Optical wireless front-end receiver design

2003

Wireless optical networks usually have demanding specifications in terms of bandwidth, dynamic range and sensitivity. The front-end is a critical element for the fulfillment of these demands. This paper discusses several design aspects of front-ends for optical wireless communications, covering techniques for achieving high gains, high input dynamic ranges, improving noise performance, and reducing electromagnetic interference (EMI). The paper further presents some experimental results of many of the techniques here described.

2006 International RF and Microwave Conference, 2006

Due to optical wireless link power budget considerations, the receiver is required to have a large collection area. One of the main noise mechanisms in wideband preamplifiers employing large area detectors is the noise due to the low pass filter formed by the detector capacitance and the input impedance to the preamplifier. Typical large photodetection area commercial detectors has capacitance are around 100-300 pF compared to 50pF in fiber link. Hence, techniques to reduce the effective detector capacitance are required in order to achieve a low noise and wide bandwidth design. In this paper analysis on the bootstrap transimpedance amplifier (BTA) for input capacitance reduction will be reported. This technique offers the usual advantages of the transimpedance amplifier together with an effective capacitance reduction technique for optical wireless detector.

WOC communication is considered as the next frontier for high-speed broadband connection due to its unique features: extremely high bandwidth, ease of deployment, tariff-free bandwidth allocation, low power ( 1/2 of radio-frequency (RF) systems), less mass ( 1/2 of RF systems), small size ( 1/10 the diameter of RF antenna), and improved channel security. It has emerged a good commercial alternative to existing radio-frequency communication as it supports larger data rates and provides high gain due to its narrow beam divergence. It is capable of transmitting data up to 10 Gbps and voice and video communication through the atmosphere/free space. WOC have two broad categories, namely, indoor and outdoor wireless optical communications. Indoor WOC is classified into four generic system configurations, i.e., directed line-of-sight (LOS), non-directed LOS, diffused, and quasi diffused. Outdoor wireless optical communication is also termed as free-space optical (FSO) communication. The FSO communication systems are also classified into terrestrial and space systems. .1 shows the classification of WOC systems.

Journal of Lightwave Technology, 2020

We experimentally evaluate the performance of Kramers-Kronig (KK) receivers for free-space optical transmission. We transmit a dual-carrier signal, each carrier modulated as a 25 Gbaud 16/32 quadrature-amplitude modulation (QAM) signal. This dual-carrier signal, with overall symbol rate of 50 Gbaud, is detected in a single receiver with about 35 GHz bandwidth. Key parameters such as the carrier-to-signal power ratio, the frequency allocation of the pilot tone and the frequency separation between both modulated carriers are optimized. In addition, we also study the effect of the receiver bandwidth limitations on the KK technique. We perform long-term measurements, beyond one hour, for both 16QAM and 32QAM signals in a 55 m outdoor free-space link during daylight with sunny weather conditions. Our measurements demonstrate that the link operates below the BER threshold assuming 20% forward-error correction (FEC) for the 32QAM signal and 7% FEC overhead for the 16QAM signal. The resulting net data rates are 208 Gbit/s and 184 Gbit/s for the 32QAM and 16QAM signals, respectively.

The demand for wireless broadband communication is growing steadily with the volatile increase of internet and mobile applications. Optical wireless and radio communications are both the viable solutions, but the promise of high un-regulated bandwidth at a low cost makes optical wireless an attractive technical alternative. The data rate in Gbps achieved in laboratory is yet not been available in indoor systems. Current research in wireless optical concentrates on increasing communication capacity and improving the performance. In this paper, the major design, performance, safety issues, and recent trends are discussed to close the gap between theory and practice.

Microwave and Optical Technology Letters, 1999

Wireless Engineering and Technology, 2013

This paper reports design of a CMOS optical receiver front-end using 0.18 μm technology. Design process is current associated with photodiode using trans-impedance amplifier (TIA) for wide bandwidth, high gain, low input referred noise and wide dynamic range. The Automated Gain Control (AGC) voltage is used to provide variable gain for multilevel signals. This design is simulated in 0.18 μm UMC technology for the performance analysis. The best simulation results are reported the maximum TIA gain of 67.26 dBΩ at 0 V AGC followed by a post amplifier gain of 86.70 dBΩ. The bandwidth range is 7.03 GHz to 11.5 GHz corresponding to 0-3 V AGC respectively. The input referred noise level value is 43.86 pA/√Hz up to 10 GHz frequency. In addition authors have obtained the common mode rejection ratio (CMRR) is 72.42 dB and rectified group delay is 144.48 ps. Verification of the design, reported results are compared with earlier published work and improvements obtained in the present results.

This paper discuss optic transceiver design and measurement of free space optical channel characteristic in term of the geometric loss. FSO is a point to point communication system in free space using infrared LED or laser as light source. FSO is supposed to be a counterpart of existing conventional microwave radio link in the future. Its application may be prefered due to some advantages such as unlicensed operation, free of electromagnetic interference and easy to deploy where cable run is not possible. Issue, such as, noise caused by surrounding light have to be taken into acccount therefore modulation scheme is used to prevent the noise and the use of aspheric plano convex lens are also made to solve a problem of optical link range. Two designs of optical transmitter with and without lens are also investigated and analyzed to figure out their geometric losses. Test and mesurement are conducted either in the indoor and outdoor environment. The test result shows that the optical link range is achieved within 300 meters at data rate of 100 Kbps and some curves of geometric loss are also produced to help optical link attenuation calculation.

Over the last two decades free-space optical communication (FSO) has become more and more interesting as an adjunct or alternative to radio frequency communication. Free-space optical (FSO) communication links are most susceptible to a tremendous amount of variability and offer a real challenge for efficient, robust system design.one method of transmitting information from one place to another by sending pulses of light through an optical fiber is Fiber-optic communication , FSO communication systems will provide a large dynamic range of performance through most cases .It is a line-of-sight (LOS) technology that transmits a modulated beam of visible or infrared light through the atmosphere for broadband communications. In a way similar to fiber optical communications, free space optics uses a light emitting diode (LED) or laser (light amplification by stimulated emission of radiation) as a point source for data transmission. However, in free space optics, an energy beam is collimate...

2001

To this end, we have carried out a comprehensive detailed modeling of electronic post-optical detection amplifiers based on CMOS technology. We have optimized such receivers for FSOI applications. We have validated our models by experimental verification using MOSIS foundry. We have demonstrated the successful operation of CMOS trans-impedance amplifier based receivers favricated in 0.35 micron process with optimized performance for FSOI links performance. 20020417 269 14. SUBJECT TERMS 17. SECURITY CLASSIFICATION OF REPORT UNCLASSIFIED