Pcb differential pair impedance calculator. For a Dk = 4. Pcb differential pair impedance calculator

 
 For a Dk = 4Pcb differential pair impedance calculator  This becomes more

[2] Calculate the top layer signal end impedance: Two tools are giving Zo=48 and Zo=47. The Si8000m assumes negligible insertion loss in the transmission line; should you wish to model insertion loss the Si9000e adds. > A good starting point is to ask you board house give you the widths and spacing for your stackup. 5. Technical Consultant Zach Peterson explores a viewer question surrounding Coplanar Routing, specifically how to route on a single-layer board. You can use all the calculators you want if you don't know the exact board make up they're using; they should be able to help you. Differential pair length tuning. . Note that these differential. 24 mm. 8 core of FR4 material, we would have a propagation delay of approximately 150 ps/inch, or approximately 6 inches/ns. 5 mil wide traces with about 6 mils of. You want to select “Microstrip Zdiff”. It seems I could largely do without any impedance matching considerations, given what the trace lengths are. Board. beammy. The JLCPCB Impedance Calculator computes track width values and recommended stack-ups from user-input values of board thickness, copper weight, layer, target impedance, conductor spacing. Differential pair into PCB calculator. Now to tuning the impedance of your diffpair’s PCB traces. For differential pairs it is important that both traces are balanced – in that each trace intersects the crosshatch symmetrically. The same in true for bottom layer. Conclusion. **Note: Like our stripline impedance calculator, all of our RF calculators allow SI prefix input. The trace width is then adjusted to achieve the neces-sary impedance. 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. Changed how the wire gauge calculator works, added max amps in air. It uses the lan9512 reference schematic. Use an online differential stripline impedance calculator Calculating Differential vs. For a differential pair, the available layers, the Preferred Width and the Preferred Gap are controlled by the selected profile. This calculator determines the differential microstrip impedance of a transmission line. In a previous article, we have seen how to route a differential pair signal. The microstrip is a very simple yet useful way to create a transmission line with a PCB. 1. Ideally you'd need 2 lines with Zo =45 Ohms. The vias on these differential pairs have their own impedance, which can create signal integrity problems on long interconnects. too. ZL =. nm um mm cm m mil inch. Yet I got a ZDiff CPW with ground capable calculator: Differential surface coplanar waveguide with ground calculations: *0. You will want to control impedance with smaller variations in gap. The visual result (in the design editor window) of the cumulative filter is determined by the highlighting methods enabled (Mask/Dim/Normal, Select, Zoom). Low-voltage differential signaling (LVDS) is codified in the TIA/EIA-644 standard and is a serial signaling protocol. 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. The closer you place the pairs together, the differential impedance gets smaller because LM and CM get larger. 4mils = 0. High-speed data on differential links must be de-skewed to achieve the maximum eye opening and avoid mode conversion. The Layer Stack Manager in Altium Designer includes an impedance calculator that accounts for copper roughness. With t = 35 um (typical for copper with plating on a pcb), Z odd drops to 44 ohms, according to LineCalc. PCB Stackup Impedance Calculator Calculates the characteristic impedance per unit length parameters of typical Some of the common Dielectrics & their values: Relative. This interactive controlled impedance routing greatly simplifies the task of designing a controlled impedance PCB. GDCPW is known for its balanced configuration, which helps reduce common-mode noise and interference in. The impedance calculator determines the signal properties and clearances (first image), use that clearance in the via shielding Distance setting. The coupling between differential pairs is different when differential traces are run over a ground (or power) plane on a PCB than when they are run using unshielded twisted pair (UTP) wires. The edge couple differential symmetric stripline transmission line is a common technique for routing differential traces. The i. Differential Pair Impedance Calculator. 8 substrates of various thicknesses. Ready to give CircuitStudio a try? Click here to get started: 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. L1=Ground, L2=signal/transmission lines, L3=Power, L4=signal or. It is important to determine the characteristic impedance of a twisted-pair cable because this impedance should match the. Incidentally, analog signal integrity may be a bigger problem than digital in this design. Similar notes exist for other devices but USB is the one I'm most interested in. 5 and I took 3. USB traces must be 90 Ohms differential. The vias on these differential pairs have their own impedance, which can create signal integrity problems on long interconnects. 6mm spacing with a trace width of 0. 6mm FR4 PCB with 7628 type stackup (4 layers), the above specifications usually result in 4. Differential Stripline Impedance Calculator. Some calculators will allow you to calculate trace impedance in a number of geometries, e. 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. Differential pairs with vias and right-angle bends are acceptable. Note: valid for (w/h) from 0. The S50 Impedance Profile is defining the routing widths, which will change according. 4 ohms; differential impedance: 90. Let's match the impedance of the same signal since differential pair routing is completed when the impedance is matched properly. 22 mm; trace distance: 0. I am trying to design a USB circuit, where the signaling is over a differential pair D+ and D- and these two lines are required by the spec to have 90 ohms of differential impedance. This is the odd-mode impedance of the differential pair. Differential pairs are defined on the schematic by placing a Differential Pair directive (Place » Directive) on each of the nets in the pair. This is good for routing space, but not so good for power delivery if there is a need for interplane capacitance. 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. 0 and (t/h) less than 0. Eurocircuits’ Impedance calculator uses real values as defined in the supplier’s data sheets. , PCIe Gen 2 and Gen 3) also use a different value for differential pair. The example below shows how adjusting the stitching via placement could affect a differential via. So my first prototype board had some issues with usb connectivity due to me not knowing anything about differential pair routing, matching/coupling and impedance control. See moreCalculate the impedance of PCB traces quickly and easilly using DigiKey's Trace Impedance Calculator. H1: Height of the dielectric between the trace and the reference plane. Also, I tried the differential tools in KiCad, and I matched both pairs to the same length (otherwise, one track is about 6 mm longer). For the Saturn PCB calculator: - Differential Pairs tab -> Play around with the values and use conductor height as you dielectric distance. 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. There are four different types of impedance used in characterizing differential trace impedances. Si TRC – Track Resistance Calculator calculates DC. 30967mm) is slightly larger the size of the smallest pad (0. Tech Consultant Zach Peterson di. This rule maintains the desired signal impedance. 08-07-2018 02:42 AM. For better impedance control, use PCB design software you can trust. The formula used in this calculator is an approximation for the characteristic impedance of a coplanar waveguide: scssCopy code. 9. One question that is important in terms of signal integrity and manufacturability is how big the antipad in a PCB should be. Dielectric constant = 3. 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. , D+ and D- (TSKEW)) must be less than 100 ps and is measured as described in. The targeted impedance for diff pair is 100 ohms, which is dependent on the width/space between conductors and hight to the reference plane. Contents. 5; w, t, s, h > 0;Made in Europe. or Differential Pairs Routing design rule. NOTE: The formulas used in the program are valid for 0. 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. You will need to know the thickness of the dielectric you will be using as well as the relative permittivity (dielectric constant). Once the option is active, click on the shortest trace and move the mouse. PCB Coplanar Waveguide Calculator RF PCBs can be complex boards that need careful interconnect design and. Unit: Options are mm, mil, μm, and inch. You can see for example, Matthew K. The required values are trace thickness, substrate heights, trace width, and subtrate dielectric in the calculator above and press the "calculate" button. Tightly coupled pairs (within a pair) are quite common and this has the advantage of having a somewhat higher single ended impedance on a per track basis within a differential pair which is often easier to implement. Figure 5 shows the dimensions of a stripline and microstrip pair. Calculates the characteristic impedance and per-unit-length parameters. For more information see "Interactively Routing with Controlled Impedances on a PCB in Altium Designer: Routing Width Design Rule" in the official documentation. This calculator determines the impedance of a symmetric differential stripline pair. To access the differential calculator, in the Primary Gap, Neck Gap, or +/- Tolerance cells, do the following steps: 4. Preferably, the length of the clock trace should be somewhere in between. This is the impedance between the two signal traces of a pair. The differential skew is adjusted with a tiny blip on one line towards the bottom of this image. Question #1: How to determine the required spacing between length-matched signals or differential pairs and the adjacent layers? If you are length matching that implies that the interface is probably fast enough to require controlled impedance. On a 1. The same applies to common mode impedance, except that. 1. 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. 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. PCB Structures / Discrete Structures / Signal Management. Flexible PCB Quotes. The following options in the Options for PCB Project dialog are used to configure this:. 5 to 4. 035 mm. Both LM and CM converge to zero as spacing goes to infinity. And that they have the same separation from each other along the entire length of the line. This will create the differential pair. Fabricators give trace impedance tables as guides to designers that need to implement controlled impedance in their PCBs. This 8W rule also applies to ground planes on the same layer. Just as PATA, I intend to use every other conductor as ground wire, which should result in a signal-to-ground impedance of around 80 ohms. Microstrip Impedance Calculator. PCB Routing Requirements for USB 2. For example, a single 0. The trace width (0. Microstrip Impedance Calculator. The crosstalk coupling calculation requires information for the driver source as well as the PCB physical characteristics. Track width of the Ethernet pairs is 0. Edge Coupled Stripline Differential Impedance Calculator. The formula used in this calculator is an approximation for the characteristic impedance of a coplanar waveguide: scssCopy code. 9. 9. Figure 2. The Impedance Calculator is a tool which allows a quick pre-layout estimation of several kinds of line impedances between different layers. Use stripline routing for better far end crosstalk performance and a tight impedance tolerance, and keep trace lengths shorter than the maximum allowed length limited by the full-channel IL and eye diagram simulation results. 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. 331 1 2 5. Now, let us see the routing of the differential pair. 6mm pcb thickness ) with 8 mil trace width, 8 mil trace spacing , 1. 1. One should always check carefully whether a calculator implements these equations under the appropriate approximations. 3mm, as shown below: This increases the impedance slightly to 91. The propagation of electrical signals through PCB traces is not instantaneous; it is subject to a delay. There are some advantages to using a microstrip transmission line over other alternatives. In the first case, assuming edge coupled traces on (or in) a PWB, each trace couples much more strongly to the ground plane than it does to. « Reply #7 on: April 21, 2023, 03:42:36 pm ». 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. Best-in-Class PCB Fabrication, Assembly, & Components. Stack Symmetry – enable to add layers in matching pairs, centered around the mid-dielectric layer. . 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. It's important to note that the TIA/EIA-644 does not define. Impedance Calculators. Several Web sites such as the examples listed below contain additional reference information. Incidentally, the trace thickness parameter does have a significant effect. The IPC Formulas and Wadell’s Method. Use the same trace widths throughout the length of the trace. Remember, the lower the impedance the greater the current drain, the higher the. To access the differential calculator, in the Primary Gap, Neck Gap, or +/- Tolerance cells, do the following steps: 4. on layer 3 from the top, between power and ground plane. The factors that influence differential pair via impedance will affect the input impedance seen at the vias. 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. Thus, for optimal performance the resistors and MOSFETs must be matched. However, in odd mode the centre of the resistor will always be at 0v. KiCad has a built-in impedance calculator! Maximize System Performance With LVDS PCB Layout Guidelines . Trace width and spacing depend on your PCB stackup. 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. pairs for aciving 85 Ohm diff. 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. The calculator shows 90 ohms can be achieved using. Using the KiCad Impedance Calculator. Impedance examples 4 layers. This video explains the most common layout topics for USB signals: impedance, trace length and matching, and printed circuit board (PCB) stack-up. In. If we want to hit the standard 50 Ohms impedance target, then we need to have a trace width of almost 110 mils!Choose a calculator to tune your PCB design. . Placing a Differential Pair directive on each pair net applies a parameter to the net,. KiCad has a built-in impedance calculator! For differential pairs of microstrips, the formulas involved are much more complicated because coupling between the traces in the differential pair must be included in the impedance calculation. The differential pair trace lengths should be matched with a tolerance of 20% of the signal rise/fall time. Let’s move onto another example. ALTIUM DESIGNER. The screenshot is as shown in the picture q1-pro-pcb. Altium Designer makes it easy to calculate geometry when you need to calculate impedance for differential pairs. /. To get the correct parameters, we have to use the specifications from our PCB house and the provided calculator. D_P and D_N) KiCad looks for these suffix pairs when using the differential pair routing tool during PCB layout. png . 5 to 4. 1<W/H<3. Such a microstrip is constructed with two traces referenced to the same reference plane with a dielectric material between them. On a reference plane, there is an edge coupled differential microstrip line with two traces. Such a microstrip is constructed with two traces referenced to the same reference plane with a dielectric material between them. 1<W/H<3. ; 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. Note: The results are only for approximation and rough estimation, the final values and the. When you are creating your schematic, you must use one of the following suffixes when naming your differential pair nets: +/- (e. Coplanar waveguides are open quasi-TEM waveguide geometries that use copper pour and a ground plane to provide shielding along the length of. 50 - 55 ohms). 8065. 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). This calculator finds both odd and even transmission line impedance. D_P and D_N) KiCad looks for these suffix pairs when using the differential pair routing tool during PCB layout. THESE FORMULAS ARE APPROXIMATIONS! They should not be used when a high degree of accuracy is required. D_P and D_N) KiCad looks for these suffix pairs when using the differential pair routing tool during PCB layout. 3 as fr4 material with 1. as well as higher uncoupled lengths in differential pairs. The velocity factor is simply: 1 / sqrt (e_r*mu_r). 29 mm width traces to obtain 100 Ohms ZDiff while using 0.  For complex impedance matching, the input impedance is important as this is the impedance seen by a. 5oz inner copper, 8 mil trace spacing) and a target differential impedance of 100 ohms, JLC's calculator suggests a trace width of 8. 25, but gives me nice trace from the module to the stub then to microcontroller. PCB Traces. Re: USB differential pair on 2 layer board. Implementation of these guidelines can help designers maximize the performance of the. The idea here is to determine the spacing required for a given width with the goal of hitting a specific differential impedance value. #2. The signal is 264MHz. If T R = 1nS. 3. T T = trace thickness. Layout basics for USB designs. I am having a hard timing getting the characteristic impedance up high enough to hit 80 ohms: The board will be a 4-layer PCB, with "prototypes" produced at JLCPCB. 01) and dielectric constant (3. To use it, first select the tolerance of the resistor: 10%, 5% or equal or smaller than 2%. ) and the LOW level is defined as zero. A PCB's trace impedance depends on its geometry, core and prepreg material, and layers. If you have copper fill on other layers, you can tie them to. With PCBWay impedance calculator, you can calculate the approximate impedance of your PCB / high frequency circuit board. Impedance. High speed digital designers should. A differential pair relies on symmetry of both. 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. This is because communication flows both ways on the CAN bus. Note the differential pairs above that look like a strand of intestine have a constant gap between the pairs. PCB Impedance-Calculation: Help with the dimensioning of the impedances of your circuit board. When you are creating your schematic, you must use one of the following suffixes when naming your differential pair nets: +/- (e. 2. Polar UK: Si9000e PCB transmission line modeling. Calculates the outer and inner layer diameters of a padstack given the drill size. D+ and D-) _P/_N (e. 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. 6 mm. 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. 05 that is free software and very. 0037” line/0. If you read many PCB design guidelines, particularly on parallel protocols and differential pair routing, you’ll see many mentions of trace length matching. 5GHz. We recommend. Note that the built-in impedance calculator does not account for the affect of vias, it assumes lossless transference from one signal layer to the next. 1. PCB Impedance Calculation. g. This transmission line calculator. 25mm trace. 254mm. PCB Trace Impedance Calculator. Sierra. which is 0. Understanding coax can be helpful when working with it. Supports Anritsu ShockLine™ MS46524B and VectorStar™ MS4647B. 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. 1,481. In other words, if you are designing to hit a differential impedance target (such as. 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. You need to set up certain rules. ’ Go to the ‘Differential pair rules’ >> ‘New rule. PCB impedance control is an important design constraint when working on high-frequency circuits. For example, a single 0. This calculator is designed to calculate the characteristic impedance of a broadside couple stripline (see diagram below). Click on Net -> All Layers -> Line under the Spacing Constraint Set. PCB Padstack Calculator. Twisted pairs are used with balanced signals. We get a lot of questions about trace impedance and how to calculate the right trace size to hit a specific impedance in a manufacturable PCB. 1. PCB Trace Impedance Calculator Calculates the characteristic impedance and per-unit-length parameters of typical printed circuit board trace geometries. But I am afraid that, even an continuous power plane will not provide a proper reference for those Eth differential pairs. ϵr ϵ r = substrate dielectric. 2. The PCB Impedance Calculator in Altium Designer. D+ and D-) _P/_N (e. The characteristic impedance of your microstrips is determined by the trace width for a given layer stackup. This routing width rule targets a class of DRAM nets. The S50 Impedance Profile is defining the routing widths, which will change according. You must estimate the differential trace insertion loss in dB/inch for the trace loss budget based on the selected PCB materials and stackup. H 1 H 1 = subtrate height 1. Differential Microstrip Impedance Calculator (Using Zo) Embedded Microstrip Impedance Calculator. Propagation delay (t pd) in PCBs is the time taken by a signal to travel through a unit length of a transmission line . If the calculator does not provide velocity (or velocity factor), it's probably because you can use e_eff instead. 4 Ethernet PHY PCB Design Layout Checklist SNLA387 – JUNE 2021 Submit Document FeedbackUnderstanding Coplanar Waveguide with Ground. • As shown in Figure 1, traces should be 100-Ω(±5%) differential impedance of differential microstrip or differential stripline. 1 to 2. The values you get from an online differential pair impedance calculator corresponds to an isolated differential pair, they do not consider the load component and they are not calculating the input impedance. But it lacks the differential impedance (impedance between these two tracks). The following are typical line widths and spacings for the more common impedance values when using ½ OZ copper: 50 Ohm Single Ended: 0. pair impedance with predifined traces’ gap. At the receiver, the signal is recovered by taking the difference between the signal levels on. Differential Pair Impedance Calculator Calculates the differential pair impedance of a balanced line. KiCad has a built-in impedance calculator!Maximize System Performance With LVDS PCB Layout Guidelines . If you can - Use a 0. I. 100 ohm differential pairs that are tightly coupled have a typical single ended impedance of around 65 ohms. Ethernet cables can be unshielded so obviously just two wires without a ground plane can work. This video will cover how to create, setup rules, and route differential pairs. 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. 3. 1 - 48 Layers 1WD Express 30 Years experience. 5 and I took 3. 5. PCB Impedance and Capacitance Calculator: Asymmetric Stripline. LVDS PCB layout guidelines aim to ensure optimal signal integrity and minimize noise interference by considering factors like impedance control, differential pair routing, grounding, etc. Above 3-5 GHzThe stackup design is very crucial for the manufacturing of a controlled impedance PCB. 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. 1 ohms; In addition to those calculation I found some other resources with some sample trace properties: Mikrocontroller. 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. 3 V, etc. The amplitude increases as the coupling length increases up to a point. 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. 1. 13 mm; substrate thickness 1. I am trying to design a CAN bus node. Differential impedance: This is the impedance of a pair of transmission lines. Dual Stripline Trace. g. 0 which can operate from 12 megahertz to around 240 megahertz. At MADPCB, we are capable of calculating and control the impedance of rigid PCBs, flexible circuits and rigid-flex PCBs. The default units for all given values, except the. Note that the y-axis is on a logarithmic scale for clarity. This calculator is designed to calculate the characteristic impedance of an edge-coupled microstrip. The odd mode impedance is the impedance of one transmission line when the pair is driven differentially. 3. But it lacks the differential impedance (impedance between these two tracks). One of the features of this type of microstrip is the coupling between lines. Also note that your best bet may actually be VERY SHORT (few mm) traces, a thinner board or a 4 layer board :-) Thanks for your suggestions. This calculator is designed to calculate the characteristic impedance of an edge-coupled microstrip. Uncoated Microstrip Differential Pair Impedance Calculator . Here, we have set the differential tracks and spacing as 8 mils. 1. 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. CAN_L is pin 2 and CAN_H is pin 7 on the standard 9-pin D-SUB connector. The calculator is available in the Electrical Domain in Constraint Manager, from theDifferential Stripline Impedance Calculator. g. 5mil clearance on a 63 mil board (1. 6 mm. 3mm, as shown below: This increases the impedance slightly to 91. Differential Pair Calculator The Differential Pair Calculator is used to perform what-if analysis to determine what values of Primary gap and width are needed to get specific differential and single line impedance. when i use Saturn PCB design to match the differential impedance to 100ohms i get 0. 127mm, or 127 μm for the calculator’s purposes. For instance, I want a 100 Ω controlled impedance pair, and have used "differential" before which seemed to work fine. Configuring the Design Rules. Stripline Trace. Note that the driver output impedance may be configurable among various values. Calculates the differential pair impedance of a balanced line. 1. ) You need a ground plane right below the impedance-controlled pair. 1. , USB. Also, be aware, 90 ohms is the differential impedance, the characteristic or single ended impedance will be more than half (ie. Chrome 92. 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. So unless you carefully design your routes within your PCB, the impedance would be uncontrolled, and its value. This form of microstrip is composed of two traces. 6mm, that will make it easier to approximate the 90 Impedance - Use as thick traces as possible, and be aware that if you let the ground pour on the top layer get too close, it will also alter the impedance.