pcb differential pair impedance calculator. Grounded Differential Coplanar Wave Guide. pcb differential pair impedance calculator

 
 Grounded Differential Coplanar Wave Guidepcb differential pair impedance calculator  Figure 81 shows the topology

This link also has a track maximum current calculator, crosstalk calculator and thermal via calculator. A coplanar waveguide calculator will operate in one of two ways. Not too tricky. e. Assuming both. For differential pairs, there is also a spacing value given. 159 OS X 10_15_7 EasyEDA. The microstrip is a very simple yet useful way to create a transmission line with a PCB. The differential pair impedance depends on the characteristic impedance and the spacing between each end of the differential pair. 5; w, t, s, h > 0;Made in Europe. png . 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. 004” trace, 0. THESE FORMULAS ARE APPROXIMATIONS! They should not be used when a high degree of accuracy is required. 19mm) traces with 7. Once you know the characteristic impedance, the differential. A differential pair relies on symmetry of both. 4 ohms; differential impedance: 90. net Forum. g. 3. 3 can then be used to design a PCB trace to match the impedance required by the circuit. 1. g. The next graph investigates this further. ZL =. Calculates the outer and inner layer diameters of a padstack given the drill size. With t = 35 um (typical for copper with plating on a pcb), Z odd drops to 44 ohms, according to LineCalc. Assuming both. In fact, striplines often make components such as band-pass filter's more accurately, with more symmetric roll-off and no lower cutoff frequency. I have a 2 layer 1. 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. PCB impedance calculator – Single ended / Differential pair. 8). 6. 4. 25. One rule of thumb for defining spacing between each trace in a differential pair is the “5S” rule, sometimes called the “5W” rule in application notes and other PCB design guidelines. We recommend the software from Polar Instruments if you want to get exact impedance calculation. 3. pH nH uH mH H kH. When you are creating your schematic, you must use one of the following suffixes when naming your differential pair nets: +/- (e. 1kOhm, 1% tolerance: Brown Black Black Brown Brown. This calculator helps translating the color bars from the resistor to its value. I make that clearance at least 3 times the distance from your diffpair to its reference plane (i. At the receiver, the signal is recovered by taking the difference between the signal levels on. 1. THESE FORMULAS ARE APPROXIMATIONS! They should not be used when a high degree of accuracy is required. Microstrip Mitred Bend Calculator. But it lacks the differential impedance (impedance between these two tracks). ISO 11898 requires a cable with a nominal impedance of 120 Ω; therefore, you should use 120 Ω resistors for. Check design with the online gerber viewer, Easy and quick PCB Price Calculator from JLCPCBWhen you are creating your schematic, you must use one of the following suffixes when naming your differential pair nets: +/- (e. PCB impedance control is an important design constraint when working on high-frequency circuits. 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. g. 35mm gives 50Ω, far easier to use. Video library. Understanding coax can be helpful when working with it. **Note: Like our stripline impedance calculator, all of our RF calculators allow SI prefix input. While you can get away with small impedance mismatches, some signal drivers will have an impedance that does not match the standard 50 Ohm value typically used with signal traces. 34, 40, and 48 Ohms single-ended impedance are common, and each of these will have a specific corresponding differential pair impedance. But I am not able to match this impedance. Simons, "Coplanar Waveguide Circuits, Components, and Systems", Wiley. Saturn PCB Design Toolkit Differential Pair Impedance Calculator. Changed how the wire gauge calculator works, added max amps in air. On an impedance controlled layer (for example, with 100 diff), find an unused area and run a differential pair and expose at each end to the surface with test pads. PCB impedance calc and clearance. 1 Answer. . 52mm fr-4, 1oz cooper) and a target of 90ohm differential impedance, i calculated a value of about. For a Dk = 4. 4. Right-click and choose Change from the pop-up menu. Use via-s (absolutely not recommended for impedance-critical routes) hack the connector and remove some of its SMD pins, and wire one pair under those pins. 00:11:15 | 18 SEP 2019. 004” line/0. We often say that PCB traces should simply have 50 Ohm impedance, but this becomes more complicated when dealing with coupling between differential pairs. 1 ohms; In addition to those calculation I found some other resources with some sample trace properties: Mikrocontroller. temperature rise. 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. when i use Saturn PCB design to match the differential impedance to 100ohms i get 0. Twisted pairs are used with balanced signals. Coaxial Line Impedance. pairs for aciving 85 Ohm diff. 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. [2] Calculate the top layer signal end impedance: Two tools are giving Zo=48 and Zo=47. A PCB impedance table will provide the trace width required to have a target impedance value on a standard stackup. PCB manufacturer generally verifies the impedances with impedance coupon (traces drown during design in a separate portion outside our. We recommend the software from Polar Instruments if you want to get exact impedance calculation. As most designers know, the impedance control in FR4 PCBs and PTFE PCBs are easy since the surface are almost absolutely flat, and there are many impedance calculating tools for choice. 1. Complete the routing of a PCB design can be one of the most demanding PCB-related tasks. Coplanar waveguides are open quasi-TEM waveguide geometries that use copper pour and a ground plane to provide shielding along the length of. This calculator is designed to calculate the characteristic impedance of an edge-coupled microstrip. Use the Series and Shunt Impedance Calculator: to try your own impedances; Change Grid: S11, (ZL normalized to source impedance Z0) Z_Load: Z_Load: Matching Network Calculator. On a reference plane, there is an edge coupled differential microstrip line with two traces. Agilent's LineCalc tool calculates Z odd = 50. trace geometry, and use this to calculate. Differential Pair Impedance Calculator. If you're trying to get your own pcb design project , you should use this tool. 100 ohm differential pairs that are tightly coupled have a typical single ended impedance of around 65 ohms. Using the KiCad Impedance Calculator. It uses the lan9512 reference schematic. Implementation of these guidelines can help designers maximize the performance of the. Ohm’s Law provides the framework for solving network analysis problems; when the curtain gets pulled back, Ohm’s Law updates to become the relationship between voltage, current, and impedance, not resistance. Microstrip Impedance Calculator. 2. 8 substrates of various thicknesses. 035 ohms; single ended impedance: 45. Si TRC – Track Resistance Calculator calculates DC. Create a new impedance profile, then select Single. Single-ended impedance of 50 Ohm. This calculator finds both odd and even transmission line impedance. This makes the problem of determining impedance much more complex, and building an initial lossless model requires a larger set of formulas from Wadell. These parameters include:This is eight layer stackup. 4mils/35um of copper thickness. The microstrip is a very simple yet useful way to create a transmission line with a PCB. The following are typical line widths and spacings for the more common impedance values when using ½ OZ copper: 50 Ohm Single Ended: 0. • As shown in Figure 1, traces should be 100-Ω(±5%) differential impedance of differential microstrip or differential stripline. Note: If this post answers your question, please click the Correct Answer button. g. PCB Traces. Skip to main content. The trace width is then adjusted to achieve the neces-sary impedance. Follow the 8W spacing for differential clocks (or explore other rules) Even greater spacing is needed for high-speed differential signals. We’ll go over how differential pairs can hel. 3. 5oz inner copper, 8 mil trace spacing) and a target differential impedance of 100 ohms, JLC's calculator suggests a trace width of 8. For more information see "Interactively Routing with Controlled Impedances on a PCB in Altium Designer: Routing Width Design Rule" in the official documentation. 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 Broadside coupled non. Using the KiCad Impedance Calculator. By running a mating ref trace through the crosshatch you emulate a solid plane and can use a standard impedance. dear friends I want to route 100 ohm differential pairs of LAN on two layer pcb ( 1. Eurocircuits also calculates the correct Differential Impedance values using the correct formula and not a ‘Rule of Thumb’ method. There are many calculators available online, as well as built into your PCB design software. 8 core of FR4 material, we would have a propagation delay of approximately 150 ps/inch, or approximately 6 inches/ns. 1. This calculator is designed to calculate the characteristic impedance of an edge coupled stripline. Microstrip Impedance Calculator. If you have a dense 16-layer board, and your note reads: “All signal layers: 0. A cheap unshielded laminated polyester FPC cable with 0. , PCIe Gen 2 and Gen 3) also use a different value for differential pair. The guides says spacing under 0. When you have a USB you need to create differential pairs and KiCad ma. 3. NOTE: The formulas used in the program are valid for 0. 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. This transmission line calculator. . Note: The 6-Layer board temporarily only provides JLC3313 Stackup. W is calculated to achieve a trace impedance (Z0) of ~50W and S is calculated to achieve a differential trace impedance of 90W. By understanding the microstrip transmission line, designers can. Earlier versions of the PCB editor included a simple impedance calculator, with limited support for unusual board structures. 0. 5. Modeling approximation can be used to design the microstrip trace. A PCB's trace impedance depends on its geometry, core and prepreg material, and layers. . In a differential pairs, there exists four kinds of characteristic impedance: Single-ended impedance ($ ext{Z}_{ ext. Track width (w) = 137 micron. 25mm between the differential pair with a width of 0. From it, apart from making all traces the same length from camera sensor to cable connector, I believe the rules I need to follow are: Differential impedance of 100 Ohm. UTP= Unshielded Twisted Pair, at least I am guessing that is what it means in this context. Several Web sites such as the examples listed below contain additional reference information. We’ll go over how differential pairs can hel. The amplitude increases as the coupling length increases up to a point. When you try to calculate track geometry (track width and spacing) for specific impedance on 2 layer PCB, usually you end up with very weird numbers - means you may give up on trying to use that width. 004” line. 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. Note: Use the following guidelines when using two differential pairs: D = Distance between two differential pair signals; W = Width of a trace in a differential pair; S = Distance between the trace in a differential pair; and H = Dielectric height above the group plane. Select a configuration: Microstrip Trace. common impedance: 19. To use it, first select the tolerance of the resistor: 10%, 5% or equal or smaller than 2%. D+ and D-) _P/_N (e. Use several of them and compare. 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. . When working with differential pairs, your trace spacing and geometry will determine the impedance of each trace and of the pair. Note that the y-axis is on a logarithmic scale for clarity. Here, we are using a USB 2. NOTE: In order to understand the PCB Toolkit version differences, I have added this brief description of the version series. The process for impedance matching in high speed PCB designs depends on the signaling standard, supply voltage levels, and signal levels. 0 and 0. Conclusion. Unit: Options are mm, mil, μm, and inch. If you need to use differential pairs, you simply define traces in each layer as differential pairs and the impedance calculator will determine the correct spacing between traces. At some point the amplitude will stay constant. PCB impedance calculator – Single ended / Differential pair PCB manufacturer normally provides information about PCB stackup and track geometry. 1 is an example of making tradeoffs between routing layers and power plane capacitance for a ten-layer PCB. There are a lot of online trace impedance calculators specifically designed for differential traces. 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. 0037” line/0. KiCad has a built-in impedance calculator!Signals on an FR4 PCB travel at approx half the speed of light, so you'd want to make your longest trace no more than 44 mm longer than the shortest trace. differential impedance: 90. First of all, we need to clarify the concept of characteristic impedance. 0. The impedance calculator determines the signal properties and clearances (first image), use that clearance in the via shielding Distance setting. The USB port (Pins USB DP and USB DM) must be routed as 90 ohm differential PCB traces. , the via is electrically short). of typical printed circuit board trace geometries. The two points at the beginning of the pair might be weakly coupled, but adding or removing some copper at the source end allows you to match pair lengths while ensuring common. If the calculator does not provide velocity (or velocity factor), it's probably because you can use e_eff instead. T1: Thickness of the trace. This will give us the appropriate trace width and trace separation for the desired differential impedance. Giving the PCB house the data can take one of two forms. 1mils. Edge Coupled Stripline Differential Impedance Calculator. g. It worked for a while, then it began destroying random devices, obviously because of other design errors. 127mm, or 127 μm for the calculator’s purposes. net Forum. Typical impedance tolerances are 10% and 7%, and can go as low as 5% or 2%. In a previous article, we have seen how to route a differential pair signal. Differential pairs are commonly found in high-speed data communication systems, such as those used in computer interfaces (e. Make sure you use an accurate tool like this. While it is not necessary or a requirement to match the PCB 'stubs' it's probably a good idea if the speeds of your RS485 bus are high (+50MHz). The other yellow rectangle is the USB connector. 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. Assuming the differential pair I am routing is requiring 90 ohm (this is what the hardware guideline say "Route the USB differential pair on the top layer with a trace width and differential spacing tuned to the PCB stack-up for 90Ω differential impedance "). beammy. Polar UK: Si9000e PCB transmission line modeling. The PCB Impedance Calculator in Altium Designer. . The Differential Pair Impedance Calculator is a specialized tool used in electrical engineering and signal integrity analysis to determine the characteristic impedance of a differential pair of transmission lines. Transferring the Differential Pairs to the PCB Editor from Schematics. Either or both of these rules may be important in your design, it all. 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. 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. 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. Impedance. 6mm thick. The two most common impedances. Just as was the case with microstrip impedance calculators, stripline impedance calculators tend to rely on either the IPC-2141 formulas or on Wadell’s equations. 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. Impedance Calculators. The impedance calculator in the Layer Stack Manager supports single and differential coplanar structures. While the length and impedance are both important, 1mm of length differential will not affect your system's performance in any way, even for usb-2. 25mm, a trace width of 0. 5mm pitch. Here it is already defined in the schematic that this is D+ and D-. So, the trace width and distance to adjacent reference plane is determined by the desired. DC power being carried by a trace determines the temperature rise in the trace, which should be limited in general. 5) and 1. Re: Differential impedance calculation. eu. This delay results in timing errors, data skew, clock, and data mismatches, and causes reliability issues. It is recommended that DP link PCB traces maintain 50 Ω±15 % single-ended and 100 Ω±20 % differential impedance to maintain signal integrity. This is the odd-mode impedance of the differential pair. 5 to 4. This assumes ~0 trace thickness. W2: Width of the top surface of the trace. The standard specifies a two-wire differential bus; the characteristic line impedance is 120 Ohm. The impedance of a differential pair depends on the self capacitance and self inductance of each trace, and the mutual capacitance and mutual inductance between each trace. The propagation of electrical signals through PCB traces is not instantaneous; it is subject to a delay. Some calculators will allow you to calculate trace impedance in a number of geometries, e. Also, be aware, 90 ohms is the differential impedance, the characteristic or single ended impedance will be more than half (ie. KiCAD doesn't have a calculator for differential coplanar waveguide. 15 mm spacing. Impedance in your traces becomes a critical parameter to consider during stackup. This coupling lowers the differential impedance between the traces. ; 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 Overview. D+ and D-) _P/_N (e. The Smith Chart achieves this by superimposing a grid on S11 that maps load impedance. With PCBWay impedance calculator, you can calculate the approximate impedance of your PCB / high frequency circuit board. This is good for routing space, but not so good for power delivery if there is a need for interplane capacitance. 5. S1: The separation between the two traces of the. In the case where you are routing differential pairs, then the potential between the two pairs will always be opposing (i. g. L R ≈ 5mm (0. Instant online PCB quote, get PCBs for only $2. Atlas Si for TDR. By the way, I’d recommend using Saturn PCB Design Toolkit for impedance and other PCB calculations. . D_P and D_N) KiCad looks for these suffix pairs when using the differential pair routing tool during PCB layout. is the impedance between two differential pair signal traces. Impedance Control. If the goal is to adjust the characteristic impedance, then you can likely do it by changing both width and spacing (keeping center-to-center the same) just as well as by changing the width without changing the spacing. The differential skew is adjusted with a tiny blip on one line towards the bottom of this image. Is there a best practice or any documents that goes into details or even a online calculator would be great. 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. These impedances depend in first approximation on the following PCB parameters. Note the differential pairs above that look like a strand of intestine have a constant gap between the pairs. Re: Calculating Differential Impedance for USB Differential Pair. This form of microstrip is composed of two traces. Configuring the Design Rules. Skin Depth Calculator. While there are a number of online calculators that calculate the characteristic impedance from the input geometry, they are all based on approximations. . Finally, all calculators provide theoretical impedance values as they cannot take in to account the variables. 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. These features become essential if you generally work on high-speed designs. PCB Impedance-Calculation: Help with the dimensioning of the impedances of your circuit board. ZO *. RS485 uses differential signaling for the cable of 100Ω or 120Ω, the terminating resistance should match the cable. 1,481. Antipads around through-hole vias are a point of contention in modern PCBs, and the debate around the use of these elements in a multilayer PCB is framed as a binary choice. Thus a "differential pair" any long distance apart will have an impedance of 98 ohms, without any coupling between the lines, i. Right-click and choose Change from the pop-up menu. 6mm FR4 PCB with 7628 type stackup (4 layers), the above specifications usually result in 4. Added ability to include Er effective to the wavelength calculator. Perhaps the most common type of transmission line is the coax. In the PCB panel, as you click on an entry in a list, a filter will be applied based on that entry. L R ≈ 50mm (2 inches). PCB Repair Quotes. The impedance calculator determines the signal properties and clearances (first image), use that clearance in the via shielding Distance setting. 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. Modeling approximation can be used to understand the impedance of. Spread the loveA Grounded Differential Coplanar Waveguide (GDCPW) is a transmission line structure used in RF and microwave circuits. As the signals are also referenced to ground, each differential pair signal also has a single ended impedance. trace width: 0. 25, but gives me nice trace from the module to the stub then to microcontroller. Supports Anritsu ShockLine™ MS46524B and VectorStar™ MS4647B. I used the Altium`s impedance profile calculator and got the parameters, but then I double checked with a Saturn PCB tool - the results were significantly different (Picture 2). Differential Protocol: Select the desired protocol from the dropdown list, this list will autofill the Target ZDiff edit box. With our 500 ps rise time for the High Speed spec, this gives a signal propagation distance. The etch length of the differential pair groups do not need to. 6 mm board that I want to create a 90 Ohm profile on. For example, ECL logic has a 50 Ω characteristic impedance, and TTL has a source impedance range of 70 to 100 Ω. Propagation delay (t pd) in PCBs is the time taken by a signal to travel through a unit length of a transmission line . With the Multi-CB impedance calculator, you can calculate the approximate impedance dimensioning of your PCB / high frequency circuit board. Unfortunately, TxLine doesn't do coplanar waveguide for differential traces. 25, but gives me nice trace from the module to the stub then to microcontroller. BGA land calculator based on the IPC-7351A specification. This 8W rule also applies to ground planes on the same layer. Try TNT or TxLine. To answer, Zac. When you are creating your schematic, you must use one of the following suffixes when naming your differential pair nets: +/- (e. For differential signals on the top layer, I have 100 ohm impedance for trace width 5 mil and gap 5. 29 mm width traces to obtain 100 Ohms ZDiff while using 0. When you need to do trace length matching in PCB design, your goal is to minimize timing differences between traces in a length-matching differential pair in a serial protocol, multiple traces. High-speed data on differential links must be de-skewed to achieve the maximum eye opening and avoid mode conversion. Cross-section geometry of a stripline trace. The velocity factor is simply: 1 / sqrt (e_r*mu_r). The online menus contain a calculator to help you to define the correct track and gap values for your layout, for example for 50Ω characteristic and 90Ω differential impedance using. Based on Zo Equation Per: IPC-D-317A:. Using this calculator, I found 100 Ohms by giving 9 mils of track width, 5 mils of track separation, 8 mils of dielectric (prepregs usually have a dielectric constant of 3. Incidentally, the trace thickness parameter does have a significant effect. Value of Zo calculated by impedance calculator is not relevant here. Sierra. To set the rules for the classes we created above, we will follow these steps: Go to ‘Design’ >> ‘Rules. when i use Saturn PCB design to match the differential impedance to 100ohms i get 0. $egingroup$ So basically your answer shows that the JLCPCB impedance calculator results are generally in the same ballpark as the proven field simulators. You want to select “Microstrip Zdiff”. This calculator is designed to calculate the characteristic impedance of an edge-coupled microstrip. png . 75 mm track on a 0. 254mm. Figure 5 shows the dimensions of a stripline and microstrip pair. Hi all, I would like to ask about the correct differential impedance calculation in the USB 2. GDCPW is known for its balanced configuration, which helps reduce common-mode noise and interference in. It shows the minimum trace-to-ground spacing required to. Impedance Calculators. 100 Ohm Differential Pair: 0. Using the KiCad Impedance Calculator. If it’s not. 6 mm. 1,481. The controlled impedance lines should be marked in the PCB schematic drawing. I am planning to manufacture the PCB at PCBWAY so I decided to use their calculator but as you can see in the photo when using the minimum allowed spacing , the width of the traces is so large for usual USB traces. pair impedance with predifined traces’ gap. This controls the differential impedance. > A good starting point is to ask you board house give you the widths and spacing for your stackup. If you read many PCB design guidelines, particularly on parallel protocols and differential pair routing, you’ll see many mentions of trace length matching. Either the desired impedance at a specific frequency is used to determine the waveguide width, or the width is entered and the impedance is calculated. Note that the net pair must be named with net label suffixes of _N and _P. 1. So unless you carefully design your routes within your PCB, the impedance would be uncontrolled, and its value. This 8W rule also applies to ground planes on the same layer. Figure 5. The High speed protocol that is being designed for determines what the single and differential trace Impedance the traces need to meet as well as the tolerance for the impedance (e. Sample coupon — Gerber Data mpcd1345. The differential impedance will be a bit less than 2x the single-ended impedance. Crosstalk Area. Note: Units do not matter for this calculation as long as they are consistent. A mistake was made when designing a set of mother and daughter PCBs, resulting the daughter board to have its LVDS pairs at ~100Ω differential impedance, while the motherboard ~90Ω. 6 mm. 1 Answer Sorted by: 4 The calculation looks correct, but the tracks are too wide. Microstrip construction consists of a differential pair and a single reference layer (typically ground). There are 3 types of single-ended models: single-ended non-coplanar, coplanar single. When routing differential signals across common PCB materials, each trace of the pair will experience different dielectric constants and corresponding signal velocities due to the differences in static permittivity (Ɛr) of the There are single end trace impedance and distance between traces in the pair. I am designing a flexible PCB to carry two types of differential signals. A PCB impedance table will provide the trace width required to have a target impedance value on a standard stackup. The Layer Stack Manager in Altium Designer includes an impedance calculator that accounts for copper roughness. Take account, the internal used formulas sometimes don't equal on Conductor Impedance tab and on Differential pairs tab (e.