scholarly journals Extending OTDR Distance Span by External Front-End Optical Preamplifier

Electronics ◽  
2021 ◽  
Vol 10 (18) ◽  
pp. 2275
Author(s):  
Adriana Lipovac ◽  
Vlatko Lipovac ◽  
Mirza Hamza ◽  
Vedran Batoš

Optical time-domain reflectometer (OTDR) is used to characterize fiber optic links by identifying and localizing various refractive and reflective events such as breaks, splices, and connectors, and measuring insertion/return loss and fiber length. Essentially, OTDR inserts a pulsed signal into the fiber, from which a small portion that is commonly referred to as Rayleigh backscatter, is continuously reflected back with appropriate delays of the reflections expressed as the power loss versus distance, by conveniently scaling the time axis. Specifically, for long-distance events visibility and measurement accuracy, the crucial OTDR attribute is dynamic range, which determines how far downstream the fiber can the strongest transmitted optical pulse reach. As many older-generation but still operable OTDR units have insufficient dynamic range to test the far-end of longer fibers, we propose a simple and cost-effective solution to reactivate such an OTDR by inserting a low-noise high-gain optical preamplifier in front of it to lower the noise figure and thereby the noise floor. Accordingly, we developed an appropriate dynamic range and distance span extension model which provided the exemplar prediction values of 30 dB and 75 km, respectively, for the fiber under test at 1550 nm. These values were found to closely match the dynamic range and distance span extensions obtained for the same values of the relevant parameters of interest by the preliminary practical OTDR measurements conducted with the front-end EDFA optical amplifier, relative to the measurements with the OTDR alone. This preliminary verifies that the proposed concept enables a significantly longer distance span than the OTDR alone. We believe that the preliminary results reported here could serve as a hint and a framework for a more comprehensive test strategy in terms of both test diversification and repeating rate, which can be implemented in a network operator environment or professional lab.

Author(s):  
Tran Van Hoi ◽  
Ngo Thi Lanh ◽  
Nguyen Xuan Truong ◽  
Nguyen Huu Duc ◽  
Bach Gia Duong

<p>This paper focuses on the design and implementation of a front-end for a Vinasat satellite receiver with auto-searching mechanism and auto-tracking satellite. The front-end consists of a C-band low-noise block down-converter and a L-band receiver. The receiver is designed to meet the requirements about wide-band, high sensitivity, large dynamic range, low noise figure. To reduce noise figure and increase bandwidth, the C-band low-noise amplifier is designed using T-type of matching network with negative feedback and the L-band LNA is designed using cascoded techniques. The local oscillator uses a voltage controlled oscillator combine phase locked loop to reduce the phase noise and select channels. The front-end has successfully been designed and fabricated with parameters: Input frequency is C-band; sensitivity is greater than -130 dBm for C-band receiver and is greater than -110dBm for L-band receiver; output signals are AM/FM demodulation, I/Q demodulation, baseband signals.</p>


2013 ◽  
Vol 284-287 ◽  
pp. 2647-2651
Author(s):  
Zhe Yang Huang ◽  
Che Cheng Huang ◽  
Jung Mao Lin ◽  
Chung Chih Hung

This paper presents a wideband wireless receiver front-end for 3.1-5.0GHz band group-1 (BG-1) WiMedia application. The front-end circuits are designed in 0.18um standard CMOS process. The experimental results show the maximum conversion power gain is 45.5dB; minimum noise figure is 2.9dB. Input return loss is lower than -9.3dB and output return loss is lower than -6.8dB. The maximum LO conversion power is 0dBm. 3dB working frequency is 1.9GHz (3.1GHz-5.0GHz) Total power consumption is 24.3mW including LNA, mixer and all buffers. Total chip area is 1.27mm2 including dummy and pads.


Author(s):  
G Vasudeva ◽  
Uma B. V.

Differential Amplifier is a primary building block of analog and mixed signal circuit for pre-processing and signal conditioning of analog signal. FINFET devices with high-k gate oxide at 22nm technology are predominantly used for high speed and low power complex VLSI circuits. FINFET based differential amplifiers are widely used in ADC’s and signal Processing applications due to their advantages in terms of power dissipation. Analog front end of complex VLSI circuits need to offer high gain, higher stability and low noise figure. Designing of FINFET based VLSI sub-circuits requires proper design procedure that can provide designers flexibility in controlling the circuit performances. In this paper, differential amplifier is designed using model parameters of high-k FINFET in 22nm technology. The conventional procedures for designing MOSFET based differential amplifier are modified for designing FINFET based differential amplifier. Schematic capture is carried out in Cadence environment and simulations are obtained considering 22nm FINFET PDK. The performance metrics are evaluated and optimized considering multiple iterations. The designed differential amplifier has slew rate of 6V/µSec and settling time of 0.9 µSec which is a desired metric for ADCs. Power Supply Rejection Ratio (PSRR) is 83 dB and dynamic range is 1.6754 V. Open loop DC gain of DA is achieved to be 103 dB with phase margin of 630 that demonstrates the advantages of DA designed in this work suitable for analog front end


Author(s):  
Tran Van Hoi ◽  
Ngo Thi Lanh ◽  
Nguyen Xuan Truong ◽  
Nguyen Huu Duc ◽  
Bach Gia Duong

<p>This paper focuses on the design and implementation of a front-end for a Vinasat satellite receiver with auto-searching mechanism and auto-tracking satellite. The front-end consists of a C-band low-noise block down-converter and a L-band receiver. The receiver is designed to meet the requirements about wide-band, high sensitivity, large dynamic range, low noise figure. To reduce noise figure and increase bandwidth, the C-band low-noise amplifier is designed using T-type of matching network with negative feedback and the L-band LNA is designed using cascoded techniques. The local oscillator uses a voltage controlled oscillator combine phase locked loop to reduce the phase noise and select channels. The front-end has successfully been designed and fabricated with parameters: Input frequency is C-band; sensitivity is greater than -130 dBm for C-band receiver and is greater than -110dBm for L-band receiver; output signals are AM/FM demodulation, I/Q demodulation, baseband signals.</p>


2013 ◽  
Vol 33 (5) ◽  
pp. 0506003
Author(s):  
张珂卫 Zhang Kewei ◽  
赵卫 Zhao Wei ◽  
谢小平 Xie Xiaoping ◽  
汪伟 Wang Wei ◽  
钱凤臣 Qian Fengchen ◽  
...  

Author(s):  
Abu Bakar Ibrahim ◽  
Che Zalina Zulkifli ◽  
Shamsul Arrieya Ariffin ◽  
Nurul Husna Kahar

The low noise amplifier (LNA) circuit is exceptionally imperative as it promotes and initializes general execution performance and quality of the mobile communication system. LNA's design in radio frequency (R.F.) circuit requires the trade-off numerous imperative features' including gain, noise figure (N.F.), bandwidth, stability, sensitivity, power consumption, and complexity. Improvements to the LNA's overall performance should be made to fulfil the worldwide interoperability for microwave access (WiMAX) specifications' prerequisites. The development of front-end receiver, particularly the LNA, is genuinely pivotal for long-distance communications up to 50 km for a particular system with particular requirements. The LNA architecture has recently been designed to concentrate on a single transistor, cascode, or cascade constrained in gain, bandwidth, and noise figure.


1997 ◽  
Vol 33 (6) ◽  
pp. 536 ◽  
Author(s):  
A.E. Kelly ◽  
I.F. Lealman ◽  
L.J. Rivers ◽  
S.D. Perrin ◽  
M. Silver

Sensors ◽  
2021 ◽  
Vol 21 (21) ◽  
pp. 7303
Author(s):  
Adriana Lipovac ◽  
Vlatko Lipovac ◽  
Mirza Hamza ◽  
Vedran Batoš

Optical time-domain reflectometer (OTDR) enables simple identification and localization of a plethora of refractive and reflective events on a fiber link, including splices, connectors and breaks, and measuring insertion/return loss. Specifically, large enough OTDR dynamic range (DR) and thus high signal-to-noise-ratio (SNR) enable clear far-end visibility of longer fibers. We point out here that, under such conditions, the optical bit-error-rate (BER) floor is dominantly determined by reflective events that introduce significant return loss. This complements the OTDR legacy tests by appropriate optical BER floor estimation in the field. As high SNR implies inter-symbol interference as dominating error generating mechanism, we could apply the classical time-dispersion channel model for the optical BER floor determined by the root-mean-square (rms) delay spread of the actual fiber channel power-delay profile. However, as the high-SNR condition is not always fulfilled mostly due to insufficient DR, we propose here inserting a low-noise optical preamplifier as the OTDR front-end to reduce noise floor and amplify the backscattered signal. In order to verify the model for the exemplar test situation, we measured BER on the same fiber link to find very good matching between the measured BER floor values and the ones predicted from the OTDR trace.


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