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Noise on op-amp supply

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When I use an operational amplifier, for example, for an inverting amplifier, how important is to have a low level noise (ripple) on the power supply? In other words, should I expect to have the same ripple of the power supply on the output signal of the op-amp superimpose to the signal?

Thanks!
 

If you read the specs for an opamp you'll see a parameter called PSRR (Power Supply Rejection Ratio). This tells you the effect on the output that deviations on the supply have. The higher the number, the better rejection you'll have.
 
The PSRR, can be very high like 60+ Db (1000:1), BUT if you have any bias networks strung across the Vcc rail to earth, the ripple at the tapping point (Vcc ripple/2) will be amplified by the amplifier, so decouple these points.
Frank
 

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