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Load line on logarithmic graph?

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I was looking at this datasheet https://www.tme.eu/en/Document/d39fe28d5ab62ea33b4d2b12fd7af44d/irl1404zpbf.pdf

Page 3, Fig 1. The graph is logarithmic.

I think I know how to draw load line on linear graph. Take max drain voltage, for example 12V when the MOSFET doesn't conduct. [0A, 12V]. Calculate max current when the MOSFET is shorted (saturated). That's 13.3 A for R=0.9ohms. [13.3A, 0V]. Draw a straight line from those two points. Is that correct?

Now, how do we draw load line on logarithmic graphs?
 

The resistor load curve in logarithmic scale isn't a straight line. Calculate three or four points and check yourself.
 

FvM said:
The resistor load curve in logarithmic scale isn't a straight line. Calculate three or four points and check yourself.
Click to expand...

That's what I said

I think I know how to draw load line on linear graph.
Click to expand...

I asked if there is any way to draw load lines on logarithmic graph. I realize it's not straight line.
 

I think you can get some point on each VGS curve, put them on a spreadsheet, then draw a linear graph on which you can draw the load line.
 

That's what I did
 

FvM said:
Right, so what's the remaining question?
Click to expand...


My question, now repeated third time in this thread was "how do we draw load line on logarithmic graphs".

Albbg's suggestion was how I did it too. And it looks like there is no other way.

FvM said:
I don't see a simple geometric design method.
Click to expand...
 

I wonder if logarithmic graph paper would have anything to do with solving this?

Or, take the log of every data point, and plot the result.

Most likely it should be log of either X or Y data, but not both. Whichever is the data column which jumps exponentially.
 

In order to solve you problem graphically you have to be able to plot a logarithmic line on the logarithmic graph paper, in the same way you draw a straight line on a linear graph paper. This means you need a logarithmic ruler.
 

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