Quote:
Originally posted by wojtek5001
1) Cascoding Q11 not solve my "unsymmetrical compensation problem"  . When Q11 is cascoded in such way, then feedback through C7 will be in wrong phase, just like C1 connected to collector of Q12 and base Q11. So I still dont know purpose of C7.
|
Yes of course, you are right. It seems I accidentally deleted the sentence where i emphasized this, when editing to cut down size to 10000 characters (it was a bit over and would not post)
Of course, one could approximate an R18 to get some measure of compensation, but as I show in the above post, there are other considerations to this.
Quote:
2) I think that Q4 (the upper 2N5486) is for maintain constant drain-source voltage over Q3. In that conditions Q3 will be very good current source, immune to voltage swing.
|
Exactly, this is a standard cascode FET CSS. The only thing is, residual capacitance may not be ideal because the Vds of the lower FET is quite low, but I think it will be just fine for this application.
I also forgot to mention that, to an extent, utilizing a high ripple PSU to get good clipping with minimum heat penalty, does increase distortion close to clipping, due to Cgd nonlinearity of the LFET. It is slightly better than VMOS/HEXFET and a lot better than ripple feedthrough, though.
|
13th November 2006, 10:22 PM
Similar Threads
