Research On CMOS Integrated Optoelectronic Devices And Differential Optical Receiver For Visible Light Communication

Visible light communication(VLC)technology can carry out high-speed communication while illuminating,which has become one of the research hotspots in the field of communication at home and abroad.It has the characteristics of rich spectrum resources,large system capacity,good confidentiality,no electromagnetic interference,and combination with existing lighting network,etc.Especially the integrated VLC system has the advantages of low cost,small size,low power consumption and high reliability,and thus it is the inevitable requirement of further popularization and industrialization of VLC technology.In order to realize VLC system integration,based on the standard CMOS technology,this thesis has carried out the researches on the new photoelectric devices,e.g.,Si-LED and color photodetectors(PDs),and the circuits,e.g.,photoelectric negative differential resistance(NDR),full differential and pseudo differential optical receivers.All of them are adapted to VLC systems and have been made into chips separately,and the test results on them are desired.The research works are as follow:1.Relevant research on the fully integrated transmitter.A high optical power density forward-biased CMOS Si-LED was studied,and two new features were discovered and scientifically explained.That is,at high currents,the output optical power increases exponentially with the increase of current;in the electroluminescence spectrum,the position of main peak shifts blue with the increase of current,and also two new peaks appear.Furthermore,a new optical interconnection system was designed and fabricated by using UMC 0.18 ?m standard CMOS technology,which can be used to realize on-chip VLC.In adition,several visible light sources in VLC system were tested and evaluated.2.Design of novel integrated color photoelectric detector.Based on the guided mode resonance effect,the scheme for designing polycrystalline silicon subwavelength grating(SWG)filters using standard CMOS process was proposed.According to this scheme,for the first time,three color PD chips with two-dimensional SWG were designed and fabricated by using TSMC 40 nm standard CMOS process.The maximum peak wavelengths of the three-color PDs are 660 nm,585 nm and 465 nm,respectively,which indicates that they have sufficient spectral selectivity.The color photomicrographs of the three PDs are different and distinct from each other,which correspond to the simulated corresponding SWG reflection spectra.3.The design of a new fully differential optical receiver.For the first time,a dual PD visible light fully differential OEIC(Opto-Electronic Integrated Circuit)optical receiver chip based on the CMSC 0.25 ?m standard CMOS process was implemented.The two PDs are different in structure,but both of them have large areas and can receive optical signals.Through the spectral response and equivalent circuit analysis,the structures of the two PDs were designed.To make the two PDs have equal load capacitance and bandwidth,the bandwidth improvement technology,optical frequency response and spectral response characteristics of integrated PD were studied,and then the total area of each PD and its minimum cell size were designed reasonably.In order to weaken the impact of input load capacitance on the receiver bandwidth,a variety of bandwidth expansion techniques were used in the circuit.Based on OOK modulation,for the fully differential receiver chip,the highest real-time data transmission rate reaches 480 Mbit/s and the voltage swing is 550 mV,which means a more sensitive light response relative to the pseudo-differential reference optical receiver chip(voltage swing,350 mV)with an equal area.4.Design of high peak valley ratio integrated photoelectric negative resistance.A photoelectric NDR with higher peak valley ratio(PVCR)was designed and fabricated by using UMC 0.18 ?m standard CMOS process.Under photo-control,the PVCR of the NDR can reach 4827,being two orders of magnitude higher than the reported photoelectric NDRs.The valley voltage is less than 0.5 V,which indicates that the NDR has better energy saving characteristics.In addition,it also has better S-type photoelectric NDR characteristics.