Dave Tweed wrote:
> A 1-bit network gives you 2R or 1R.
> A 2-bit network gives you 3R, 2R, 1.2R or 1R.
> A 3-bit network gives you 4R, 3R, 2.2R, 2R, 1.33R, 1.2R, 1.05R or 1R.
> A 4-bit network gives you 5R, 4R, 3.2R, 3R, 2.33R, 2.2R, 2.05R, 2R,
>                    1.43R, 1.33R, 1.23R, 1.2R, 1.08R, 1.05R, 1.01R or
> 1R.
>
> As you can see, each additional switch puts twice as many values into
> the lowest 1R span of resistance values, and even at just 4 switches,
> you need to be able to distinguish values that are as little as 1%
> apart. There's no straightforward way to "linearize" this.

Yeah, I just worked it out too and I can see that a R-2R ladder doesn't wor=
k
for resistance after all.

Sorry for the confusion.


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