Have you ever succeed in buiding a input stage with current mirror?

[thanh]

Hê hê! nobody can know the "lovely resistor" ! It is Emitterresistor of VAS , another pin of it connects with CFB diff
mike! I use b649/d669 for VAS .I intend to use a1011/c? .I also want to simulate it but I can't found its model
p/s if you cannot view my post ,you click menu View/ encoding / utf8

 

[bocka]

Hi Mike,

you can find the folded cascode in the Tietze Schenck Halbleiter-Schaltungstechnik as Breitband-Operationsverstärker. In my issue (9th) it's on page 504.

 

[thanh]

mike! sorry to my english

 

[mlloyd1]

MikeB:
are you saying you added two series R-C networks, one each across R10 and R11?
if so, what values did you settle on to eliminate the oscillation also, after doing this, did you remove or change any of the other countermeasures you previously employed to remove the oscillations?
and, did you ever try CCS in place of R10 and R11? Did you still need the R-C networks in such case?

thx,
mlloyd1

Hi !

I stopped oscillation by simply adding a RC from emitter of cascode
to rail. Like in my previous amps: Oscillating ? RC always fixes it !

to lumanauw: I planned the ccs for the Vref, but not much place left
on my testboard... But by connecting both vrefs and avoiding going
to ground, the vref is at least always symetrical.

I wanted to use leds, but i had to use what i've found in my box...
...
Mike

 

[MikeB]

Hi mlloyd1, that's a very long time ago...
Which schematic are you referring to? I mean which r10/11...
I dismantled the prototype a long time ago.

Mike

 

[mlloyd1]

MikeB:

thanks - it was a long time ago indeed.
this one from post # 184

mlloyd1

 

[MikeB]

Yes, the RC were across r10/11, but i do not remember more.
I did not try the ccs, and as i remember my later amps sounded better.
I was not very experienced these days...

Mike