i'm trying to do some power supply ripple rejection tests, this requires my DC input to my circuit to have a ripple on it so i can study the ripple at the output, my question is how does one juxtapose AC and DC.There are other concerns but for now i just want to get the ball rolling, lets pretend i have every circuit design tool and part available,any ideas?
A power transformer isn't going to work at 20mhz. How about using a power BJT or FET between the load and the ground? Bias the transistor as close to saturation as you can and you can drive the base for your AC ripple at whatever frequency the transistor will allow.