Research Of The Transmission Characteristic And Compensation Of HDMI Line

With the rapid development of digital technology, the new techniques in thefield of multimedia technology continually appear. And it gradually transformsanalogue interface technology into digital interface technology. In the area of videoimage, data transmission rate has been entering into Gbps with the increasing ofclock frequency of information age. The HDMI interface technique and standardare raised to support high quality audio and video signals. However, the demand forlong HDMI cable has been growing, as the high-definition digital home theater andmultimedia room become more and more popular.The subject of this thesis comes from Lontium Semiconductor Corporation.The theoretical model of the transfer characteristic of the HDMI transmission lineis necessary for designing the driver circuit. Taking the HDMI interface techniqueas a start and introducing HDMI specification content requirements, the influenceto the signal caused by transmission line loss is researched firstly in this thesis,established on the theory of transmission line and signal integrity. Then, the testdata according to the practical tests for the different length of HDMI transmissionlines is analyzed. Combining differential pairs and differential signal theory, thisthesis begins with differential mode transmission loss of HDMI transmission lines,by using high frequency simulation software HFSS and ADS to model and simulate.Then a HDMI transmission line equivalent circuit model is designed and presented.Also, the influence of HDMI transmission line and interface to the signal on thefoundation of the equivalent circuit model is researched and analyzed. A goodmatch of the magnitude of Sdd21has been observed between the equivalent circuitand the measurement in the range of0-6GHz. With the help of the theoreticalmodel given by the equivalent circuit, it will be easier to design the signal receiverand transmitter.Additionally, the preliminary research on the compensation circuit based onthe presented HDMI equivalent circuit is given in this thesis. The NE68618transistor with high bandwidth is chosen to design the compensation amplifiercircuit on the basis of the principle of equalization and transistor differentialamplification. The circuit designed could make compensation for the HDMItransmission line at1.5GHz frequency range efficaciously. The magnitude of Sdd21after compensation of15meters HDMI transmission line is-4.16dB at1.125GHz. The difference of compensation intensity of HDMI lines from8meters to15metersis also discussed with the help of the HDMI equivalent circuit.