Q-Band LNA-Antenna Co-Design: Exploiting Antenna Matching for System Noise Figure Optimization

Abstract

This paper presents a novel approach to low noise amplifier (LNA)-antenna co-design in the Q-band frequency range, leveraging the antenna as an integral part of the LNA matching network to achieve broadband noise figure improvement.Unlike conventional designs, the proposed LNA does not include a 50$\,\Omega$ input matching network, allowing direct access to the complex frequency-dependent impedance (${\Gamma _{opt}}$) associated with the LNA’s minimal noise figure (${NF_{min}}$). The antenna input impedance is optimized to match the LNA for minimal noise contribution, effectively enhancing system performance. Noise figure measurements of the active antenna prototype confirm the achievement of ${NF_{min}}$, ranging from 1.9 to 1.4 dB within the 35 to 40 GHz frequency band. Additionally, the receiver system demonstrates a gain of 14.5 dB and a noise figure below 3.6 dB across the operating frequency range. These results validate the effectiveness of the proposed co-design approach in reducing noise while maintaining high gain, making it a promising solution for next-generation millimeter-wave communication and sensing applications.