Hi Manu, How are you connecting the scope probes? Unless things are perfect, there's a danger they will be picking up switching noise & ringing from the circuit as well as signal. That's what the traces look like to me. Where you are looking at the voltage drop across the source resistor, connect the probe ground to the earth end of the resistor. Make sure that all probe leads are as short as possible and that there is minimal loop area between the earth lead and the signal lead at the probe. Or use a differential probe connected across the resistor - even if one of the probes is at "ground". There can be significant difference between the "ground" voltages for pulse waveforms. Or pull one leg of the resistor and put a short (as possible) wire loop on it and use a current clamp type sensor for the scope. If you haven't got one you might be able to use a single turn through a ferrite bead with a multiturn secondary and a load resistor. Might be tricky to calibrate though. You can get an indication of FET current by looking at the voltage drop when "ON", but it is (die) temperature dependent so varies with individual devices & heatsinking arrangement as well as recent load history etc..... RP On 26 June 2016 at 20:14, RussellMc wrote: > Quick comment for now without having looked at your waveforms. > > Vds MINIMUM is a measure of Id_on as it is ~=3D Rdson x Id. > If you can model Rdson or accept a rough approximation you can "quite > easily" I'm told determine Id. > I'm told this concept is patented but I don't know by who or when. > I was told that maybe 5 years ago? > > > R > -- > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .