A mathematical technique for RF mixer linearization using second order Intermodulation injection

In this paper, an applied mathematical method is proposed in which the effect of second order Intermodulation injection in elimination of the third order Intermodulation is examined and circuit parameters will be achieved with calculation to obtain the best IIP3 response of the circuit. The suggested mathematical technique is applied to a down converter Gilbert cell mixer in 2.4 GHz. This mixer is designed in TSMC 0.18 µm CMOS technology and is simulated using ADS2006A. The operation conditions of the mixer are 1.8 v supply voltage and total current consumption of 2.7 mA. The proposed mixer provides 11 dB conversion gain and 11.1 dB SSB noise figure. This mathematical linearization method causes IM3 to reduce to 14.4 dB and increases IIP3 from 1 dBm to 8 dBm. This technique does not have a significant effect on conversion gain and noise level of the mixer and only requires a small amount of current about 0.05 mA. By performing this technique the best IIP3 will be achieved with 10% error which is remarkable and shows its high ability in linearization.