A Broadband Distributed Low-Noise Amplifier with Full-Band Noise Optimization and Built-In Balun

This paper presents a distributed low-noise amplifier (LNA) achieving over 100 GHz bandwidth with full-band noise optimization. The proposed design inherently provides balun functionality, enabling direct interfacing with commonly employed single-ended antennas and balanced mixers. Dominant noise sources across different frequencies are identified and mitigated using targeted noise-canceling techniques and optimization strategies. At low frequencies, gate-termination noise is canceled using an active termination. At mid frequencies, a common-drain buffer followed by common-source and common-gate amplifiers enables channel-noise cancellation within the active core while preserving wide bandwidth and balun operation. At high frequencies, the noise transfer function is optimized to suppress gate-noise contributions by selecting an optimal number of distributed elements. The fabricated LNA occupies 0.24 mm² and demonstrates a measured 6–110 GHz bandwidth with over 10 dB gain, achieving a minimum noise figure of 2.21 dB and 0.034 dB/GHz flatness. The full-band noise performance is comparable to state-of-the-art single-frequency LNAs, and the LNA supports wideband modulation of 34/27 Gb/s 16-/64-QAM with low EVM.