This will help you to route the high-speed traces on your printed circuit board. Read Article UART vs. However: The Raspberry Pi Computer Module 4 (CM4) datasheet states: 2. FR4 SDD21 Insertion Loss vs Frequency for Various Trace Lengths Using the same PCB board stackup, simulations also show a correlation between trace length and slew rate. However: The Raspberry Pi Computer Module 4 (CM4) datasheet states: 2. And, yes, this means generally using all 0402 components for that RF path. Klopfenstein trace taper return loss spectrum for a 50 to 40 Ohm transition. SPI vs. Improper trace bends affects signal integrity and propagation delay. This 6-layer PCB stackup can enable orthogonal routing on L1/L3 and on L4/L6. As the signal travels along the trace, energy is dissipated as heat, leading to a weaker signal. Impedance profoundly impacts signal quality in high-speed PCBs. That is why tuning the trace length is a critical aspect in a high speed design. PCB Design for Manufacturing: Prevent PCB Vias Defects by Talking to Your Manufacturer One of my ex-girlfriends. The caveat is that any editing of the clock or the traces on the edge of the tolerance band is likely to upset. The space between differential pairs must be at least 2× the trace width of the differential pair to minimize loss and maximize interconnect density. Try running a 10 GHz signal through that path and you will see loss. Essentially, impedance control in PCB design refers to the matching of substrate material properties with trace dimensions and locations to ensure the impedance of a trace’s signal is within a certain percentage of a specific value. Generally, PCB trace thickness ranges from 0. Frequency Keeping high speed signals properly timed and synchronized requires PCB trace length matching vs frequency. Figure 1: Insertion loss of FR4 PCB traces. 5 ns, so a 7-inch or more track carrying this signal should be treated as a transmission line. If the bends are required, then 135° bends should be implemented instead of 90°as shown in figure (5, Right side). The signal line is equal in width and the line is equidistant from the line. What PCB trace width should I use and can someone give me a guideline on how to select the PCB trace width based on the frequency. 6mm-thick board it'll be impractical. This characterstic impedance is independent of length and trace material. With today's advanced interactive routing features in modern PCB design tools, designers no longer need to manually draw out length tuning structures in a PCB layout. It is sometime expressed as "loss tangent". Guide On Pcb Trace Length Matching Vs Frequency Advanced Design Blog Cadence. Sudden changes in trace direction can cause changes in impedance or the dielectric constant can change across the length or width of a PCB. 0). The answer is always framed as an always/never statement. And the 100ps would be equal to 15-20 mm in trace length difference, which is huge. Microstrip Trace Impedance vs. Match the etch lengths of the relevant differential pair traces. The PCB trace may introduce 1 ps to 5 ps of jitter and 0. Again, this ideal length for the clock is found by subtracting the tolerance (or most of it) from the longest trace once everything is optimized. CSI-2 (MIPI serial camera): The CM4 supports two camera ports: CAM0 (2 lanes) and CAM1 (4 lanes). There's no need to length match SDA and SCL. As discussed previously, the lengths of the two lines in the pair must be the same length. Just like single-ended signals, differential signaling standards may have a maximum length constraint. The lengths of the traces that make up a differential pair must be very tightly matched; otherwise, the positive and negative signals would be mismatched. 127 mm traces with 0. PCB trace length matching vs frequency affects the signal integrity of your circuit designs. Trace Length Matching : This allows the user to. 2. Therefore, you must adjust the trace length for all parallel interfaces. How tightly should trace lengths be matched for a 1Gbps serial databus? It seems to me that 100ps (15mm) should be more than sufficient. 92445. The PCB trace on board 3. Routing between connectors on a board and. The Fundamental Frequency and Harmonics in Electronics. and by MAC (for RGMII transmit). 5Gbps. ;. For any distance over which I2C is a viable means of communication, and certainly within a single PCB, there is no need for any trace length matching constraint between SCL and SDA. Eventually, the impedance of your power delivery network will. RF transmission line matching. If the chips themselves are able to do the de-skewing, of course you should use that feature rather than extend the traces to do length matching. Trace Height (H) Figure 4. Follow asked Nov 27, 2018 at 12:32. Correcting a trace length mismatch requires placing meanders in the shorter traces in the net so that they match the length of the longest trace. During that time both traces drive currents into the same direction. About a year ago I designed a PCB with a processor and RAM (400MHz and 133MHz speed respectively). 025, the frequency as 10 GHz, the surface roughness as 6 μm, and the length of the trace as 1 inch. The flex cable to TOSA (ROSA) elements At point 2, the reflection is primarily generated by the PCB layout. SPI vs. 6 mm or 0. As the driving frequency increases, mutual inductance between circuits in your board will cause the impedance of your power delivery network to increase. 22 mm or 0. trace loss at frequency. Impedance may vary with operating frequency. Unfortunately, infinite length PCB traces only exist in theory but not in practice. How to do PCB Trace Length Matching vs. SPI vs. It won't have any noticeable effect on the signal integrity or timing margins. How to do PCB Trace Length Matching vs. SPI vs. Once you know the characteristic impedance, the differential impedance. Once all the input parameters are entered, click on Calculate Loss. How Parasitic Capacitance and Inductance Affect Signal Integrity. 5in, ~4cm) for a trace on a PCB with a dielectric constant of 4. Decoupling capacitor values vary by application and may be staggered to achieve the best overall impedance vs. Here’s how length matching in PCB design works. However, it rarely causes any problem at low speeds. Why FR4 Dispersion Matters. According to these. SGMII vs. Rather than using QUCS again, I switched to another and a bit more complex tool. frequency calculator that. Trace Width Selection 1. If you are to use a 1. Cables can be miles long but a PCB trace is likely to be no longer than a foot. In particular, the transit time of signals often needs to be synchronized by matching the copper length of the traces on the PCB. character as the physical length of traces becomethe s aconsiderable fraction of the signal wavelength. Here’s how length matching in PCB design works. 3. There is something similar to the length-tunned traces in the PCB(blue circle) but it's not length-tunned trace because they are cutted-out. It would be helpful to know the tolerance in length difference that is allowed while designing this PCB. For PICMG COM Express designs, traces on the bus must have differential impedance of 92 Ohms (COMCDG Rev. Everything You Need To Know About Circuit Board Traces Pcba. The trace length decided to match with Wavelength of the frequency Wavelength (Lambda) = Wave Velocity (v) / Frequency (f) =299792458 /700000000 =428. you can use simulations found within your PCB design software to find the amount of source impedance needed to match the trace and the load. Well, if you manage to get 50 Ohm trace for this LCD on a 2-layer board with meaningful trace widths please find me :) I hope you are aware of the fact that the PCB thickness should be very low. 3 ~ 4. Frequency Keeping high speed signals properly timed and synchronized requires PCB trace length matching vs frequency. Frequency Keeping high speed signals properly timed and synchronized requires PCB trace length matching vs frequency. For a single-ended trace operating at one frequency (e. Frequency Keeping high speed signals properly timed and synchronized requires PCB trace length matching vs frequency. That is why tuning the trace length is a critical aspect in a high speed design. This allows you to automatically calculate and compensate propagation delay in your PCB without manually measuring traces with. Fast rise/fall times alone doen't need length matching. It's an advanced topic. Therefore, the minimum length over which the signal must be routed as transmission line is given by ?/10 = 0. Relative Permittivity: 4. The fast integrated circuit chip with a very high clock frequency, which is now commonly used, has such a problem. matching requirements include PCB trace delays, different layer propagation velocity variance, and crosstalk. On a real substrate, say FR4, the impedance of a real PCB trace will vary with frequency due to the dielectric constant and loss of the dielectric varying, and the resistance of. These traces could be one of the following: Multiple single-ended traces routed in parallel. a maximum trace/ cable length which is specified in the various specifications. Frequency Keeping high speed signals properly timed and synchronized requires PCB trace length matching vs frequency. Today, PCB designers are spoiled with CAD tools that make it extremely easy to apply length matching sections to a differential pair. The length of traces can cause problems with loss and jitter for LVDS signals. The world looks different, one end to another. 5. Therefore, their sum must add to zero. Here’s how length matching in PCB design works. cable length performance far exceeding IEEE specifications and features that provide lower cost solutions, for both 10BASE-Tand 100BASE-TXEthernet protocols, the devices ensure compatibility and inter-. $egingroup$ Thanks @KH ! If you will focus on the questions that are in the body and not in the title, I guess the answer will be a bit shorter. 2. Whether you see a specific length specified or a time specified, either value will only apply for a specific PCB laminate and trace geometry. . This variance makesTraces should be length matched to within tight tolerances, differential pairs should be tightly coupled on the same layer, and stub lengths to each memory device should be as short as possible to prevent transmission line effects and resonance in a stub. On theseFor a given PCB laminate and copper weight except for the width of the signal trace (W), the equation given below can be used to design a PCB trace to match the impedance required by the circuit. CSI signals should be routed as 100Ω. Frequency Keeping high speed signals properly timed and synchronized requires PCB trace length matching vs frequency. Note: Loosely coupled traces are easier to route and maintain impedance control but take up more routing area. In a PCB, mismatch is usually small (about 10 Ohms), but signal drivers can have much higher impedance mismatch (30 Ohms or more). 8 A, making it. Design PCB traces with controlled impedance to minimize signal reflections. Frequency Keeping high speed signals properly timed and synchronized requires PCB trace length matching vs frequency. This question (paraphrased) goes as follows: Do length-tuning structures create an impedance discontinuity? The answer is an unequivocal “yes”, but it might not. 5in, ~4cm) for a trace on a PCB with a dielectric constant of 4. There a several things to keep in mind: The number of stubs should be kept to a minimum. I2C Routing Guidelines: How to Layout These Common. Trace Length Matching vs. Altium DesignerWhat are the differences between subclass 1 and subclass 2? Part 2 delves in timing requirements related to deterministic latency and factors for choosing one subclass over another. The stub length must not exceed 40 mils for 5 Gbps data rate. Frequency Keeping high speed signals properly timed and synchronized requires PCB trace length matching vs frequency. So I think both needs to be matched if you want to work at rated high frequency. I2C Routing Guidelines: How to Layout These Common. Teardrop added to a trace in a PCB. 3041mm. Here’s how length matching in PCB design works. Read Article UART vs. Ethernet: Ethernet lines. Here’s how length matching in PCB design works. I have been informed by a equalizer manufacturer that up to 1mm intrapair skew (P-N length mismatch) is hard to measure, and will have no effect on signals up to 12. I am designing a PCB with an MCU and there will be JTAG, SPI, I2C and USB. 25mm trace. I2C Routing Guidelines: How to Layout These Common. In which case the voltage and current are in exactly the right ratio for the resistor. For example, a maximum frequency of 100 MHz corresponds to a risetime of 3. Here’s how length matching in. 4. 0 113D view of trace routing in a multi-layer PCB. For instance, the quarter wavelength (λ/4) of 433 MHz is 172. At an impedance mismatch, a portion of the transmitted signal isAn RF PCB design is a bit different from a conventional board. These two equations can be decoupled into their own wave equations: Wave equations for voltage and current in a lossy transmission line model. 3. For example, for 1GHz on a microstrip FR4-based PCB, thecritical length is approximately 0. While every trace has an impedance, we don't care about the trace reactance if the trace is only carrying DC current. Use shorter trace lengths to reduce signal attenuation and propagation delay. If the traces differ in electrical length, the signal on the shorter trace changes its state earlier than the one on the longer trace. The crosstalk issue becomes more severe, especially in HDI PCBs, when traces run at high frequency and high edge rate. It leads to either: - rising edges on SCL become too slow, which means the signal spends a lot of time around the receiver's 0/1 threshold. Set up your differential traces for success. The Ethernet protocol was standardized in the 1980s and rapidly evolved from speeds of 10 M to 10 G+ bit/s. 5 High Speed USB Bias Filter AT85C51SND3Bx high-speed USB design requires a 6. We only ever have perfect matching at specific frequencies, but there are mid-range frequencies where the return loss spectrum is flat. 6. 2. (5) (6) From the results above we can see that the setup and hold margin are both greater than 0 as desired. $egingroup$ This is more like what a conductor looks like at extremely high frequency. Here’s how length matching in PCB design works. The PCB trace on board 3. Impedance mismatch: Impedance mismatches between the source, transmission line, and load can. Depending upon the type of components and the signals routed to and from them, trace length, copper weight, and spacing must all be chosen to maximize signal integrity. To reduce those problems and maintain length matching, route long distance traces at an off-angle to the X-Y axis of. 010 inches spacing between them. SPI vs. Matching the impedance can be accomplished by tying the trace down with a resistor near the source or the load. In this article, we’ll examine a few tips and tricks for high-speed printed circuit board designs. Be this a power-carrying trace, a high-impedance node, a high-speed signal, and so on. traces may be narrower for stripline routing. 2) It will be vise to match the PCB trace impedance to the cable impedance, or you may get reflections. High-Speed PCBs vs. You'll have a drop of about 0. 5 cm Any PCB trace length greater than 1. What Are Pcb Traces Assembly Yun. Whether you’re new to PCB design or you’ve made your career out of it, there are many times in RF and high speed design where you need to design microstrip and stripline traces to have a specific impedance. 5 mm. 008 Inch to 0. As a thumb rule At what trace lenths should i used differential drivers (LVDS,RS485) etc for SPI interface. Frequency Keeping high speed signals properly timed and synchronized requires PCB trace length matching vs frequency. CBTU02044 also brings in extra insertion loss to the system. The IC only has room for 18. Set up trace lengths, length matching, differential pairs, and other rules and constraints beforehand to ensure that everything will meet the requirements while you route. Currently the trace lengths are approx. Device Pin-Map, Checklists, and Connection Guidelines x. Serpentine is best kept to those inner layers. Problems from fiber weave alignment vary from board to board. This rule maintains the desired signal impedance. Tightly Coupled Routing Impedance Control. Every board material has a characteristic dielectric loss factor. PCB Trace Stubs and Discontinuities • If possible, avoid routing high-speed frequency traces through the vias. Designing a PCB for PCIe Signals 11 Tsi381 Board Design Guidelines 60E1000_AN001_06 Integrated Device Technology Figure 1: PCIe Board Trace Width and Spacings Example 1. Read Article UART vs. Read Article UART vs. In vacuum or air, it equals 85. Now, to see what happens in this interaction, we have to. Therefore the edge rate can be about 400 ps, so 100 ps difference wouldn't make much of a shift in eye crossover position. frequency is known as dispersion, which causes different frequency components in an electrical pulse in a PCB trace to travel with different velocities. g. 64 mil for single-ended vs. Running through a number of calculations it’s obvious that the only case where the length of the PCB trace doesn’t matter is when trace and load impedance are matched. 005 inches wide, but you may have specific high speed nets that need 0. • Adjustable on-die termination (ODT) with dynamic control that provides ODT sup-port during writes without having to wire the ODT signal. If you use a different PCB laminate. I2C Routing Guidelines: How to Layout These Common. Default constraints for the Matched Lengths rule. Frequency Keeping high speed signals properly timed and synchronized requires PCB trace length matching vs frequency. Read Article UART vs. The maximum PCB track length is then calculated by multiplying tr by 2 inch/nanosecond. In summary, we’ve shown that PCB trace length matching vs. To minimize PCB layer propagation variance, it is recommended that signals from the same net group always be routed on the same layer. The general idea is that transmission-line effects become significant when the length of the line is comparable to or greater than the wavelength of the signal. I don’t often like to give answers in absolute terms to PCB design questions, but in this case the answer is clear: Never route a signal over a gap in a ground plane. PCB design software, like Altium Designer ®, has high-speed design functionality for routing and trace tuning built into it. The IC pin to the trace 2. Because trace, source, and load impedance mismatches are a critical concern in high frequency design, you need a PCB trace length matching vs. Impedance matching for PCB traces is not an issue until total trace length between 75 Ohms input connector and MAX2015 input is below 5-7 mm. 4,618 6 6 gold badges 42 42 silver badges 86 86 bronze badges $endgroup$. 6 USB VBUS The TPS2560 is a dual channel power distribution switch that can handle high capacitive loads and short circuit conditions. Frequency Keeping high speed signals properly timed and synchronized requires PCB trace length matching vs frequency. 5 cm or about 0. If you are a PCB board designer, you do not need to perform this calculation manually, you just need to use the. . Trace Length Matching: Trace length matching should be a top priority when routing differential pairs. The higher the frequency, the shorter the wavelengthbecomes. Use uniform copper as reference planes for high-speed/high-frequency signals. Read Article UART vs. Obviously, these two points are related; all PCB vias have (or should have) a landing pad that supports the via and provides a place to route traces into a via pad. The matching impedance between traces and components reduces signal reflections. For the signal trace of width W and thickness T, separated by distance H from a ground (or power) plane by a PCB dielectric with. 5 inch. Problems from fiber weave alignment vary from board to board. Technologies DDR3 Routing Topology Page No #5 DQ/DQS/DM:If a transmission line has a 50 ohm impedance, then connecting it abruptly to a 1 V source will cause a 1 V voltage wave and a 20 mA current wave to start travelling along the line. Frequency with Altium Designer. In the pair with larger spacing (10 mil), a 21 mil amplitude length tuning section has small sets of traces with odd-mode impedance of 53 Ohms. Trace routing is one of the critical factors in constraint settings. Read Article UART vs. From inside this window, you need to select the pair of pins that will define the endpoints for a length matching determination. I2C Routing Guidelines: How to Layout These Common. Alternatively, in terms of length, the matching translates to +/-60 mils using 160 ps per inch of trace length. The period of your 24MHz clock is 41. Frequency Keeping high speed signals properly timed and synchronized requires PCB trace length matching vs frequency. Frequency Keeping high speed signals properly timed and synchronized requires PCB trace length matching vs frequency. How Trace Impedance Works. It has easy manufacturability and has the wireless range acceptable for a BLE application. As I understand, the camera max frequency is 720 mbps, or 1380 ps of unit interval. To help you achieve this feat, Sierra Circuits has introduced the Bandwidth, Rise Time and Critical Length Calculator. To achieve this, you may have to put small sections of trace tuning into the shorter line to equalize them. The length of a high-frequency trace should be designed so that the critical rise time of the circuit board is shorter than the rise time of the signals. 5 cm should not be routed as transmission line. In that case I need to design a transmission line which has characteristic impedance of 50. On the left, a microstrip structure is illustrated, and on the right, a stripline. the signal frequency is equivalent to adjusting time delay (tDelay) vs. C. The bends should be kept minimum while routing high-speed signals. SSTL 15 IO Standard (1) FPGA Side on-board termination(2. Cables can be miles long but a PCB trace is likely to be no longer than a foot. Ensuring that signals arrive in time to process means that trace lengths may need to match. Here’s how length matching in PCB design works. com PCB Trace Length Matching vs. This, in turn, enhances the signal quality and minimizes signal loss. 4 Trace Length Matching PCIe signals have constraint s with respect to trace lengths and matching in order to meet jitter and loss. 2 mm. Dispersion in the PCB substrate causes the signal velocity to vary with frequency. I2C Routing Guidelines: How to Layout These Common. Since my layer thickness is 0. I2C Routing Guidelines: How to Layout These Common. How to do PCB Trace Length Matching vs. Here is how we can calculate the propagation delay from the trace length and vice versa: Where: Vis the signal speed in the transmission line; In a vacuum or through the air, it equals 85 picoseconds/inch (ps/in). 7cm. There is another important point to consider, which is trace length matching for parallel buses. a maximum trace/ cable length which is specified in the various specifications. For high-speed devices with DDR2 and above, high-frequency data is required. Trace impedance and trace resistance are different things, important in different situations. Here’s how length matching in PCB design works. I2C Routing Guidelines: How to Layout These Common. rise time (tRise). 152mm. There are two design rules that are obeyed during length tuning, the Matched Length rule and the Length rule,. 7. Why insertion loss hurts signal quality. If your PCB has the space, why not match the lengths? It's good to practice length-matching any time you have the chance. Jun 21, 2011 at 0:11. 1V and around a 60C temperature. In lower speed or lower frequency devices,. For traces of equal length both signals are equal and op-posite. The IC pin to the trace 2. Changes in trace length can lead to impedance mismatches, signal reflections, and signal integrity issues. But for EMC reasons you may very well want to do better than that, in which case you should also take care to maintain the controlled impedance over the portions of the trace that are length matched. Test Setup The cable used for this investigation was category-5 Belden MediaTwist™. USB,. Tolerance - specifies a length tolerance when comparing each net with the longest net in the set. Traces and their widths should be sized. In differential pairs, each trace in the pair carries the same magnitude, but opposite polarity. Search for jobs related to Pcb trace length matching vs frequency or hire on the world's largest freelancing marketplace with 22m+ jobs. 2) It will be vise to match the PCB trace impedance to the cable impedance, or you may get reflections. Here’s how length matching in PCB design works. RF reflection becomes a concern when the trace or conductor’s length is equal to or larger than 1/4 of the signal’s wavelength. As the name suggests this is the laying out of a design that matches the lengths of two or more PCB tracks, also known as traces. How to do PCB Trace Length Matching vs. ALTIUM DESIGNER. PCIe: From PCI-SIG standards, PCIe Gen1 has 100 Ohms differential impedance, and Gen2 and higher have 85 Ohms differential impedance. The PCB trace on board 3. Wavelength of the highest frequency signal, 𝛌 𝐦 = 𝐯/𝐟 𝐦. Guide on PCB Trace Length Matching vs Frequency. Frequency is inversely proportional towavelength. rinsertion loss across frequency on the PCB. The traces must be routed with tight length matching (skew) within the differential traces. Cadence Orcad Guide OrCAD - PCB Solutions | PCB Design Software EDA Tools and IP for Intelligent System Design |. I'm making a high-speed transceiver design and want some direction regarding layout of trace length from P to N. frequency. This extra margin could be used to relax layout requirements on trace length matching and impedance control on cost sensitive PCBs. You should use 45-degree corners in the serpentine routing, and space the traces out at a minimum distance of 3 times the trace width. Tip #1: Reference Planes. I2C Routing Guidelines: How to Layout These Common. Read Article UART vs. SPI vs. Cite. Frequency Keeping high speed signals properly timed and synchronized requires PCB trace length matching vs frequency. SPI vs. SPI vs. Frequency Keeping high speed signals properly timed and synchronized requires PCB trace length matching vs frequency. Although that is a simple example, there are a lot more rules that can help in the design of high speed and RF traces: Trace Lengths: This rule allows the user to set a target value. More important will be to avoid longer stubs. There is also a frequency-dependent loss pattern called transfer impedance, which is affected by impedance effects on coaxial weave patterns, foil. Here’s how length matching in PCB design works. – Any discontinuities that occur on one signal line of a differential pair should be mirrored on the otherUse the same trace widths throughout the length of the trace. Keeping traces short is another way to combat reflections and ringing. Frequency Keeping high speed signals properly timed and. If the round-trip time is short enough, reflections may die down quickly enough to not pose a. The switchback pattern requires a shorter total length than the serpentine pattern for a given level of skew compensation requirement. Understanding PCB trace length matching vs frequency means knowing at what point you can operate propagation delay within expected or necessary signal integrity. 203mm. If there are high-speed transition edges in the design, you must consider the problem of transmission line effects on the PCB. I2C Routing Guidelines: How to Layout These Common. At the very least, routing through vias should be minimized in these devices when possible. If you use narrower trace (12 mil) with 20 mil pads, you will have unwanted. Two of the traces have no reference plane beneath, and their lengths are Trace 1, 35mm, and Trace 2, 120mm. Length of the trace; As mentioned earlier, the input parameters are subject to change depending on the chosen impedance structure. Here’s how length matching in. 5Gbps. 3 High-Speed Signal Trace Length Matching Match the etch lengths of the relevant differential pair traces. This is more than the to times trace width which is recommended (also read as close as possibly). However, you don't always have the freedom to place. This means we need the trace to be under 17. How to do PCB Trace Length Matching vs. Read Article UART vs. Low-voltage differential signaling (LVDS) is codified in the TIA/EIA-644 standard and is a serial signaling protocol. If you know about dispersion, then you know that you’ll have to do PCB trace length matching vs. How to do PCB Trace Length Matching vs. Eq. Two common structures are shown in Figure 3. Probably the most common electrical uses for LVDS are as an physical layer for SerDes links, long-reach channels in backplanes, or board-to-board connections. Here’s how length matching in PCB design works. If the length of the track is between 1/6 or 1/4 of the effective length of a feature like an edge a system can be regarded as lumped. Optimization results for example 2. Trace stubs must be avoided. 2. 5/5/8 GT/s so the hardware buffers can re-align the striped data. SPI vs. Strictly control the length of the trace of the critical network cable. I2C Routing Guidelines: How to Layout These Common. When two signal traces are mismatched within a matched group, the usual way to synchronize. 36 RF / Microwave Design - Line Types and Impedance (Zo) Coplanar Waveguide)CPW Allows Variation of Trace. For the signal trace of width W and thickness T, separated by distance H from a ground (or power) plane by a PCB dielectric with dielectric constant εr, the characteristic impedance is Impedance matching between copper traces is critical for differential routing and between the board materials for high-speed (frequency) signal transmission. How to do PCB Trace Length Matching vs. when i use Saturn PCB design to match the differential impedance to 100ohms i get 0.