In both cases, you’ll need to enter your stackup information into the calculator to get accurate results. Given Relative permittivity of air ε = 1; Relative permittivity of dielectric ε = 4. How to analyze the Sievenpiper high-impedance structure supporting a backward wave. g. By adding the formulas of the dielectric and copper, a similarly simple formula of total attenuation is obtained. Altium Designer’s differential line impedance calculator will set up your impedance-controlled differential pair routing widths for you. The differential signals need to be driven with opposite polarity signals. You could use thinner traces with these differential microstrips, but you would need to use a smaller spacing. Based on Zo Equation Per: IPC-D-317A: Formula:0. p = (Zi - Zo) / (Zi + Zo) Let us consider the case Zi = Zo. Dual Stripline Trace. Enter one of the three values and the calculator will output the other two. For example, going from 10 mil to 20 mil alumina, or two-mil to four-mil GaAs. 3mil seems like a substantial enough difference. Changed the microstrip impedance calculator formula to a complex version for accuracy. 588 mm and relative permittivity of 2. Calculating the Differential impedance is a two-step process, first Calculate the single ended impedance Zo and then use this value to calculate the differential impedance. An example of a wire microstrip might most often be found in prototypes or reworked boards where a wire is used over the top of pcb or copper clad material. Take note that this assumes that the distance between the conductor and the planes is not the same for both reference planes; hence the asymmetric term. Coplanar waveguides are open quasi-TEM waveguide geometries that use copper pour and a ground plane to provide shielding along the length of a PCB trace. 6. Calculate Coplanar impedance for given PCB parameters. Coplanar Waveguide With Ground Characteristic Impedance Calculator. The even mode impedance is twice the common mode impedance, giving a value of approximately 40 ohms. 90 Ohm Differential Pair: 0. The edge couple differential symmetric stripline transmission line is a common technique for routing differential traces. 9D/B) Zo = Single Ended impedance. 5. VSWR, Return Loss and Reflection Coefficient. A stripline resembles a microstrip line and comprises a center conductor pattern symmetrically embedded completely within a dielectric, the top and bottom layers of which are conducting ground planes. Before we can start routing the PCB, we need to define Design Rules for our differential traces. By calculating and designing microstrip traces with the desired differential impedance, engineers can optimize the performance of RF circuits, antennas, and filters. 5oz. Impedance. Edge-Coupled Microstrip. Impedance (Z o ): 76. Creating and Configuring an Impedance Profile. 08. The required inputs are the Dk value for the dielectric constant of the PCB substrate, and the. 2-side PCB, one side with signals, the other with GND. ( 0. Calculate odd mode impedance of differential PCB transmission line (Since R2022b) dgs: Create defected ground structure of PCB element (Since R2023a)I read this at si-list and thought that it may be useful for the PCB Designer. For better impedance control, use PCB design software you can trust. In design, the physical dimensions must be determined given the desired electrical properties. T T = trace thickness. If, in addition to a differential impedance (Z Diff), you also need a defined Z 0, proceed as follows:. Since stripline traces are typicallyStripline vs. This is the same reason we have to consider spacing between traces in differential pairs: the two conductors interact with each other to determine the odd-mode (and differential) impedance . In the Electrical Parameters window, you should see that the resulting value of the characteristic impedanceIn the modules documentation it says that the LVDS differential impedance shall be 100ohm, but no tolerance. Another example of using large distances to separate out unwanted components might be to calculate the impedance of a. Spacing and width value pairs that will give a differential impedance of 100 Ohms on Dk = 4. The Impedance Calculator is a tool which allows a quick pre-layout estimation of several kinds of line impedances between different layers. Transform Delta to Y: Add Series/ Parallel Resistor: None R in Series with R1 R in Series with R2 R in Series with R3 R in Parallel with Ra R in Parallel with Rb R in Parallel Rc. With t = 35 um (typical for copper with plating on a pcb), Z odd drops to 44 ohms, according to LineCalc. This is a required. For the 70. Working with coplanar. 4-Layer Impedance Control Stackup. The edge couple differential symmetric stripline transmission line is a common technique for routing differential traces. Grounded Differential Coplanar Wave Guide. mm mils. g. One of the features of this type of microstrip is the coupling between lines. 50 - 55 ohms). Pi-Matching Impedance Network Calculator. Calculate odd mode impedance of differential PCB transmission line (Since R2022b) dgs: Create defected ground structure of PCB element (Since R2023a)Differential Microstrip Impedance Calculator | Differential Microstrip Impedance Calculator (Using Zo) | Embedded Microstrip Impedance Calculator | Microstrip Width Calculator | Transmission Line Mitred Bend Calculator ; Radar Calculators:Differential Impedance Differential Impedance: the impedance the difference signal sees ( ) ( ) 2 2( ) Z 0 small I V I V diff Z diff one one = = ≈ − Differential impedance decreases as coupling increases +1v -1v I one x I two How will the capacitance matrix elements be affected by spacing? C 12 C 11 C 22 Eric Bogatin 2000 Slide -18. The finished layout is shown in Figure 5. For example, if you wish to input "25000000", just type "25M" instead. A. The calculator is set up to handle an asymmetric arrangement, where traces are not centrally located in the PCB layer stack. It actually depends upon the D/H ratio. 5. 1. 1. ϵr ϵ r = substrate dielectric. So it should be possible for the velocity to change without the characteristic impedance changing, but. The driver has an output impedance of 10 ohms. These parameters include:The characteristic impedance (Z o) of a microstrip transmission line can be calculated using the active calculator or the equations at the bottom of the page. and thats the first time iam doing ethernet things. This structure supports both an even and an odd mode. Impedance (Ω): The desired impedance. Learn how to design microstrip and CPW power dividers using Keysight EEsof EDA tools in this technical overview. We will explore the need of the controlled impedance and will try to understand how to acheive it. coupledmicrostrip = coupledMicrostripLine (Name=Value) sets Properties using one or more name-value arguments. Microstrip Differential Impedance Calculator; Impedance To Turns Ratio Calculator; Impedance to Voltage Calculator; To calculate the impedance of a stripline, divide 60 by the square root of the relative permittivity of the dielectric material. In fact, striplines often make components such as band-pass filter's more accurately, with more symmetric roll-off and no lower cutoff frequency. The stripline impedance calculator provided below is useful for gaining an initial estimate of trace impedance for striplines. The amount of the voltage reflected back is given by the following equation. 77 mm gave me a differential impedance very close to 90 Ω. By calculating and designing microstrip traces with the desired differential impedance, engineers can optimize the performance of RF circuits, antennas, and filters. com To use the Microstrip Differential Impedance Calculator, follow these simple steps: Input the known values into the corresponding fields: Characteristic Impedance (Ω) Height of Dielectric Substrate (m) Width of Microstrip Trace (m) Leave one field blank, as this will be the variable you want to calculate. 8. e. This calculator is designed to calculate the characteristic impedance of an embedded microstrip - a flat conductor suspended over a ground plane with a dielectric between it. The advantage of this method is that we need to work only one time to define the constraints. microstrip (Name,Value) sets properties using one or more name-value pairs. 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. *Comparisons show minimal differences to ADS linecalc and Polar Instruments Quicksolver industry standard tools. Z diff = 2* Z o (1 - 0. 13mm (depends on manufacturer's specs) and you get a trace width of ~0. Polar or rectangular grids only allow direct reading of S11. differential impedance : NOTE: numbers are in scientific notation (e. The Smith Chart achieves this by superimposing a grid on S11 that maps load impedance. IEEE, 1997. Use several of them and compare. 50Ω. 8 substrates of various thicknesses. DIFFERENTIAL MICROSTRIP IMPEDANCE CALCULATOR Trace Width (w) mils Trace Separation (d) mils Trace Thickness (t) mils Dielectric Thickness (h) mils Dielectric. Pasternack's RF calculators and conversions section provides engineers valuable and easy-to-use tools ranging from complex mathematical formulas to simple conversions. 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. Allows for a 0. Embedded Microstrip Trace. We recommend the software from Polar Instruments if you. 6 ohms and Z even = 110 ohms for your geometry, very close to your result. Note that the "h", for dielectric thickness in this formula is omitted in some other Polar publications. Signal 2. For now let us focus on the single ended impedance. i know that i can use. microstrip ('Thickness',0. This calculator will convert voltage or power gains into decibels. If, in addition to a differential impedance (Z Diff), you also need a defined Z 0, proceed as follows: Calculate Z 0 as normal Microstrip, until you get the desired value, e. guideline pertaining to microstrip PCB impedance. Where: Z e trace impedance Er e die-electric constant Er e 4. Calculates the differential pair impedance of a balanced line. Note that Zdiff (differential impedance) is equal to 2 * Zodd, so a Zodd of 45 Ω gives us a Zdiff of 90 Ω. The differential impedance will be a bit less than 2x the single-ended impedance. 1. The dielectric constant of air is 1,and the dielectric constant inside the pcb stackup is usually 1. Added calculation for Electrical Length as Air Line equivalent; Added calculation for Delay time ;. The Smith chart center (1*Z0) is your reference impedance. A symmetrical stripline is shown in Figure [Math Processing Error] 3. 3. Tpd: propagation delay. 3V B . Ω/mΩ/in. A typical 4 Layer Stackup looks as follows. Ask Question Asked 1 year, 4 months ago. Differential Impedance of Microstrip. Note: Differential impedance is the ratio of voltage to current on a pair of transmission lines when driven in the differential mode (one signal positive and the other negative). Impedance is the resistance that a transmission line presents to the flow of energy along the transmission line. The problem of determining the frequency dependence of the impedance of a microstrip line is very important in order to create circuit models of the electronic components and touchstone-files in the virtual strip. Microstrip Calculators. Such a microstrip is constructed with two traces referenced to the same reference plane with a dielectric material. w = Trace Width. nm um mm cm m mil inch. Compared to waveguides, microstrip is generally has a lower power handling capacity, and higher losses due to the fact that it is not enclosed. However, if the impedance of the transmission line changes for any reason, a part of the electromagnetic wave is reflected back towrds the source. A simple microstrip is located on the top of the board, while an embedded microstrip is located inside the board substrate as illustrated below. The characteristic impedance of your microstrips is determined by the trace width for a given layer stackup. 6mm 4 layer PCB, 1oz outer copper, 0. Simons, "Coplanar Waveguide Circuits, Components, and Systems", Wiley. A typical 4 Layer stack up. The microstrip is a very simple yet useful way to create a transmission line with a PCB. 5 (FR-4) Er e 2. 5 GHz. Zcommon is half the value of Zeven. Antenna Calculators. For this calculation, the units of d,h, t and w can be ignored as long as they have the same units (mils, mm, inches). This calculator assumes. 0075e-6) creates a microstrip transmission line with thickness of 0. 5. Equation Source: Ulaby "Fundamentals of Applied. 3 enable the electrical characteristics to be determined given the material properties and the physical dimensions of a microstrip line. 3 CPW Structures; 3. Figure 5. The two most common impedances. Reference: R. [m] height of trace above return plane. , the structure is made up of two dielectric materials: air and the substrate material). Just enter the given values for trace thickness, substrate heights, trace width, and substrate dielectric. The differential impedance of a microstrip can be calculated using the online calculators. Relative Dielectric Constant ( εr ): Track Width. 01 Mar 1998. With hundreds of coaxial RF cables in-stock and ready to ship worldwide immediately, our coax capacitance calculator lets you calculate the impedance of a coax by allowing you to enter the outer diameter dielectric width and inner conductor diameter. *The structure may propagate in 3 modes: coplanar waveguide, coupled slot lines and microstrip. H (Dielectric thickness) :Clemson Vehicular Electronics Laboratory: Transmission Line Impedance Calculator. I checked out TNT, but couldn't seem to be able to do the same with that either. The two most common impedances. Calculating the Differential impedance is a two-step process, first Calculate the single ended impedance Zo and then use this value to calculate the differential. The Pi match circuit is so named because the circuit topology can resemble a pi symbol. 0; 1 < ε r < 15 ) Select the units for all dimensions: mm mils. These are considered to be standardized impedance values with cables readily available. 1oz 2oz inner Copper Weight. 7mil. Altium Designer allows you to analyze the signal integrity of your PCB design at the schematic capture stage. This helps ensure that your microstrip trace impedance and stripline trace impedance will match to the desired value within a predefined tolerance interval. Introduction to dispersion diagrams and eigenmode simulator. The results are summarized in figure 4. This calculator can calculate the impedance and propagation delay of any microstrip by taking its respective height, width, thickness & dielectric constant. The default units for all given values, except the subtrate. The stripline impedance calculator provided below is useful for gaining an initial estimate of trace impedance for striplines. Attenuator Calculators. 0 2. For the odd mode, the differential impedance can be obtained by setting the integration region to enclose only one of the microstrips, and the characteristic impedance of the odd mode is half the differential impedance, approximately 22 ohms. For microstrip traces, a solid ground plane is needed under the signal traces. Make sure the correct Layer is selected before changing this option. Lossless impedance formulas for PCB traces without parasitics (left) and with parasitics (right) to a quiet line or plane. The PCB Impedance Calculator in Altium Designer. (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 differential impedance will be a bit less than 2x the single-ended impedance. 5 Ohms higher than the formula method. For example, coupledMicrostripLine (Length. g. This calculator determines the differential microstrip impedance of a transmission line. Most RF Coaxial Cables have an impedance of 50 ohms or 75 ohms. H1. In tab “TransLine” i chose “Coupled Microstrip Line” and i can calculate the impedance of only one track. The formulas developed in Section 3. Based. Modified 1 year, 4 months ago. Impedance Calculator - Sierra Circuits. e. εeff is the calculated effective dielectric constant of the microstrip line due to the nonhomogeneous nature of the structure (i. 427e-9 s/m = 1. Coplanar Waveguide With Ground Characteristic Impedance Calculator. A Clemson ECE635 Project by Adam Schreiber and Jason Byers. differential trace impedance for USB (90 Ohms) on 2-layer FR4 board. The default units for all given values, except the subtrate. I used the differential impedance calculator in the x-section dialog and also the allegro impedance workflow a few times. W2: Width of the top surface of the trace. Board thickness (h) = 50 micron. 0 specs requires a differential impedance of 90 Ohms and a common mode impedance of 30 Ohms (with some tolerance). Usually Microstrip separated from the ground by using dielectric substrate. ( 0. This assumes ~0 trace thickness. The figure-1 above depicts differential. 1 to 3. While this calculator will provide a baseline, any final design considerations should be made towards loss, dispersion, copper roughness, phase shift, etc. coupledmicrostrip = coupledMicrostripLine creates a default coupled microstrip transmission line with a Teflon substrate and default properties for a resonating frequency of 1. This Mantaro calculator tells me that I need a trace width of 11. Typical realisation technologies are printed circuit board (PCB), alumina coated with a. 7. *Solder resist PCB coating will have the effect of lowering the impedance (due to the 30um or so of Er 3. Odd mode impedance is defined as impedance of a single transmission line when the two lines in a pair are driven. An example of this calculation using the Si8000m Quick Solver is shown below in figure 4. Track width (w) = 137 micron. While commonly constructed using printed circuit boards, this structure can also be built using other materials as long as there is a conductor separated from. The input impedance, Zin, of the shorted microstrip line is shown in Figure 3. The grounded differential coplanar wave guide is the differential version of the grounded coplanar wave guide and is used in high-speed digital systems that require maximum noise immunity. e. 8. 542 mm, a substrate height of 1. Z diff = 2* Z o (1 - 0. Continuously updated with new calculators. This has been a research topic for differential serial protocols over the last several years, and standards like USB 4 place specific requirements on broadband signal integrity metrics. RF calculations and RF conversions include metric. Increasing t decreases Zo, although it has small effect on Zo. Width (w) Trace Thickness (t) Dielectric Thickness (h) Relative. How to Determine Impedance? Impedance is usually between 25 to 125 ohms in a trace, depending largely on the following factors: The width and thickness of a copper trace;. Radio Frequency Engineering Calculator. 6 Ω and ε e = 6. h = Dielectric Thickness. First, consider a microstrip. EasyEDA directly supports controlled impedance designs for 4 and 6 layer PCBs only. Equation 3. 0. But it lacks the differential impedance (impedance between these two tracks). I have calculated a Microstrip Line in AppCAD and in Saturn. This, by definition, gives a target of an odd mode impedance of 45 Ohms and an even mode of 60 Ohms. Several people have developed. In other words, if you are designing to hit a differential impedance target. Click the button corresponding to the characteristic impedance to calculate its value. At low frequencies near 0 GHz, the input impedance is inductive since. But it lacks the differential impedance (impedance between these two tracks). Differential Impedance Ω. h = rfckt. ) and the LOW level is defined as zero. For example, if u = 1 and ε r = 10, then from the figure, Z 0 ε e = 126 Ω and ε e / ε r = 0. This calculator finds both odd and even transmission line impedance. Z 0 Differential impedance (Ω): Calculate. You can also define the supply nets and use the Tools menu to provide average track impedances and route lengths. Simulation setup for microstrip fed patch antenna. Z diff = 2* Z o (1 - 0. 3. One should always check carefully whether a calculator implements these equations under the appropriate approximations. We recommend the software from Polar Instruments if you want to get exact impedance calculation. H. *Accurate for arbitrary values of Er and w/h ratios. But practically (especially in a dense design like your example), they also interact with surrounding conductors, and the coplanar ground, or ground beneath a differential microstrip will affect the characteristic impedance. This calculator determines the impedance of a symmetric differential. In the case where you are routing differential pairs, then the potential between the two pairs will always be opposing (i. 36) Co Equation: IPC-D-317A (Eq. Just as a sanity check, we can quickly calculate the total inductance of a trace determined with this method and compare it with typical values. Line length Lz = 5 inches TaskDetermine the routing mode, parameters, and impedance calculation. On the other hand, microstrip will radiate more energy due to its exposure on an exterior layer to air. An Oscilloscope has rated bandwidth of 10 GHz. Separation between Planes. It is important to determine the characteristic impedance of a twisted-pair cable because this impedance should match the. For microstrip traces, a solid ground plane is needed under the signal traces. W + 2 × S ≤ 5 × H, dielectric constant >3. The impedance of a differential via pair cannot be treated with a single via impedance calculator unless the vias are spaced far apart. I have calculated width and gap of two microstrip lines, substrate height using single ended impedance Zo=50Ω and differential impedance Zdiff=100Ω, dielctric constant er=4. Provide values for the four parameters H 1, H, T, W, and the relative permittivity of the dielectric. For this calculation, the units of d and h can be ignored as long as they have the same unit. The differential impedance depends upon the D/H ratio. INPUT DATA. The reason for this is that the conductor width scales with substrate height, so thicker substrates mean fatter conductors. Provide values for the four parameters H 1, H, T, W, and the relative permittivity of the dielectric. This function converts of a set of conventional, 2-port, single-ended S-parameters into a 1-port differential impedance. This sets the single-ended impedance AND differential impedance to the target value, even if there is no. To calculate the. There are 3 types of single-ended models:. Using an online differential impedance calculator, the height of the dielectric layer, h, is needed. To avoid microstrip modes, have h >> (w+2g) and extend component side ground away from the trace by > (w+2g). mm mils. The range of accepted values is 20 to 90 Ω for single-ended and 50 to 150 Ω for differential signals. 003” flex cores for a stripline configuration. Calculating the Differential impedance is a two-step process, first Calculate the single ended impedance Zo and then use this value to calculate the differential impedance. 4mil and the dielectric thickness to the first intermediate layer (this is a 4-layer board) is 6. trace is typically quoted as being 5 to 10 nH. The microstrip PCB differential impedance calculator is also vital in RF and microwave systems, where differential signaling is used for RF and IF signal transmission. I tried to use the tool “PCB calculator” to determine the size of mi USB tracks. Broadband Impedance Matching with Transformer; Ferrite Toroidal Coil (Amidon) Helical Coil Calculator; Impedance Calculator : XL, XC; Iron Powder Toroidal Coil (Amidon)They has confirmed me, that the used formulas are very simple formulas. Include both the pcb dielectric thickness as well as the wire insulation in the height calculation. ; Apply the values to the differential calculation, e. Equation 3, which was developed by Martin Marietta in the mid 1980s, is a method for predicting the impedance of buried microstrip transmission lines. LineCalc was used to calculate the length and width for a quarter wave transformer. Note: Units do not matter for this calculation as long as they are consistent. 5 was. Coplanar Waveguide Analysis/Synthesis Calculator. Single-ended signals are fairly straightforward. This is the reason why engineers specify the trace width in their designs. H = distance to nearest reference plane. With specific circuit. I'm designing a custom PCB around the Raspberry Pi RP2040 MCU. For a case of dielectric constant of 4. Note that the y-axis is on a logarithmic scale for clarity. Calculates the differential impedance of a microstrip pair. THESE FORMULAS ARE APPROXIMATIONS! They should not be used when a high degree of accuracy is required. 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. RF/Microwave Design; Digital Design; Layout Services. The trace width is important as it determines the single-ended and differential impedance, capacitance, and inductance. The closer the two traces, the smaller is. Decibel Calculator. 1. The allegro calculator gives a value of 56. 4. Agilent's LineCalc tool calculates Z odd = 50. Simulation setup for microstrip fed patch antenna. A Grounded Differential Coplanar Waveguide (GDCPW) is a transmission line structure used in RF and microwave circuits. 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). 100 Ohm diferential impedance microstrip PCB traces geometries. Impedance To Turns Ratio Calculator. 3. That tool has an asymmetric edge coupled microstrip impedance calculator built in. example. 3. The required values are trace thickness, substrate heights, trace width, and subtrate dielectric in the calculator above and press the "calculate" button. The Dk calculator software can provide outputs as raw Dk data or as averaged output data points. 7. 6: Microstrip Design Formulas. Zo (diff) is calculated to be 244 ohms, so dividing by two yields a value of 122 ohms for the semi-coplanar structure. Using a 4 GHz reference antenna, the variations of input impedance and radiation patterns are compared, for (a) changing the feed positions to the non-radiating edge against (b) changing the width of a. Figure 4 Differential impedance comparison of 50 mil gap. What is the approximate actual rise time of the signal. Microstrip. So I decided to try and verify the calculator - jlcpcb offer an impedance calculator in their quotation system, and for a 6-layer 1. [m] height of trace above return plane. H 1 (Dielectric thickness) : mm mils. 5. The equations quoted below are from Reference 1, and are offered here as a starting point for a design, subject to further analysis, testing and design verification. ε r = Relative Dielectric. If the width of the trace is two times the height of the dielectric (for FR4, Dk from 4 to 4. It shows the minimum trace-to-ground spacing required to. I am trying to design a USB circuit, where the signaling is over a differential pair D+ and D- and these two lines are required by the spec to have 90 ohms of differential impedance. If a. For example, if you wish to input "25000000", just type "25M" instead. This calculator can calculate the impedance and propagation delay of any microstrip by taking its respective height, width, thickness & dielectric constant. [22] Figure 2 keeps the impedance Z 0 at 50 W while changing the dielectric "r; this requires the ratio w/h to change. Coupled microstrip transmission line. PCB Trace Impedance Calculator. 5 GHz. They will give very similar answers. zip (170k) AP117. The required inputs are the Dk value for the dielectric constant of the PCB substrate, and the. For example, coupledMicrostripLine (Length. Edge-coupled coated differential microstrip Edge coupled differential microstrip for flex PCB. The plots show the magnitude and phase of the input impedance. 8. It can also produce a comma-delimited file for modeling and programming purposes, such as for use in circuit model development. 3 Design Formulas for a Stripline. I finally have the microstrip characteristic impedance thing figured out. 347 e -2. Description. D = Separation between the differential traces. Create a new impedance profile, then select Single-Coplanar or Differential-Coplanar from the Impedance Profile Type drop-down list. A differential stripline pair refers to two traces located between two reference plane layers, which are routed as a differential pair. View All Tools. Since the numerator is the propagation constant, we. This calculator requires symmetry in the trace widths and location between plane layers. 8. The following are typical line widths and spacings for the more common impedance values when using ½ OZ copper: 50 Ohm Single Ended: 0. To avoid microstrip modes, have h >> (w+2g) and extend component side ground away from the trace by > (w+2g). 74mm. All transmission lines are 1 ounce thick (1. so i have had a look at a App-Note of the PHY chip: it contains a lot of good information - and for me its clear i have to do a differential pair for the TX+/TX- and RX+/RX- traces.