Analysis and Design of Broadband LC-Ladder FET LNAs Using Noise Match Network

Abstract

A noise match network for the LC-ladder input network of a broadband inductively source-degenerated common-source (CS) field effect transistor (FET) low-noise amplifier (LNA) is established through noise transformation matrix to derive the noise parameters of a broadband LNA. Analytical formulas for the noise factors of a CS FET LNA with a three-section LC-ladder input network are thus obtained based on the design algorithm of optimal noise and input match developed in this paper. Two 3.7-10.5 GHz two-stage LNAs of the same topology are demonstrated using 0.15-mu m pHEMT technology to validate the design methodology. One LNA has all the fully integrated inductors and the other uses two on-chip inductors replaced by two high-Q bondwire inductors for better noise performance. The measurement results show 11-dB power gain with 2.1-dB noise figure for the LNA with the fully integrated inductors and 11-dB power gain with 1.6-dB noise figure for the LNA with two bondwire inductors, respectively.