[sdiy] discrete DAC accuracy

[harrybissell]

As pointed out earlier... the resistors are probably the most benign component
to choose in a homemade DAC.   If you look at the early Sequential Circuits DACs
(maybe approaching 8 bit resolution)... you will find that some of the bits were
sourced from parallel CMOS buffers, because the internal impedance and current
drive capacity of these parts was becomming an issue... that is at the EIGHT bit level.

How are you going to go for 16 bits at that rate ?   Some modern monolythic DACs have
internal trims (laser, zener zap) and even internal calibration PROMs to factor out
uncontrolled
process variation.

This is one spot I would not try to 'roll my own' ... unless I was on Apollo 13 and
there
was no other way home....

H^) harry