
Wojciech Kazubski _______________________________________________ geda-user mailing list [email protected] http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
