On Tuesday 03 April 2007 17:37, Dan McMahill wrote: > I have to agree 100% with Al here. The ability to easily run > the ac analysis at whatever operating point you have, be it > from an explicit operating point analysis or where a > transient stopped, is extremely important. Al's class-B amp > is a good example because of course the output devices > undergo very large signal changes and you should be concerned > with small signal stability over the entire output range. > Other circuits may not have a d.c. operating point that means > anything.
The real fun one with the class-B amp is that the usual Spice operating point is exactly in the middle of the crossover region. If there really is no quiescent current, the AC analysis gives you no output at all. If you bias it up a bit, now class-AB, the current is still low, making the transconductance low, making the output impedance high, still useless. Try a two-tone test and you can see a reason why some early transistor amplifiers sounded so bad. _______________________________________________ geda-user mailing list [email protected] http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
