Hi All,

I wonder how to reduce the 60 Hz power line ripples in real measurement?

I grounded the inputs of my amplifier, but the output shown on the oscilloscope had a big ripple (around 30 mVpp) mainly 60 Hz freq component. I probed a high-impedance node through a discrete buffer, the buffer output impedance is low (tens of ohms), the oscilloscope input impedance is 1 Mohm.

Through all corner simulations my PSRR is not bad at 60 Hz (> 80 dB), and usually op amp PSRR is better at low freq than higher freq.

I wonder where usually these 60 Hz ripples would coupled in, from the discrete buffer? I am not sure.

Thank you for the help.

Leon