I'm building a 3.3V 400mA power supply around an ultra fast buck reg (3 MHz or 1.6 MHz, LM2734Z/X.) According to simulations, the ripple will be <2mVp-p. The noise floor of my scope is about 500µVp-p on 5mV/div (the minimum setting), so how do I measure such a small signal?
I'm thinking I'm going to need an amplified probe of some kind, but I suspect these will be very expensive.
I was thinking of fine tuning the trigger and using the averaging function to remove the noise from the signal, but would this be adequate for power supply ripple? Scope is a HP 54501A, 100 MHz -3dB b/w, 10 MS/a digitising, quite an old scope but only cost £150.