6 GHz Direct Modulation 20 Km Reach Analog Optical Transceiver Design

Optical links for the transmission of analog signals have continued to expand thanks to its simplicity, low loss, large bandwidth, low cost, and immunity to electromagnetic interference from external RF sources. However, due to the lack of economic analog transceiver which has the highest operation frequency between 3 to 10 GHz in current market, the applications within this band need to use the 10 GHz transceiver product, which inevitably complicates the system design and increases the associated cost. \n \nIn this thesis, a cost effective 6 GHz 20 Km reach optical analog transceiver is proposed, designed, and experimentally demonstrated. Theoretical analysis and design of the system is performed through the power budget analysis, bandwidth budget analysis, noise analysis, linearity analysis, and economic consideration. Several criteria for choosing components are proposed accordingly. An OptiSystem RoF application simulation is conducted to verify the analysis results. After choosing components and fabricating the circuit, we perform DC and AC test for both transmitter and receiver, link S parameter measurement, SFDR measurement by two tone test, and 20 Km fiber transmission UWB OFDM single channel test and multi-channel test, the result demonstrates that the proposed transceiver has more than 6 GHz 3-dB gain bandwidth with -10 dB link gain and very good match at its input and output impedances, 31 dB link noise figure, -9 dBm output P1dB, 10 dBm OIP3 and 102 dB SFDR, and it’s an ideal option for OFDM UWB RoF systems. \n \nIn RoF system, a post amplifier is almost following the optical receiver. It boosts the output RF signal power to facilitate the further use of the signal. A proposed 6 GHz 30 dB gain 1 Watt power amplifier is also designed, fabricated, and experimentally demonstrated within this thesis. \n \nFinally, the further search for better components to improve the transceiver performance, the size optimization of the transceiver, and the design of an adaptor for LC receptacle and LC connector are proposed as future research topics.