Ahh, I see what you mean..
1bit converters works quite differently than older parallel converters.
In the old parallel converters, all bits were level set in parallel at
the same time.
Those were also called successive approximation converters, and was
build on a ladder resistor network, each step in the ladder being
calculated, and lazer trimmed to hairfine tolerenses, to power-of-2
voltage steps.
A 1bit converter will look at the level difference in the analog
signal from each convertion sample to the next, and set the next word
to the determined new value. In other words, it's based on
voltage/level comparators.
And no, it doesn't change one bit only at a time ;)
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