loose-electron
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Best Design Tool = Capable Designers
Posts: 1638
San Diego California
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A couple of flavors to solve this:
A ring oscillator with multiple delay elements gets you all kinds of phases with respect to the input. Probably the most common solve used here.
Another approach:
LPF until you got a sinusoid Create a V to I converter Dump the I into a series RC Differentially observe the V across the resistor Differentially observe the V across the capacitor
90 degrees of phase difference, Voila! Mind you, that one requires some items to support the operating voltage on the capacitor from not wandering away. However, that approach was used in peak detectors in disk drive read channels for a number of years.
Jerry
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