Research On The Design Techniques Of High-Speed,Strong-drive And De-nosing Optocoupler Chip

With the rapid development of the optoelectronics industry and the widly used of the optocoupler technology, the research, design and develop of the optocoupler will be more and more important. Because the optocoupler is more and more used in the high speed, strong drive and high voltage environment, the response speed, driving ability and noise suppression have become a prominent problem which restricted the development of the optocoupler. The traditional and simple design method could not integrate these three main factors together, which creates a hard problem to be solved during the design of the production that combined the high speed, driving ability and stable work.Under the background of the above, for the application, the key technology and the circuit structure of the optocoupler is presented in this dissertation. At the same time, the problems such as the slower response speed, lower drive ability and the noise suppression ability are solved. The three factors are integrated and realized in one chip.The main research results and innovations are as follows:1. Aiming to achive the high speed during the application of the optocoupler, a "Sudoku" type photoelectronic detection array is presented. Using the "half shade-half pass" structure this array converts the received photon into photocurrent efficiently. Meanwhile, in order to ensure the high speed from the photocurrent to the voltage signal, a high sensitive transresistance amplifier is designed which matchs the symmetric photoelectric detection array exactly. From the combination of the symmetric structure, not only the speeds from photon to electricity but also from photocurrent to voltage are improved. Compared with the original asymmetric array and the single input structure, the symmetric construction reduces the noise interference greatly and guarantees the stable, clean photocurrent entering the after circuit. The test results verifiy the feasibility and effectiveness of the proposed methods.2. In view of how to improve the drive ability of the optocoupler, the photoelectric signal front-end processing module and the back-end driving module are presented.Realize the processing from the weak signal to strong signal and ensure the stable strong driven current from the afterwards circuit. In order to prevent the stronge current interfere the weak signal, the diversified internal power to supply for the other modules is proposed. Based on the theory of the photocurrent, analyze the generation of the photocurrent from the front-end module, construct the circuit structure from photocurrent to the voltage signal and the voltage signal is amplified, compared, filtered, shaped and adjusted. It ensures the signal flows to the backward circuit. In the back-end driving module, the logic and deadtime control circuit is designed. The circuit not only generates the strong current to drive the MOS gate in the driving unit, but also prevents large current burned peripheral circuit when the conduction of the NMOS and PMOS arrays at the same time.3. Because of the optocoupler is the "bridge" between the high and low voltage, the circuit of hierarchical noise reduction and real-time protection are presented. According to the different stages of photoelectric signal processing, designs the de-noising circuit in the front-end and back-end modules seperately. It minimizes the noise in the process of photoelectric signal processing and ensures that no more noise interfaces the backward circuit. Under the normal working state, in order to prevent the high voltage and strong current impact the primary circuit, according to the trend of the photoelectric signal and the power signal, isolates the high and low voltage module in the safety area in the overall layout.This dissertation researches the response speed, driving ability and the de-nosing characteristics of the optocoupler. Through the simulation and experiment, the resules show when the optocoupler works stable, the rise propagation delay time of the whole chip is 205.5ns-216.2ns, the decline propagation delay time is 143ns-155ns. The peak output current of the designed chip can be up to 2.5A. All of the results will give a experimental base and the important guiding significance for the design of photoelectric coupling system.