A high IIP2 and IIP3 CMOS down-conversion active mixer

Two linearization techniques for double-balanced active mixers are introduced in this paper. The proposed techniques are based on cancelling the second- and third-order kernels of the transconductance stage output current. The second-order kernel is cancelled by adding a second-order intermodulation (IM2) current with an opposite sign generated by injecting a first-order term to the transconductance stage and also attenuating the third-order kernel of the transconductance current significantly by an improved form of the IM2 injection method. The proposed mixer has been designed for IEEE 802.11 applications with input frequency and output bandwidth equal to 2.4 GHz and 20 MHz, respectively, and simulated using a 90 nm RF-CMOS technology. Spectre-RF simulation results show that the proposed techniques have simultaneously improved IIP2 and IIP3 by approximately 26.7 dB and 21.4 dB, respectively, while only a 0.2 mA extra current is drawn from a 1.2 V power supply. In addition, the proposed techniques have no effect on the other parameters of the mixer such as the noise figure and conversion gain.