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With the rapid advancement of new-generation information technologies such as 5G, cloud computing, and artificial intelligence (AI), data centers, serving as the operational platforms for information systems, have seen a continuous rise in energy consumption, currently reaching 30kW per rack. The necessity to reduce power consumption in data centers cannot be overstated. Optical modules in data centers, serving as the bridge for information exchange, account for over 40% of the total power consumption of switches. Low-power optical modules have become a hot topic in the industry. To reduce the energy consumption of optical modules, various low-power solutions have been proposed, such as Co-Packaged optics, linear drive pluggable optics (LPO) without digital signal processing (DSP), and linear receive optics (LRO) with half-DSP, but their performance ultimately depends on high-speed, low-power driver chips. This paper uses simulations and experiments to develop a 4×13Gbps multi-channel ultra-low-power linear drive optical transmitter based on the current bias circuit, which can achieve an extinction ratio ranging from 2.3 to 7.3 dB, an eye height of 196 μW, and an eye width of 43.1 ps when operated at a modulation voltage of 500 to 1100 mV. The power consumption is reduced to 1.08 mW/Gbps. Compared to traditional optical modules, this solution reduces energy consumption by about 80% and costs by 30%. Additionally, experimental results have demonstrated that the key elements in the design of a multi-channel linear direct-drive optical transmitter based on the bias circuit also include: 1) the use of a sink current source to supply power in a manner that effectively prevents signal reflection; 2) traditional multi-channel current source chips cannot achieve effective channel isolation, and passive filters need to be added for channel isolation to reduce high frequency signal interference between channels; 3) Since the re-timer has been eliminated, it's necessary to rigorously optimize the link impedance and minimize signal reflection. This solution integrates the advantages of both low cost and low power, making it applicable in short-distance interconnection scenarios such as those between data center internal racks and backplanes.
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