A high IIP2 and IIP3 CMOS down-conversion active mixer

Abstract

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.

Bayesian Neural Networks for Identification and Classification of Radio Frequency Transmitters Using Power Amplifiers’ Nonlinearity Signatures

“…The classifier accuracy appears insensitive to variations in the IIP2 values that were chosen, although it is unclear as to whether this speaks to the robustness of the classifier or the high IIP2 values investigated. The range of IIP2 covered in this sweep does fall to 25 dB below the lowest listed IIP2 in [34]'s comparison table so as to account for IIP2 degradation elsewhere in the overall transmit/receive system. However, these results are for a model that was trained prior to being fed data through a behavioral model with varying levels of IIP3/2.…”

“…10 before AWGN is added to set an overall SNR. The coefficients of the nonlinear block were set to give a typical conversion gain of 12 dB and an IIP2 and IIP3 in a range typical for 2.4 GHz down-conversion CMOS mixers [34]. The LO frequency was set to give an IF of 1 MHz as is often used for Bluetooth [35].…”

“…16. The IIP2 and IIP3 ranges were chosen so as to be characteristic of differential 2.4 GHz CMOS down-conversion mixers [34]. As can be seen, inference accuracy falls significantly as receiver IIP3 worsens and contaminates the RF features produced by the PAs.…”