Research On Solutions Of Improving PCB Signal Quality In Analyzing Instrument

Analyzing Instrument is an important part of instruments. It can identify and measure material constituents. The Analyzing Instrument has three main kinds of production: spectroscopy, chromatography, and mass spectroscopy. With the development of New High-technology, such as microelectronics, micromachining, Information Technique, new material, computer science, Analyzing instrument tends to develop to modularization, miniaturization, intelligent. These force that the volume of chip becomes smaller and smaller, the density of the Printed Circuit Board (PCB) becomes more and more intensive, the working frequency of system becomes faster and faster. So the problem faced by Analyzing Instrument same as High-speed Digital Circuit Design is Signal Integrity Problems.Signal Integrity (SI) is the signal quality of transmission line on the PCB. The typical SI problems are reflection, crosstalk, ring, simultaneous switching noise (SSN). In a interconnection system, transmit line effect caused by the package of chip, signal interconnection, via, pad and dielectric material can not be negligible in High-speed Digital Circuit Design. This paper studies how to solve the SI problem on the analyzing instrument board in two aspects: the simulation analysis of SI and the PCB design. That combines with a typical High-speed Signal Acquisition Board of Analyzing Instrument, the SI simulation and PCB design is implemented. All of the above, these elucidate that High-speed Digital Circuit Design is very important to the PCB design of Analyzing Instrument.The main contents of the thesis are: Firstly, this paper analysis transmission line theory and the typical problems of SI and summarizes the design rule of PCB by actual experience. Secondly, take a typical High-speed Signal Acquisition Board of Analyzing Instrument for an example. The simulation is performed before place and layout by SI simulation software SpecctraQuest and Power Integrity (PI) simulation software Ansoft Siwave. Then PCB design is performed. Where the key chip placed is decided by simulating the Power Plane and Gnd Plane with fixed structure. How to solve the SI problems by reflection and crosstalk is came up with by simulating the key signal. Timing constraints of data signal is defined by analyzing the timing system. The PCB design rule is made a summary according to the characteristics of Analyzing Instrument signal. Finally, post-simulation and design optimizing of High-speed Signal Acquisition Board are executed after PCB place and layout were finished. The aim of this simulation is to make sure that the signal noise by reflection, crosstalk and the power noise by discontinuity power plane are meeting the requirements of design system. The solution of signal quality on the Analyzing Instrument Board, based on the simulation of Signal Integrity, can solve any SI problem that may come along in Process Design. That can guarantee the signal quality, then period of design is shortened, and cost of design is reduced, competitiveness for enterprises is improved.