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Investigation On Monolithic InP-Based PIN-PD+HBT Integrated Photoreceiver Front-End

Posted on:2009-05-24Degree:DoctorType:Dissertation
Country:ChinaCandidate:A MiaoFull Text:PDF
GTID:1118360245969621Subject:Electromagnetic field and microwave technology
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The research works described in this paper were supported by the grants from many research projects, including Basic Research Program of China (973 Program) "Basic Research on Integrated Optoelectronic Devices and Microstructure Optical Fibers with Structure and Technology Innovations for Future Advanced Optical Communications" (2003CB314900), Doctoral Subjects Research Grants of Ministry of Education "Monolithic OEIC photoreceiver modules based on RCE photodetectors and HBT" (20020013010) , Hi-tech Research and Development Program of China (863 Program) "High Performance InP,GaAs Based Long-wavelength RCE Photodetector" (2003AA31G050) and "Independent Innovation of WDM Integrated Demultiplexing Photodetector and Research on Key Processes" (2003AA312020).With the rapid development of optical communication technologies, the demands for wide bandwidth are increasing, fiber communication will evaluate to the new generation network with intelligent, integrated, low cost and high reliability. Compared with the discrete optoelectronic devices, the optoelectronic integrated circuits (OEICs) have the advantages of smaller dimension, lower parasitics, lower cost, better performance and higher reliability. OEICs have already become one of the most attractive research subjects in the areas of optical communications and optoelectronics.A great deal of efforts have been focused on the basic theory, fabrication processes, measurement, modeling technique of discrete devices as well as the monolithic integrated photoreceiver front-end circuit. The main achievements are listed as follows:I .The Photodetector1. In the aspect of Photodetector measurement: A more complete wide-band calibration method for Photodetector frequency response measurement by optical heterodyne detection technique has been proposed. The errors introduced by extra fixture as well as laser output fluctuations were considered and eliminated simultaneously, and the accuracy can be improved largely; Aiming at improving the measurement accuracy of photodetector's S21 parameter with sweeping frequency technique, "Flow-graph" calibration method has been proposed. This method takes into account the effects caused by various frequency responses inaccuracy and mismatches between different ports. Experimental results show obvious improvement in calibration of S21 parameter has been achieved; An automatic photodetector's spectral response measurement system has been built up, with this measurement system the absolute quantum efficiency of Photodetector chip can be measured precisely without complex beam concentration system.2. In order to improve the high frequency performance of the photodetectors, a method by increasing the inductance in the output port has been proposed. The simulation and experiment show that by adding spiral inductors in the output port of the Photodetector and without decreasing the active region area, the frequency response limitation introduced by junction capacitance can be reduced, and the bandwidth of the Photodetector can be increased.3. The small signal equivalent circuit model parameters of the PIN-photodetector have been extracted with genetic algorithm successfully. The parameter extraction procedure using genetic algorithm has overcome the limitation of forthcoming parameter extraction software. The modeled frequency responses are well matched to the measurements. A self-adaptive genetic algorithm is proposed. Reproduction, crossover and mutation operators are automatically optimized in the proposed algorithm. In the process of extracting device model parameters with the proposed self-adaptive genetic algorithm, the premature convergence problem in traditional genetic algorithm can be avoided, and calculation speed and accuracy can be improved significantly.4. Based on the process flow of our laboratory, the fabrication processes of InP-based PIN-photodetector were developed. With the active region area 22×22μm2, the 3dB bandwidth of the fabricated PIN-photodetector is 15GHz.II .The HBT1. A method removing parasitic introduced by pads has been proposed, by measuring the S parameters of pads in the condition of "open" and "short", we can make HBT model more fit to the real device.2. The small signal equivalent circuit model parameters of the HBT have been extracted with the proposed genetic algorithm. The modeled frequency responses are well matched to the measurements.3. Based on the process flow of our laboratory, the fabrication process InP-based HBT has been developed. The current-gain cutoff frequency of 38GHz, turn-on voltage of 0:43V, breakdown voltage of more than 2V, and DC current gain of about 100 were realized in the fabricated InP/InGaAs HBT with 2μm of emitter width grown by MBE. The current-gain cutoff frequency of 40GHz, turn-on voltage of 0.4V, breakdown voltage of more than 2V, and DC current gain of about 30 were realized in the fabricated InP/InGaAs HBT with 2μm of emitter width grown by MOCVD.III. The integrated device1. Based on models of PIN-photodetector and HBT, several forms circuits for photoreceiver front-end have been designed. We optimize and contrast the circuit styles according to the simulation results. The noise performance has been analyzed. The thermal noise introduced by the resistance of base region plays an important role in the total noise of the integrated photoreceiver front-end circuit.2. The inductor peaking technique has been investigated. The simulation results show that not only the parameter of S21 has been improved significantly, but also the thermal noise introduced by the resistance of base region has been reduced effectively, which could reduce the total noise of the front-end circuit and improve the S/N ratio.3. The photomasks for PIN-PD+HBT monolithic integrated photoreceiver front-end based on 2μm and 3μm of the HBT's emmiter width have been designed, respectively. The PIN-PD+HBT monolithic integrated photoreceiver has been fabricated successfully. The active region area of PIN-photodetector is 22×22μm2, the amplifer circuit is transimpedance feedback amplifer with one stage common emitter and output buffer circuits. When the detector added 2.5V reverse bias voltage and the circuit added 2V bias voltage, the test result of 3dB-bandwidth reaches 3GHz, the transimpedance is up to 800. Further, preliminary fabricating and testing of RCE-PD +HBT integrated device have been carried out. Such integrated structure has effectively solved the trade off problems of designing shared epitaxy, can increase the quantum efficiency of the detector notably while keeping HBT high-frequency performance.
Keywords/Search Tags:PIN-photodetector, heterojunction bipolar transistor(HBT), opto-electronic integrated circuit(OEIC), accurate measurement, parameter extraction, monolithic integrated photoreceiver front-end
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