Trace temperature calculation. Output voltage = 0. Like mutual inductance, self-inductance can be either a friend or foe in electronics design. t is the thickness in cm (PCB copper @ 1 oz/ft2 = 0. Reference: R. Our impedance tolerance is from ±5% to ±10%. How do you calculate PCB trace inductance? The inductance of a PCB trace can be approximated using various formulas, such as the Wheeler’s formula: L = 0. Calculate the impedance of a twisted-pair cable given dimensions and find the signal propagation delay, capacitance, and inductance per unit. 19 inductance 12. Approximations for the impedance, delay, inductance, and capacitance of microstrips and striplines, as a function of trace geometry, are reproduced in my book, High-Speed Digital Design ISBN:0-13-395724-1. In this case, there will be both an IR component due the small trace resistance (RM) and an L*dI/dT term due to the trace inductance (LM). The self inductance of a single wire in free space is defined below. Also see the via calculator. [H] = Henry. 54cm trace at the non-inverting input of a high. This is the reason why engineers specify the trace width in their designs. The standard signal integrity tool in a PCB editor for crosstalk and reflection waveforms can help with a lot of up-front qualification of signal behavior (rise/fall time, overshoot, crosstalk, consistent impedance, and ringing) before moving into a more advanced analysis tool. In this case, there will be both an IR component due the small trace resistance (RM) and an L*dI/dT term due to the trace inductance (LM). Relative Permeability is assumed to be 1. Inductance: L=5. •One of the first online tool for multilayer inductance calculation and design and will give TI a competitive advantageA differential stripline pair refers to two traces located between two reference plane layers, which are routed as a differential pair. PCB Trace Width Calculator Current (I) A Thickness (t) Temperature Rise (TRise) Ambient Temperature Trace Length Formula First, calculate the Area: Then, calculate the. The microstrip is a very simple yet useful way to create a transmission line with a PCB. 7 – Excessive trace length. 21) PCB Trace Width and Clearance Calculator 22) Series and Parallel component (R, L and C) calculations. 2. Stripline Impedance Calculator Embedded Microstrip Impedance Calculator Microstrip Impedance Calculator Dielectric Thickness (mils) C Dual Stripline Impedance Calculator Asymetric Stripline Impedance Calculator Zo Equation: IPC-D-317A (Eq. One trace is the signal and the other is the return path applied to this inductance calculator. half the inductance. With PCBWay impedance calculator, you can calculate the approximate impedance of your PCB / high frequency circuit board. 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 impedance matched to the. The first way to reduce via separation is to use smaller decoupling caps. 378 [mils/oz/ft2]) (I) Then, calculate the maximum current: IMAX = (k · TRISEb) · Ac (II) Where: A is the cross-section area [mils 2 ] T is the trace thickness [oz/ft 2 ] W is the trace width [mils] I MAX is the maximum current [A] T RISE. *The structure may propagate in 3 modes: coplanar waveguide, coupled slot lines and microstrip. Hershenson, S. The calculator then uses a formula to calculate the width and spacing of the trace or transmission line required to achieve the desired characteristic impedance. 427 nH) See also notes on Inductance Calculations page. Additionally, using a ground plane underneath the trace can help reduce inductance. It is one of the most crucial factors that should be calculated and analyzed when designing a PCB. d = Winding depth in inches. 435A. 031”) thick PCB (FR-4) has: ˜ 4nH and 0. The resistance of a trace on a PCB depends on several factors, including the width and thickness of the trace, the length of the trace. . Adequate trace width is necessary to ensure the desired amount of current can be transported without overheating and damaging your board. m) vs rough (RMS=2. The inductance of the loop must be found to select a capacitor value for resonance. Voltage Drop: Volts. The program has additional plugins to. Simply put, PCB trace impedance is a measure of the resistance that a circuit opposes to a current once a voltage is applied. These traces will have different impedance if they are driven in odd-mode or even-mode. Note: µ0 = 4¶·10 -7 [Hm -1 ] (Absolute Permeability)The wavelength of the signal that can propagate effectively inside a microstrip is called the guided wavelength. We can use these impedances to calculate the mutual capacitance and mutual inductance between these traces. 3 can then be used to design a PCB trace to match the impedance required by the circuit. W. You can see here that an inch of an average PCB trace can have between 0. The basic "Parallel-plate capacitor" capacitor formula for capacitance is. Approximations for the impedance, delay, inductance, and capacitance of microstrips and striplines, as a function of trace geometry, are reproduced in my book, High-Speed Digital Design ISBN:0-13-395724-1. Trace Width and Trace Space to the minimum permitted. High-speed designs carry a requirement for controlled impedance, crosstalk control, and the need for interplane capacitance. . 2. The overall trace temperature can be calculated as follows T TEMP = T RISE + T AMB. You’ll need to get the Trace Widths and Thickness and Length. 4. 725. PCB Trace Resistance ; Trace Width ; mils to um; Parallel Wire Inductance Calculator; Calculate x power y; mils to Inches ;. 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. Traces on PCBs are small and therefore have small inductance levels. 3 LVDS Traces • As shown in Figure 1, traces should be 100-Ω(±5%) differential impedance of differential microstrip or differential stripline. The suface microstrip. 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. A). According to script, this inductor would have inductance of ~3. And this PDN impedance is becoming more and more of a. Inductance (in a General sense) is a function of Wire/Trace length, cross-section-area…material properties, etc. Capacitance = ϵ ∗ Area/DielectricThickness C a p a c i t a n c e = ϵ ∗ A r e a / D i e l e c t r i c T h i c k n e s s. Refer to the bottom of the page for explanation of input variables and other notes. Your breadboard wiring or PCB traces will act as additional inductances. H = Seperation between wires in in. Even and Odd Mode Impedance. A PCB is composed of a number of parallel conducting elements that are separated by an insulator, basically forming a capacitor. PCB Coil Calculator. DLY is a standard parameter associated with PCBs. Inductance Calculator. Calculate the required trace width for a specified current using the PCB Trace Width calculator. 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. PCB Trace Width Calculator & PCB Trace Resistance Calculator per IPC-2152. 2 0. Stick to these design rules when you’re designing your stack-up. . Comparison of smooth (RMS=0. O. Online calculators will generally use. Lant 0 N 1. 1. Coplanar Waveguide Calculator. More advanced (but more accurate). This transmission line calculator was. The characteristic impedance is given by: Eq. 4. Figure 3. Conditions: W>>H, H>T. 17 dynamic pcb effects 12. Where: H is the height of the PCB above the ground plane. The fabrication etching process will have a greater effect on traces that are long and isolated, so it is better to make them wider when possible. Optional Inputs: Temperature Rise:. ESL effective. 48ohms resistance. The process of designing and simulating planar coils to achieve reliable results is commonly limited on accuracy and or geometry, or are too time-consuming and. In general, a 10-mil-wide PCB trace, separated from the ground plane by 0. The real structure of any. Edge Coupled Trace Inductance Calculator. For example a PCB that uses 1 oz. This tool will also compute the resistance of the microstrip, the voltage drop, and the power. At some point the amplitude will stay constant. I believe that some friends have been able to guess what factors affect the circuit impedance from the above PCB trace impedance calculation formula. Partial Resistance – from Serial Resistance Calculator. This article traces the effort to see what PCB board parameters have the most impact in. Likewise, conductors on a PCB will inevitably form complete loops, creating an equivalent inductor. I seem to recall the one by TechNick is pretty good. Figure 7: PCB traces with their parasitics – circuit model and impedance vs. 67nH. In these PCBs, the PDN should be arranged with at least one power/ground plane pair placed closely to. 7 ground noise and ground loops 12. calculate the inductance of wide trace over a ground plane. 100 x 2. 031”) thick PCB (FR-4) has: ˜ 4nH and 0. Just enter the given values for trace thickness, substrate heights, trace width, and substrate dielectric. An overview about how via impedance control affect signal integrity. Mounting Inductance is the additional series inductance contribution associated with the mounting of the capacitor on the PCB. An equation(6) to estimate the inductance of this loop with about 95% accuracy is: The equation to find the capacitor value is: Same unloaded Q Rrad L C Rloss (a) L C (b) par Board layout Series Circuit Parallel Circuit (c) C RFinput a) Loop antenna physical. Propagation delay (t pd) in PCBs is the time taken by a signal to travel through a unit length of a transmission line . Voltage drop calculationMicrostrip Max Current Calculator. We recommend the software from Polar Instruments if you want to get exact impedance calculation. I am also told my trace is to be 1000 micrometers long (1mm) and 45nm wide. Get accurate measurements with Keysights premium oscilloscopes – Source: Keysight. How to find the inductance of a PCB trace? Trace inductance increases with. In terms of the characteristic impedance in line 1, mutual. 7E-6 [Ω · cm] L is the trace length [cm] T is the trace thickness. If you’re designing an RF PCB for. 063″ = 1. 3. 035mm) The original for this equation is by F. These models attempt to. Low. Dual Stripline Trace. Heat is generated through ohmic heating P = I2 ⋅R P = I 2 ⋅ R of the copper trace. 252 Ω (σ of copper 5. If you’re designing an. Calculations are made using the formula below: Where: Enter the frequency and inductance into the calculator, choose the measurement […] This calculator computes the inductance of a microstrip etched on a PCB. 5), where w is the width of the trace and d is the distance between the trace and the ground plane. As with the case of a single-ended microstrip, you could apply the same type of model and procedure to striplines. To use this calculator, just enter the required values and press. The variables used in this tool are the diameter of the wire conductor and the diameter of the wire loop. The power plane pair between the capacitor and the IC adds to the effective inductance. Create a flat coil with only a few turns of very thin wire, or create a flex PCB with just a few traces. w is the Width in cm. This calculator requires symmetry in the trace widths and location between plane layers. Once these decisions are made, a designer needs to determine the PCB trace width required to hit their required PCB transmission line impedance. r = Coil radius in inches. Trace temperature calculation. The PCB Impedance Calculator in Altium Designer. First, calculate the area according to the following formula: A = (T · W · 1. Inductance is the ability to store energy in a magnetic field, and coils are a common way to create inductance. Dimensions are in meters. So It is recommended to avoid trace widths less than 6mil, unless it's absolutely necessary. For example, a 2. The inductance represented by the combination of one signal via and one return via at distance s equals: In metric mks units ( h, s, and r in meters, L in Henries), the constant μ/2π works out to 2·10 -7 H/m (assuming a non-magnetic dielectric). 1996. In total the. This calculator computes the inductance of a microstrip etched on a PCB. See more . 08h× [ln(4H/D1)+1] [2] where ε is the relative dielectric constant of PCB, D1 is the diameter of the via, D2 is the diameter of the anti‐pad, T is the thickness of the PCB, and H is the length of the via. Note: µ0 = 4¶·10 -7 [Hm -1 ] (Absolute Permeability) Microstrip Impedance Calculator. 24 pH, where pH is units of microhenries. 37) If H1<1. When in doubt, use 1 for copper, . The inductance of a rectangle loop has three geometric variables: W – rectangle long side; h – rectangle short side; d – wire diameter; Rectangle Loop Inductance Model. To learn more about the capabilities of EMI Analyst, sign up to access our download area or send us a. R 50Ω R 50Ω RM VS LM VS VI V=L V=IR d dT Scope Input I Figure 7. What is the rule of thumb for trace inductance? A common rule of thumb for trace inductance is that wider and shorter traces have lower inductance. Stick to these design rules when you’re designing your stack-up. It is important to note that in industry we can find that some differential pairs are routed this way for a strong coupling, but the actual return for the signal is on a. Optimize power transfer with our Impedance Matching Calculator. g. E. Differential Pair Impedance. Traces on PCBs are small and therefore have small inductance levels. Twisted Pair Impedance. 0. A = L. The current-carrying capacity of a piece of copper is determined, to a first-order approximation, by two factors — the rate of heat generation and the rate of heat dissipation. The insertion loss difference for the microstrip circuits shown in figure 4 have more improvement due to the smooth copper,The formula for calculating the inductance of an air-core flat spiral coil is: Where. This Tables converts Cu Oz to mils. 023mV/A. W. 2235* (w+h)/b) where: w is width of the strip in inches, b is the length in inches, h is the distance between the strip and the ground plane, and. 1. Brad - January 29, 2008 Ivan, Inductance requires a few more input parameters, so I have a separate calculator:PARAMETERS of inductor traces: witdh = 0. Remember, self-inductance is also known as back EMF. 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. The Via Inducatance according to Howard Johnson can be given by the following formula ( which is not very accurate as it does not take into account the return path of the current). 19 INDUCTANCE 12. 949. Heat is dissipated through conduction, convection, and radiation. 5. Now consider a sine wave coming into the trace. Option 1 - Flat coil. 4. 023mV/A. A series of simulation studies are conducted in ANSYS to analyse the relationship between the overlapping area, winding loss, magnetizing inductance, core loss, and parasitic capacitance. = 1. It should also be noted that blind and buried vias involve a higher production cost, so it is advisable to plan their use in advance in order to respect the budget allocated to the PCB. Thanks,The Smith Chart graphically maps S11=reflection coefficient= (ZL-Z0)/ (ZL+Z0) to Load Impedance (ZL), normalized to Z0 (source impedance = center of chart). 4k 33 142 257 asked Nov 26, 2012 at 23:13 mFeinstein 4,313 12 46 85 Sounds interesting and dangerous. A copper Thickness of 1 oz/ft^2 = 0. 26%; Circuit amplitude = 62. This tool is designed to calculate the resistance of a microstrip trace with a copper conductor. Coils produce a magnetic field when current flows through them, storing energy in their magnetic field. Graph Paper. 2mm trace width, 45 turns, inductance= 20uH and 0. First choice: Don't. The round-wire geometries are loops of wire with various shapes. The calculator has an input box for the resistivity which defaults to 1. This procedure produces the result ( w/h) = 1. Figure 9 Shorten the trace between gate and driver output 4. •Based on the PCB manufacturing rules, set: –a. A PCB. 25mm, a trace width of 0. However, at 13. interference coefficient = 0. This calculator is designed to calculate the characteristic impedance of a microstrip - a flat conductor suspended over a ground plane with a dielectric between them (see diagram below). This means that the actual trace width for a 50 ohm line could vary from design to design. 561235. Here is a calculator for pcb trace inductance. according to Saturn PCB calculator trace resistance would be ~0. Max Current calculation. In order to acquire inductance parameters of the coils on PCB, a method is proposed to calculate the self-inductance and mutual inductance based on the Neumann formula. 2 laminate. And that's why the Rogowski coil's design comes with an integrated circuit and a large shared inductance. Coplanar Waveguide Calculator. Radio Frequency Engineering Calculator. First, calculate the area according to the following formula: A = (T · W · 1. 68uH and Rant = 1. Just enter the given values for trace thickness, substrate heights, trace width and substrate dielectric in the calculator above and press the "calculate. 5 nH, which is consistent with typical trace inductance values. The propagation of electrical signals through PCB traces is not instantaneous; it is subject to a delay. Prev: China's market development should be improved PCB terminals. Using the example numbers: L = 20 x 10^-3 * 12 x 10^-12 = 240 x 10^-15 henries or 0. Specifications of the Rogowski Coil. 2dB (at the power level) Configuration of the circuitry ranges from 50Hz to 1kHz . Stripline Impedance. Engineering Paper (Printable PDF)Max Current calculation. 25 mm) for 1A, 40 mils (1. Therefore, with a few inches of circuit board trace and the terminal capacitance of the operational amplifier, it is conceivable that there can be 15−20 pF on each operational amplifier. Broadside coupled traces are on adjacent planes and the return is identical to the trace in width and length. If you’re designing an RF PCB for microwave or higher frequencies, controlled impedance routing should be top of mind to ensure signal integrity. What PCB trace width should I use and can someone give me a guideline on how to . A trace resistance calculator is a tool used to calculate the resistance of a trace on a printed circuit board (PCB). 5. The tool implements numerical solutions of Maxwell’s equations to render accurate and consistent results. In other words, for proper impedance control, the load impedance must be equal to the characteristic impedance of. Stripline Trace. Figure 1 Cross section of a PCB 1 E. Backwards crosstalk creates a pulse width that is twice that of the propagation time of the pulse traveling the coupling distance. 1mm) or 6mils(0. 5), where w is the width of the trace and d is the distance between the trace and the ground plane. This decreases inductance and should be as wide as possible to reduce resistance. 4 0. Where: T TEMP is the trace temperature [°C], T RISE is the maximum desired temperature rise [°C], T AMB is the ambient temperature [°C]. This is a 6-layer pcb. Keep in mind that the reactance of the ideal inductor has the same magnitude as its impedance. Traces such as these are found on adjacent planes with the return being identical to the trace both in length and in. This transmission line calculator was. Very typical/basic knowledge…. Overview. (1) where w = the width of the rectangle (wide dimension) h = the height of the rectangle (short dimension), and a = the wire radius. Calculations are made using the formula below: Where: Enter the frequency and inductance into the calculator, choose the. For a 1 inch trace, this value would have a total inductance of ~7. Related Products: Magnetics, Transformer MiscNow add a second trace in parallel (connected at each end) of the same length and dimensions, such that it also has the same inductance x x. Introduction A coil is a common electrical component that provides inductance in circuits. 008. The inductance of a path depends on the area of the loop created by the current flow. 5+0. PCBCart is capable of manufacturing printed circuit boards with controlled impedance according to your requirement. Advanced Circuits is MIL-PRF-31032, MIL-PRF-55110G, AS9100C, ISO 9001:2008 Certified, IPC 6012 Class 2, 3 and 3A Qualified, and ITAR Registered. Abstract. 9 ground isolation techniques 12. Reference: R. Microstrip PCB Impedance in an electric circuit causes an electromotive force to be generated by a change in the current flowing. PCB Trace Power Handling Calculator. Log In No account yet? You can Sign Up for free!. trace with a total loop inductance of 211 NH. In addition to DC inductance and resistance calculation, EMS is equipped with AC Magnetic and eddy current. For a given form, an inductance is characterized, as shown in Fig. Impedance quality = Q = L/Rs 2. 7E-6 [Ω · cm], L is the trace length [cm], α is the resistivity temperature coefficient, whose value for copper is 3. EEWeb offers a free online copper PCB trace resistance calculator. The PCB Impedance Calculator in Altium Designer. Loop Inductance Model. ant = R. = 2. (2) Where: H = thickness of dielectric T = thickness of microstrip conductor W = width of microstrip conductor Valid for 0. : 1. A trace is a conductive path on a PCB that carries electrical signals between components. 3 0. 7 10^ (-6) Ohm-cm. 0. Calculates the current a conductor needs to raise its temperature over ambient per IPC-2152. Equation 3. 1. 0: 0. 3 shall be used. Therefore it doesn't change (to a first order approximation) at different frequencies. Calculate trace width values based using the IPC-2221 charts by providing inputs such as current thickness and temperature values. length = 503mm. Component: Copper Traces Purpose: Interconnect two or more points Problem: Inductance and Capacitance x = length of trace (cm) w = width of trace (cm) h = height of trace (cm) t = thickness of trace (cm) e r = PCB Permeability 0. And as the PCB circuit complexity. com If it. You can get a good estimate of the parasitics of your layout by entering the plane/trace dimensions in a trace impedance calculator. 28) Opamp. Electric Vehicle. Protože se tyto vzorce řídí logaritmickými pravidly, jsou určeny pro některé konkrétní hodnoty. 1. This calculator is designed to calculate the characteristic impedance of a microstrip - a flat conductor suspended over a ground plane with a dielectric between them (see diagram below). To use it, first select the tolerance of the resistor: 10%, 5% or equal or smaller than 2%. Lcoil = μrμ0N 2A l = μrμ0N 2πr2 l L c o i l = μ r μ 0 N 2 A l = μ r μ 0 N 2 π r 2 l. Output voltage = 0. This calculator computes the inductance of a microstrip etched on a PCB. Jensen, “Accurate Models for Microstrip Computer-Aided Design,” 1980 IEEE MTT-S Digest, pp. w (strip width)The parasitic inductance that resides along a PCB trace increases the impact of any voltage spike induced by switching power supplies. l = Coil length in inches. 427e-9 H = 1. If the line width is equal to the spacing from the ground plane, then the total inductance of a PCB trace is close to 10 nH/inch. 7E-6 ohm-cm. One should always check carefully whether a calculator implements these equations under the appropriate approximations. IPC 2221 calculator uses a single graph and an equation for determining the track current denoted by 1. The inductance of a wire loop is a common textbook example of a circuit with inductance. In other words, this is the impedance the signal actually experiences as it travels on an individual line. Inductance and Impedance – from Capacitance and Frequency Calculator. THESE FORMULAS ARE APPROXIMATIONS! They should not be used when a high degree of accuracy is required. The tool implements numerical solutions of Maxwell’s equations to render accurate and consistent results. Trace capacitance calculation. The surface finish is neglected. And this PDN impedance is becoming more and more of a. 22 PARASITIC EFFECTS IN INDUCTORS 12. calculate the impedance and capacitance of PCB traces. In this case, there will be both an IR component due the small trace resistance (RM) and an L*dI/dT term due to the trace inductance (LM). Where, Area = Thickness*Width. Inductance is the ability to store energy in a magnetic field, and coils are a common way to create inductance. This calculator is designed to find the characteristic impedance of an asymmetric stripline - a flat conductor between two ground planes. The multi-turn inductors are used for higher inductance value design. 35mm gives 50Ω, far easier to use. 26. Convert psi to bar, kgf/cm2 to psi, bar to kgf/cm2, and other units like pa, mmH2O, inches H2O, psf and atmosphere with the pressure measurement conversion calculator. μ. You can see the input HV connector that goes through the DC blocking HV cap and the HV reed relay. It should also be noted that blind and buried vias involve a higher production cost, so it is advisable to plan their use in advance in order to respect the budget allocated to the PCB. Generally, when we talk about the. 4, by the number of turns n, the width of the conductor w, the spacing between turns s, the thickness t of conductor, the conductor’s total length lt, the average diameter, the diameters outside and inside dout and din. If. 0. The mutual inductance equation is: The terms in the denominator state that the odd-mode and even-mode capacitances must be evaluated at epsilon = 1. 725. FIGURE 2: PCB COPPER LOOP 34mmx12mmx1mm Using Equation 4, we calculate radiation resistance at 434 MHz as Rrad = 0. Since the goal of trace design in a PCB is generally to get close to an impedance target, designers will need to use some equation to calculate the impedance of a trace or a transmission line impedance calculator to properly size a trace in a PCB layout. (2) Where, • N = Number of turns • w = Average width of the rectangle • h = Average height of the rectangle • a = PCB trace width • µ0 = Permeability of. Designers need numerical tools and the correct analytical formulas to calculate the inductance of their PCB. 2 of the Microstrip Calculator, h=H1 and b=H2-H1. 44, c = 0. Conductors are assumed to be separated by a homogeneous medium having permittivity and permeability . The required values are trace thickness, substrate heights, trace width, and subtrate dielectric in the calculator above and press the "calculate" button. We may increase the copper plate thickness to increase the current carrying capacity or reduce the required width. There is no ground plane off course. Current and heat considerations: Depending on which. Mutual and Leakage Inductance. Conductor is assumed to have zero thickness and to have uniform height. A coil inductance formula is based on the basic loop inductance. 00508*b* (ln (2*b/ (w+h))+. Windings with 5. You can then check this PCB trace width against. Here’s how you can size your traces correctly and ensure they have sufficiently low PCB trace inductance. You would need to tune this inductor to resonate at 13. Impedance matching is the way of configuring the input impedance of a load or the output impedance of its signal source. 5. Plug in the values into the inductance formula: L = N²/R. As the driving frequency increases, mutual inductance between circuits in your board will cause the impedance of your power delivery network to increase. This tool will also compute the resistance of the microstrip, the voltage drop, and the power. Select the coil layout: ENTER THE INPUT DATA: L. 24 pH, where pH is units of picohenries. Visit to learn more about our other electrical engineering tools and resources. 4 Figure 2. The target impedance value of a design is given by the equation: Z = ( V x ripple%) / ( 50% x Imax) The formula represents a combination of voltage fluctuation and transient current. The current can bypass the inductance loop even if there is an impedance mismatch in the via. Trace inductance that includes the current path through the ground net; Trace capacitance with respect to the ground net; Together, these values define the transmission line impedance,. The calculator then uses a formula to calculate the width and spacing of the trace or transmission line required to achieve the desired characteristic impedance.