How to convert from IM3 to IP3?

What is the relation between IM3 (3rd order intermodulation component) and IP3 (third-order intercept point)? How do I convert from IM3 to IP3?

Check the following article:
http://www-tcad.stanford.edu/~rnavid...ip3.mems01.pdf
It might help.

Third order Intermodulation product (IM3) is an in band spurious frequnecy component which degrades the sensitivity of the desired signal. IIP3 point is a measurement to determine the severity of this effect hence the linearity of the system. The intercept point is when the fundamental component sweep intersects with the third order component sweep. Hope this helps

Rgds

IP3 = SCL + | 3OIM / 2 |

Where SCL is the Single Carrier Level (dBm)

3OIM is the relative level of the Third Order Intermodulation Product (dBc).

Be sure it is tested in linear range.

There is a nice paper describing what do you want to know from Prof. Willy Sansen, "Distortion in Elementary Transistor Circuits", IEEE TCAS2, vol. 46., no. 3, Mar. 1999.

From this paper we can see that, for small signal, weakly nonlinear system and first order approximation, IM2 = 2HD2 and IM3 = 3HD3.

As well as IP3 = Vin/sqrt(IM3) or (IP3)dB = (Vin)dB - (IM3)dB/2

Obviously, the small IM3, the larger in value of IP3.

Exactly.
There is another book from Sansen
Distortion analysis of Analog Integrated Circuits