40 Gb/s PAM-4 Transmitter IC for Long-Wavelength VCSEL Links

Soenen, Wouter; Vaernewyck, Renato; Yin, Xin; Spiga, Silvia; Amann, Markus‐Christian; Kaur, Kamalpreet; Bakopoulos, P.; Bauwelinck, Johan

doi:10.1109/lpt.2014.2372041

Cited by 30 publications

(13 citation statements)

References 9 publications

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“…The link is pushed to its limits at 50 Gb/s BTB, given the fact that the remaining power budget is a marginal 1.5 dBm, and is broken at 200 m and at 55 Gb/s BTB. Applying equalization to the modulation signal or adopting for 4-level modulation could restore the power budget or cover longer distances, as demonstrated in [18] with the previous generation of this VCSEL. Energy efficiency, defined as heat-to-data ratio, measures 130 fJ/bit at 50 Gb/s and is on par with the fastest multi-mode VCSEL [4].…”

Section: Dynamic Characteristicsmentioning

confidence: 83%

Single-Mode High-Speed 1.5-μm VCSELs

Spiga

Soenen

Andrejew

et al. 2017

J. Lightwave Technol.

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Abstract-Single-mode 1.5-µm InP-based vertical-cavity surface-emitting lasers (VCSELs) with a 1.5-λ long semiconductor cavity and two dielectric distributed Bragg reflectors (DBRs) are presented. The electrical, thermal and optical characteristics are studied as a function of tunnel junction diameter and for different temperatures ranging from -10°C up to 65°C. Small-signal modulation bandwidths in excess of 21 GHz at room temperature are demonstrated for a DC power consumption below 10 mW. In this paper, the superior dynamic characteristics of these VCSELs are shown by demonstrating error-free operation at data rates up to 50 Gb/s in back-to-back configuration by non-return-to-zero modulation and without any equalization. Neither forward error correction nor digital signal processing were required.

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Section: Dynamic Characteristicsmentioning

confidence: 83%

Single-Mode High-Speed 1.5-μm VCSELs

Spiga

Soenen

Andrejew

et al. 2017

J. Lightwave Technol.

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“…A 7-% hard-decision (HD) FEC was assumed and powerful equalization at the receiver side was needed. In [14] also 56 Gb/s PAM-4 with bit error rates (BERs) below 1E-6 was demonstrated for optical back-to-back (b2b) enabled by a 4-tap preemphasize driver and a 22-GHz VCSEL at 1533 nm. And in [12] we demonstrated 56 Gb/s and 84 Gb/s PAM-4 transmission over up to 15 km and 1 km SSMF, respectively, with a 18-GHz long-wavelength VCSEL at 1525 nm using simple transceiver DSPs and the assumption of HD-FEC with a BER-limit of 3.8E-3.…”

Section: This Workmentioning

confidence: 99%

“…Chromatic dispersion in combination with the frequency chirp of the VCSEL and the low extinction ratio (normally around 3 to 5 dB) result in a tight power budget and a short transmission distance [15], which becomes even worse at higher data rates. In addition, VCSEL nonlinearities and a maximum bandwidth of around 22 GHz [14] impose further challenges to the system. Powerful signal processing/equalization is thus required to allow the transmission of data rates of > 100 Gb/s using VCSELs and to enable costefficient high capacity links.…”

Section: This Workmentioning

confidence: 99%

Experimental Demonstration of 84 Gb/s PAM-4 Over up to 1.6 km SSMF Using a 20-GHz VCSEL at 1525 nm

Eiselt

Grießer

Wei

et al. 2017

J. Lightwave Technol.

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“…Four-level pulse-amplitude modulation (PAM4) is currently under consideration in order to enable longer transmission distances and operation with reduced circuit bandwidth relative to non -return-tozero (NRZ) modulation [1]. PAM4 modulation has been recently demonstrated with directly -modulated VCSELs [2], monolithically-integrated Mach-Zehnder modulators [3], and microring resonator modulators [4,5]. However, the previous microring resonator demonstrations operating above 20Gb/s have utilized elaborate lab setups involving arbitrary waveform generators in order to generate the PAM4 levels with the nonlinear devices.…”

Section: Introductionmentioning

confidence: 99%

A 40 Gb/s PAM4 silicon microring resonator modulator transmitter in 65nm CMOS

Roshan-Zamir

Wang

Telaprolu

et al. 2016

2016 IEEE Optical Interconnects Conference (OI)

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A s ilico n p h o to n ic micro rin g res o n ato r mo d u lato r tran s mitter u tilizes a s eg men ted p u ls ed -cas co d e o u tp u t s tag e fo r v o ltag e lev el co n tro l to ach iev e PA M4 mo d u latio n o n a s in g le micro rin g d ev ice. Th e 65n m CMOS tran s mitter ach iev es 40Gb /s o p eratio n at 3.04mW / Gb /s wh en d riv in g d ep letio n -mo d e micror in g mo d u lato rs with 4.4Vppd s win g . Introducti onMicroring resonator devices have great potential to meet the growing the bandwidth density demands of data center and supercomputing systems due to their compact size and high -Q response allowing for inherent wavelengthdivision multiplexing (WDM). Four-level pulse-amplitude modulation (PAM4) is currently under consideration in order to enable longer transmission distances and operation with reduced circuit bandwidth relative to non -return-tozero (NRZ) modulation [1]. PAM4 modulation has been recently demonstrated with directly -modulated VCSELs [2], monolithically-integrated Mach-Zehnder modulators [3], and microring resonator modulators [4,5]. However, the previous microring resonator demonstrations operating above 20Gb/s have utilized elaborate lab setups involving arbitrary waveform generators in order to generate the PAM4 levels with the nonlinear devices. This work presents a 40Gb/s transmitter designed in 65nm CMOS that utilizes a segmented pulsed -cascode output stage for voltage level control to achieve PAM4 modulation on a single microring device. V (a) (b) (c) Fig. 1. (a) T op and cross-section views of a carrier-depletion microring modulator. Measured normalized transmission curves with different reverse bias voltages: (b) dB scale and (c) linear scale. Carrier-Depletion Ring ModulatorAs shown in Fig. 1(a), the carrier-depletion microring modulator utilized in this work has an 8μm radius with outer p+ and inner n+ doping on the ring waveguide to form a pn junction and p++ and n++ doping utilized for ohmic contacts. The device displays an 18GHz bandwidth and 7500 Q factor, as shown in the measured transmission curves of Fig. 1(b). Due to the relative small tunability of the ring modulator (~20pm/V), a high -swing (>4V) driver is necessary. Moreover, modulator non-linearity due to the voltage-to-index and index-to-intensity responses must be considered for uniform PAM4 level spacing. In order to address this, the input laser wavelength is slightly offset from the resonant wavelength to optimize the linearity of the optical output response with different bias voltages, as illustrated in the linear-scale transmission curve of Fig. 1(c). Also, the high-speed driver must have the flexibility to generate the necessary voltage levels for symmetrical PAM4 levels. Fig. 2(a) shows a block diagram of the proposed half-rate PAM4 microring modulator transmitter. The odd and even bits from a 16-bit pattern generator are serialized separately to full-rate to form the PAM4 MSB and LSB signals. This full-rate data goes through buffers and level shifters to generate the predriver signals for th...

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40 Gb/s PAM-4 Transmitter IC for Long-Wavelength VCSEL Links

Cited by 30 publications

References 9 publications

Single-Mode High-Speed 1.5-μm VCSELs

Single-Mode High-Speed 1.5-μm VCSELs

Experimental Demonstration of 84 Gb/s PAM-4 Over up to 1.6 km SSMF Using a 20-GHz VCSEL at 1525 nm

A 40 Gb/s PAM4 silicon microring resonator modulator transmitter in 65nm CMOS

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