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A 700mW 4-to-1 SiGe BiCMOS 100GS/s Analog Time-Interleaver
... In [16] a 55 nm SiGe BiCMOS 2-to-1 AMUX with a sampling rate of 120 GS/s is reported with a large power consumption of 2.2 W. The 2-to-1 AMUX from [15] achieved >110 GHz analog bandwidth at 180 GS/s using a 0.25 µm InP HBT process, however, requiring digital pre-processing to compensate the limited switching speed [17]- [19]. In [20] we reported a 4-to-1 interleaver with an analog bandwidth beyond Nyquist at sampling rates up to 100 GS/s using a 55 nm SiGe BiCMOS. The interleaver is based on the generation and summation of return-to-zero (RZ) signals from analog inputs. ...
... This paper is an extension of our work demonstrated in [20]. In this work we provide an explicit explanation on the architecture and its implementation. ...
We demonstrate a four-to-one 100-GS/s time interleaver realized in a 55-nm BiCMOS technology. The interleaver comprises two stages of two-to-one sub-interleavers. Each sub-interleaver is implemented using a return-to-zero generation and summing architecture. This sub-interleaver architecture ensures lower clock feedthrough and contains an inherent feed-forward equalizer. Effective number of bits (ENOB) measurements have been performed revealing the interleaver's ENOB of 4.9 at 3 GHz. In addition, the transfer function is measured to show the capabilities of the inherent feed-forward equalizer of the sub-interleavers. The measured analog output bandwidth of the four-to-one interleaver is 73 GHz. Finally, a 100-GBd PAM-4 (200 Gb/s) signal is generated by interleaving four 25-GBd PAM-4 streams while consuming 700 mW.
European Technology Platform NetWorld2020; Strategic Research and Innovation Agenda 2021-27
This letter reports on a 108-GHz bandwidth 0.5-
$\mu \text{m}$
InP DHBT analog-multiplexer-driver (AMUX-driver). To the best of the authors’ knowledge, this 2:1 AMUX-driver shows unprecedented 1.9-V
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160-GSa/s 160-GBd non-return-to-zero (NRZ) and 2.4-V
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100-GSa/s 100-GBd PAM-4 output swings, with very high-quality eye diagrams, without any digital signal processing (DSP) or postprocessing. Up to 3.2 V
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is obtained in NRZ at 100 GBd. The lumped AMUX-driver also shows record 25.7-dB gain and 2.08-THz gain-bandwidth product with 11.1-dB equalizing capabilities at 86.6 GHz.
Systems modulating, transporting, and detecting lightwaves have evolved tremendously in the past four decades. The first systems which were relying on intensity modulation with direct detection have little in common with those manufactured today. Not only have optical fibers and electro-optic components drastically improved, systems now employ digital signal processing for its agility and versatility, initially deployed for long-reach communication systems but slowly making its way into systems covering shorter distances. In this paper we review the evolution of fiber-optic communication systems, from intensity modulation with direct detection to coherent transceivers and DSP-assisted direct detection. We address the main impairments preventing large bitrate-reach products for systems relying on intensity modulation with direct detection. We present a few reasons leading to the recent surge of the short-reach transceiver market segment, especially those covering distances between 10 to 100 km. We summarize a few proposals for this market modulating and recovering an increasing number of degrees of freedom of the lightwave while maintaining self-beating direct detection. We conclude with remarks on the use of coherent technologies to address this market segment
We demonstrate intensity-modulated direct-detection (IMDD) optical transmission at a record-high data rate with single wavelength and single polarization. The high data rate is achieved with simple optics by using electronic and electro-optic devices with large operation bandwidths. We use a digital-preprocessed analog-multiplexed digital-to-analog converter with a >100-GHz analog multiplexer (AMUX) to drive an 80-GHz Mach-Zehnder optical modulator (MZM). The AMUX is based on 0.25-μm-emitter-width InP heterojunction bipolar transistor technology, and the MZM has InP n-i-p-n heterostructure optical waveguides with capacitance-loaded travelling-wave electrodes. We employ discrete multi-tone modulation controlled by a margin-adaptive bit-loading algorithm. In the experiment, the signal was transmitted over a 20-km dispersion-compensated single-mode fiber link and received by a single photodiode followed by a digital signal processor including a nonlinear equalizer. At a gross bit rate of 400 Gbps, the bit error rate of the received signal was below the threshold of 20%-overhead soft-decision forward error correction code. This result corresponds to a net data rate of 333 Gbps.
An 8-bit 100-GS/s digital-to-analog converter (DAC) using a distributed output topology in 28-nm low-power CMOS for optical communications is presented. The DAC can convert 1-k symbols stored in the 1-kbyte design-for-test on-chip memory cyclically. By interleaving four 25-GS/s return-to-zero DACs, the highest signal frequency of the 100-GS/s DAC is about 25 GHz and the output image is located beyond 75 GHz. The 3-dB bandwidth exceeds 13 GHz at 100 GS/s. The effective number of bits and spurious-free dynamic range ranges from 5.3 bit and 41 dB to 3.2 bit and 27 dB from dc up to 24.9 GHz at 100 GS/s, respectively. Transmission rates of 120 and 45 Gb/s are obtained in an electrical and an optical back-to-back experiment, respectively. The DAC test chip consumes 2.5 W from a power supply with multiple outputs of 1.1, 1.5, and 2 V.