Power Supply Rejection (PSRR)

Power Supply Rejection (PSRR)

A battery powered application can see a change in the power supply voltage of several hundreds of millivolts over the life of a product. Moreover, the op-amp is also often supplied from noisy lines and must, therefore, reject the noise adequately. For these reasons, it is important to know how a change or noise on the power supply manifests itself at the output of an op-amp.

It quantifies the amplifier’s sensitivity to power supply changes. Ideally, the power supply rejection ratio should be infinite, which means power supply changes do not affect the output. Typical specifications for a power supply rejection ratio of an amplifier range from 60 dB to 100 dB.

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The picture below shows the MCP601 power supply rejection specification.

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