A Distributed Low-Noise Amplifier for Broadband Linearization of a Silicon Photonic Mach–Zehnder Modulator

RF photonic components suffer from poor spurious-free dynamic range (SFDR) due to the high noise and distortion generated by a silicon photonic (SiP) Mach-Zehnder modulator (MZM). This work demonstrates a distributed silicon-germanium (SiGe) heterojunction bipolar transistor (HBT)-based low-noise amplifier (LNA) co-designed for linearization with a SiP MZM for a broadband radio-over-fiber (RoF) link. The SiGe LNA incorporates a distributed, tunable predistortion scheme that is inherently wideband and improves the third-order intercept point over an 18-GHz range. The assembled SiGe LNA and SiP MZM prototype demonstrates an SFDR as high as 120 dB· Hz
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at 9 GHz, a 14-dB improvement over previous SiP RF components or RoF links.