A 0.1–26 GHz SerDes-Based Broadband White Noise Generator for Ethernet Compliance Tests

This study introduces a novel SerDes-based broadband noise generator developed to evaluate the robustness of wireline communication links for data center applications. The system supports high-speed transmission rates of 26Gbaud and 53Gbaud. In accordance with Ethernet compliance tests, the generator can produce normally distributed noise with integral output power above -4.4dBm, ensuring adequate impairment injection into the Device Under Test (DUT). The proposed solution integrates multiple high-bandwidth transmitter output signals to develop a differential white noise generator. This approach leverages key SerDes components, including the PseudoRandom Binary Sequence (PRBS) generator and the Finite Impulse Response (FIR) filter, which are configured to achieve a flat output frequency response up to 26GHz. To ensure the normality of the output signal, the output distribution is theoretically analyzed using the Central Limit Theorem, with results validated through time-domain measurements. The selected SerDes component is an advanced electro-optic re-timer designed to operate in a differential 100Ω environment. This re-timer can achieve a Return Loss (RL) below -10dB across the entire operating bandwidth, ensuring minimal signal reflection and optimal performance. The noise generator, as a result, achieves an overall Crest Factor greater than 12dB, indicating a high peak-to-average power ratio. Moreover, the Excess Noise Ratio (ENR) exceeds 64dB, highlighting the generator’s capability to produce a significant level of noise above the thermal noise floor. Thanks to FIR filter equalization, the final spectrums exhibit a competitive power density flatness within ±1.6dB with an overall digital and analog power supply consumption of 815mW.