Re: gEDA-user: Current source rail blocking

[John Griessen <john_g@xxxxxxxxxx>]

Karel Kulhavy wrote:
> > > > > In my broadband high sensitivity amplifier I have a rail where bases of 
> > > > > all
> > > > > current source transistors are hooked up. .
.
.
.
 what happens if some load puts a surge of electricity into the
> collector of one of them and it gets through the C-B capacitance on the
> connected bases.
.
.
.
. The transistor has E-B
> charged to constant voltage and that corresponds to the pre-set current.

Only if the series base resistor is overriding factor so RF thru capacitance 
from C to base only small percentage effect.

How much does the load or driven voltage vary on the output of theese current 
sources?  If not a big voltage swing, maybe lower perf transistor is all you need...


If you find some LOW gain transistors (Igain = 30?) for these DC current 
sources, your series R's will need to be lower, base current higher, and 
oscillation less likely and feedback thru input or output capacitance less and 
problems go away...


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