A 5-35 GHz Broadband LNA Using Cascode Structure and RLC Feedback

In this paper, a broadband low-noise amplifier (LNA) that operates across the 5–35 GHz frequency range is presented, which is implemented using both cascode and common-source structures combined with RLC feedback technique. The cascode structure in the first two stages provides sufficient gain while reducing the bandwidth limitations caused by <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\boldsymbol{C_{gd}}$</tex>, The introduction of peaking inductors and source degeneration inductors mitigate the effects of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\boldsymbol{C_{ds}}$</tex> and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\boldsymbol{C_{gs}}$</tex>, respectively. The third stage is a Common Source Amplifier, where the feedback is controlled by adjusting the RLC network to enhance high-frequency gain, achieving broadband performance. The proposed broadband LNA has been validated by a 0.1-μm GaAs pHEMT technology. It delivers an average gain of 31 dB across a 3 dB bandwidth of 5 GHz to 35 GHz, while maintaining a minimum noise figure (NF) of 1.56 dB.