Real-time 4x3.5 Gbps sigma delta radio-over-fiber for a low-cost 5G C-RAN downlink

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Low power all-digital radio-over-fiber transmission for 28-GHz band using parallel electro-absorption modulators

We present a low-power all-digital radio-over-fiber transmitter for beyond 28-GHz using sigma-delta modulation, a 140mW NRZ driver and parallel electro-absorption modulators. 5.25Gb/s (2.625Gb/s) 64-QAM is transported over 10-km SSMF at 1560nm with 7.6% (5.2%) EVM

Germanium photodetector with monolithically integrated narrowband matching network on a silicon photonics platform

High data rate transceivers typically consist of a system with hybrid integration of the electronics and photonics. Impedance levels provided by the opto-electronic device are often not the same as the levels desired by the electronic circuit. This mismatch introduces suboptimal operation and can even be detrimental for the overall system performance. Consequently, a matching circuit is often implemented on the electronic IC together with the main electronic functionality. Direct RF matching of the opto-electronic devices on the photonic IC has the potential to significantly reduce the overall system cost as the area cost of photonic chips is much lower. In this paper, narrowband LC-matching is shown for a germanium photodetector on the iSiPP50G silicon photonics platform to convert the output impedance to a more standard 50 Ω impedance level at 30 GHz. By tuning the photodetector reverse biasing voltage between 0 Volt and 3 Volt, a reflection coefficient lower than -20 dB is obtained over the frequency range between 24.3 and 30.4 GHz

Silicon photonics traveling wave photodiode with integrated star coupler for high-linearity mm-wave applications

Next-generation wireless communication will require increasingly faster data links. To achieve those higher data rates, the shift towards mmWave frequencies and smaller cell sizes will play a major role. Radio-over-Fiber has been proposed as a possible architecture to allow for this shift but is nowadays typically implemented digitally. as CPRI (Common Public Radio Interface). Centralization will be important to keep next-generation architectures cost-effective and therefore shared optical amplification at the central office could be preferable. Unfortunately. limited power handling capabilities of photodetectors still hinder the shift towards centralized optical amplification. Traveling wave photodetectors (TWPDs) have been devised to allow for high-linearity, high-speed opto-electronic conversion. In this paper, an architecture is discussed consisting of such a TWPD implemented on the iSiPP25G silicon photonics platform. A monolithically integrated star coupler is added in the design to provide compact power distribution while preserving the high linearity of the TWPD. The traveling wave structure (using 16 photodetectors) has a measured 3 dB bandwidth of 27.5 GHz and a fairly flat S-21 up to 50 GHz (less than 1 dB extra loss). Furthermore, the output referred third-order intercept point at 28 GHz, is improved from -1.79 dBm for a single Ge photodiode to 20.98 dBm by adopting the traveling wave design. (C) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreemen

53 GBd PAM-4 DAC-less low-power (1.5 pJ/b) silicon integrated transmitter

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