S1: The separation between the two traces of the. Here it is already defined in the schematic that this is D+ and D-. Differential pair impedance depends on a lot of variables in reality,. When you are creating your schematic, you must use one of the following suffixes when naming your differential pair nets: +/- (e. Going to route the following signals: 100R differential pair (Zo = 50R) 90R differential pair (Zo = 45R) Planning to use the stack up JLC7628, with a 4 layer PCB, in total 1. Such a microstrip is constructed with two traces referenced to the same reference plane with a dielectric material between them. The test sample consists of a pair of differential traces at the top layer, followed by a differential via to the inner traces, then a second differential via connects to the BGA landing pads at the top layer again. Radar Calculators. A PCB impedance calculator uses field solvers to accurately approximate impedance values. To use this calculator, simply input your microstrip geometry and Dk value, and the tool will return the differential impedance value for a pair of microstrip traces. Note that the driver output impedance may be configurable among various values. Keep the spacing between the pair consistent. There is a slightly different, but tightly coupled question here with this impedance calculator: "stripline differential impedance": Stripline here seems to be placed in some inside layer. At that point the rest of the description is missing, which includes wire diameter, insulation thickness and dielectric constant, and the number of twists per inch or other unit of distance. In a differential pairs, there exists four kinds of characteristic impedance: Single-ended impedance ($ ext{Z}_{ ext. I've learnt about it now and using my pcb specs (1. 8). So, strive to keep your traces short and far apart in high-speed design. In both cases, you’ll need to enter your stackup information into the calculator to get accurate results. In general, it is double the odd-mode impedance, which is the value we care about for differential signaling, as it is used in high-speed PCB design. Calculates the outer and inner layer diameters of a padstack given the drill size. Agilent's LineCalc tool calculates Z odd = 50. 8 substrates of various thicknesses. A PCB impedance table will provide the trace width required to have a target impedance value on a standard stackup. 1 mm. For example, ECL logic has a 50 Ω characteristic impedance, and TTL has a source impedance range of 70 to 100 Ω. A differential pair relies on symmetry of both. It’s sufficient to minimize your diffpair coupling to unrelated copper. Since it is always important that the trace impedance remain constant over the entire length, this means that the coupling must remain constant over the entire length. So, I am trying to figure out how to use Kicad’s PCB Calculator for “Coupled Microstrip Lines”: I’m unsure about what a couple of the parameters mean and can’t find an explanation in the docs (it just. Rs =. 81. . Before we can start routing the PCB, we need to define Design Rules for our differential traces. While the distance between the differential signals is lower (for impedance), area two show that the differential pair makes turns to make it longer while not keeping the same signal wire. This will give us the appropriate trace width and trace separation for the desired differential impedance. As the signals are also referenced to ground, each differential pair signal also has a single ended impedance. Differential pair length tuning. As logic circuits developed, the need for faster interconnects increased, making impedance levels increasingly important. This calculator finds both odd and even transmission line impedance. A differential stripline pair refers to two traces located between two reference plane. arrow-right Download and install the Analog Engineer's Calculator. Terminate far end of the pair with 90 Ohms resistor (it is odd mode. For the signal trace of width W and thickness T, separated by distance H from a ground (or power) plane by a PCB dielectric with dielectric constant εr, the characteristic impedance isEdge-coupled coated differential microstrip Edge coupled differential microstrip for flex PCB. Such a stripline is constructed with two traces referenced to the same reference planes above and below the traces with a dielectric material between them. These are pure estimates to. And doing so would avoid having to re-route the tracks, which is what you asked for. Atlas Si for VNA – Insertion loss test system – Delta-L 4. Given the defaults (1. pairs for aciving 85 Ohm diff. Fig 1 Typical Pi termination for a coupled line pair. g. So if layer 1 and layer 3 are ground planes and you place an RF signal track on layer 2 it will need to be x mm wide for 50. Impedance Calculators. 0: Conclusion. As also noted in the picture, the subsequent calculations are on the: [2] top-layer single-end impedance; [3] top-layer differential impedance; [4] inner-layer differential impedance. beammy. Use several of them and compare. Value of Zo calculated by impedance calculator is not relevant here. It's important to note that the TIA/EIA-644 does not define. This calculator requires symmetry in the trace widths and location between plane. One should always check carefully whether a calculator implements these equations under the appropriate approximations. The source for formulas used in this calculator (except where otherwise noted) is the Design Guide for Electronic Packaging Utilizing High-Speed Techniques (4th Working Draft, IPC-2251, February 2001. The following are typical line widths and spacings for the more common impedance values when using ½ OZ copper: 50 Ohm Single Ended: 0. The differential pair trace lengths should be matched with a tolerance of 20% of the signal rise/fall time. Note: The results are only for approximation and rough estimation, the final values and the. A PCB impedance table will provide the trace width required to have a target impedance value on a standard stackup. NOTE: The formulas used in the program are valid for 0. In order to maintain the impedance, I would like to use a power plane as reference beneath the signals, instead of the GND plane, as it provides better dimensions for routing (width and spacing) in the PCB toolkit calculator. L1=Ground, L2=signal/transmission lines, L3=Power, L4=signal or. When selecting trace geometry, priority should be given to matching the differential impedance over the single ended impedance. For example, when two traces with Z =50 W are well separated (uncoupled), the differential impedance between them should be precisely Z DIFF = 2. While commonly constructed using. Several Web sites such as the examples listed below contain additional reference information. 6. Added ability to include Er effective to the wavelength calculator. 5 to 4. g. 5) and 1. e. 5. The same in true for bottom layer. H1: Height of the dielectric between the trace and the reference plane. Modeling approximation can be used to understand the impedance of. In high-speed digital protocols, data is. Z0 = (60 / √εr) * ln ( (8h) / (w + s)) Where εr is the dielectric constant of the substrate material, h is the substrate height, w is the trace width, and s is the spacing between traces. As discussed previously, the lengths of the two lines in the pair must be the same length. There are a lot of online trace impedance calculators specifically designed for differential traces. 004” line. , broadside coupled, embedded microstrips, symmetric or asymmetric stripline, or regular microstrips. Finally, all calculators provide theoretical impedance values as they cannot take in to account the variables and. The targeted impedance for diff pair is 100 ohms, which is dependent on the width/space between conductors and hight to the reference plane. The impedance calculator in the Layer Stack Manager supports single and differential coplanar structures. This calculator finds both odd and even transmission line impedance, including four different types of impedance used in characterizing differential trace impedances, for microwave antennas, couplers and filters applications. , D+ and D- (TSKEW)) must be less than 100 ps and is measured as described in. Note that these differential. But it lacks the differential impedance (impedance between these two tracks). Some calculators will allow you to calculate trace impedance in a number of geometries, e. 4mils = 0. I used the KiCAD PCB calculator, asked the PCB manufacturer about the tangent loss (0. High-speed PCB design goals • Tight impedance control (eg 100Ω ±5%) • Minimize impedance mis-match (eg 100Ω ±10%) • Minimize use of via and via stub • Minimize insertion loss (typical -1. is the impedance between two differential pair signal traces. However, PCBWay's calculator also reports a single-ended impedance along with the differential impedance. 15 mm spacing. For instance, I want a 100 Ω controlled impedance pair, and have used "differential" before which seemed to work fine. The guides says spacing under 0. High-speed data on differential links must be de-skewed to achieve the maximum eye opening and avoid mode conversion. png . 4mils, w = 12. 8065. W W = trace width. zip (170k) AP117. g. 1. Sierra Circuits’ Via Impedance Calculator uses the physical dimensions of a via to calculate its capacitance, inductance, and impedance. 0 and (t/h) less than 0. 3. Impedance and PCB Stacking The trace impedance is affected by many factors such as the width of the trace, th e thickness of the copper, the PCB material, the PCB stacking specification, and the spacing between the differential pairs. In case your board only routes differential pairs between two connectors, you may not even have ground connected via cable shield to connector metal frame. Atlas Si for TDR. There are some signal integrity issues with de-skewing in traces: Impedance. Just as important as determining an appropriate trace width for a single-ended trace is determination of an appropriate spacing between two traces in a differential pair. Ls =. 1<W/H<3. microstrip Zo vs Edge Cpld Ext Zo). D+ and D-) _P/_N (e. The typical method for matching timing in a differential pair is to match the lengths of the two lines at the source of the interconnect, also known as phase matching. Learn more about working with design rules and constraints. Also, be aware, 90 ohms is the differential impedance, the characteristic or single ended impedance will be more than half (ie. (Sorry guys, I live and I have grown up in a metric world ) With these values, Saturn PCB's off-line calculator gives 57 Ohm differential impedance. For assistance, we provide our impedance calculator. NOTE: The formulas used in the program are valid for 0. Using the KiCad Impedance Calculator. When enabled. Make sure you use an accurate tool like this. TheIt does not work. CAN bus layout design. You must estimate the differential trace insertion loss in dB/inch for the trace loss budget based on the selected PCB materials and stackup. To calculate the impedance, I use Saturn PCB impedance calculator software, Inc - PCB Toolkit V8. The reason for this is that the input impedance is what matters, and the input impedance at the via transition will look like the trace impedance (i. D+ and D-) _P/_N (e. With PCBWay impedance calculator, you can calculate the approximate impedance of your PCB / high frequency circuit board. In high-frequency systems using differential pairs, unbalanced currents, or ground currents, take the path with the least impedance. L R ≈ 5mm (0. Low-voltage differential signaling (LVDS) is codified in the TIA/EIA-644 standard and is a serial signaling protocol. KiCad has a built-in impedance calculator!Maximize System Performance With LVDS PCB Layout Guidelines . DC power being carried by a trace determines the temperature rise in the trace, which should be limited in general. I used Saturn PCB design to calculate width and spacing between conductors. Differential impedance is another factor you should probably consider when dealing with impedance. This will leave the rest of the signals which are rather non-critical like I2C, power good signals, etc. Learn how to configure, define, and use your design’s impedance requirements for single-sided and differential on each layer, with Altium Designer’s Layer St. The grounded differential coplanar wave guide is the differential version of the grounded coplanar wave guide and is used in high-speed digital systems that require maximum noise immunity. BGA land calculator based on the IPC-7351A specification. A twisted-pair cable is simply two wires that are twisted together so as to reduce radiated EMI (electromagnetic interference) and mitigate the effects of received EMI. 1. Take account, the internal used formulas sometimes don't equal on Conductor Impedance tab and on Differential pairs tab (e. I am using Altium Designer and it has a nice impedance calculator which tells you the required track width for a desired impedance given the layer stack you have configured. Modeling approximation can be used to design the microstrip trace. differences being that if you wish to change the track thickness and spacing as the differential pair changes layers in the PCB to control impedance then they should be defined as a Physical CSet. The factors that influence differential pair via impedance will affect the input impedance seen at the vias. 5 to 4. e. For context, as I understand it, the Ethernet pairs between the PHY and magnetics need to be impedance controlled to 100ohm and they need to be routed (ideally) in parallel, and the trace space and trace width are important variables in the impedance control. I am designing a flexible PCB to carry two types of differential signals. 08-07-2018 02:42 AM. g. A cheap unshielded laminated polyester FPC cable with 0. In a previous article, we have seen how to route a differential pair signal. The differential via design shown in Figure 2 was built and tested. Remember, the lower the impedance the greater the current drain, the higher the. The surface finish is neglected. This simple impedance calculator had a number of limitations, including requiring return paths to be implemented by plane layers, only supporting symmetrical stripline board structures, and no support for differential. 2. Is this a good practice for Ethernet? This is a capture of the PCB right now: This is the schematic that I am using. 6193. 5mm pitch has about 100 ohm differential impedance in the configuration where a differential data pair wires are between ground. Take a look the new Conductor Impedance tab Assymetric Stripline, where they are already enabling to select to internal used formula. Suggested typical numbers for LVDS PCB using microstrip are, t = 1. The designer needs to create a stackup for the board and then calculate the trace values for differential pairs and single-ended nets. To optimize the PCB trace impedance and stackup, you must follow the key notes below: If thin dielectric layers with high dielectric constant (Dk) cannot be. This calculator determines the impedance of a symmetric differential stripline pair. One thing is for sure: When you are routing a high-speed PCB design you are going to be working with impedance-controlled routing and differential pairs. The nice part about coax is that it can be bent and flexible unlike most pcb transmission lines. When you are creating your schematic, you must use one of the following suffixes when naming your differential pair nets: +/- (e. 3) to calculate trace width and. High speed digital designers should. Fringing Electromagnetic Fields Coupled Fields Microstrip StriplineThe PCB design tools in Allegro include an impedance calculator that will help you size your traces so that they have defined characteristic impedance. In many application notes how to make an Ethernet interface, the wiring. The weave is much too coarse which means that as the pair runs along the board, the impedance changes continuously due to the dielectric constant varying. 5 mil (2116 prepreg) or 8. Technical Consultant Zach Peterson explores a viewer question surrounding Coplanar Routing, specifically how to route on a single-layer board. The latter for embedded dual stripline layers only. 3mm, as shown below: This increases the impedance slightly to 91. There are four different types of impedance used in characterizing differential trace impedances. 03) it gives me almost 160 Ohm - and even if use 53mil conductor height or. It's true that generally the impedance value is determined by the following parameters; trace layer (microstrip or stripline), trace width, distance. Finally, all calculators provide theoretical impedance values as they cannot take in to account the variables. Also, be aware, 90 ohms is the differential impedance, the characteristic or single ended impedance will be more than half (ie. beammy. The Smith Chart achieves this by superimposing a grid on S11 that maps load impedance. Zachariah Peterson | Created: November 22, 2021 | Updated: June 25, 2023 Table of Contents Differential Impedance Defined Formulas for Differential Impedance Should You Use Characteristic or. To calculate geometry for 90OHMs Differential pairs routed on 2 layer PCB (Differential impedance of Microstrips) you need to know: width of the traces, space (gap) between the traces, height of dielectric above return plane, trace thickness and relative permittivity of the dielectric. This makes the problem of determining impedance much more complex, and building an initial lossless model requires a larger set of formulas. png . of typical printed circuit board trace geometries. 0175mm of Copper (1/2 oz), gives me a best estimate of 9mil trace, 4mil space for a 90R differential microstrip impedance. USB traces must be 90 Ohms differential. Differential pair routing information; High-speed routing information such as constraints for trace lengths, matched lengths, topologies, and controlled impedance lines; Don’t be afraid to add as much information as possible to the schematic to promote design intent in the board layout. Z 0 Differential impedance (Ω): Calculate. The geometry of the traces, the permittivity of the PCB material and the layers. THESE FORMULAS ARE APPROXIMATIONS! They should not be used when a high degree of accuracy is required. 75 mm track on a 0. 3 V, etc. If they aren't that high, then don't worry about matching on the PCB, but use. or Differential Pairs Routing design rule. In tab “TransLine” i chose “Coupled Microstrip Line” and i can calculate the impedance of only one track. 50 - 55 ohms). Note: If this post answers your question, please click the Correct Answer button. 25, but gives me nice trace from the module to the stub then to microcontroller. 9. Dimensional units: mm mils. Some differential impedance requirement for differential pairs, where the signals must be routed together Just as an example, consider a 2-layer board on standard thickness 62 mil core (Dk = 4. The example below shows how adjusting the stitching via placement could affect a differential via. Ethernet cables can be unshielded so obviously just two wires without a ground plane can work. The etch length of the differential pair groups do not need to. 22 mm; trace distance: 0. This video explains the most common layout topics for USB signals: impedance, trace length and matching, and printed circuit board (PCB) stack-up. Understanding coax can be helpful when working with it. 3 as fr4 material with 1. Altium Designer makes it easy to calculate geometry when you need to calculate impedance for differential pairs. We’ll go over how differential pairs can hel. Additionally, it only takes into account single-ended structures (not. To use this tool, enter the values for. If you’re designing an RF PCB for. Impedance Calculation. ; Edge coupled differential pair ; Edge coupled internal symmetric differential pair ; Edge coupled internal asymmetric differential pair ; Edge coupled embedded differential pair ; Broadside coupled shielded differential pair This calculator is designed to calculate the characteristic impedance of a broadside couple stripline (see diagram below). Now to tuning the impedance of your diffpair’s PCB traces. For differential vias, stitching vias can affect the impedance, but the impedance is much more sensitive to antipad sizes and layer arrangement/Dk value on each layer. Quote Now . « Reply #7 on: April 21, 2023, 03:42:36 pm ». But it lacks the differential impedance (impedance between these two tracks). Click on Setup -> Constraints > Electrical Constraints Set - > Differential Pair Value - > Calculator > If you put 10 in the Line Width, the calculator calculates the single ended as well as differential impedance. There have been trace routing tools available for a long time that help with differential pair routing. 5GHz. Distance between pairs should be (traces on top layer = microstrip) 4 times the layer. . 6mm thick. 8 core of FR4 material, we would have a propagation delay of approximately 150 ps/inch, or approximately 6 inches/ns. Eurocircuits’ Impedance calculator uses real values as defined in the supplier’s data sheets. I believe the 100-ohm differential equates to 50-ohm single ended because you can think of the two 100-ohm impedances as being in parallel resulting in an effective 50-ohm single-ended equivalence. Figure 81 shows the topology. 30967mm) is slightly larger the size of the smallest pad (0. 6mm thick, 1. This controls the differential impedance. nm um mm cm m mil inch. 5 mil as the thickness of 3313 prepreg when the controlled impedance tracks are on top/bottom, use 5. PCB Trace Impedance Calculator Calculates the characteristic impedance and per-unit-length parameters of typical printed circuit board trace geometries. Propagation delay (t pd) in PCBs is the time taken by a signal to travel through a unit length of a transmission line . Eurocircuits’ Impedance calculator uses real values as defined in the supplier’s data sheets. Differential pair into PCB calculator. 1. The ICD Stackup Planner calculates characteristic impedance plus edge coupled and broadside coupled differential impedance. To be precise, the current flows through the. 90 Ohm Differential Pair: 0. There is only one method I am aware of that gives any level of accuracy for differential via impedance calculations, and it starts from a calculation of the propagation delay through a pair of differential vias. D+ and D-) _P/_N (e. This note describes some of the practical difficulties you'll sometimes run into when testing a controlled impedance PCB. The amplitude increases as the coupling length increases up to a point. Unfortunately, stating “should match the input impedance of the differential vias/pads” in Point #3 is easier said than done. This is representative of a 50 Ω microstrip on the top layer of a 4-layer PCB. The receiver, which is on the motherboard, is a standard LVDS receiver, with 100Ω termination resistors. PCB Routing Requirements for USB 2. Microstrip Mitred Bend Calculator. Several Web sites such as the examples listed below contain additional reference information. With its fast, accurate, frequency-dependent transmission line modeling, the Si9000e is designed to model transmission line loss, impedance at given frequencies and extract full transmission line parameters over a wide range of popular PCB transmission lines (over 100 structures). Try TNT or TxLine. Typical impedance tolerances are 10% and 7%, and can go as low as 5% or 2%. The CAN bus shall be split-terminated with 120Ohm, 60Ohm for each line. They are very simple to read, and the. Grounded Differential Coplanar Wave Guide. Changed how the wire gauge calculator works, added max amps in air. . Added edge. It always defaults to 10mil. 2 PCB Stack-Up and Board Layout. Vias (plated holes) are used to route electrical signals among different layers of a multilayer layer PCB. If you require a controlled impedance PCB, you should discuss. The differential skew is adjusted with a tiny blip on one line towards the bottom of this image. 004” line/0. pair impedance with predifined traces’ gap. The same figures put into pcbway's calculator give me 115R, and the same. PCB manufacturer generally verifies the impedances with impedance coupon (traces drown during design in a separate portion outside our. 8. Distance between tracks (s) = 254 micron. Use Saturn PCB's toolkit with the "Differential Pairs" tab. The impedance calculator determines the signal properties and clearances (first image), use that clearance in the via shielding Distance setting. Using the wrong impedance will cause the signal to be reflected inside the track. Assuming both. This is good for routing space, but not so good for power delivery if there is a need for interplane capacitance. Impedance and PCB Stacking The trace impedance is affected by many factors such as the width of the trace, th e thickness of the copper, the PCB material, the PCB stacking specification, and the spacing between the differential pairs. The next graph investigates this further. However, in odd mode the centre of the resistor will always be at 0v. 4mils = 0. Placing a Differential Pair directive on each pair net applies a parameter to the net,. It could result 5 Ohm resistance. For example, a single 0. differential impedance: 90. Supports Anritsu ShockLine™ MS46524B and VectorStar™ MS4647B. It is okay to specify the single-ended impedance for each differential pair member. PCB Trace Impedance Calculator. 0 interface. 4 ohms; differential impedance: 90. The idea here is to determine the spacing required for a given width with the goal of hitting a specific differential impedance value. Differential Stripline Impedance Calculator. For FR4, the route length at which transmission line effects need to be considered can be calculated as: L R ≥ T R × 49. The calculator shows 90 ohms can be achieved using. AC coupling capacitors can be positioned anywhere throughout the differential pair’s length. When designing high-speed boards, you need to worry about two things: length matching in parallel nets and differential pairs, and specified trace lengths to comply with specific routing standards. Single-ended and differential pair routing guidelines impedance will have defined geometry to ensure impedance goals are met. The same applies to common mode impedance, except that. Now to tuning the impedance of your diffpair’s PCB traces. Going to route the following signals: 100R differential pair (Zo = 50R) 90R differential pair (Zo = 45R) Planning to use the stack up JLC7628, with a 4 layer PCB, in total 1. The image below tells a thousand words. But for extreme geometries and for many differential pair structures, these approximations can. eu. The tool implements numerical solutions of Maxwell’s equations to render accurate and consistent results. There are some advantages to using a microstrip transmission line over other alternatives. Using the KiCad Impedance Calculator. Note that the net pair must be named with net label suffixes of _N and _P. Crosstalk Area. Differential Pair Routing. For differential pairs, there is also a spacing value given. Copper thickness (t) = 18 micron. KiCad has a built-in impedance calculator!The two traces comprising a differential pair, when routed close together, share a certain amount of cross-coupling. But I'm unsure if the Height I entered is. This calculator helps translating the color bars from the resistor to its value. Advertisement Board thickness (h) = 50 micron. The trace width is then adjusted to achieve the neces-sary impedance. The standard specifies a two-wire differential bus; the characteristic line impedance is 120 Ohm. The formula used in this calculator is an approximation for the characteristic impedance of a coplanar waveguide: scssCopy code. ; Make sure D > 2S to minimize the crosstalk between the two differential pairs. 25mm between the differential pair with a width of 0. Note the differential pairs above that look like a strand of intestine have a constant gap between the pairs. H 1 H 1 = subtrate height 1. • As shown in Figure 1, traces should be 100-Ω(±5%) differential impedance of differential microstrip or differential stripline. ZO *. PCB Trace Impedance Calculator. I make that clearance at least 3 times the distance from your diffpair to its reference plane (i. Therefore i tried using this paper to calculate a characteristic impedance of 60Ohm for a coplanar strip attaching the CAN-Transceiver to a Twisted Pair cable, the CAN bus medium. When you are creating your schematic, you must use one of the following suffixes when naming your differential pair nets: +/- (e. A differential stripline pair refers to two traces located between two reference plane layers, which are routed as a differential pair. 004” trace, 0. Coax Impedance (Transmission Line) Calculator. For differential pairs, there is also a spacing value given. The default units for all given values, except the. The via transitions start to really matter above 5 GHz. Differential impedance: This is the impedance of a pair of transmission lines. While, when it comes to flexible and. Board. PCB Impedance Calculation. 3 * 1. $egingroup$ Note that it is possible to get 'free' impedance test coupons (the PCB fabricator will charge you for them). So in Saturn PCB I have indicated in target zdiff : 90 Conductor spacing: I don't. The following options in the Options for PCB Project dialog are used to configure this:. 34, 40, and 48 Ohms single-ended impedance are common, and each of these will have a specific corresponding differential pair impedance. The differential pairs should be loosely coupled. Note: Units do not matter for this calculation as long as they are consistent. As also noted in the picture, the subsequent calculations are on the: [2] top-layer single-end impedance; [3] top-layer differential impedance; [4] inner-layer differential impedance. With PCBWay impedance calculator, you can calculate the approximate impedance of your PCB / high frequency circuit board. PCB Stackup Impedance Calculator Calculates the characteristic impedance per unit length parameters of typical Some of the common Dielectrics & their values: Relative. Trace width and spacing depend on your PCB stackup. First and most common is to have a set of instructions or a table on the fabrication drawing describing the target impedance of traces broken down layer by layer for each impedance type in use. temperature rise. Step 1 Calculate singled ended impedance for each: Use "impedance + trace space" from top drop down box: Set Z=50R, click single ened, gives a result of track. The differential impedance of MIPI tracks should be 100 Ohms, not 90 (USB requires 90). Select the Calculator button. Changed how the wire gauge calculator works, added max amps in air. 1<W/H<3. 1,481. It was very hard to achieve a differential impedance of 100R with such a thin dielectric, so it was suggested that I used a hatched ground. There are 3 types of single-ended models: single-ended non-coplanar, coplanar single. The Layer Stack Manager in Altium Designer includes an impedance calculator that accounts for copper roughness. This calculator determines the differential microstrip impedance of a transmission line. Stack Symmetry – enable to add layers in matching pairs, centered around the mid-dielectric layer. Oct 29, 2021.