The closer you place the pairs together, the differential impedance gets smaller because LM and CM get larger. 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. High-quality circuit boards as prototype and series at reasonable prices. Differential routing uses a pair of traces to carry complementary signals, often targeting 100 ohm impedance. The amplitude of this crosstalk is what this tool calculates. 50 to 60 Ω is a common target impedance used in many designs, and for differential pairs, 90 Ω or 100 Ω differential impedance is common. Impedance; Signal Loss; S Parameter; Crosstalk; Geometry Information . Modeling approximation can be used to design the microstrip trace. Edit: also, think ahead if you are going to use ground pours around the traces. On a reference plane, there is an edge coupled differential microstrip line with two traces. Calculates the differential pair impedance of a balanced line. [2] Calculate the top layer signal end impedance: Two tools are giving Zo=48 and Zo=47. On a 1. Now to tuning the impedance of your diffpair’s PCB traces. The ICD Stackup Planner calculates characteristic impedance plus edge coupled and broadside coupled differential impedance. g. The calculator is available in the Electrical Domain in Constraint Manager, from theDifferential Stripline Impedance Calculator. Units ( mils ) Show PCB Dielectric Material. Insertion Loss. Placing a Differential Pair directive on each pair net applies a parameter to the net,. 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. It always defaults to 10mil. (to the next pair and to the ground plane. Differential pairs are becoming common place in high speed design reducing. , USB. Atlas Si for TDR. Eurocircuits also calculates the correct Differential Impedance values using the correct formula and not a ‘Rule of Thumb’ method. The other yellow rectangle is the USB connector. 1 is an example of making tradeoffs between routing layers and power plane capacitance for a ten-layer PCB. Assuming both. ALTIUM DESIGNER For better impedance control, use PCB. The amplitude increases as the coupling length increases up to a point. They will give very similar answers. 10. The trace width (0. 965 mm. 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. This assumes ~0 trace thickness. ETA: USB 2. SET2SEIL. 8065. When you are creating your schematic, you must use one of the following suffixes when naming your differential pair nets: +/- (e. 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 flat flex cable used with Raspberry Pi CSI-2 camera interface has 0. This transmission line calculator. 0 and (t/h) less than 0. The screenshot is as shown in the picture q1-pro-pcb. 50 - 55 ohms). Layout basics for USB designs. nm um mm cm m mil inch. 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. I am routing LVDS pair on a flex board. g. 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. Use 3. beammy. g. 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. In terms of how these calculators work, the impedance of a transmission line in a PCB can be calculated in four ways: Use the R, L, C, G parameters from the Telegrapher’s equations to calculate the impedance of the transmission line. 3mm, as shown below: This increases the impedance slightly to 91. Single-ended signals are fairly straightforward. . Ideally the traces in the differential pair only interact with each other, as another answer said. 08-07-2018 02:42 AM. The characteristic impedance of the microstrip line means that is the uniform impedance provided by the uniform cross-sectional dimensions along the microstrip (flat copper conductor) length; to prevent signal reflection. Fig 2b Equivalent termination (showing Rc open circuit) in even mode. Differential Microstrip Impedance Calculator (Using Zo) Embedded Microstrip Impedance Calculator. The critical dimension that must also be taken into account is the distance between the signal pairs. CAN bus layout design. Earlier versions of the PCB editor included a simple impedance calculator, with limited support for unusual board structures. Overview. Design Parameters. 36 mm substrate, has an impedance to ground, unbalanced, of about 49 ohms. 159 OS X 10_15_7 EasyEDA. 36 mm substrate, has an impedance to ground, unbalanced, of about 49 ohms. When you are creating your schematic, you must use one of the following suffixes when naming your differential pair nets: +/- (e. When working with differential pairs, your trace spacing and geometry will determine the impedance of each trace and of the pair. The same figures put into pcbway's calculator give me 115R, and the same. 1. USB traces must be 90 Ohms differential. This video will cover how to create, setup rules, and route differential pairs. 4. 6 mm is used) can anybody help me how to calculate 100 ohm impedance. The total length of the signal path is about 1,330mils. 50 - 55 ohms). To use it, first select the tolerance of the resistor: 10%, 5% or equal or smaller than 2%. Calculates the outer and inner layer diameters of a padstack given the drill size. For example, a single 0. Using these highlighting methods, you can quickly highlight all differential pairs in a particular. PCB Impedance Calculation. 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. I am designing a flexible PCB to carry two types of differential signals. Impedance Calculation. Learn more about working with design rules and constraints. 3) to calculate trace width and. Given the defaults (1. If you read many PCB design guidelines, particularly on parallel protocols and differential pair routing, you’ll see many mentions of trace length matching. We recommend the software from Polar Instruments if you want to get exact impedance calculation. Note: The 6-Layer board temporarily only provides JLC3313 Stackup. PCB impedance calc and clearance. PCB Impedance-Calculation: Help with the dimensioning of the impedances of your circuit board. 5 mil wide traces with about 6 mils of. 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. PCB Trace Impedance Calculator. Updated formulas for all of the differential pair impedance models. png . 6 mm. High speed PCBs and signaling standards almost entirely use differential pairs with precise impedance. Other calculators are like a black box; you have no idea which formulas they are using and no way to check the accuracy of these calculations. If you require a controlled impedance PCB, you should discuss. /. g. 3 Answers. 6mm thick, 1. 6mm spacing with a trace width of 0. The visual result (in the design editor window) of the cumulative filter is determined by the highlighting methods enabled (Mask/Dim/Normal, Select, Zoom). 127mm, or 127 μm for the calculator’s purposes. This becomes more. Although JLCPCB can produce boards with 2 oz external copper, the calculator only supports 1 oz because (1) the wider tolerance of 2 oz traces hinders impedance control, and (2) most signal traces only carries small currents. g. For example, with a thickness of 0. 25, but gives me nice trace from the module to the stub then to microcontroller. KiCAD doesn't have a calculator for differential coplanar waveguide. High-speed data on differential links must be de-skewed to achieve the maximum eye opening and avoid mode conversion. Here, we are using a USB 2. ’ Go to the ‘Differential pair rules’ >> ‘New rule. Otherwise, keep shopping. 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. 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. With the Multi-CB impedance calculator, you can calculate the approximate impedance dimensioning of your PCB / high frequency circuit board. If you're trying to get your own pcb design project , you should use this tool. g. zip (170k) AP117. 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. Differential pair length tuning. As the signals are also referenced to ground, each differential pair signal also has a single ended impedance. AC coupling capacitors can be positioned anywhere throughout the differential pair’s length. 1<S/H<3. 3mm of the microcontroller), therefore i rounded the width to 0. This tool calculates the crosstalk. Preferably, the length of the clock trace should be somewhere in between. High speed digital designers should. W W = trace width. Modeling approximation can be used to design the microstrip trace. PCB Impedance and Capacitance Calculator: Asymmetric Differential Stripline. There are various ways to de-skew a differential pair: in the via anti-pad area or in the trace. Calculates the characteristic impedance and per-unit-length parameters of typical printed circuit board trace geometries. To automatically select all traces that belong to a specific impedance profile, you can select Nets in the the PCB Panel and click the appropriate net class. 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. Use an online differential stripline impedance calculator Calculating Differential vs. Modeling approximation can be used to understand the impedance of. 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. PCB Traces. The accuracy of a controlled impedance trace on a PCB is usually critical to the correct performance of the PCB. The only unified PCB design package with an integrated trace length calculator and PCB trace length matching vs. 2 Answers. Differential pair impedance depends on a lot of variables in reality,. frequency capabilities. FWIW, the calculator I've used in the past is called Polar SI8000 which apparently has been superceded by Speedstack PCB. Impedance in your traces becomes a critical parameter to consider during stackup. Added edge coupled embedded differential pair to calculator. The idea here is to determine the spacing required for a given width with the goal of hitting a specific differential impedance value. RS485 uses differential signaling for the cable of 100Ω or 120Ω, the terminating resistance should match the cable. Yes, that's right. 120E (Differential pairs): CAN; Note: Actual impedance during manufacturing can vary by 5%/10% due to micro-level trace width changes (due to temperature variations) during the manufacturing process. The formula used in this calculator is an approximation for the characteristic impedance of a coplanar waveguide: scssCopy code. 5) and 1. 1 has six signal layers, but only has one pair of planes closely spaced. The differential micro strip calculator requires some parameters. Differential impedance: This is the impedance of a pair of transmission lines. on layer 3 from the top, between power and ground plane. 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. 75 mm track on a 0. Incidentally, the trace thickness parameter does have a significant effect. This calculator helps translating the color bars from the resistor to its value. e. Dimensional units: mm mils. The IPC Formulas and Wadell’s Method. But I'm unsure if the Height I entered is. 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. The trace separation is varied from 1. The trace impedance or PCB impedance damages the integrity of both analog and digital signals. Bog standard FR4, the type used as standard by PCB manufacturers is not really up to the task of Gen3 PCIe. 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). As an example, If I want to meet the 80Ω diff/ 40Ω single impedances, taking the first inner signal layer, and using the Saturn Edge Coupled asymmetric calculator, the input would be: H2= 180um H1= 176um w = 0. 25mm between the differential pair with a width of 0. temperature rise. 1. The single-ended impedance of a trace in a differential pair will depend on the distance to the other trace, and applying a length-tuning structure is equivalent to changing the distance between the traces while meandering. Using the KiCad Impedance Calculator. Trace width and spacing depend on your PCB stackup. Conclusion. 4mils = 0. Here it is already defined in the schematic that this is D+ and D-. Track width (w) = 137 micron. Note that the driver output impedance may be configurable among various values. (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. . The distance between the differential pair should be decided as per the stack-up design. Atlas Si for VNA – Insertion loss test system – Delta-L 4. Is there a best practice or any documents that goes into details or even a online calculator would be great. The geometry of the traces, the permittivity of the PCB material and the layers. This will give a 50ohm impedance from each trace to ground. Using the KiCad Impedance Calculator. The termination resistors on a cable should match the nominal impedance of the cable. Right-click and choose Change from the pop-up menu. 254mm. . Each end of a differential pair. The guides says spacing under 0. Re: Differential impedance calculation. And that they have the same separation from each other along the entire length of the line. D+ and D-) _P/_N (e. Added ability to include Er effective to the wavelength calculator. When enabled. Let’s discuss the need for impedance. For sample: 45-46 Ohm single end traces impedance can be used in diff. Embedded Microstrip Trace. thanks to 6 layers I am now pretty confident that I can place all diff pairs on top and bottom layers, directly above the ground planes. 4mils/35um of copper thickness. I. Impedance Calculators. W2: Width of the top surface of the trace. D_P and D_N) KiCad looks for these suffix pairs when using the differential pair routing tool during PCB layout. 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. Implementation of these guidelines can help designers maximize the performance of the LVDS-based system across a wide range of applications. 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. Zeven: This is the even-mode impedance of the differential pair. The differential impedance will be a bit less than 2x the single-ended impedance. This is because communication flows both ways on the CAN bus. By controlling the PCB impedance, unexpected damages or errors can be limited to some extent. It uses the lan9512 reference schematic. Phone: +44 (0)1425 489 111 / +49 (0) 8104 628 0. To have designs be robust from PCB manufacturing errors and defects design the traces impedance be as close to the recommended value. While, when it comes to flexible and. Fabricators give trace impedance tables as guides to designers that need to implement controlled impedance in their PCBs. The trace width is then adjusted to achieve the neces-sary impedance. pH nH uH mH H kH. 1. Saturn PCB - Toolkit for Impedance Calculation. best to use a stackup calculator to provide quick ‘what if’ analysis of the possibilities. Understanding coax can be helpful when working with it. Procedures: Use differential impedance calculator to determine transmission line geometry for given differential impedance Zdiff=90 Ohms (impedance seen between two lines of a pair). KiCad has a built-in impedance calculator!$egingroup$ To avoid crosstalk from neigbouring signals - including its own, you should apply the 3W rule of thumb - traces should be at least 3 times their width apart. Differential pair into PCB calculator. We recommend. KiCad has a built-in impedance calculator!Maximize System Performance With LVDS PCB Layout Guidelines . This is not usually a routing rule a designer might consider unless they are doing something very intentional with RF design, or they are routing differential pairs that require a specific impedance. 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. The JLCPCB results are more reliable than (some of) the simple formula-based approaches. It's true that generally the impedance value is determined by the following parameters; trace layer (microstrip or stripline), trace width, distance. A PCB impedance table will provide the trace width required to have a target impedance value on a standard stackup. This calculator requires symmetry in the trace widths and location between plane. You will need to know the thickness of the dielectric you will be using as well as the relative permittivity (dielectric constant). 5. The edge couple differential microstrip transmission line is a common technique for routing differential traces. The PCB is the JLC7628 Stackup:. 2 PCB Stack-Up and Board Layout. They are very simple to read, and the. Probably the most common electrical uses for LVDS are as an physical layer for SerDes links, long-reach channels in backplanes, or board-to-board connections. H eff = H 1 + H 2 2 H e f f = H 1 + H 2 2. 6 mm PCB; 1. 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. Such a microstrip is constructed with two traces referenced to the same reference plane with a dielectric material between them. 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). 3. Using the KiCad Impedance Calculator. The two most common impedances. g. The vias on these differential pairs have their own impedance, which can create signal integrity problems on long interconnects. 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. Using the wrong impedance will cause the signal to be reflected inside the track. We often say that PCB traces should simply have 50 Ohm impedance, but this becomes more complicated when dealing with coupling between differential pairs. Oct 29, 2021. From here, we can see that there are specific stack-ups where a CPW and a microstrip/stripline will have 50 Ohm impedance and the same trace width, even though the ground clearance is quite close clearance to the trace in the CPW. 071 ohms; All About Circuits. The default units for all given values, except the. Impedance captures the real. Make sure you use an accurate tool like this. Differential Impedance in Constraint Manager Advanced Constraints can be used to view the Differential Impedance in Constraint Manager. Complimenting these features are various differential pair routers, high speed design rules, and much, much more to help you get the job done. Vias (plated holes) are used to route electrical signals among different layers of a multilayer layer PCB. This rule maintains the desired signal impedance. This means that the channel dimensions of both FETs must be the same and that R 1 must equal R 2. 25. 035 mm. Using the built-in Simbeor ® impedance calculator, the PCB editor's Layer Stack Manager calculates the trace width needed to deliver the specified impedance. The Ethernet pairs are length matched. While commonly constructed using. It works in parallel with the standard. A differential stripline pair refers to two traces located between two reference plane. $endgroup$ –The microstrip impedance represents the characteristic impedance of the microstrip line. 6193. 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. You will need to know the thickness of the dielectric you will be using as well as the relative permittivity (dielectric constant). 25mm trace. But it lacks the differential impedance (impedance between these two tracks). 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. Standard FR4 is on the left. ’ Give a name to this rule (100 ohms in this case) and double-click. I make that clearance at least 3 times the distance from your diffpair to its reference plane (i. PCB Traces. Thus, for optimal performance the resistors and MOSFETs must be matched. 03) it gives me almost 160 Ohm - and even if use 53mil conductor height or. Characteristic impedance or surge impedance is the impedance of a PCB transmission line without including the effect of other transmission lines. It is the ratio of voltage and current amplitudes of a single wave propagating along the line in the absence of reflections from other directions. Inductance – the impedance calculator uses the Impedance value to calculate the inductance per unit length. pair impedance with predifined traces’ gap. Note that the net pair must be named with net label suffixes of _N and _P. 6mm PCB you are looking at traces nearly 3mm wide and then you'll need distance between them to make differential pair. When you need to calculate or simulate differential pair via impedance and S-parameters, use a set of PCB design and analysis tools with integrated field solvers and analysis. Eq. I use Microstrip & Stripline calculator developed by Jean Nicolle. 1,481. PTN33xx and CBTL061xx I/O impedance is targeted at 50 Ω single-ended and 100 Ω differential. It shows the minimum trace-to-ground spacing required to. except for W, the width of the signal trace. The image below tells a thousand words. So, strive to keep your traces short and far apart in high-speed design. 22 mm; trace distance: 0. 6 mm. This is the odd-mode impedance of the differential pair. One should always check carefully whether a calculator implements these equations under the appropriate approximations. PCB Trace Impedance Calculator Calculates the characteristic impedance and per-unit-length parameters of typical printed circuit board trace geometries. g. Most formulas calculate impedance from width, because width is a boundary condition and it's easier to calculate forward from a boundary condition, than backwards to reconstruct it. 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. If you can - Use a 0. 3. Remember, the lower the impedance the greater the current drain, the higher the. Because the traces are together on the same layer (plane) I'm not sure how "coplanar". Differential Protocol: Select the desired protocol from the dropdown list, this list will autofill the Target ZDiff edit box. 3 * 1. Follow the 8W spacing for differential clocks (or explore other rules) Even greater spacing is needed for high-speed differential signals. NOTE: The formulas used in the program are valid for 0. UTP= Unshielded Twisted Pair, at least I am guessing that is what it means in this context. 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. 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. or Differential Pairs Routing design rule. To calculate the impedance, I use Saturn PCB impedance calculator software, Inc - PCB Toolkit V8. First of all, we need to clarify the concept of characteristic impedance. NOTE: The formulas used in the program are valid for 0. Updated formulas for all of the differential pair impedance models. 0055” spacing. This routing width rule targets a class of DRAM nets. BGA land calculator based on the IPC. 35mm gives 50Ω, far easier to use. Differential impedance: 90 ohms (tolerance: +/- 15%) On a typical 1. THESE FORMULAS ARE APPROXIMATIONS! They should not be used when a high degree of accuracy is required. Terminate far end of the pair with 90 Ohms resistor (it is odd mode. D+ and D-) _P/_N (e. There are some signal integrity issues with de-skewing in traces: Impedance. Broadside coupled non-shielded differential pair. PCB manufacturer generally verifies the impedances with impedance coupon (traces drown during design in a separate portion outside our. 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. Advertisement Board thickness (h) = 50 micron. For sample: 45-46 Ohm single end traces impedance can be used in diff. PCB Repair Quotes. 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. The differential impedance will be a bit less than 2x the single-ended impedance. By running a mating ref trace through the crosshatch you emulate a solid plane and can use a standard impedance. NEW Methodical Method to Hardware & PCB Design - you can calculate single-ended impedance. With today’s modern PCBs,. This transmission line calculator. 6mm) That should give the traces around 90 Ohms differential impedance according to the PDF, but when I try to input it to my impedance calculator (Saturn PCB toolkit V7. The USB port (Pins USB DP and USB DM) must be routed as 90 ohm differential PCB traces. Differential Microstrip Impedance From Zo. I used the KiCAD PCB calculator, asked the PCB manufacturer about the tangent loss (0. Rule of thumb: 0. The stackup on the left side of Figure 2. 4mils/35um of copper thickness. The velocity factor is simply: 1 / sqrt (e_r*mu_r). ; 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). 9. trace geometry, and use this to calculate. 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. 2. We’ll go over how differential pairs can hel. It is important to determine the characteristic impedance of a twisted-pair cable because this impedance should match the. Herndon's (Apple) paper from DesignCon 2003 "Noise Allocation for Near-end Crosstalk and for Uncertainty in Characteristic Impedance". 5) and 1. Microstrip Impedance Calculator. #PCB #KiCad #HowtoIn this video, we show you how to create a deferential pair in KiCad. Development Kits. USB traces must be 90 Ohms differential. 6mm pcb thickness ) with 8 mil trace width, 8 mil trace spacing , 1. 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. 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. Then Right click -> Create-> Differential pair. Altium Designer makes it easy to calculate geometry when you need to calculate impedance for differential pairs. P/N De-skew Strategy on Differential Pairs. Quote Now . too. Note: If this post answers your question, please click the Correct Answer button. 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. 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. They are very simple to read, and the values in. 2. With PCBWay impedance calculator, you can calculate the approximate impedance of your PCB / high frequency circuit board.