1‐V continuous‐time equalizers for multi‐gigabit short‐haul optical fiber communications

Guerrero

IEEE Trans. Ind. Electron.

et al. 2015

This paper presents a new CMOS analog continuous-time equalizer aimed to compensate the limited frequency response of SI-POF, a transmission medium very attractive for industrial applications as factory automation and process control networks because of its cost and immunity to electromagnetic interference. The structure overcomes the limitations of the most widely used continuous-time equalizer, the degenerated differential pair, for 1-V supply voltage. The linear equalizer has been proved for multi-gigabit short-range applications targeting up to 2 Gb/s through a 50-m SI-POF. The prototype consumes 2.7 mW.Index Terms-Equalization, industrial application, low power, step-index polymer optical fiber (SI-POF).

“…Compared with previous split-path equalizers, the proposed structure achieves lower power consumption due to the reduction of the number of stages [7] and higher CMRR [8].…”

Section: Post-layout Resultsmentioning

confidence: 99%

“…In previous works, the authors have proposed structures based on a conventional split-path topology that overcome these limitations [7]. However, these topologies present lower common-mode rejection ratio (CMRR) than the degenerated differential pair, which can become a problem for the correct operation of the front-end.…”

Section: Introductionmentioning

confidence: 99%

Continuous-Time Linear Equalizer for Multigigabit Transmission Through SI-POF in Factory Area Networks

Guerrero

IEEE Trans. Ind. Electron.

et al. 2015

“…Because the operation of the adaptation loop relies on the comparison of powers, no phase information is necessary. As an example, in two line equalizers are presented along with their frequency response obtained both analytically and experimentally. Figure shows the typical frequency response of a line equalizer, which, depending on its architecture, can be modified to adapt to the channel characteristics.…”

Section: Description Of Ctaes In the Frequency Domainmentioning

confidence: 99%

A methodology to design continuous‐time adaptive equalizers

Aguirre

et al. 2016

Circuit Theory & Apps

Self Cite

Serial communications systems suffer from channel bandwidth limitations that result in eye closure and inter-symbol interference. Adaptive equalization at the receiver is widely implemented to alleviate this, and a number of continuous-time techniques aiming multi-gigabit operation have been proposed. The operation of adaptive equalizers is based on signal filtering carried out by loop filters whose characteristics are usually given ad-hoc after a trial and error process. This paper presents a unified analysis of the operation of continuous-time adaptive equalizers that results in a general design methodology to select the frequency characteristics of the filters implemented in the adaptation loop. Using the proposed methodology, a novel adaptation loop filter combination incorporating two low-pass filters is presented.

“…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. 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.…”

mentioning

confidence: 99%

“…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).…”

mentioning

confidence: 99%

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

Guerrero

et al. 2017

Circuit Theory & Apps

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 ...