This calculator is for the case of a
microcontroller (uC) digitizing an analog signal using the 1-bit Sigma-Delta
(ΣΔ) approach.
You must keep C1=C2 when uC input threshold is
at Vdd/2.
There may be chip-chip variations in input
threshold level from an assumed Vdd/2. So it may be wise to pick resistors
that allow an input range greater than that required... (For example, with
R1=R2=100k a max. input of 3.3 volts is expected with the Propeller uC,
however, this may not work and R2=150k is advised).
