This Javascript web calculator calculates the trace width for printed circuit board conductors for a given current using formulas from IPC-2221 (formerly IPC-D-275). Design and stackup in altium, For ex: 8 layers and impedance control of 100 ohms on layer 2 and 7 and ask your fabricator to suggest a stackup for same 8 layers and trace impedance of 100 ohms for layer 2 and 7 and compare the values. It gave me a trace width of 6. Modeling approximation can be used to understand the impedance of. 0. To use this tool, enter the values for trace thickness, substrate height, trace width, trace spacing, and dielectric constant in the calculator above and press the "calculate" button. In reality, we don’t need to use that trace width due to the way the traces in differential pairs will couple to each other. Just as a sanity check, we can quickly calculate the total inductance of a trace. A PCB impedance table will provide the trace width required to have a target impedance value on a standard stackup. TLDR: 1. To calculate the trace width/spacing, I used SaturnPCB. It’s a three-in-one. 725. I'm not sure which calculator to trust. Changing the stack-up will affect the calculated trace width for impedance-controlled traces; however it will not automatically update existing traces. 025mm, impedance will be thereafter changed by 5 to 6 ohm. H (Dielectric thickness) :This means that the actual trace width for a 50 ohm line could vary from design to design. Impedance control with BGA escape routing in HDI PCBs H eff = H 1 + H 2 2 H e f f = H 1 + H 2 2. so i opend the KiCad PCB Calculator and tried to get some values out of this. 378 [mils/oz] ) For IPC-2221 internal layers: k = 0. You may use this online tool to calculate an estimate of the minimum trace width for a given current and copper weight. IPC-2221 establishes standards for PCB design aspects such as schematic, material selection, thermal management, DFM, DFA, DFT, and quality assurance. For example: Yellow Violet Red Gold: 4 7 x100 ±5% = 4700 Ohm, 5% tolerance. 4mil and the dielectric thickness to the first intermediate layer (this is a 4-layer board) is 6. For example the width of the trace(W) is 6 mils and the distance between the differential pair(A) is 8 mils. 5x trace width for the drill diameter, and drill + trace width for the pad. 29 mm width traces to obtain 100 Ohms ZDiff while using 0. Sierra Circuits can: Help you with your controlled impedance stack-up. Thickness. 6mils that is the same as given in the stack-up. Calculate the impedance of a twisted-pair cable given dimensions and find the signal propagation delay, capacitance, and inductance per unit. 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. Also, the copper thickness affects the minimum trace. While this calculator will provide a baseline, any final design considerations should be made towards loss, dispersion, copper roughness, phase shift, etc. It mentions formula or equations used in this Microstrip Width Calculator. ΔW = (W-W1) ( mils ). A pair of lines can be modeled as follows: Differential pair line. Calculate the effective dielectric constant. Use the results from #3 to calculate the width profile with. Electrical Spacing. PCB Trace Impedance Calculator. They are very simple to read, and the values in. The manufacturer performs a test to. 3 is a 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). 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). 024 x dTI = 0. e. Group components of specific applications together to reduce the loop areas. Impedance vs. The characteristic impedance of the trace can be calculated using the below formula: Formula to calculate characteristic impedance of a PCB trace. Most of the microstrip impedance calculators you’ll find online use a similar process: enter your microstrip geometry and Dk value for your PCB substrate materials, and the tool will return the impedance for your. ViaMin. Use our online tool to calculate the minimum trace width for a given current and copper weight. Impedance Matching Calculator Inductance Conversion Op amp voltage & gain Passive Filter Calculator PCB trace width Pull up Pull down resistors Transformer Turns Calculator Twisted pair impedance Manufacturer Tools; Reference DesignsI will not be held responsible for any mishap or loss, either direct or consequential, that may occur as a result of relying on the figures herein. 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. The trace width required to deliver a specific impedance can be calculated as part of an impedance profile, in the Impedance tab of the Layer Stack. It is important to note that in industry we can find that some differential pairs are routed this way for a strong coupling, but. QSPICE RF Impedance Matching CalculatorUsing this calculator, based on my earlier question I'll need to make sure to approach 90Ohms with the "Impedance (differential)". We will also tell you by how much you can. 25 mils, Impedance = 50 Ohm. To use it, you simply need to input your circuit's impedance and the voltage you. For controlled impedance, if the built in trace width calculator calculates that the traces need to be incredibly thin, the you need to change something else in the design, like the dielectric material or the dielectric thickness. 035 mm, we have a PCB trace width of w = 0. An embedded microstrip can be constructed using a microstrip with a solder mask. You can better understand your calculator results by becoming familiar with the following formulas. 22mm. View All Tools. 2. 725. This design tool is based on the charts in IPC-2221. Share. 35mm gives 50Ω, far easier to use. e. The IPC-2141 trace Impedance calculator will help make initial design easier by allowing the user to input basic parameters and get a. The Calculator has the following tools:. The PCB Impedance Calculator in Altium Designer. Most designers take the controlled impedance approach and devise a target for their trace width/spacing for single-ended and differential channels. Perhaps try sharing the entire layer stackup, not just the impedance calculation portion?The simplest way for a controlled impedance is to just calculate some track width, (and gap for differential pairs), send the geometry to any PCB manufacturer and hope for the best. However, if you select “impedance control” options when getting a quote from a manufacturer, it’s important to know that this will bring additional engineering costs. To calculate PCB trace resistance, The 50 ohm PCB trace calculator is designed considering the following formula. I would like to calculate the trace width of a dipole PCB antenna in order to match a 50ohm impedance. net Forum. T=trace height . T-Match Topology. For two layer boards, a coplanar waveguide geometry usually gives more useful dimensions than a microstrip geometry. (Fat!) Formulas for calculating this can be found in various. A trace width calculator is a tool used to calculate the width of a trace on a printed circuit board (PCB). This calculator helps translating the color bars from the resistor to its value. Sierra Circuits’ PCB Conductor Spacing and Voltage Calculator calculates the minimum spacing between two conductors if the potential difference between them is provided. The JLCPCB Impedance Calculator computes track width values and recommended stack-ups from user-input values of board thickness, copper weight, layer,. Differential Impedance Ω. Impedance Controlled Routing Starts with the Right Calculator In some cases, impedance calculators can be very useful as they allow you to calculate the impedance of an isolated trace by. A cross-hatch plane is shown in the image below. 2. 0mmCurrent layer:4-layer. 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. 010 to 0. Microstrip Differential Impedance Formula. Radar Calculators. 5 mm, trace width W = 0. F-A t t enua t o rs. Round up to nearest 5 mils. 4 mm, trace spacing S = 0. Calculates the characteristic impedance and per-unit-length parameters of typical printed circuit board trace geometries. ] Internal Layer Results: Copper Area: External Layer Results: [Mils] [Square Mils] [Volts] Trace Width Calculator Results: Via Current. Instructions. t t is the trace thickness, in oz/ft 2. 2 of the Microstrip Calculator, h=H1 and b=H2-H1. 15 mil, and the inductance would be 6. 2mm 1. Make sure you understand the factors that influence transmission line impedance, and if needed, use a calculator to get an initial estimate of impedance before programming the required trace width as a design rule. What is the width of a trace for 100 ohm impedance? The width of a PCB trace for a specific impedance depends on factors like dielectric material and thickness. The Layer Stack Manager in Altium Designer can be used to easily arrange signal and plane layers in a PCB stackup and determine the impedance of traces in each layer. The PCB trace impedance increases as the width decreases. The channel width is the distance between the centers of two vias between which traces will be routed. Dielectric thickness. Inputs: Optional Inputs: Results for Internal Layers: Results for External Layers in Air: Notes: The trace width is calculated as follows: First, the Area is calculated: See full list on protoexpress. Calculates the characteristic impedance and per-unit-length parameters of typical printed circuit board trace geometries. Via is considered as a cylinder of copper and its circumference is 2 𝝅r or 𝝅d where d is the size of via hole. Figure 35: Trace Width for different. To manufacture controlled impedance printed circuit boards, one must be able to measure impedance. Looking at the design I should have done the following but do not think them alone would explain the results. A 3D view of a complex impedance controlled PCB in Altium Designer. Most board manufactures will have a preferred tool that PCB designers can use to calculate the Impedance but there. 8W + T)] Where: Z: Characteristic impedance of the microstrip trace. Based on Figure 4, it can be concluded that as trace width changes by 0. It displays the impedance of the input and output match in a 50Ω test environment as measured on a network analyzer. See below for the definition of these impedances. PCB trace impedance can range from 25 to 125 ohms. Tuning the Width and Gap Settings. 0. 6mm 2. Altium will assume you want to confine the signal to your trace (and ground plane), rather than cause radiation. of typical printed circuit board trace geometries. 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. Gaps in signal traces impact the entire test waveform, and its single-point impedance is too high, making the entire waveform uneven. These calculators will return an impedance value for pairs of trace width, substrate thickness, and copper weight values. Dual Stripline Trace. One of the most common inquiries that we encounter at Bittele electronics are regarding our standard trace widths for a given board thicknesses and copper weight. 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. This calculator determines the impedance of a symmetric differential stripline pair. 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. Via impedance Via step response Via DC resistance Via impedance Via resonant frequency Via thermal resistance Via voltage drop Via power dissipation in dBm. 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. The default units for all given values, except the substrate dielectric, is in mil. Cite. Pulse Repetition Frequency (PRF) Calculator. IPC 2141 Trace Impedance Calculator. The Smith Chart graphically maps S11=reflection coefficient= (ZL-Z0)/ (ZL+Z0) to Load Impedance (ZL), normalized to Z0 (source impedance = center of chart). Going Forward with a Trace Impedance Calculator. With PCBWay impedance calculator, you can calculate the approximate impedance of your PCB / high frequency circuit board. Figure 24. For differential pairs, there is also a spacing value given. The edge couple differential microstrip transmission line is a common technique for routing differential traces. Trace impedance is dependent on not only. 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. Using the EEWeb Microscrip Impedance Calculator, I find that with 1oz/ft^2 copper and a substrate height of 0. The JLCPCB Impedance Calculator computes track width values and recommended stack-ups from user-input values of board layer, thickness, copper weight, target. These fields are generated by the interaction between electric and magnetic field lines. Track width, in this specific case where impedance control is not needed, must guarantee a smaller enough resistance to the trace. Just enter the given values for trace thickness, substrate heights, trace width, and substrate dielectric in the. The aim of the Impedance Calculator is to support the. H1=> 8. ε: Dielectric constant of the PCB material. When I was 12 years old, I opened a television for the first time, and that was when my passion for electronics started. 6. Single Ended Impedance Ω. 15 mm spacing. TransLine. Microstrip Trace: Embedded Microstrip Trace: Stripline Trace: Dual Stripline Trace: Geometric Parameter Definitions. The impedance of a trace is decided by its width and height from a reference plane. For a 1 inch trace, this value would have a total inductance of ~7. H 2 H 2 = subtrate height 2. A circuit trace routed on the inside layer of the PCB with two low-voltage reference planes (i. 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. FR4 Impedance Distortion Calc 5. For example, if you wish to input "25000000", just type "25M" instead. Matching the differential trace length and keeping the distances between the traces consistent is a common practice. The inductance of a broadside coupled trace is easy to calculate. Enter the values of trace width (w), trace thickness (t), trace dielectric thickness (h), overall dielectric thickness (h1), and the dielectric constant (er). The calculator below uses Wadell’s. 25mm between the differential pair with a width of 0. For a first design (e. To use it, first select the tolerance of the resistor: 10%, 5% or equal or smaller than 2%. What's Inside. This calculator finds both odd and even transmission line impedance. Menu. Using this calculator, I found 100 Ohms by giving 9 mils of track width, 5 mils of track separation, 8 mils of dielectric. With Altium Designer, you can easily determine trace impedance, propagation delay, rise times, and PCB trace length. Calculates the characteristic impedance and per-unit-length parameters. This is more than the to times trace width which is recommended (also read as close as possibly). The trace width is calculated as follows: First, the Area is calculated:. I used a few different tools to calculate the trace impedance with different results. Trace Spacing Calci 3. com PCB Trace Impedance Calculator. 5mm). 98mil. Via Current Calci 1. W: trace width: T: trace thickness: H (/H1)The trace width calculator uses empirical formulas based on long traces with no special heat sinking. Now also calculates DC resistance with temperature compensation. A PCB. The tool implements numerical solutions of Maxwell’s equations to render accurate and consistent results. No ground plane under Antenna. Impedance calculators or formulas like the one mentioned earlier can help determine the required trace width. 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. The CircuitCalculator. It is not always possible to adjust trace length and width, hence implementing lower copper thickness is one of the feasible ways. Electromagnetic fields are part of the spectrum ranging from static magnetic fields to high-intensity gamma rays. PCBWay is a professional quick-turn PCB prototyping, PCB Assembly and low-volume production manufacturer located in Shenzhen China. When dealing with transmission lines, Characteristic impedance is a crucial parameter, probably the most crucial that you will encounter. The Microstrip Impedance Calculator is a vital tool in the design and analysis of microwave circuits. So Adjust trace width to match the impedance to 50 Ω Ω. Cross-hatched copper plane in a flex stack-up for controlled impedance. ϵr ϵ r = substrate dielectric. Differential Impedance of. The microstrip is a very simple yet useful way to create a transmission line with a PCB. If the calculated routing trace width is a value that cannot be ordered, you can tune the width and gap settings. BGA3. Dual Stripline. Enter 9. Coil Inductance Calculator. **Note: Like our stripline impedance calculator, all of our RF calculators allow SI prefix input. Simons, "Coplanar Waveguide Circuits, Components, and Systems", Wiley. They are:. Geometric Parameter Definitions: W: trace width: T: trace thickness: H (/H1) height of trace or dielectric above return plane: C: distance between the differential stripline pair: er. The surface finish is neglected. Modeling approximation can be used to design the microstrip trace. F-A t t enua t o rs. If copper foil. 25 mils , t = 1. 254mm, spacing between both is required 0. The tool provides two networks that will have the desired impedence at that frequency. ) such real numbers for the line impedances are sufficient. 44 x A0. Maintain consistent trace widths to ensure controlled impedance. To use these to design for a target impedance, simply cycle through various geometric. Home;. Figure- Allegro automatically assigns trace width 12. The dialog is accessed from the PCB Editor by clicking the Impedance Calculation button in the Layer Stack Manager dialog. 949. /sq. 76mm Rogers4350B substrate at a certain frequency and with 35 micron. layout impedance. Calculate trace width values based using the IPC-2221 charts by providing inputs such as current thickness and temperature values. The aim of the Impedance Calculator is to support the designer in such a pre-layout design phase. AS9100D – Military & Aerospace. The impedance Z 0 of a transmission line consisting of a circular signal conductor having a diameter d and centered between parallel ground planes separated by a distance h is given by: Eq. 062. Note: The results are only for approximation and rough estimation, the final values and the. 4. The Impedance Formula Editor dialog. If you want a thinner microstrip, you need to reduce the substrate height using one of the following solutions: Use a thinner 2-layer PCB, for example 0. 0 ()' 0 0 K k K k. 7 x 10-6 ohm-cm αcopper. 414 times higher than the actual trace width. This tool includes an industry-standard field solver that is built into your PCB layer stackup. So, you need to calculate how much resistance a PCB trace can provide. Obviously, there is no ground on the bottom side. These calculators will return an impedance value for pairs of trace width, substrate thickness, and copper weight values. A coplanar waveguide with groundplane distance H = 1. If your boards are to be manufactured in arrays, click on the option “Yes”. 41)] * ln [5. At 10 MHz, you don't need to worry about trace width/impedance unless you're using long traces and very fast rise/fall times. This is found to be 10mm. 1 to 2. (dielectric constant Dk=4. The tool implements numerical solutions of Maxwell’s equations to render accurate and consistent results. 031. Hi there, and welcome to the Tools portion of EEWeb. 25mm trace. Determining trace impedance and propagation delay in PCB traces takes a trace length calculator and impedance profiler tool, and these features work best when they are integrated into your PCB design software. I made the calculator as an Excel Spreadsheet and posted it on Zoho Sheet. 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. However, when using EEWeb's impedance calculator, I get much different values. Impedance calculation8 chapters - 115 pages - 150 minute read. It supports both balanced and unbalanced lines. 906mil. 7E-6 [Ω · cm] L is the trace length [cm] T is the trace thickness [cm] W is the trace width. The Fairchild application note also says that the differential characteristic impedance of the D+ and D- lines should be 90 ohms. For this reason, trace width is important in the design of striplines. 293, 50% of the copper removal can be achieved. For this example, we will use 2. If you need to mass produce PCB's at low cost, the minimum trace width should not be pushed too hard. For a first design (e. 0 and (t/h) less than 0. The trace width calculator uses empirical formulas based on long traces with no special heat sinking. You can use the following PCB impedance trace formula to calculate its circuit impedance: εr : The dielectric constant of the material;. Neither of those cover controlled impedance calculations, if you need those look elsewhere. Some of the important things to be considered are discussed below: 1. 1 of the Microstrip Calculator using H2 in place of h, εr,eff can be computed as specified in Eq. 725. Discontinuities cause signal reflections due to impedance mismatch compromising signal integrity. 5mm pitch BGA. This tool includes an industry-standard field solver that is built into your PCB layer stackup. 378 [mils/oz/ft. Using typical values of W= 9 mil, H= 24 mil, T = 1. The trace width formulas are: I = 0. The PCB design tools in Allegro include an impedance calculator that will help you size your traces so that they have defined characteristic impedance. PCB Trace Width Calculator & PCB Trace Resistance Calculator per IPC-2152 . Once the required impedance and trace geometry are determined, the next step is to calculate the trace width. It is a full-featured Excel-based tool that helps plan the PCB stack-up so that controlled impedance traces can be effectively implemented. Qorvo Calculators and Design Tools MatchCalc Qorvo MatchCalc is a free downloadable RF/microwave matching calculator with ideal tunable passive components. Height: Height of the substrate. It is not uncommon that the calculated trace width will be a value that cannot be ordered, for. So you must adjust the impedance according to your requirement by keeping the losses in mind. Impedance control: Here, the impedance is controlled through the dielectric thickness, the trace width, and space. Through PCB impedance control, the impedance offered by the trace to an alternating current signal can be predetermined. Trace width is an important design parameter in PCB design. the current table. Should I just go with SaturnPCB's values and pray it works? The difference seems pretty severe (10%) but I guess would fall within the 25% tolerance, so. 25 °C Ambient temperature 1 mm thickness 50 mm trace lengthThis 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. Microstrip Impedance Calculator. All the impedance matching trace width calculator seem to consider that there is a ground plane on bottom. Calculates the current a conductor needs to raise its temperature over ambient per IPC-2152. Some of its key features include:. 5; results odd impedance: 45. This procedure produces the result ( w/h) = 1. Our current online trace width calculator is useful for clients who need to calculate the minimum/maximum trace widths for. This tool will also compute the resistance of the stripline, the voltage drop on it, and the resulting power dissipation. 19mm) traces with 7. 5mil clearance on a 63 mil board (1. 68. There are many calculators available online, as well as built into your PCB design software. Here are the steps to validate your design using Better DFM: 1. EEWeb provides a suite of Microstrip Impedance Calculators as follows: Microstrip Impedance Calculator; Embedded Microstrip Impedance. 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. 8. This can be set to zero, but the calculated loss will not include conductor losses. 44. Reset. As an example with 1 A. differential trace impedance for USB (90 Ohms) on 2-layer FR4 board. In any case, you do not want to use the Altium estimate for the trace width to achieve a given impedance to design an antenna. where: I = maximum current in Amps dT = temperature rise above ambient in °C A = cross-sectional area in mils². Voltage regulator circuit board. Multiply the result by the square root of the ratio of (1 + (2 * h / w)) to (1 – (2 * h / w)). Rectangle Loop Inductance Calculator. 0. Knowing that the test cable and the test output are 50 ohms, it is possible to use Equation 3 to calculate the impedance of the trace under test. Share. 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). However, minimum trace width recommendations from manufacturers should be. 1< W/H < 3. PCB Trace Impedance Calculator. The impedance of a trace is decided by its width and height from a reference plane. 8W + T)] Where: Z: Characteristic impedance of the microstrip trace. 093. Modeling approximation can be used to understand the impedance of. Select a trace impedance profile over the length of the taper. The information below details some of the key capabilities that PCBWay can offer and. 5 mil which we can round to 14 mil. And this is enough to initiate low-level oscillations. 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. If the Length, l, to diameter, d, ratio is known, you can calculate the Inductance, L, series resistance, Rs and the aspect ratio l/d is related to Q = L/Rs for a given conductor material. Stripline Trace. If impedance control is necessary, determine the trace width required to reach your impedance target. Using. The manufacturer can then choose to make a test cupon on the frame outside the actual board and use this width for impedance control. The impedance value of the 20 mils trace is 37. 6mm2. Z0,air Z 0, a i r = characteristic impedance of air. Stripline Impedance. Length-tuning structures and their effects on impedance. If you reduce this trace width to 19 mils, the characteristic impedance will result in about 52. ) such real numbers for the line impedances are sufficient. The shortcomings of crosshatch or mesh as a high frequency return path. 4 mils) and are 5 mils above the nearest plane with a dielectric whose relative dielectric constant is 4. Where: Z0 Z 0 = characteristic impedance of the asymmetric stripline in ohms (Ω). These calculators will return an impedance value for pairs of trace width, substrate thickness, and copper weight values. Not all calculators will explicitly state this. This will work with the controlled dielectric approach, where you specify the stackup, and then you adjust the width and dielectric constant to hit a trace width and impedance target. T is the trace thickness [oz/ft 2], W is the trace width [mils], R is the resistance [Ω], ρ is the resistivity parameter, whose value for copper is 1. Vacuum press in. A higher current requires thicker traces while a thicker. Impedance (Z) = [87 / √ (ε + 1. Off the top of my head, I can think of Polar and z-calc but I never liked these. thermal, and signal integrity aspects of traces on a PCB. Board Classes. Microstrip Impedance Calculator. 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. This calculator determines the impedance of a symmetric differential stripline pair. Best is 5mils, but 4mils is OK, too. There are several parameters to consider when determining impedance, including:. R. Optimize power transfer with our Impedance Matching Calculator. You can use our trace width calculator to design the right traces for your boards. H 2 H 2 = subtrate height 2. There are several formulas and online calculators that can be used to calculate trace width. trace width and thickness, distance from other copper features, dielectric constant, and dielectric thickness or distance to reference plane of the board material all contribute to the impedance of a. The characteristic impedance is given by: Eq. TransLine. These are precisely the characteristics of a pair of lines to be designated as a differential pair. Features: Three-in-one calculator. 0 ohms; even impedance: 38. Typ e, V ref and, if needed, I a d j , select the field you want to calculate (one of the resistors or the output voltage) and enter the other two values. These measurements were gathered from traces that targeted a 50 Ohm impedance. Dielectric constant. Impedance depends on many parameters, including but not limited to trace width, trace thickness, and laminate thickness.