A new input matching technique for ultra wideband LNAs

Abstract

A noise reduction input matching technique for broadband low noise amplifiers (LNAs) is presented. The proposed LNA employs a positive active feedback network besides of the conventional common-gate (CG) amplifier to achieve both wideband input signal matching and low noise figure (NF), simultaneously. Compared to the conventional broadband noise cancellation techniques, the presented approach achieves the same NF with much less power consumption and high linearity. Circuit level analysis and simulation results are provided to verify the usefulness of the proposed LNA technique. In contrast to the traditional noise cancellation circuit, the proposed LNA does not degrade the linearity and its IIP3 is similar to the simple common-gate LNA. The proposed technique is applied to an LNA operating in 2∼6.5GHz bandwidth.