Signal Transmission And Noise Suppression In High Speed Digital Circuit

With the rising date rate of electronic system and the rapid development of integrated circuit technology, people pay more attention to the analysis and design of high speed system. The efficiency and quality of application design can be effectively improved by studying on signal transmission and noise suppression in high speed digital circuit.signal integrity(SI) problems determine the signal transmission quality and the overall circuit performance directly. SI is a bottleneck in today’s high-speed digital design, it associates with power integrity(PI), electromagnetic integrity(EMI), timing integrity(TI) closely and influences each other. The focus of the research shifts from SI to PI. Rules of thumb and the existing signaling technology can used to improve data rate and signal quality. Power noise suppression is a important job in high speed design. The EBG(electromagnetic bandgap) structure can exhibit full performance with scientific and rational design. It provides conditions to advance the overall SI and PI. Meanwhile, as an important carrier of signal transmission, the connector can provide conditions for the high speed transmission of board level interconnect with better transmission mode.According to the basic theory of high-speed circuit, and the research contents and objectives of the National Natural Science Foundation “Analysis of SSN and ISI in high speed SIP/PCB system(60672027)” and “Power integrity and reliability analysis in high speed and high density interconnect package(60871072)”, based on the previous research results, several common signal integrity problems and improved methods in practical applications are analyzed. In order to improve the transmission rate, the equalization method of the capacitive coupling connector is studied. The wideband suppression of SSN(simultaneous switching noise) using EBG structure is focused on, some important conclusions are obtained. At the same time, a new high performance EBG structure is proposed. This dissertation consists of six chapters, the main work can be summarized as the following four parts:The first part focuses on the SI of LVDS in signal transmission. According to the basic principle and application of LVDS technology, simulation and analysis on SI of different termination, length of differential pair and separation are done by practical LVDS receiver and transmitter in high speed lossy transmission. By the contrast of variation of overshoot and timing which caused by reflection because of different parameters, their relation with each other on signal integrity is discussed.The second part focuses on the crosstalk in high speed PCB. Simulation and analysis on the lossy transmission of microstrips are implemented with practial chips. By the contrast of variation of NEXT and FEXT because of different space, length and width of microstrip, the produce and suppression of crosstalk is investigated. The corresponding conclusion offers a reference to rational use of microstrip for signal transmission.The third part focuses on the equalization of capacitive coupling connector. Based on the capacitive coupling connector in high speed connector, the factors influencing the receiver-side pulse amplitude and delay is analyzed. The drawback of series coupling capacitance equalization is discussed. An ALTERA driver-side equalization scheme is proposed. The proposed scheme can improve the receiver-side pulse amplitude and reduce pulse delay synchronously. The way of selecting equalization ratio is improved, the accurate equalization ratio can be calculated by a formula, so the inter-symbol interference can be eliminated effectively. The simulation results show that the ALTERA equalization scheme significantly increase the pulse amplitude in receiving end and eliminate ISI, and improve the effective signal transmission rate.The fourth part focuses on SSN(simultaneous switching noise) suppression with EBG structure. In order to suppress SSN effectively, the characteristics of the EBG structure composed of regular hexagonal patches is analyzed in the frequency domain and time domain. Respective influences of the side length of patches, space between patches and the radius of vias on the band-gap and transmission characteristics are investigated from the theory of the equivalent circuit. Mathematical equations estimating accurately the upper and lower cutoff frequency and bandwidth of the band gap for different side lengths of patches are obtained and verified. Meanwhile, a new S shaped bridge EBG structure for deeper ultra-wideband SSN suppression is proposed. Comparing with the existing EBG structure, the lower cutoff frequency decreases obviously, the suppression bandwidth of band-gap increases significantly. the deeper the suppression depth, the more obvious the advantage. the overall performance of proposed structure is enhanced greatly. A useful basis for improving the application performance of high speed digital circuit is provided and the efficiency of design can be improved effectively.