The Signal Integrity Analysis Of AC Coupled Connector

High-speed interconnect systems are affected by many factors such as interconnectdensity, aggregate bandwidth, signal integrity and power requirements. With the trendof the modern electronic systems toward higher speed, higher density, lower power,lower supply voltages and larger current, the system’s data transmission rate has beenincreasing rapidly and high-speed interconnects with even wider bandwidth are requiredmore than ever. How to acquire high bandwidth interconnect systems capable ofmulti-Gbps signaling are currently under investigation by a number of groups. ACcoupled interconnects show promise to enable high data rate interconnection betweenIC’s. AC coupled interconnects include capacitive coupling and inductive coupling. Forthe signal transmission interface is non-contact, AC coupled interconnects can be builtof a lot denser and simpler than mechanically mated interconnect. Based on extensivelysummarization of the relative research results, the thesis systematically discusses thefeasibility of transmiting high-speed digital signals through the capacitive couplinginterconnects on board level, and an effective equalization approach for AC coupledinterconnects is proposed to extend the application scope of AC coupled interconnects.Moreover, the effects of the location of capacitor on the suppression of simultaneousswitching noise are analyzed. The new ideas of dissertation are mainly listed as follows:1. According to AC coupling principle, a design of board-level capacitivecoupling connectors is presented in this paper. This design is implemented by couplingthe signal of the transmitter to the receiver through the capacitance consisting of twotightly-coupled transmission lines. The impact of the pins wear and oxidation areeliminated because of the contactless of the signal transmission interfaces, which bringgood transmission of signals. Simulation results show that the design of capacitivecoupling connectors ensures high quality of signal transmission in4Gbps signaling datarates.2. According to the crosstalk coupling mechanism between the high-speedinterconnects, the effect of the physical structure of capacitive coupling connector onthe pulse waveform of the receiver-side is analyzed, and the selection strategy for thesize of connectors is proposed.3. AC coupled connector can be used for multi-Gbps signal transmission on boardlevel. With the increasing of signal transmission rate or transformer inductance（coupling capacitance） value, the receiver-side of the AC coupled connector willsuffer excessive inter-symbol interference, and the signal can not be effectively recovered. To solve this problem, the driver-side equalization scheme is proposed byanalysing the reasons of inter-symbol interference and the equalization ratio calculationmethod of this scheme is also given. Simulation results show that using the driver-sideequalization scheme can effectively eliminate inter-symbol interference and the choiceof inductance （capacitance） value and signal transmission data rate independent ofeach other, therefore the application scope of AC coupled interconnects is extended.4. The transmission and suppression of the simultaneous switching noise areinvestigated based on microwave network principle, and a new method for suppressionof the noise transmission with multi-stage capacitors is presented in this paper. Thesimulation results show that the multi-row capacitors and the larger transmission loss ofnoise path could improve the ability to suppress the noise transmission and theefficiency of the noise suppression with capacitors. Finally, the performance of themethod is verified with FDTD simulations, and the design rules of the method withmulti-stage capacitors are derived.