W-Band Low-Noise Amplifier with Neutralization-Based Feedback and Positive Feedback Circuits

This study presents a gain-enhancement feedback technique for W-band (75～110 GHz) low-noise amplifiers (LNAs), which is experimentally validated to enhance the gain performance of millimeter-wave integrated circuits. The proposed method combines a transformer-based neutralization feedback circuit with a positive feedback circuit to enable high gain and improved stability in W-band LNAs simultaneously. The fabricated LNA, featuring the integrated feedback circuits, measures 1×2 mm2 and exhibits approximately 2 dB of gain improvement compared to a reference LNA without these feedback circuits, along with a frequency-upward shift in noise performance. These results demonstrate that the proposed circuit technique effectively enhances gain in the millimeter-wave and submillimeter-wave frequency ranges, where the maximum available gain is typically constrained.