LM13600 Linearizing Diodes?

[electrosonic]

I have read that the LM13600 has "linearizing diodes at the inputs" more times than I can remember. Since I always think of diodes as being non-linear at least with respect to current / voltage plots. I have no idea what that means. Any of you smart people care to explain.

Thanks,
Andrew.

[R.G.]

The diodes are set up to pre-distort the signal in the opposite way that the circuit will distort it. The two distortions tend to "cancel out", and the result is less distorted up to much higher signal levels.

[electrosonic]

OK, googling for "predistortion diode" gets me very academic papers. Anyone have any links explaining this on a more basic level?

Andrew.

[PRR]

> explaining this on a more basic level?

The OTA *amplifier* distorts (is non-linear).

The diode is also non-linear, and with the same bentness.

Clever connection makes the diode distortion and amplifier distortion cancel-out (up to a point).

[electrosonic]

Another mystery explained.

Thanks,
Andrew.

[bluebunny]

Looked up "bentness" on Wikipedia, but got no hits... 

Another nice illustration, Paul.  Thanks!

[PRR]

> Looked up "bentness" on Wikipedia, but got no hits... 

Go to Home Depot, lumber aisle, buy a bundle of 1x4 strapping, and unbundle it. You'll know what "bentness" means.

Same thing: if one stick is bent left-curve, find another stick with similar bentness and put it opposite so the bentnesses cancel-out.

Unlike HD's cheapest wood, in Silicon junctions the bentness is all the "same". Even at different currents. Especially when all fabricated on the same wafer, and same/similar geometry. So per National's app-guides, you don't have to think how much current to run in the compensation diodes. Much more than signal current, much less than maximum current, which is a wide range. Nat says to run 1mA in the diodes unless you find some critical reason do do otherwise.

[bluebunny]

You'll know what "bentness" means.

So you've seen the walls in my house...