The circumference will be analogous to the trace. The dielectric constant of a material IS slightly frequency dependent. g. The IPC-2141 trace Impedance calculator will help make initial design easier by allowing the user to input basic parameters and get a calculated impedance according to the IPC-2141 standard. Via Current Calci 1. 7 10^ (-6) Ohm-cm. A differential stripline pair refers to two traces located between two reference plane layers, which are routed as a differential pair. Z 0, ss1 is the characteristic impedance of symmetrical stripline with b=h1 (Ɛr=1). It is not always possible to adjust trace length and width, hence implementing lower copper thickness is one of the feasible ways. they normally use 7. Reset. 44 x A0. At the point of bending, the trace width is 1. These important design features are. One commonly used formula for calculating the characteristic impedance of a PCB trace or transmission line is the capacitance per unit length formula: Z0 = 1 / (C / L) where Z0 is the. Hello ; Considering your post " I am not sure how it's supposed to work " Since JLCPCB produces high precision PCBs then every single parameter should be controlled carefully and that's why we are providing this guide calculator to define what is the trace width and trace space to set in order to maintain a certain impedance value. Our Impedance Calculator uses a 2D field solver to calculate near-end crosstalk based on the following equation: NEXT = V b /V a = ¼ (C mL / C L + L mL / L L). Microstrip Trace Impedance vs. Then, using a standard PCB trace impedance calculator or using the formulas in a textbook, you’ll find that the required trace width is 13 mils. H1=> 8. It's open-source to download. Using this calculator, based on my earlier question I'll need to make sure to approach 90Ohms with the "Impedance (differential)". Using this application, you can quickly identify the thermal resistance of a single or a combination of vias. I had a request for a calculator to find the width of a PCB trace based on its voltage drop or power dissipation. This time I am trying something new. The inductance of a broadside coupled trace is easy to calculate. But it can calculate the wave impedance of a trace that feeds an antenna structure. To manufacture controlled impedance printed circuit boards, one must be able to measure impedance. IPC 6012 CLASS 2. Modeling approximation can be used to understand the impedance of. PCB Trace Impedance Calculator. Just enter the given values for trace thickness, substrate heights, trace width and substrate dielectric in the calculator above and press the "calculate" button. ( 0. Use a field solver that can account for dispersion and copper roughness. This calculator determines the impedance of a symmetric differential stripline pair. F-A t t enua t o rs. This is. The trace width of the GCPW was approximately 24 mils. Track width (w) = 137 micron. To use this tool, enter the values for trace thickness, substrate height, trace width. It is likely that the calculated trace width will be a value that cannot be ordered, for example, 0. Next, determine the trace width. Embedded Microstrip. 7E-6 to 2. 510 mm, or 20 mils, and the minimum inductance is 292 nH/m. Use our online tool to calculate the minimum trace width for a given current and copper weight. 44, c = 0. They are very simple to read, and the. By inputting the dielectric constant, trace width, trace height, and trace thickness, the calculator provides a quick and reliable way to determine the required trace geometry. 35mm gives 50Ω, far easier to use. In the attachment you can see that in the Stack up Editor, I can calculate trace width for single ended trace that gives 50 ohm impedance for a given stack up settings. Keep in mind that the reactance of the ideal inductor has the same magnitude as its impedance. Impedance; Signal Loss; S Parameter. Just enter the given values for trace thickness, substrate heights, trace width, and substrate dielectric in the. To use this tool, enter the values for trace thickness, substrate height, trace width, trace spacing and subtrate dielectric in the calculator above and press the "calculate" button. 8. There are some advantages to using a microstrip transmission line over other alternatives. Click the button corresponding to the unknown parameter to calculate its value. Generally, the wagon wheel spokes do not have to be anywhere near as wide as long traces. It is possible to select other units. For example: Yellow Violet Red Gold: 4 7 x100 ±5% = 4700 Ohm, 5% tolerance. While the manufacturer uses Si9000, the result does not match with what the other tools get. Transformer Turns Calculator Twisted pair impedance Manufacturer Tools; Reference Designs. 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. Electrical Spacing. Microstrip lines have three parameters that we can change to achieve 50 ohm impedance: copper thickness (T) substrate thickness (T) track width (W) Due to design constraints, there is only one parameter (track width,) left to achieve 50 ohm. Different board materials, the dielectric layer thicknesses and constant (Dk), and the thickness of the metal traces all need to be part of the calculations. Simply enter your required temperature rise limits and operating current (RMS). Share. The. . Coplanar Waveguide Calculator. = room temperature (25⁰C) L= Length of trace. 2mil is the calculation trace width(the adjusted trace width,need to adjust trace width to meet impedance)Contents. It shows the minimum trace-to-ground spacing required to. 3mm, as shown below: This increases the impedance slightly to 91. Rise time-Max length Calci 2. Learn More about using the Altium Designer’s impedance calculator in this brief tutorial. It is not always possible to adjust trace length and width, hence implementing lower copper thickness is one of the feasible ways. To use it, specify the trace dimensions and the ambient temperature. This is the structure that the freeware impedance calculator analyzed and incorrectly reported the impedance to be 50 ohms. A temperature rise in PCB trace width calculator is a tool or software that helps engineers and designers estimate the temperature rise in a PCB trace based on the trace width, current, and other parameters. It is now a major exercise to evaluate the impedance using a calculator or spreadsheet. To calculate absolute impedance multiply the Smith Chart result by Z0; Click buttons below to view S11 with on different grids: All choices generate the same grid-less position (X,Y)=(S11re,S11im) The Smith Chart grid reads ZL=(ZLre,ZLim) The Polar grid reads S11=(S11mag, S11phase) The Rectangular grid reads S11=(S11re,S11im)I wanted to use Altium to calculate the width of the trace automatically, so that it had a 50 Ohm impedance. Trace Height (H) Figure 4. While this calculator will provide a baseline, any final design considerations should be made towards loss, dispersion, copper roughness, phase shift, etc. Microstrip Trace Impedance vs. BGA3. Get latest updates and offers. An embedded microstrip can be constructed using a microstrip with a solder mask. H 2 H 2 = subtrate height 2. 41)] * ln[5. Some calculators opt for Wadell's results, yet they simply state they are "based on Wheeler’s method" without providing references. A PCB impedance calculator uses field solvers to accurately approximate impedance values. The KiCad PCB Calculator is a set of utilities to help you find the values of components or other parameters of a layout. 6. Qorvo Calculators and Design Tools MatchCalc Qorvo MatchCalc is a free downloadable RF/microwave matching calculator with ideal tunable passive components. Where: Z0 Z 0 = characteristic impedance of the asymmetric stripline in ohms (Ω). 4mil and the dielectric thickness to the first intermediate layer (this is a 4-layer board) is 6. This tool will also compute the resistance of the microstrip, the voltage drop, and the power. Most designers take the controlled impedance approach and devise a target for their trace width/spacing for single-ended and differential channels. Chemandy on the other hand tells me 14. The Simbeor SFS. Designing trace width for HDI impedance adjustments. Most CAD systems provide an impedance calculator for this. Color Code. T= Experimental temperature. The trace width is calculated as follows: First, the Area is calculated: Area [mils^2] = (Current [Amps]/ (k* (Temp_Rise [deg. Stripline Trace. The IPC-2221 standard and IPC-2152 standard both include this guidance on designing for thermal reliability, and there has been some debate as to the applicability of each standard. where Z 0,surf can be computed as specified in Eq. This tool is designed to calculate the resistance of a microstrip trace with a copper conductor. Note: The trace on the inner layer need to be much wider than the trace on the outer. The required values are trace thickness, substrate heights, trace width, and subtrate dielectric in the calculator above and press the "calculate" button. For a standard FR-4 substrate with a dielectric constant of around 4. Another advantage of assigning the impedance property is that allegro automatically assigns the width of the track based upon the. This tool calculates the matching network necessary to terminate a line of the specified characteristic impedence (Z o) in a specific complex load impedence (R L + jX L) at a specified frequency. Where, εr is the dielectric constant of the material (as per the datasheet) H is the height of the trace above ground. Cross-hatched copper plane in a flex stack-up for controlled impedance. Not all calculators will explicitly state this. Reference: R. Figure 2. Impedance calculators or formulas like the one mentioned earlier can help determine the required trace width. This tool will also compute the resistance of the stripline, the voltage drop on it, and the resulting power dissipation. 1 mm. Instructions. Let's consider the impedance for copper at 1 MHz. Calculates the current a conductor needs to raise its temperature over ambient per IPC-2152. 1 Answer. The wider a trace is, the easier it is to fabricate. This tool includes an industry-standard field solver that is built into your PCB layer stackup. Thickness. Place critical components,. The Calculator has the following tools: Regulators. 92. Altium will assume you want to confine the signal to your trace (and ground plane), rather than cause radiation. With the RF Attenuator utility you can calculate the values of the resistors needed for different types of Matching the differential trace length and keeping the distances between the traces consistent is a common practice. There is some relationship with trace width and board cost in mass production. Just enter the given values for trace thickness, substrate heights, trace width and subtrate dielectric in the calculator above and press the "calculate" button. , power and/or GND) constitutes a stripline layout. It displays the impedance of the input and output match in a 50Ω test environment as measured on a network analyzer. Now also calculates DC resistance with temperature compensation. There are a few methods for calculating trace impedance in a circuit board as long as the dielectric constant and trace geometry are known: Use the IPC-2141 equation for microstrip or stripline impedances. Via pad diameter (in mils) Trace/space width (in mils): This is the width of the trace and the space between them. This is a tool I developed to assist us at the Cambridge University Spaceflight Club to design a patch antenna for telemetry. To calculate PCB trace resistance, The 50 ohm PCB trace calculator is designed considering the following formula. The PCB trace impedance increases as the width decreases. For example, when a trace bends at an angle of 90 degrees, trace width changes significantly. Other conductor properties include: ; Conductor skin depth ; Conductor voltage drop ; Conductor. A higher Dk value also leads to higher dielectric loss. If a signal encounters impedance discontinuity, it will generate jitters in PCBs and hampers the signal integrity. Aside from impedance and annular ring calculations, one of the other major formulas specified in this standard relates temperature rise, trace width, and trace current. This form of microstrip is composed of two traces. W=trace width. 1 mm gives roughly 50 ohms impedance. 1-800-408-8353. So just set the trace width constraint in your PCB router to 13 mils, and your routes will all be precisely 50 Ohms. For your convenience, we have designed a Impedance Calculator to help you calculate the impedance and trace width you need. (Trace thickness) : mm mils (Trace width) :This tool uses formulas from IPC-2221 to calculate the width of a copper printed circuit board conductor or "trace" required to carry a given current while keeping the resulting increase in trace temperature below a specified limit. The tool generates odd, even, common, and differential impedance as output values. H 1 H 1 = subtrate height 1. Then, using a standard PCB trace impedance calculator or using the formulas in a textbook, you’ll find that the required trace width is 13 mils. copper trace on a 4-layer board with 8 mil thick dielectric and Dk = 4. e. ) Increasing the trace width crazily: Or. If you are using very fast rise/fall times (regardless of frequency) and ringing is your problem, you'll need to use a trace impedance calculator, with the trace. Stripline Impedance. Where I is maximum current in Amps, k is a constant, dT is temperature rise above ambient in °C, & A is cross sectional area of trace mils². For single-ended routing, go to ‘Interactive routing’ >> ‘Route’ and repeat the above steps. The dimensions of traces and their spacing significantly affect impedance values. This is more than the to times trace width which is recommended (also read as close as possibly). trace width. As a quick rule of thumb for 50 ohms, you want the ratio of the trace width to the height above the ground plane (probably your board thickness) to be around 1. 031. If the ratio is about 0. T=trace height . Calculate the width of a copper-printed circuit board conductor (internal trace) necessary to carry a specified current. 015mm. 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. 5 mil (0. Talk to a Sierra Circuits PCB Expert today. 6 ohms. 0mmCurrent layer:4-layer. Odd Mode Impedance (Zodd) Ω . 75 mm=30 mil). 29mm but this width is about 10 times larger than the pins. R. when i use Saturn PCB design to match the differential impedance to 100ohms i get 0. Trace Impedance Calculator; Length Conversion; Wire Size Conversion Calculator; Inductance Conversion; See. When working with a power rail, high-voltage components, and other portions of your board that are sensitive to heat, you can determine the power trace width you need to use in your layout with a PCB trace width vs. The coax is a good way to create a transmission line. Review: A new PCB stack-up design and impedance calculator is available for download from Istvan Nagy (see link below). 0 ()' 0 0 K k K k. , broadside coupled, embedded microstrips, symmetric or asymmetric. A differential stripline pair refers to two traces located between two reference plane layers, which are routed as a differential pair. Impedance control: Here, the impedance is controlled through the dielectric thickness, the trace width, and space. Modeling approximation can be used to design the microstrip trace. T is the thickness of the trace. The aim of the Impedance Calculator is to support the designer in such a pre-layout design phase. To learn more about trace impedance calculators, Wadell’s equations, and some drawbacks of impedance calculators, read this article on single-ended microstrip impedance calculators. In HDI boards, where BGAs of fine pitch are used, careful selection of trace widths and height are employed to escape the traces between pads and vias in pads. Vias (plated holes) are used to route electrical signals among different layers of a multilayer. The following formula is used to calculate the differential impedance of a microstrip: To calculate the differential impedance of a microstrip, divide the characteristic impedance of the microstrip by 2. 68. Impedance Matching pins of IC to microstrip line. Online impedance calculators are fine if you only care what happens at a single frequency, such as in high frequency analog signals. dear friends I want to route 100 ohm differential pairs of LAN on two layer pcb ( 1. Sierra Circuits’ Trace Width, Current Capacity and Temperature Rise Calculator is an advanced PCB tool that works based on the latest IPC-2152 standard. 1< W/H < 3. Introducing the newest version of the Microwave Impedance Calculator from Rogers’ Advanced Connectivity Solutions. ViaMin. 8 substrates. Multiply the result by the square root of the ratio of (1 + (2 * h / w)) to (1 – (2 * h / w)). 5mil; Er: 4. IPC-2221 establishes standards for PCB design aspects such as schematic, material selection, thermal management, DFM, DFA, DFT, and quality assurance. Impedance quality = Q = L/Rs 2. 035mm and Er = 4. 2. 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. Calculating the Impedance. When I google “impedance calculators pcb” this website is the first hit. (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. W is calculated to achieve a trace impedance (Z0)Controlled impedance. 4 mils). Access Advanced Circuits' printed circuit board trace width tool. Using the built-in Simbeor ® impedance calculator, the PCB editor's Layer Stack Manager calculates the trace width needed to deliver the specified impedance. Impedance trace widths based on Bittele's standard Stackups. This calculator graphs an impedance function for a power distribution system on a PCB with an arbitrary number of capacitors with arbitrary. 1< W/H < 3. This calculator can calculate the impedance and propagation delay of the embedded microstrip. Now with the values shown above for the characteristic impedance and the trace width/spacing pairs, we can determine the spacing that causes the trace width for a 50 Ohm odd-mode impedance to also produce a 50 Ohm. To update trace width, select the traces of interest and use the "Route > Retrace Selected" command. Calculations are made using the formula below: Where: Enter the frequency and inductance into the calculator, choose the. Cite. Effective Dielectric Constant (Ɛ_eff) Impedance. Share. All of the transmission lines are 1 ounce (1. The characteristic impedance (Z o) of coplanar waveguide with ground or microstrip lines with signal side ground plane can be calculated using the active calculator or the equations at the bottom of the page. Trace impedance calculators can help you determine the right trace width for your board. The CircuitCalculator. 5 nH, which is consistent with typical trace inductance values. A standard trace width for an ordinary signal (no special requirements) may be in the 7-12 mil range and be as long as a few inches, but there are many things that should be considered when defining the width and length of a trace. But results can vary, and you can make necessary changes in trace width according to results. Some calculators opt for Wadell's results, yet they simply state they are "based on Wheeler’s method" without providing references. With a standard 0. The video. See full list on protoexpress. Microstrip Transmission Line Models. Microstrip Trace: Embedded Microstrip Trace: Stripline Trace: Dual Stripline Trace: Geometric Parameter Definitions. No Solder mask, No Etchback, No L2 Ground Plane. The tool generates odd, even, common, and differential impedance as output values. 05; The manufacturer provides a stack up as well as a 2D calculator for determining trace width: here The manufacture's calculator computes 3. Controlling the impedance in your design is dependent on the board layer stackup you. my board thickness is 1,5mm (base material) and 35um Cu. Next, determine the trace height/length. This calculator requires symmetry in the trace widths and location between plane layers. The calculator utilizes the formula for calculating the impedance of a microstrip trace: Impedance (Z) = [87 / √(ε + 1. Provide values for H, T, W and the relative permittivity of the dielectric and click the button corresponding to unknown parameter Z o to calculate its value. To configure the board layers and input the material widths, go to the “Design” pulldown menu and click on “Layer Stack Manager”. Next, determine the trace. /sq. Advanced Electronics Solutions. You can build your own board layer stack or you can choose to work with one. To use this tool, enter the trace width, thickness, ambient temperature, temperature rise, and the microstrip length and click the "calculate" button. 3 as fr4 material with 1. (Trace width) : mm mils:To help you achieve this feat, Sierra Circuits has introduced the Bandwidth, Rise Time and Critical Length Calculator. 74mm. Calculate the trace parameters for controlled impedance: Determine trace thickness, height, and length along with the dielectric constant of the material. 25 mm (about 10 mils) might achieve a 100-ohm characteristic impedance. There are two ways to calculate the impedance of each layer in a stackup. Sorted by: 8. It is important to calculate the impedance of the line. Via is considered as a cylinder of copper and its circumference is 2 𝝅r or 𝝅d where d is the size of via hole. This calculator finds both odd and even transmission line impedance. per sq. 3 V DC ±5%). This Javascript web calculator calculates the resistance, voltage drop, and power loss of printed circuit board vias. /. Trace width for breaking out 100Ω differential microstrip from 0. The JLCPCB Impedance Calculator computes track width values and recommended stack-ups from user-input values of board layer, thickness, copper weight, target. Trace Width (W) ( mils ) Calculate W . Cable Impedance Calculator. This calculator is designed to calculate the characteristic impedance of a broadside couple stripline (see diagram below). 378 [mils/oz/ft. The efficiency of transmission of the embedded microstrip greatly depends on its characteristic impedance. For my senior project, I am designing a simple rectangular patch antenna array that is steerable using a phase shifter IC. 0. Controlled differential impedance starts with characteristic impedance. Calculate the impedance gradient and the reflection coefficient gradient. Controlled Impedance; PrePreg Chart. This online microstrip impedance calculator calculates the characteristic impedance of the microstrip (Ω), W/H ratio, and effective dielectric constant (εe) by entering the value of dielectric material relative permittivity (εr), the width of the copper trace (W), and dielectric height (H). As explained in Part 1 of this series ( Circuit Cellar 367, February 2021 [3]), PCB manufacturers can propose different PCB stack-ups, and specifying a low thickness for the so-called “top prepreg” will help to reduce the trace width. This can be easily visualized if we vary the width (really, the ratio W/H in these equations) while keeping all other parameters constant. 8 with 2-oz copper. It supports both balanced and unbalanced lines. These important design features are incorporated into your design rules, making impedance-controlled routing quick and easy. Computes trace width, maximum temperature rise above ambient, and current capacity; Calculates resistance and voltage drop across a given trace length For a first design (e. Used interchangeably with controlled dielectric by some PCB designers. H 2 is the subtrate h2. Engineering/Technical. PCB Trace Impedance Calculator. Get latest updates and offers. 81. Impedance depends on many parameters, including but not limited to trace width, trace thickness, and laminate thickness. The IPC-2141 trace Impedance calculator will help make initial design easier by allowing the user to input basic parameters and get a calculated impedance according to the IPC-2141 standard. 03) it gives me almost 160 Ohm - and even if use 53mil conductor height or. Reflex Klystron Calculator. ε: Dielectric constant of the PCB material. Menu. 92445. Keep signal traces perpendicular to adjacent layersThe width of each track should be as per the requirements. Distance between tracks (s) = 254 micron. You only need to know the resistance, the inductance, and the capacitance values connected in series or parallel. Use the following guidelines. For differential pairs, there is also a spacing value given. This application note from Fairchild (alternative link), which is one of the top Google results, says that D+ and D- trace single-ended impedance should be 45 ohms. What's Inside. to select appropriate isolation materials, layer thickness, trace width, distance between traces,. You can use the following PCB impedance trace formula to calculate its circuit impedance: εr : The dielectric constant of the material;. With Altium Designer, you can easily determine trace impedance, propagation delay, rise times, and PCB trace length. **Note: Like our stripline impedance calculator, all of our RF calculators allow SI prefix input. Figure 24. I used a few different tools to calculate the trace impedance with different results. Resistor Calculator Length Conversion Ohm's Law Calculator Parallel and Series Resistor Calculator PCB Trace Width Calculator Pressure Conversion Reactance Calculator Resistor Color Code Calculator Series and Parallel Capacitor Calculator Temperature Conversion Time Constant Conversion Voltage Divider Calculator Volume Conversion. Symmetric Stripline Impedance Calculators and Formulas; To really see how the trace widths for these transmission lines compare, we need to plot the characteristic impedance vs. Designing trace width for HDI impedance adjustments. This calculator determines the impedance of a symmetric differential stripline pair. Traditional measurements of PCB impedance use a Smith chart . 4. Input your data. (dielectric constant Dk=4. 2 of the Microstrip Calculator, h=H1 and b=H2-H1. The shortcomings of crosshatch or mesh as a high frequency return path. Passive Filter Calculator PCB trace width. Different calculators may use different formulas, with different accuracy and different ranges of applicability. Factors affecting impedance. What are the limits of the trace width calculator? The formulas used in the calculator are based off IPC-2221 (formerly IPC-D-275), which covers up to 35 Amps, trace widths up. Also for differential LVDS signals the tool can calculate the trace width and spacing for 100 ohm impedance for a given stack up setting. 679 nH. For example, row ‘a’ above shows details of layer 1 (100. Pick a signal frequency for your taper. Dielectric thickness vs. Optimization results for example 2. Using the built-in Simbeor ® impedance calculator, the PCB editor's Layer Stack Manager calculates the trace width needed to deliver the specified impedance. 49mil trace width. Measuring the trace width we get a width of 5mm. Pasternack PCB Microstrip Calculator is an online calculation tool that lets you compute a microstrip's height/width ratio, impedance and relative dielectric constant for a microstrip transmission line. Advanced mode. This calculator helps translating the color bars from the resistor to its value. Some calculators will allow you to calculate trace impedance in a number of geometries, e. 12cm, with 1. Broadside Trace Inductance Calculator. Controlled Impedance; PrePreg Chart. It’s a three-in-one. T represents trace thickness. 25mm, a trace width of 0. The impedance of a trace is decided by its width and height from a reference plane. A calculator designed to calculate the trace width of a stripline based on the maximum current rating Embedded Microstrip Impedance Calculator This calculator helps you compute the characteristic impedance of an embedded. 7 pages of equations to evaluate the impedance. Rectangle Loop Inductance Calculator. All transmission lines are 1 ounce thick (1. To use it, first select the tolerance of the resistor: 10%, 5% or equal or smaller than 2%. Board thickness (h) = 50 micron. The channel width is the distance between the centers of two vias between which traces will be routed. PCB Trace Width Calculator. They are:. The default units for all given values, except the subtrate dielectric, is in millimetres. 08 mm: 3. 0. Overview. ). These calculators give us essential trace spacing and differential pair spacing if needed. Select the trace under properties. 25cm recommended. Figure 2. Even Mode Impedance (Zeven) Ω . 49. 3, a trace width of approximately 0. 35 ohms. A stripline is similar to the microstrip except that the flat conductor is now. Using this tool, you can calculate 3dB bandwidth (BW), fastest signal rise time (tr), critical length (lc), maximum data transfer rate (DTR), and maximum frequency content (Fmax). Coil Inductance Calculator. Rectangle Inductance Description. Note further that, for standard fab widths (minimum trace width) and component pitches (maximum practical trace width), you can't get impedances very low on two layer board (even 0. to select appropriate isolation materials, layer thickness, trace width, distance between traces,. 98H / (. 3mil seems like a substantial enough difference. 3W spacing between critical traces 3. Figure 2-1 provides an illustration of the recommended trace spacing while Table 2-1 gives some trace calculation examples. There are many factors that go into calculating the width of an impedance controlled trace. Figure 3 is the plot of impedance versus trace width for the three most common types of transmission lines in PCBs—surface microstrip (SMS); buried microstrip (BMS) and centered stripline (CSL). The Differential microstrip impedance calculator is used to compute the differential (Zd) and single-ended impedance (Zo) of an edge-coupled microstrip line just by entering the width, separation and thickness of the trace along with the dielectric thickness and constant of the coupled line. 0.