Differential signals transmission ideally maintains good signal integrity and exhibits low electromagnetic emission or electromagnetic interference. Hfss results create report im or re z11 or 1y11 and find at which frequency the line could be used as a resonator. It shows the electric and magnetic vector fields at 10ghz as well as. Differentials open, locked, limited slip, edl, quattro the. Broadsidecoupled routes one trace exactly over the other on 2 separate layers as dual stripline. This discussion will focus attention upon signal termination only as it applies to differential data transmission over twisted pair cable. Included in these notes are links to short tutorial videos posted on youtube. 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. Window functions and timedomain plotting in hfss and siwave. 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.
The acronym stands for highfrequency structure simulator. Hfss is a commercial finite element method solver for electromagnetic structures from ansys. Business business, international computers and office automation circuit printing design and construction printed circuit boards. Design a differential via pair and investigate the signal. 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. 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. A differential amplifier has two inputs, one inverting and one noninverting. A good guideline to determine when the transmission line approach is necessary for logic signals. It is essential for the design of high frequency and highspeed component design 4. When the longitudinal components of the fields for the dominant mode of a microstrip. 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.
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. Then essential simulation parameters include 3 figure 6. The acronym stands for high frequency structure simulator. Ansys hfss tutorial simulate and analyze an example of trace and via. 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. 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.
Analysis of commonmode noise for weakly coupled differential. In hfss, you can directly obtain the modal responses and characteristics of a multiconductor. Wu microstriplines microstrip structure inhomogeneous structure. Sep 24, 2015 a differential amplifier has two inputs, one inverting and one noninverting. 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. Najmabadi, ece102, fall 2012 1933 differential mode circuit. Consider two differential pairs routed on the same signal layer as shown in figure 9 with a height h from the reference plane. Can i make differential excitation direct in cst or hfss.
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. A novel method to reduce differential crosstalk in a high. I have done the impedance calculations to figure out the. Much of the material of chapters 26 and 8 has been adapted from the widely. It was approved in november of 1995, and first published in march of 1996. Differentials open, locked, limited slip, edl, quattro. Can i make differential excitation direct in cst or hfss or. Base specification and design guide for serdes highspeed. Next, the unitcell of the sievenpiper mushroom structure has to be drawn in hfss. 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.
They are attached directly to the end of the left and right output. Often, this feature is used to calculate a step response or timedomain reflectometry tdr plot of the structure being simulated. Using hfss for simulation and adk 7 for postprocessing. Hfss is an interactive simulation system whose basic mesh element is a. Aug 07, 2017 this is an animation from a simulation of a coplanar waveguide cpw done in ansys high frequency structural solver hfss. Signal transmission analysis of differential pairs using. Due to the fields within two guidedwave media, the microstripdoes not support a pure tem wave. 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. Considerations for pcb layout and impedance matching. Single ended and differential operation basic differential. Emiemc and coexistence simulation methodology xavier. To get help about a specific, active dialog box, click the help button. Design a differential via pair and investigate the.
Window functions and timedomain plotting in hfss and. Often, this feature is used to calculate a step response or timedomain reflectometry tdr plot of the. Introduction antenna definitions w what is an antenna. This slide refer the paper from ansofts an, differential pair analysis by j. 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. I have a question about the differential pair definition in hfss driven terminal simulation.
Ansoft hfss online help provides assistance while you are working. Hybrid simulation of a reflector antenna lecture 9. Again, the exact number may be less, depending on the speed of the interface. It was originally developed by professor zoltan cendes. Techniques for analyzing antenna lattice structures. Pdf how to model differential pairs on different layers with tline models. Investigations have been led to define the appropriate cutout clearance rules.
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. Signal integrity analysis of highspeed interconnects. First we must configure hfss to use its eigenmode solver. How to model vias of highspeed differential pairs with. Ansys high frequency structure simulator hfss tutorial. Figure 3 compares an optical module driver in both singleendeda and differential b modes. This book is an emphasis on engineering practice hfss electromagnetic simulation design tutorials. Search the hundreds of courses available and improve your. Ansys hfss tutorial simulate and analyze an example of trace and via tianjian lu 02014 tianjian lu ece 546. Ansoft high frequency structure simulator v10 users guide 5. 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. Base specification and design guide for serdes highspeed electrical signaling document version. Much has been written about terminating pcb traces in their characteristic impedance, to avoid signal reflections.
This video compares the sparameter results for the differential pairs after solving the printed circuit board in ansys siwave with and without hfss regions. Numerical example of 15 signal viapairs and 20 ground shielding vias in 6 layer board. Voltages about the symmetry line are equal in value and opposite in sign. Currents about the symmetry line are equal in value and opposite in sign. Their models include each via pair and the differential signal trace.
Magnetic nearfield map of a digital interface with 4 differential pairs 3 data lanes and 1 clock figure 7. However, in practical circuits, the differential signal pairs may accompany unwanted common. Training and tutorial material are available for both a broad range of ansys products and users experience. It is essential for the design of high frequency and highspeed component design. An903a comparison of differential termination techniques. L wi for i 1, 2 are the inductances per unit length of the appropriate micriostrips, having widths w 1 and w 2, respectively.
Emiemc and coexistence simulation methodology xavier lecoq. I am trying to get the results of the paper attached. New editions of this manual will incorporate all material updated since the previous edition. Differential equations department of mathematics, hkust. Layout driven assembly in ansys electronics desktop. Tools options hfss options general tab check use wizards for data input when creating new boundaries check duplicate boundariesmesh operations with geometry click ok. Eecs 117a demonstration 4 hfss simulation of a transmission line. 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. 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. However, it may not be clear when transmission line techniques are appropriate. The end goal of this example is to run a transient circuit analysis or lna simulation. How to use hfss to simulate the coupled striplines or make even. Within the wave port dialog, the differential pairs tab controls the creation.
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. The objective is to provide a very thorough introduction to hfss as applied to antenna design, which may be followed stepbystep in. Transceiver link design guidelines for highgbps data. Although the dual backtoback vtcts do not introduce a length. Differential amplifier basics, usage and differences. 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. Ee105 fall 2015 microelectronic devices and circuits. The differential pair in hfss driven terminal simulation. Compute the reflection and transmission coefficients of a frequency selection surface. But in driven terminal the sheet is defined as port and we just need to. Inside the microchip or pair of discrete transistors, the positive and negative signals are added and the resultant becomes the single output. The larger the coupling tight coupling is, the lower the differential.
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. It consists of a square patch, a via, and a square block of substrate as shown in fig. Position and dimensions enter the position and the dimensions of the created cylinder as shown in the gure below. Find the quality factor of the resonator by sweeping the magnitude of impedance of a short line and observing the 3db bandwidth. However, the simulation results show that the differential impedance is 116. This is an animation from a simulation of a coplanar waveguide cpw done in ansys high frequency structural solver hfss. 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. Hfss high frequency structure simulator hfss is an industrystandard simulation tool for 3d fullwave electromagnetic field simulation. Click on the image to open in a new window the left and right drive gears have teeth on their sides. Let ports 1, 2, 5, 6 denote the first pair and ports 3, 4, 7, 8 denote the second pair. 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. Hfss and siwave allow for timedomain plotting of sparameters.
Considerations for pcb layout and impedance matching design. Aggressor separation microstrip routing requires a separation of 6h and 7h to properly manage the crosstalk coupling to. 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. Razavi, design of analog cmos integrated circuits, mcgrawhill, 2001.
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