The OPAx391 are unity-gain stable, precision operational amplifier free from unexpected output and phase reversal. The OPAx391 are optimized for full rail-to-rail input, allowing for low-voltage, single-supply operation or split-supply use. These miniature, high-precision, low-noise amplifiers offer high-impedance inputs that have a common-mode range 100 mV beyond the supplies and can tolerate the full supply voltage across the input. The OPAx391 precision amplifier is designed for sensor amplification, low-power analog signal chain applications in low or high gains, as well as a low-power discrete MOSFET or bipolar driver.