Design Of Interface Circuit In USB2.0 Extension Controller Chip

The USB interface is widely used in computer systems because of its stable transmission performance and convenient plug-and-play mode.However,its short transmission distance limits its application in industrial control,security,and medical applications.This thesis designs an interface circuit scheme applied to the USB extension control chip,using the common Cat-5 twisted pair cable as the transmission medium.It can extend the USB transmission distance to more than 100 meters,breaking the limitations of 5 meters.The thesis first analyzes the technical challenges involved in high-speed signal's long-distance transmission and analyzes the causes of distortion in the transmission.Since the previous simulation model is difficult to accurately evaluate the real transmission effect,the thesis establishes a twisted pair transmission model,and then uses Matlab tools to convert the model into a IIR filter and calculates the coefficients,finally uses the Verilog-A simulator of Cadence ADE to establish a simulation model.Simulation results show that within distance of 30 m to150m,the attenuation characteristic of the simulation model is close to the industry standard of the cable,and in addition,it has shorter simulation time.On this basis,the thesis compares and analyzes the characteristics of structural and electrical of LVDS,CML,LVPECL,etc.Then the thesis studies the key points and challenges of the transmission equalization and reception equalization,uses CML driver with pre-emphasis at the transmitter and the continuous time linear equalization circuit(CTLE)at the receiver.The thesis designs complete duplex transceiver circuits,consist of a CML driver,a transmitting equalizer,a CTLE receiving equalizer,a differential comparator,and a level shift circuit.Based on the 0.11?m process of UMC,the thesis completed the interface circuits design and layout design,and then completed the pre-simulation and post-simulation.The simulation results show that in the power supply range of 2.97?3.63 V,the interface circuit can completely recover the signal after the 100-meter twisted-pair model attenuation under each process conner.The results indicate that the specifications are covered,and it has the advantage of low power consumption.The overall layout area of the interface circuits is 0.11mm~2.At the 3.3V power supply voltage,the overall power consumption of the circuits is 124 mW.The high-speed interface circuits designed in this thesis have important theoretical significance and application value for the implementation of the USB extension control chip.