A 2.5-Gb/s multi-rate continuous-time adaptive equalizer for short reach optical links

Gimeno, C.; Sánchez-Azqueta, Carlos; Guerrero, E.; Aguirre, J.; Aldea, C.; Celma, S.

doi:10.1109/esscirc.2015.7313824

Cited by 8 publications

(8 citation statements)

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“…Figures 19 and 20 show the eye diagrams at the input of the equalizer for 400 Mb/s, 1.25 Gb/s, and 2.5 Gb/s for 10-and 50-m length SI-POF. Nevertheless, we propose to use the following simple figure of merit [11] FOM ¼ BitRate Gb=s ð Þ⋅Fiberlength m ð Þ Power mW ð Þ (18) Table I summarizes the main performances of the proposed equalizer and compares them with the results of other adaptive equalizers aimed for the same channel (SI-POF). Figures 21 and 22 show the eye diagrams at the output of the equalizer for 400 Mb/s, 1.25 Gb/s, and 2.5 Gb/s for 50-and 10-m length SI-POF, respectively, with the three loops operating normally.…”

Section: Measurement Resultsmentioning

confidence: 99%

“…A direct comparison with other adaptive equalizers is not easy, as they either use different technology or provide measures only for single bit rate. Nevertheless, we propose to use the following simple figure of merit [11] FOM…”

Section: Measurement Resultsmentioning

confidence: 99%

“…Therefore, an analog continuous-time equalizer is preferred in this case as they present a good trade-off for low-power, high-speed applications, reducing design complexity and area.Although some receivers with adaptive equalization have been already proposed in the literature [9,10], this is the first time that a continuous-time equalizer able to adapt its response to changes in the bandwidth, amplitude, and bit rate of the signal is fully described and characterized. Some preliminary results of the proposed equalizer were announced in [11]. However, in this paper, we provide its complete description, getting deeper into the different sub-systems and presenting new interesting measurement results that prove its suitability for reliable short-haul high-speed POF links.The paper is laid out as follows.…”

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confidence: 95%

“…Experimental results are shown to demonstrate its feasibility. Some preliminary results of the proposed equalizer were announced in [11]. Therefore, the faster the communication required, the higher signal equalization is needed [5].…”

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confidence: 99%

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Design of a CMOS multi‐rate adaptive continuous‐time equalizer based on power spectrum estimation

Gimeno

Guerrero

Sánchez-Azqueta

et al. 2017

Circuit Theory & Apps

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An adaptive continuous-time equalizer for reliable short-haul high-speed serial communications is described in this paper. The adaptive equalizer uses the spectrum-balancing technique to adapt its response to changes in the bandwidth, amplitude, and bit rate of the input signal. In this way, it is able to compensate the frequency response of a 1-mm diameter step-index plastic optical fiber, for lengths up to 50 m, and bit rates ranging from 400 Mb/s to 2.5 Gb/s. Experimental results are shown to demonstrate its feasibility. Copyright transmission channel to meet the high data rate requirement. Therefore, the faster the communication required, the higher signal equalization is needed [5].In a previous work [6], an analog line equalizer cell aimed to compensate the limited frequency response of SI-POF was proposed. In a real communications link, however, there are many other factors that degrade the transmitted signal, such as the losses inherent to the physical material of the fiber (0.14 dB/m at 650 nm), the capacitance of the receiver PD (whose diameter is larger than 0.4 mm), and the bandwidth-length trade-off (~50 MHz · 100 m). Considering the previously mentioned variations expected, the line equalizer needs a mechanism to automatically adapt its frequency response accordingly and avoid to over-compensate or under-compensate the signal, which otherwise would increase the bit error rate.Hence, the equalizer proposed here is implemented altogether with two feedback loops to independently adjust both the boosting and the gain to compensate variations in bandwidth and amplitude of the received signal.In addition, by means of the wavelength-division multiplexing technique, a single optical link is able to transmit a number of optical carrier signals by using different wavelengths. In consequence, it is possible to transport different standards, such as Synchronous Optical Networkin OC-9 (466 Mb/s) and Synchronous Digital Hierarchy STM-16 (2.5 Gb/s), and it is expected to allow different data rates in the same receiver. Therefore, a multi-rate characteristic is a must if the equalizer is to be fully implemented in such applications.Several techniques can be used to implement the equalizer circuit and to choose the right equalization strategy depending on the particular application and channel characteristics. In the case of POF links, several authors use decision feedback equalization (DFE) (always with a previous linear equalizer) with some algorithms such as least mean square or minimum mean square to implement the adaptation [7]. Although DFE is an effective strategy for channels with severe intersymbol interference, for short lengths (up to 100 m), the advantage in performance between a DFE and a linear one is much less, and it may not justify the increase of complexity, area, and power consumption [8]. Therefore, an analog continuous-time equalizer is preferred in this case as they present a good trade-off for low-power, high-speed applications, reducing design complexity and area.Although some receivers with ...

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Section: Measurement Resultsmentioning

confidence: 99%

Section: Measurement Resultsmentioning

confidence: 99%

mentioning

confidence: 95%

mentioning

confidence: 99%

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Design of a CMOS multi‐rate adaptive continuous‐time equalizer based on power spectrum estimation

Gimeno

Guerrero

Sánchez-Azqueta

et al. 2017

Circuit Theory & Apps

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“…The inputs of the XOR are the data signal and the output of the FF, whereas the output of the XOR gate goes to the FF, which is controlled by the clock signal. This structure presents a major drawback, which is the necessity of a very careful adjustment of the delay time of the cells to ensure a correct operation [2]. The second one is formed by an AND gate, which processes both the data and clock signals and whose output goes to a frequency divider.…”

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confidence: 99%

3.125 Gbit/s CMOS transceiver for duobinary modulation over 50‐m SI‐POF channels

et al. 2017

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This Letter presents a novel CMOS transceiver for short-reach multigigabit communication over step-index plastic optical fibre (SI-POF), a very interesting transmission medium for industrial and home-end applications due to its low cost, ease of handling and inherent immunity to electromagnetic interference. The transceiver uses amplitude duobinary modulation, which is added to continuous-time equalisation. For that purpose, a duobinary precoder and a duobinary decoder have been fabricated in a standard 0.18-µm CMOS technology, consuming only 28.4 mW. The system enables a 50-m SI-POF channel bandlimited to 100 MHz to operate at a data bit rate of 3.125 Gbit/s.

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Polymer-optical fibres for data transmission

Stępniak

Schüppert

Bunge

2017

Polymer Optical Fibres

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A 2.5-Gb/s multi-rate continuous-time adaptive equalizer for short reach optical links

Cited by 8 publications

References 9 publications

Design of a CMOS multi‐rate adaptive continuous‐time equalizer based on power spectrum estimation

Design of a CMOS multi‐rate adaptive continuous‐time equalizer based on power spectrum estimation

3.125 Gbit/s CMOS transceiver for duobinary modulation over 50‐m SI‐POF channels

Polymer-optical fibres for data transmission

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