[sdiy] Best CA3280 projects?

[Ian Fritz]

At 05:55 AM 6/30/2012, Tom Bugs wrote:
>Makes me wonder...
>
>Would it be possible to make a very compact sub-board discrete CA3280 clone?
>
>Anyone done any work on such areas?

Yes, I posted about this about 4-5 years ago, so you could probably find it 
it the arrchives.

I was shooting for performance comparable to the CA3280.  I eventually got 
there, but it wasn't easy.  Matching of the transistors is crucial.  The 
only thing that worked well enough was some of the  MATs -- Vbe matching to 
better than 50 uV.  Good matching is needed for both the current mirror and 
for the linearization diodes, if you want to include those.  The whole deal 
was very expensive.

Once again, matching for a balanced circuit is much more critical than for 
a VCO front end, where matching is only for temperature compensation, not 
electrical performance.

Ian