Precision Absolute Value Circuits

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You can build a precision absolute value circuit using two op amps and two precision resistors. If you use an op amp and an IC difference amplifier, no user supplied precision resistors or resistor adjustments are required. Circuits shown are suitable for precision split supply operation and for single-supply operation. When used with a rail-to-rail op amp, the single supply circuit can approach a 0 to 5V full-wave rectified output from a ±5V input when operating from a single +5V power supply.