Power supply rejection ratio describes how well an amplifier rejects variations in the power supply voltage. PSRR is defined as the shift in offset per volt of shift in power supply, and generally is given in units of micro-volts per volt ( µV/V ). The OPA828 used in this design note has a maximum PSRR of 7 µV/V. Thus, for the OPA828, the power supply can change 1 V with only 7 µV of shift in the offset. Note that this is DC PSRR, where as PSRR in general is frequency dependent. As frequency increases, PSRR decreases. Equation 12 can be used to calculate the offset error due to PSRR for a given power supply ripple voltage.