Linearity(iIP3) of Cascaded gain stages

[mvj]

Hi All,

May I know how the linearity get affected when multiple gain stages are cascaded?
For example: say I have two gain stages of gain G1 and G2 and their linearity numbers (iIP3) are iIP3_1 and iIP3_2. When cascaded, the resultant gain would become G1*G2, may I know what the resultant linearity would be?

Thanks a lot in advance!!
mvj

 

[AmrZohny]

If iIP3_2 < iIP3_1 then you are limited by iIP3_2

Otherwise, you are limited by iIP3_1

That is if you want to work continuously in the linear region

Otherwise....the resultant linearity of overall 1 dB compression point or the 3rd order IP for a cascade of n stage (each having gain Gn and P1dB - or IP3- Pn) is given by:



Both G and P are in linear form, not in dB!

Cheers mate


you can also find it here...

http://www.alphalpha.org/radar/rf/rf1_e.html