| Visible light communication(VLC)has drawn increasing attention in recent years due to the advantages of unlicensed bandwidth,high security,immunity to radio frequency in-terference,compatible with existing lighting network and low-cost.In aspect of fabricating-cost,dimensions,power-consumption and reliability,the performance of integrated circuit is much better than printed circuit board module.Considering the demand of popularization of VLC technology,it is necessary to design the VLC application specific integrated circuit.In this dissertation,the key technologies of integrated VLC system are studied.The main contents of this dissertation are the analysis of the relationship between noise and bandwidth in VLC systems,the design of an integrated high-speed commercial phosphorescent white LED(Light Emitting Diode)driver chip,the design of an avalanche photodiode chip and a fully integrated VLC receiver chip,the setup of a fully integrated VLC system.Based on the UMC(United Microelectronics Corporation)0.18?m CMOS(Complementary Metal Oxide Semiconductor)process,the design of VLC application specific integrated circuit is fabricated and measured.The main contributions of this dissertation are summarized as fol-lows:1.An analysis of the relationship between noise and bandwidth in VLC systems.Firstly,the VLC system based on printed circuit board is realized.Due to the pre-emphasis and post-equalization,the-3d B bandwidth of white LED is extended from 3MHz to 200MHz.Then,we theoretically compared the bandwidth and noise of three different transceiver structures comprising a single pre-emphasis circuit,a single post-equalization circuit and a combination of pre-emphasis and post-equalization circuits,respectively.The conclusion of theoretical analysis is that for the same resonant frequency,and for high signal-to-noise ratio,VLC systems employing post-equalization or pre-emphasis have the same bandwidth extension ability.The transceiver employing both the pre-emphasis and post-equalization techniques has a bandwidth 2 times the bandwidth of the systems employing only the pre-emphasis or post-equalization.For low signal-to-noise ratio,the noise performance of VLC systems employing only pre-emphasis is better.For all signal-to-noise ratio conditions,the VLC system with only active pre-emphasis shows the better noise performance.Finally,we validated the presented theoretical analysis by experimental results.2.Phosphorescent white LED driver chip.In order to increase the modulation band-width of LED,by the means of pre-emphasis and adjustable remaining-carrier sweep-out circuit,the-3d B bandwidth of white LED is extended from 3MHz to 80MHz.Based on the OOK(On-Off Keying)modulation,the best obtained real-time baud-rate is 112Mbps,and the bit-error-ratio is 1.04×10-3.In order to solve the problem of simulation accuracy of op-tical modules in integrated circuit design process,we proposed the design method based on the S-parameter.Utilizing this design method,the simulation accuracy could be improved significantly,which is also a simple and feasible design method for the VLC application specific integrated circuit.3.Avalanche photodiode(APD)chip and a fully integrated VLC receiver chip.Based on the VLC free-space channel characteristics,three APDs of different size are fabricated and measured.Considering the trade-off between responsivity and bandwidth,we finally choose the 150?m×150?m APD for the VLC receiver design.Based on the research on visible light detectors,a fully integrated VLC receiver chip is proposed.Utilizing laser diode as the experimental light source,the-3d B bandwidth of the VLC receiver is 420MHz.4.Fully integrated VLC system.Based on the VLC application specific integrated cir-cuit above,a fully integrated VLC system is built up.Experimental result shows that the-3d B bandwidth of the fully integrated VLC system is 160MHz,based on the OOK modula-tion,the best obtained real-time baud-rate is 120Mbps,and the bit-error-ratio is 3.77×10-3. |
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