A new linearization technique for CMOS low noise amplifiers with balun circuitry

Abstract

In this paper, a new linearization technique for differential low noise amplifiers (LNAs) is introduced. It removes the common-mode current at all frequencies. One of its main advantages is that it allows the receiver to have a single-ended input and a differential output LNA which attenuates even-order inter-modulations. Also, this technique improves the LNA linearity in three ways. Firstly, it removes the common-mode current of all inter-modulations. Secondly, it attenuates even-order inter-modulations because of its balun circuitry operation. Finally, it improves the third input intercept point (IIP3) due to the possibility of different bias currents for input transistors. Simulation results using a 0.18μm RF-CMOS technology with HSPICE-RF show that the IIP3 improves about 13 dBm at the expense of increasing the noise figure about 0.7 dB in constant voltage gain and equal DC-power respected to the conventional differential LNA.