Electronic load for testing low voltage high current PoL supplies

[asmi]

Hey TE gurus over here! I am designing a PoL power supply for midrange FPGA device, which requires up to 30 Amps @ 1V, so I wonder if cheap-ass DC load (like Rigol DL3021(A)) is going to do the job, or there are any issues working with such low voltages? FPGA that will be powered by this PS is rather picky about the quality of the power on this rail (ripple voltage, regulation precision, noise level all need to be in check over wide range of power consumed), so I will need to perform quite precise measurements, and it won't be possible if EL itself will add enough noise to ruin precision. Just to give you an idea of the kind of numbers we're talking here, one rail requires 1V±3% accuracy with < 30mVpp of noise (DC-20 MHz BW), and some other rail demands 1V±3% and <10mVpp@20MHz BW.

[Tjuurko]

The first problem will be in providing a low total resistance of the "wire + DC load".
For such a source, this resistance should be no more than 30 mΩ.

[Berni]

The way to do that is to add an additional 30A lab power supply in series to generate extra dropoff voltage for the dynamic load, this lets electronic loads reach 0mOhm apparent resistance. Or even let the load "push" current trough a 0V source(ie a piece of wire)

Proper electronic loads have separate voltage sense wires to allows you to bypass and ignore the voltage of that extra series helper PSU while using it to help push current trough the load. The manual for the electronic load will likely explain how to wire this up.