[sdiy] AN299 VCO (was: SDIY list troubles)

[ASSI]

On Mittwoch 30 April 2008, Ian Fritz wrote:
> I've heard that too, but I don't understand it.  Aren't Q1 and Q2 the
> best matched pair, wherever they are located on the die?  I mean, on
> the wafer the matched pairs aren't always in the same relative
> location.

They should always be in the same place of the die, it's a monolithic 
transistor array after all.  I've never heard of anyone changing a 
bonding plan based on the measurement of whatever parameter and it 
would certainly be almost impossible to do on a DIP leadframe even if 
you wanted to.  It may well be that the matching between different 
transistors could be noticeably different, but that would be a function 
of layout just and should therefore be pretty consistent.

On Mittwoch 30 April 2008, Samppa Tolvanen wrote:
> I bet someone here has both -CA3086/CA3046s and
> electrone-microscope.. :)

I lack the former, but have access to the latter.  But I don't think you 
need a REM for these, in fact it would be quite difficult to use on 
such large structures.  I'd expect these transistors to be somewhat 
larger than the LM13600 pictured at http://www.idea2ic.com/ - plain 
optical at ~50x magnification would suffice.


Achim.
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