LM398 app note

[Martin Czech]

In the already mentioned Linear app. book from National I found an
(maybe) interesting idea: low droop s&h by using two cascaded s&h. The
first uses a LM398 s&h with 1nF, the second with 1uF. The voltage is
frist sampled with the fast s&h , if this is done the already sampled
voltage is again sampled into the 1000x slower s&h, not much droop will
happed during this time.  Then the output is switched from the fast
s&h to the slow one.  Better would be to fade slowly between both s&h,
cause this will avoid the switching spike.

m.c.