However, it may not be clear when transmission line techniques are appropriate. Much has been written about terminating pcb traces in their characteristic impedance, to avoid signal reflections. Emiemc and coexistence simulation methodology xavier. One hfss 3d model of a connector, one hfss 3d layout project of a package design with two differential pairs of nets, and one hfss 3d layout project of a section of a board with two. As a concrete example, we look into the design of an inter layer connection represented by a differential pair of vias built within a 18 layer pcb stackup. Hfss is an interactive simulation system whose basic mesh element is a. Differential equations department of mathematics, hkust. It was approved in november of 1995, and first published in march of 1996. Ansys hfss tutorial simulate and analyze an example of trace and via tianjian lu 02014 tianjian lu ece 546. The larger the coupling tight coupling is, the lower the differential. The end goal of this example is to run a transient circuit analysis or lna simulation. Hfss is one of several commercial tools used for antenna design, and the design of complex radio frequency electronic circuit elements including filters, transmission lines, and packaging.
Ansoft high frequency structure simulator v10 users guide 5. Inside the microchip or pair of discrete transistors, the positive and negative signals are added and the resultant becomes the single output. An903a comparison of differential termination techniques abstract the purpose of this application report is to remove some of the confusion that may surround signal termination. Ee105 fall 2015 microelectronic devices and circuits. Tools options hfss options general tab check use wizards for data input when creating new boundaries check duplicate boundariesmesh operations with geometry click ok. Aggressor separation microstrip routing requires a separation of 6h and 7h to properly manage the crosstalk coupling to less than 1% for next and fext, respectively. We can model differential vias with hfss and combine the model with siwave transmission line models to achieve a tradeoff between accuracy and simulation speed. Differential signals transmission ideally maintains good signal integrity and exhibits low electromagnetic emission or electromagnetic interference. Pdf how to model differential pairs on different layers with tline models. Design a differential via pair and investigate the.
Single ended and differential operation basic differential. Hfss and siwave allow for timedomain plotting of sparameters. The differential pair in hfss driven terminal simulation. However, the simulation results show that the differential impedance is 116. Compute the reflection and transmission coefficients of a frequency selection surface. Much of the material of chapters 26 and 8 has been adapted from the widely. It is essential for the design of high frequency and highspeed component design. The acronym stands for highfrequency structure simulator.
When the longitudinal components of the fields for the dominant mode of a microstrip. Getting started with hfss v9 for antenna design october, 2003 this getting started training material is intended for new users of hfss. How to use hfss to simulate the coupled striplines or make even. This book is an emphasis on engineering practice hfss electromagnetic simulation design tutorials. L wi for i 1, 2 are the inductances per unit length of the appropriate micriostrips, having widths w 1 and w 2, respectively.
Apr 09, 2018 this video compares the sparameter results for the differential pairs after solving the printed circuit board in ansys siwave with and without hfss regions. The part of the left is the differential part on right is a viscous coupling anyway, ill explain and you can look at the diagram. Base specification and design guide for serdes highspeed electrical signaling document version. Differential amplifier basics, usage and differences.
An ideal differential ramped step source with a magnitude of 1 v and a rise time t r of 50 ps is now driving the dsdml. Differential pair use early applications for differential pairs mecl i 1962 mecl ii 1966 mecl iii 1968 mecl 10k 1979 mecl 10kh 1981 ansitiaeia6441995 is the generic physical layer standard for lvds. Department of electrical engineering national taiwan university prof. Investigations have been led to define the appropriate cutout clearance rules. But, depending on the application, the differential pairs will most likely need to be relative to the length of other differential pairs in the same group. This video compares the sparameter results for the differential pairs after solving the printed circuit board in ansys siwave with and without hfss regions. Base specification and design guide for serdes highspeed. Since each trace is more tightly coupled to its adjacent reference plane than the opposite reference plane, any noise on the planes will not be common to both traces and thus, will not be cancelled at.
Aggressor separation microstrip routing requires a separation of 6h and 7h to properly manage the crosstalk coupling to. It consists of a square patch, a via, and a square block of substrate as shown in fig. Hfss ansys hfss is a 3d electromagnetic em simulation software for designing and simulating highfrequency electronic products such as antennas, antenna arrays, rf or microwave components, highspeed interconnects, filters, connectors, ic packages and printed circuit boards. An903a comparison of differential termination techniques. This is an animation from a simulation of a coplanar waveguide cpw done in ansys high frequency structural solver hfss. This slide refer the paper from ansofts an, differential pair analysis by j. A simple twinrod model for a differential via transition, consisting of a uniform differential pair, can be used to describe a differential via using simple coupled transmission lines as illustrated in figure 3.
New editions of this manual will incorporate all material updated since the previous edition. The objective is to provide a very thorough introduction to hfss as applied to antenna design, which may be followed stepbystep in. Mos differentialpair basic configuration two matched mos transistors common current bias differential signls applied to v g1 and v g2 equal amplitude but opposite sign differential outputs are produced at v d1 and v d2 note in differential configuration, v gs is fixed for both q 1 and q 2 i d1 i d2 i 2 i 2 k n 2 v gs. Can i make differential excitation direct in cst or hfss or. Figure 3 compares an optical module driver in both singleendeda and differential b modes. Their models include each via pair and the differential signal trace. In the lumped element model we have a pair of differential equations to describe the voltage and current along the line under the limiting argument which converts the circuit to distributed element form, we now have a pair of partial differential equations, which when.
I have done the impedance calculations to figure out the. I am trying to get the results of the paper attached. Hfss high frequency structure simulator hfss is an industrystandard simulation tool for 3d fullwave electromagnetic field simulation. Techniques for analyzing antenna lattice structures. I have a question about the differential pair definition in hfss driven terminal simulation. Sep 24, 2015 a differential amplifier has two inputs, one inverting and one noninverting. Consider two differential pairs routed on the same signal layer as shown in figure 9 with a height h from the reference plane. Analysis of commonmode noise for weakly coupled differential. Next, the unitcell of the sievenpiper mushroom structure has to be drawn in hfss. Numerical example of 15 signal viapairs and 20 ground shielding vias in 6 layer board. Hybrid simulation of a reflector antenna lecture 9. Position and dimensions enter the position and the dimensions of the created cylinder as shown in the gure below.
Wu microstriplines microstrip structure inhomogeneous structure. Let ports 1, 2, 5, 6 denote the first pair and ports 3, 4, 7, 8 denote the second pair. To get help about a specific, active dialog box, click the help button. Najmabadi, ece102, fall 2012 1933 differential mode circuit. Considerations for pcb layout and impedance matching. Ansoft hfss online help provides assistance while you are working. Emiemc and coexistence simulation methodology xavier lecoq. In the lumped element model we have a pair of differential equations to describe the voltage and current along the line under the limiting argument which converts the circuit to distributed element form, we now have a pair of partial differential equations, which when solved yield a solution that is a 1d traveling wave 23. Can i make differential excitation direct in cst or hfss.
Business business, international computers and office automation circuit printing design and construction printed circuit boards. Often, this feature is used to calculate a step response or timedomain reflectometry tdr plot of the structure being simulated. Considerations for pcb layout and impedance matching design. A differential amplifier has two inputs, one inverting and one noninverting. Click on the image to open in a new window the left and right drive gears have teeth on their sides. Ansys hfss tutorial simulate and analyze an example of trace and via.
Again, the exact number may be less, depending on the speed of the interface. Often, this feature is used to calculate a step response or timedomain reflectometry tdr plot of the. Find the quality factor of the resonator by sweeping the magnitude of impedance of a short line and observing the 3db bandwidth. Differential via two singleended vias used for differential signaling the minimum via pitch size is determined by the manufacturing specification the coupling overlap of e,h field lines changes the differential impedance, zdiff20. Differentials open, locked, limited slip, edl, quattro. Window functions and timedomain plotting in hfss and.
It shows the electric and magnetic vector fields at 10ghz as well as. Signal integrity analysis of highspeed interconnects. Search the hundreds of courses available and improve your. Problem description getting started create the 3d model analysis setup plot sparameters vs. Signal transmission analysis of differential pairs using semicircleshaped via structure r a b fig. Layout driven assembly in ansys electronics desktop. A good guideline to determine when the transmission line approach is necessary for logic signals. Aug 07, 2017 this is an animation from a simulation of a coplanar waveguide cpw done in ansys high frequency structural solver hfss. Most of the available toolbars are displayed in this illustration of the ansoft hfss initial screen, but your ansoft hfss window probably will not be arranged this way.
The acronym stands for high frequency structure simulator. In hfss, you can directly obtain the modal responses and characteristics of a multiconductor. Within the wave port dialog, the differential pairs tab controls the creation. Included in these notes are links to short tutorial videos posted on youtube. It is essential for the design of high frequency and highspeed component design 4. Design a differential via pair and investigate the signal. Currents about the symmetry line are equal in value and opposite in sign. I am wondering is the differential terminal port impedance equal to the odd impedance and the common terminal port impedance equal to the even mode impedance in the couple line. Window functions and timedomain plotting in hfss and siwave. Then essential simulation parameters include 3 figure 6. Hfss is a commercial finite element method solver for electromagnetic structures from ansys. This discussion will focus attention upon signal termination only as it applies to differential data transmission over twisted pair cable. A novel method to reduce differential crosstalk in a high. Differential amplifiers single ended and differential operation basic differential pair commonmode response differential pair with mos loads hassan aboushady university of paris vi b.
Using hfss for simulation and adk 7 for postprocessing. Although the dual backtoback vtcts do not introduce a length. How to model vias of highspeed differential pairs with. Due to the fields within two guidedwave media, the microstripdoes not support a pure tem wave. Preface these are notes for the lecture course \di erential geometry ii held by the second author at eth zuric h in the spring semester of 2018. They are attached directly to the end of the left and right output. Magnetic nearfield map of a digital interface with 4 differential pairs 3 data lanes and 1 clock figure 7. The objective is to provide a very thorough introduction to hfss as applied to antenna design, which may be followed stepbystep in hfss with the investment of only a few hours of time. Signal transmission analysis of differential pairs using. However, in practical circuits, the differential signal pairs may accompany unwanted common. Hfss results create report im or re z11 or 1y11 and find at which frequency the line could be used as a resonator. Transceiver link design guidelines for highgbps data. Razavi, design of analog cmos integrated circuits, mcgrawhill, 2001.
Introduction antenna definitions w what is an antenna. May 12, 2010 classified document the information in this document is ibmintel confidential and is protected by a confidential disclosure agreement when disclosed to other individuals of other corporations or entities. It was originally developed by professor zoltan cendes. Eecs 117a demonstration 4 hfss simulation of a transmission line. Training and tutorial material are available for both a broad range of ansys products and users experience. Ansys high frequency structure simulator hfss tutorial. Differentials open, locked, limited slip, edl, quattro the. Broadsidecoupled routes one trace exactly over the other on 2 separate layers as dual stripline. Voltages about the symmetry line are equal in value and opposite in sign. But in driven terminal the sheet is defined as port and we just need to. First we must configure hfss to use its eigenmode solver.