Design And Research Of The Dual Programmable Line Driver

Due to the popularity of Internet technology and with the widespread use of the computer in various industries,the computer's communication has played the more and more important part.The signal transmission between different computer communication equipment needs to meet specific agreements and regulations in order to correctly send and receive signals.Serial communication protocol,due to its advantage of less wire and low cost,has been used more and more widely in the industry of microcomputer systems and measurement and control systems.In this thesis,the principle of line driver chip is studied deeply.Based on the EIA's RS-423 standard,a low frequency dual-channel line driver which can be compatible with TTL and CMOS levels is designed.Each channel of the line driver has an input and an output to achieve an unbalanced transmission of communication.Based on the conventional line driver circuit structure and combined with the design target,the complete topology of the line driver circuit is determined.The design of the circuit module is determined,and the function each module in the design of the line of the line driver circuit is clarified;On the basis of the above research,the circuit design of each circuit module is complete,including of the comparator circuit,the slew rate control circuit,the bias circuit,the output stage circuit and the protection circuit,and the parameters of the key deviced such as triodes,resistors end capators in each circuit module are determined;Based on Huahong NEC's process library and with the spectre,the design of the circuit and the simulation and optimization are completed,the dual-channel line driver circuit and it's layout are designed and meet indicators,The layout rule checking is adopted,including DRC,LVS,and ERC.Based on the caliber PEX to extract parasitic parameters from layout,using Spectre and Caliber for post-simulation verification,and optimizing the layout according to the simulation results,the final design of dual-channel programmable slew rate line driver is completed with Huahong NEC 350 nm BCD process.The pre-simulation and post-simulation results show that the operating frequency ranges from 1k to 100 k Hz and the input voltage ranges from 0 to 3V when the supply voltages are ± 12 V ± 10% and working temperature is-55 ~ 125 ?,where the input low voltage ranges from 0 ~ 0.8V,the corresponding output voltage is high voltage that ranges from 4 to 6V;where the input high voltage ranges from 2 ~ 3V,the corresponding output voltage is low voltage that ranges from-6 to-4V,the output slew rate can be controlled by the external resistance,and the parameters meet the design targets.