. ; Apply the values to the differential calculation, e. 1mm (3. KiCad has a built-in impedance calculator!The common-mode rejection ratio is a key figure of merit of any differential system because its primary role is to reject undesired common-mode currents with minimal impact on the desired differential-mode currents. The trace width (0. To calculate this, you need some values. Although widely applied to coaxial cables against EMI susceptibility problems, the Zt parameter can be easily extended to coaxial cables EMI emissions. Also, I tried the differential tools in KiCad, and I matched both pairs to the same length (otherwise, one track is about 6 mm longer). This technique is used for routing internal layer differential pairs. If a different frequency is required, pick. Sorted by: 1. 0037” line/0. That option operates on a single trace. Z diff equals Ra||(2Rb) (p model) or 2R 1 (T model). 08-07-2018 02:42 AM. Unfortunately Online Calculators are deceiving unless you actually draw the numbers and understand the ratios and tolerance effects. Figure 4. Differential Stripline Impedance Calculator. The resultant current is called common-mode current. 2 of the Microstrip Calculator, h=H1 and b=H2-H1. Twisted pairs are used with balanced signals. , USB. There are four different types of impedance used in characterizing differential trace impedances. The IPC-2141 trace Impedance calculator will help make initial design easier by allowing the user to input basic parameters and get a. THESE FORMULAS ARE APPROXIMATIONS! They should not be used when a high degree of accuracy is required. The Signal Integrity tool is examining the series termination needed based on the line's characteristic impedance If you are examining a trace in a differential pair, the Signal Integrity tool is still only used the characteristic impedance, not the odd-mode impedance. There are a lot of online trace impedance calculators specifically designed for differential traces. Note that the y. This is typically used when golfers play only a partial round or when a full 18-hole round isn’t completed. When a differential pair is routed on a printed circuit board we assume that the signals will be of equal magnitude and opposite polarity. It incorporates many features that PCB designers and engineers are in regular need of like current capacity of a PCB trace, via current, differential pairs and much more. Figure 1 shows a typical wiring diagram for the differential pair of an Ethernet PHY device such as the Integrated Circuit Systems ICS1893BK, which integrates the differential serial output to an RJ-45 jack and. Calculates the differential pair impedance of a balanced line. Careful differential pair routing, impedance control, grounding, and noise reduction techniques are key factors for performance optimization. 5mil trace + 4mil spacing - which is close to their absolute minimum). Hence, without loss of generality, one. If it is different, you need to increase the length of shorter track to match with the longer track. e. The odd mode impedance is the impedance of one transmission line when the pair is driven differentially. ETA: USB 2. By Perrine Juillion / April 8, 2020. (Differential Impedance, Ohms) = Note: 1oz = 1. The calculator shown below uses Wadell’s equations for differential impedance, which can be found in the seminal textbook Transmission Line Design Handbook. Don’t ignore ESD. 3. Twisted Pair Impedance Calculator . Ask the board manufacturer for the values. This means the slope resistance is 7 V 0. Differential Pair Calculator The Differential Pair Calculator is used to perform what-if analysis to determine what values of Primary gap and width are needed to get specific differential and single line impedance. Anyone know of any free software that can do that? The only one I was able to find was Si9000 and Si8000m by Polar instruments, but they aren't free. The designer needs to create a stackup for the board and then calculate the trace values for differential pairs and single-ended nets. Note: Units do not matter for this calculation as long as they are consistent. 75 m A = 9333 ohms. If I calculate it for embedded edge coupled differential pair, it is still only 39. Now select the two nets that you want to declare differential. This calculator finds both odd and even transmission line impedance. Incidentally, analog signal integrity may be a bigger problem than digital in this design. This calculator is designed to calculate the characteristic impedance of a broadside couple stripline (see diagram below). The calculator shows 90 ohms can be achieved using. Use an impedance calculator to determine the trace width (W) and spacing (S) required for the specific board stack-up being used. In case you need to calculate single ended or differential pair impedance on your PCB, try following links: I use Microstrip & Stripline calculator developed by Jean Nicolle. Skin effect: The skin effect in a PCB trace, including coplanar waveguides, adds additional AC and DC resistance to the total impedance. Just enter the given values for trace thickness. Comparator tab . Polar or rectangular grids only allow direct reading of S11. P/N De-skew Strategy on Differential Pairs. For better impedance control, use PCB design software you can trust. But I'm unsure if the Height I entered is. Schelkunoff in 1934, is a very convenient parameter for the prediction and control of EMI coupling through cable shields. Incidentally, the trace thickness parameter does have a significant effect. Using the KiCad Impedance Calculator. EEWeb offers a free online broadside coupled stripline impedance calculator. Make sure to follow below for efficient RS485. Enter your board parameters and get instant results. The impedance of a differential via pair cannot be treated with a single via impedance calculator unless the vias are spaced far apart. With this combination of powerful impedance modeling you can quickly determine the manufacturing variations for each of your designs and model resin-rich areas between differential traces to achieve the highest yields from yourThis is the odd-mode impedance of the differential pair. There is a slightly different, but tightly. This sets the single-ended impedance AND differential impedance to the target value, even if there is no. This application note provides a brief theoretical background to the impedance calculation methods used in the Polar Si series field solvers. 3. 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. Differential Impedance in Constraint Manager Advanced Constraints can be used to view the Differential Impedance in Constraint Manager. There have been trace routing tools available for a long time that help with differential pair routing. Relative Dielectric Constant ( εr ): Track Width. Anyone have suggestion of one? Thanks Alan . Mutual inductance and capacitance exist between the two traces in a differential pair. Note that the driver output impedance may be configurable among various values. I used the Altium`s impedance profile calculator and got the parameters, but then I double checked with a Saturn PCB tool - the results were significantly different (Picture 2). It refers to the impedance that a pair of differential (opposite phase) signals will see in a microstrip transmission line configuration. 9. 75 mA 7 V 0. Ideally the traces in the differential pair only interact with each other, as another answer said. Transferring the Differential Pairs to the PCB Editor from Schematics. $$Z_{0_{diff}} = 2Z_{0_{odd}}$$ Common Impedance. Even mode impedance for commonly-driven transmission lines . Then enter the values of the impedances as complex. 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. Note that the net pair must be named with net label suffixes of _N and _P. The idea here is to determine the spacing required for a given width with the goal of hitting a specific differential impedance value. case of Figure 1, the mismatch occurs between the characteristic impedance of the twisted pair (typically 100Ω) and the 4 kΩinput resistance of the DS26LS32A. Near 50 ohms, many of these approximations are within a few percent accurate. It can't be used with differential pairs, which are dominantly used with impedance-controlled high-speed signals;. In case you need to calculate single ended or differential pair impedance on your PCB, try following links: I use Microstrip & Stripline calculator developed by Jean Nicolle. Following is the list of useful converters and calculators. Notes: 1) Calculation assumes traces are centered vertically. • If finite tail impedance and asymmetry are both. 8). Note: The 6-Layer board temporarily only provides JLC3313 Stackup. This rule maintains the desired signal impedance. e. When you have a USB you need to create differential pairs and KiCad ma. Signal Management. 0 and CAN-FD might be slow enough to get away without it (and I'm honestly not sure, the performance will depend on the specific configuration), but if I were reviewing a layout with diff pairs without a ground reference I would be very unhappy with it. These calculators give us essential trace spacing and differential pair spacing if needed. Figure 4. The differential impedance target, as well as the single-ended impedance of each trace, is maintained by keeping the spacing between the two traces constant. ’ Go to the ‘Differential pair rules’ >> ‘New rule. Useful converters and calculators. This makes the problem of determining impedance much more complex, and building an initial lossless model requires a larger set of formulas. They will give very similar answers. Track and gap widths are of concern in controlled impedance, but unless your speaker and mic connections (I assume audio frequencies) are going a long way you should not have any particular requirement for controlled impedance. Enter the relative permitivity, width of the trace, the ground plane spacing, and the substrate thickness to calculate the characteristic impedance. This calculator finds both odd and even transmission line impedance. Differential Pairs can be defined as an Electrical CSet or a Physical CSet. Download Saturn Pcb Design Toolkit. I did my research on what the differential impedance is and how should I approach it. 293, 50% of the copper removal can be achieved. To find the impedance of a capacitor (Zc) and an inductor (Zl) in an AC circuit, you use the following formulas: For the capacitor: Zc = 1 / (2πfC) For the inductor: Zl = 2πfL Where f is the frequency, C is the capacitance, and L is the inductance. Now I'd like to get into this topic and the first task would be to create a ~ 10cm board to board interconnect flex PCB with 90 ohm (USB) and 100 ohm (LVDS) controlled impedance traces on it. 300" away from the Ethernet front end. Controlled impedance is typically applied in single-ended microstrip, embedded microstrip, stripline differential pair, and planar PCB transmission lines. 5 mil as the thickness of 3313 prepreg when the controlled impedance tracks are on top/bottom, use 5. 004” line. The test sample consists of a pair of differential traces at the top layer, followed by a differential via to the inner traces, then a second differential via connects to the BGA landing pads at the top layer again. There are many demands placed on PCB stackup design. Several equations are. 1,393. As discussed in the first section of The MOSFET Differential Pair with Active Load, the magnitude of this amplifier’s gain is the MOSFET’s transconductance multiplied by the drain resistance: AV = gm ×RD A V = g m × R D. . Fig 1. These calculators ALL use wrong naming for "differential impedance". This means that the channel dimensions of both FETs must be the same and that R 1 must equal R 2. 6mm FR4 PCB with 7628 type stackup (4 layers), the above specifications usually result in 4. To set the rules for the classes we created above, we will follow these steps: Go to ‘Design’ >> ‘Rules. 6 ohms and Z even = 110 ohms for your geometry, very close to your result. 90 Ohm Differential Pair: 0. 50 - 55 ohms). Assuming the differential pair I am routing is requiring 90 ohm (this is what the hardware guideline say "Route the USB differential pair on the top layer with a trace width and differential spacing tuned to the PCB stack-up. Then Right click -> Create-> Differential pair. By understanding the microstrip transmission line, designers can. No matter what the case was, if you did not have an impedance calculator, you had to rely on measurements, or some other data set to get an accurate value for trace width in your PCB. If the ratio is about 0. 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. Still, as you correctly analyzed it is much better to think of the individual lines in a differential pair as two length-matched single-ended lines, both with the half impedance. The bus impedance of the RS485 is approximately 100-120 Ohms differential and control trace impedance as ~50 Ohms. I am using microstrips on external layers only. The ratio of cross-hatch conductor width (HW) to cross-hatch pitch (HP) plays an important role while characterizing the cross-hatch plane. 75 mm track on a 0. Your relay is single line with characteristic impedance of 50 Ohms. 1) isn’t overly complicated. When you are creating your schematic, you must use one of the following suffixes when naming your differential pair nets: +/- (e. These tools allow you to calculate a highly accurate impedance and propagation delay model for your differential pairs, and you can use these results to specify delay. A cheap unshielded laminated polyester FPC cable with 0. Placing a Differential Pair directive on each pair net applies a parameter to the net,. 36 mm substrate, has an impedance to ground, unbalanced, of about 49 ohms. It is okay to specify the single-ended impedance for each differential pair member. , "Characteristic Impedance of the Shielded-Strip Transmission Line," IRE. Select the Calculator button. While the edge couple differential symmetric stripline transmission line is a common technique for routing differential traces. 35,851. Layers: Total number of copper layers in. 1. 3 V, etc. Differential impedance is defined as the impedance between the two lines when the line pair is driven differentially. I used the KiCAD PCB calculator, asked the PCB manufacturer about the tangent loss (0. Yet I got a ZDiff CPW with ground capable calculator: Differential surface coplanar waveguide with ground calculations: *0. This routing width rule targets a class of DRAM nets. Can I / should I add extra components to the bus traces, to reach the. Details: In the list below, [1] is the reference design stackup information; [2] and [3] are the processes to get the result close enough to the reference design target so as to know the tool is valid; and [4] is the calculation in question because it is either 5. This simple impedance calculator had a number of limitations, including requiring return paths to be implemented by plane layers, only supporting symmetrical stripline board structures, and no support for differential impedance calculations. Simply put, differential impedance is the instantaneous impedance of a pair of transmission lines when two complimentary signals are transmitted with opposite polarity. Rule setup for differential pair (100 ohms) routing using Altium Designer. You will need to know the dielectric constant and the copper thickness to calculate trace impedance. g. In some cases, we can also use 75-ohm differential impedance. 3. The Differential Pair Impedance Calculator simplifies the process of designing PCBs and high-speed communication systems, ensuring that signals are transmitted efficiently and reliably. Eurocircuits’ Impedance calculator uses real values as defined in the supplier’s data sheets. Calculating the impedance . Most often, the only specified requirement of a differential pair is its differential impedance. Impedance in your traces becomes a critical parameter to consider during stackup. Learn how to configure, define, and use your design’s impedance requirements for single-sided and differential on each layer, with Altium Designer’s Layer St. 3mm, as shown below: This increases the impedance slightly to 91. It incorporates many features that PCB designers and engineers are in regular need of like current capacity of a PCB trace, via current, differential pairs and much more. So, strive to keep your traces short and far apart in high-speed design. Although widely applied to coaxial cables against EMI susceptibility problems, the Zt parameter can be easily extended to coaxial cables EMI emissions. This form of microstrip is composed of two traces. For double termination, the source needs to provide R O = 50 Ω on each side for a 100-Ω differential output imped-ance, and the line needs to be terminated with R L = 100 Ω. Technical Consultant Zach Peterson explores a viewer question surrounding Coplanar Routing, specifically how to route on a single-layer board. This calculator is designed to find the characteristic impedance of an asymmetric stripline - a flat conductor between two ground planes. The topology pre-dates the solid-state era and is generally attributed to Alan Blumlein, when it appeared in one of his patents in 1936. MX6 Design recommendations about 100 Ohms for differential pair is quite reasonable for FlexCAN. Length matching is required per segment, and any length added (typically a ‘serpentine’ section) for the sake of matching a pair should be added near the location where the mismatch occurs. The Saturn PCB Toolkit is the best freeware resource for PCB related calculations you can find. Adding stitching vias adds distributed capacitance in. Both gives me only 20 Ohm differential impedance. Schelkunoff in 1934, is a very convenient parameter for the prediction and control of EMI coupling through cable shields. g. A printed circuit board (PCB) mechanically supports and electrically connects electronic components on a circuit board. The test sample consists of a pair of differential traces at the top layer, followed by a differential via to the inner traces, then a second differential via connects to the BGA landing pads at the top layer again. The stackup design is very crucial for the manufacturing of a controlled impedance PCB. 8. 0. 2 High-Speed Signal Trace Lengths As with all high-speed signals, keep total trace length for signal pairs to a minimum. Differential pairs: even or common mode? PCB impedance calculator – Single ended / Differential pair. Simply put, differential impedance is the instantaneous impedance of a pair of transmission lines when two complimentary signals are transmitted with opposite polarity. While the length and impedance are both important, 1mm of length differential will not affect your system's performance in any way, even for usb-2. The differential impedance will be a bit less than 2x the single-ended impedance. The calculator is available in the Electrical Domain in Constraint Manager, from theTable 1-1. If they aren't that high, then don't worry about matching on the PCB, but use. As discussed previously, the lengths of the two lines in the pair must be the same length. I use the software a lot to calculate impedance, maximum current for t. In other words, if you are designing to hit a differential impedance target. That's why the numbers Mikrocontroller. You can make your own spread sheet using formulas provided by Wedell's book "Transmission Line Design Handbook" page 196, 197, 198 (attached)Relative dielectric constant (er) mm. Development Kits. It is important todetermine the characteristic impedance of a twisted-pair cable because this impedance should match the impedance. One of the features of this type of microstrip is the coupling between lines. . The via transitions start to really matter above 5 GHz. Note the differential pairs above that look like a strand of intestine have a constant gap between the pairs. The twisted pair helps create a more uniform inductance and capacitance per unit length of wire to ensure a constant impedance, by keeping the return path as close to the signal as possible. 1. The return path between two pairs also creates some loop inductance, which can receive crosstalk as differential mode noise. 6 inches - this is very easy to do; If you can access a differential impedance calculator, then use. . Going through Saturn PCB Calculator - which is free and useful software for engineers. The calculator shown below uses Wadell’s. Such a stripline is. dBm to Watt converter Stripline Impedance calculator Microstrip line impedance Antenna G/T Noise temp. Preferably, the length of the clock trace should be somewhere in between. s4p files with Delta-L 4. and thats the first time iam doing ethernet things. You can calculate it with the following equation: Z (z) = V (z)/I (z). Dielectric Constant The. 1. Jan 31, 2016 #2 FvM Super Moderator. This calculator is designed to calculate the characteristic impedance of an edge-coupled microstrip. 3mm of the microcontroller), therefore i rounded the width to 0. The impedance calculators below are completely free to access and use. 120 Ohm Differential Pair: 0. KiCad has a built-in impedance calculator!The impedance calculator determines the signal properties and clearances (first image), use that clearance in the via shielding Distance setting. 5. The differential pair—sometimes called the long-tailed pair—is a widely used building block in electronic circuits, particularly in op amps. The twisted pair helps create a more. 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. Differential Pair Routing. Finally, all calculators provide theoretical impedance values as they cannot take in to account the variables. g. No matter what the case was, if you did not have an impedance calculator, you had to rely on measurements, or some other data set to get an accurate value for trace width in your PCB. ALTIUM DESIGNER. It has been correlated many times. To achieve impedance control, PCB design software with an integrated field solver can help in designing the right trace width for the HDI layer stack-up. D_P and D_N) KiCad looks for these suffix pairs when using the differential pair routing tool during PCB layout. input signals, the half circuit can be used to calculate. Ensure optimal signal integrity in high-speed communication systems with our Differential Pair Impedance Calculator. trace geometry, and use this to calculate. It is widely used for data communications and telecommunications applications in structured cabling systems. This is the same calculator integrated in other open-source tools like the microwave circuit simulator Qucs, or the circuit board design tool KiCad. Other calculators will use different. When designing the trace configuration for your differential pairs, you are typically targeting 100 ohms differential. In case I reduce the width and the distance of tracks to 0. You can use all the calculators you want if you don't know the exact board make up they're using; they should be able to help you. The track widths should. Even and Odd Mode Impedance 3. (Differential Impedance, Ohms) = Note: 1oz = 1. 1<S/H<3. When you are creating your schematic, you must use one of the following suffixes when naming your differential pair nets: +/- (e. The guides says spacing under 0. g. The vias on these differential pairs have their own impedance, which can create signal integrity problems on long interconnects. The odd mode impedance is the impedance of one transmission line when the pair is driven differentially. 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. In the case where you are routing differential pairs, then the potential between the two pairs will always be opposing (i. 4mils = 0. It is often said that differential pairs do not have a return path, which is not true. Modeling approximation can be used to understand the impedance of. . The example below shows how adjusting the stitching via placement could affect a differential via. 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. Visit to learn more about our other electrical engineering tools. Staff member. Now let’s incorporate the finite output resistance: And next we recall that the small-signal analysis technique. is the impedance between two differential pair signal traces. Using this calculator, I found 100 Ohms by giving 9 mils of track width, 5 mils of track separation, 8 mils of dielectric (prepregs usually have a dielectric constant of 3. Use several of them and compare. PCB impedance calculator – Single ended / Differential pair PCB manufacturer normally provides information about PCB stackup and track geometry. Spacing and width value pairs that will give a differential impedance of 100 Ohms on Dk = 4. Email: info@multi-circuit-boards. e. 0. 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. This will give us the appropriate trace width and trace separation for the desired differential impedance. Only a 2D field solver can accurately calculate the differential impedance. they normally use 7. 1. Calculate the Differential Microstrip Impedance of a transmission line based on the the distance between the strips, height of the substrate, trace thickness and dielectric constant of the substrate. model impedance by combining Polar's proven boundary element field-solving engine with easy graphing of process windows. What is the characteristic impedance of twisted pair cables? 100 ohms. There is a slightly different, but tightly coupled question here with this impedance calculator: "stripline differential impedance": Stripline here seems to be placed in some inside layer. Impedance Calculation for PCB Designers - Altium. This definition effectively makes it equal. Both gives me only 20 Ohm differential impedance. The two ends of a differential pair must be the same length. Ready to give CircuitStudio a try? Click here to get started: impedance. A differential amplifier multiplies the voltage difference between two inputs (Vin+ - Vin-) by some constant factor Ad, the differential gain. Ask the board manufacturer for the values. This kind of functionality is present in only some PCB design programs, and those with it have varying degrees of accuracy in their output. 1 Answer. Formula: Applicability: w ÷ t ≤ 0. The Si8000 Quick Solver is convenient to use for this purpose, as shown in Figure 4. For an embedded (internal) microstrip, the formulas provided in paragraph 4. The correction can be done with the menu option: Route → Tune Differential Pair Length Skew/Phase. Edge coupled differential pair Edge coupled internal symmetric differential pair Edge coupled internal. W is calculated to achieve a trace impedance (Z0) of ~50W and S is calculated to achieve a differential trace impedance of 90W. Differential impedance, Z diff, is the impedance between the two conductors. Coplanar Waveguide Calculator. It is assumed that the output impedance of the. 4mils/35um of copper thickness. For differential pairs, this meant that there was a differential pair impedance requirement, or rather an odd-mode impedance requirement. Finally, all calculators provide theoretical impedance values as they cannot take in to account the variables and. While it is not necessary or a requirement to match the PCB 'stubs' it's probably a good idea if the speeds of your RS485 bus are high (+50MHz). 4mils = 0. A PCB impedance calculator is necessary to set the constraints for trace structures during fabrication; they can vary in complexity, speed, and accuracy. The receiver, which is on the motherboard, is a standard LVDS receiver, with 100Ω termination resistors. This means that the channel dimensions of both FETs must be the same and that R 1 must equal R 2. Other calculators will use different equations for the same system, depending on the relevant approximations used in the derivation of the formula. The return path is defined by the reference plane near the pairs and the distance between the two pairs. to NFThe impedance of the structure is the ratio of the voltage between, and the current in, the conductors. We’ll go over how differential pairs can hel. Figure 81 shows the topology. Speedstack Si – Insertion loss & impedance PCB stackup design including Si9000e. Hello! I'm trying to calculate the trace width for a differential pair (carrying MIPI CSI-2 signals), using JLC's impedance calculator. To calculate the impedance, I use Saturn PCB impedance calculator software, Inc - PCB Toolkit V8. 34, 40, and 48 Ohms single. Capacitance (C) = pF/ cm. The HIGH level is brought up to a logic level (5 V, 3. The following options in the Options for PCB Project dialog are used to configure this:. 2. Impedance Calculator - Sierra Circuits. Since stripline traces are typicallyThis is why the differential impedance of a differential pair is often (but not always) slightly lower than two times the single-ended impedance of an individual trace. The impedance of the surface microstrip shown is 50 ohms, so the impedance of the broadside coupled differential pair will be twice 50. Note: If this post answers your question, please click the Correct Answer button. When the trace impedance is well-controlled, it indicates that it is constant along the whole PCB path. Enter the number n n of impedances in parallel as a whole number and press "Enter". When you click on the track, you can see the length of skew. Differential pairs are becoming common place in high speed design reducing. There’s an actual free 2D impedance calculator out there (arbitrary transmission line calculator, or ATLC). If the goal is to adjust the characteristic impedance, then you can likely do it by changing both width and spacing (keeping center-to-center the same) just as. Those pairs connect via a dedicated FFC cable. 1. 331 1 2 5. A pair of tracks of the same cross-section (i. Differential pair routing. CSI-2 interface data pairs require a 100 ohm differential impedance. Controlled impedance traces are determined by their physical dimensions and the property of the dielectric material used in the circuit board. Our impedance calculator features two main types of impedance models, single-ended and differential, within each trace structure. $egingroup$ So basically your answer shows that the JLCPCB impedance calculator results are generally in the same ballpark as the proven field simulators. This is assuming that you have a Design Rule in place which links the impedance profile to a. About Saturn PCB Toolkit (latest v8. I am routing differential pairs in Altium 20 and using controlled impedance profiles. 8 substrates of various thicknesses. Figure 1. Calculation tip for defined Z 0 as well as Z Diff. KiCad has a built-in impedance calculator! Inductance – the impedance calculator uses the Impedance value to calculate the inductance per unit length.