current sources, and other discretes

[John Geary]

Posted to CCD-world:
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I know some of you swear by current sources as loads for CCD output
transistors, while other have used simple resistors with acceptable results.
Anyone care to comment of their recent experiences of current sources vs
resistor loads in fostering output linearity, etc.?

One reason I am asking is the increasing difficulty in getting many special
discrete semiconductors.  For instance, I am contemplating using the Temic
SST507 current source in a design.  It is listed as an item in their 1997
catalog, but US suppliers seem not to have it on their screens anymore. (Of
course, it doesn't help that Temic was recently sold, and do not even have a
current web page!).

Similar situation for some JFETs.  I have tried to find the Toshiba SK389
here in the US for a month, after hearing from Preben N. that these were
pretty good.  The only response I could get was that maybe I could order a
lot of 50000 (!).  No spec sheets seem to be available.  It is also getting
hard to find the 2N5564 - I surveyed 6 or more vendors and was able to
scrape up the last 50 or so in stock.  Try getting any small-package
Roederstein polypropylene caps for coupling or integrator use - can't be had
in lots of less than 2000 (can get almost as good from Panasonic, tho).

And so it goes.  Anyone else have any recent tales to tell, or parts to
trade?  Back to barter, I guess.

--JG

"1 + 1 = 3 for sufficiently large values of 1".

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