Configuring the meander. The flex cable to TOSA (ROSA) elements At point 2, the reflection is primarily generated by the PCB layout. Documentation must somewhere state need of length/impedance matching; Each bus (data, address, control) should preferably be routed on its own layer. 0 dB to 1. Below ~5GBps not something to worry about at all. The above also assumes that the output side of the taper is perfectly matched to the via, but this may not be the case. 0 113D view of trace routing in a multi-layer PCB. Inter-pair skew is used toImpedance matching of lower frequency analog signals is required when the impedance mismatch at the ends of an interconnect is large. As the signal travels along the trace, energy is dissipated as heat, leading to a weaker 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. 254mm. Dispersion in the PCB substrate causes the signal velocity to vary with frequency. A PCB trace is a thin conductor on a printed circuit board (PCB) that carries electrical signals between components. According to these. For high-speed devices with DDR2 and above, high-frequency data is required. So for bottom traces there will be massive high-frequency signals underneath them on the motherboard within 1-2mm distance. As the frequency increases, PCB traces behave like transmission lines, with a precise impedance value at each point on the trace. Tolerance - specifies a length tolerance when comparing each net with the longest net in the set. 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. 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. When it comes to high-speed designs, we are typically concerned with two areas. The length of traces can cause problems with loss and jitter for LVDS signals. PCB trace length matching is a crucial process in designing high-frequency digital circuits, designers can minimize signal integrity issues. Understanding PCB trace length matching vs frequency means knowing at what point you can operate propagation delay within expected or necessary signal integrity. Here’s how length matching in PCB design works. 8 substrates of various thicknesses. Frequency Keeping high speed signals properly timed and synchronized requires PCB trace length matching vs frequency. Digital information synchronizes to a clock signal. 22 mm or 0. – Vintage. 3 ~ 4. Trace Length Matching : This allows the user to. How To Work With Jumper Pads And. 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. For analog signals, the critical length (l c) is defined as one-fourth of the wavelength of the highest signal frequency contained in the signal. The series termination is an often-used technique. The trace length decided to match with Wavelength of the frequency Wavelength (Lambda) = Wave Velocity (v) / Frequency (f) =299792458 /700000000 =428. Here’s how length matching in PCB design works. Here’s how length matching in PCB design works. 4 High Speed USB Trace Length Matching High-speed USB signal pair traces should be trace-length matched. Therefore, you should make the 50Ω impedance traces 5. I am trying to make a good layout for the Quad SPI NOR flash memory MT25QL256ABA1EW9-0SIT with the STM32 MCU. 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. I use EAGLE for my designs. 2. It covers topics such as component placement, trace routing, impedance matching, and signal integrity. 16,416. Diorio: Transmission lines 12Track length matching is key when trying to maximise the performance of your PCB. Because the longer trace, which isPick a signal frequency for your taper. Traces and their widths should be sized. Here’s how length matching in. So to speak, PCB design differential traces the most important rule is to match the line length, the other rules can be flexible according to the design requirements and practical applications. • Within the PCB breakout region, use the following SMT recommendations: − Ball-to-ball pitch: 1. How to do PCB Trace Length Matching vs. 64 mil for single-ended vs. Here’s how length matching in PCB design works. How tightly should trace lengths be matched for a 1Gbps serial databus? It seems to me that 100ps (15mm) should be more than sufficient. The matching impedance between traces and components reduces signal reflections. As you know, there are two types of interfaces in PCB design and length tuning will be different for each of them. 56ns. The ‘3W’ Rule (s) This actually refers to three rules. Most hardware problems with I2C come from having too much capacitance on the bus. Three important points in bus routing are designing for consistent trace impedance, proper termination, and a tight ground return path to minimize loop inductance. 50 dB of loss per inch. Here’s how length matching in PCB design works. 54 cm) at PCIe Gen4 speed. the RGMII-ID configuration to be connected to a PHY without the use of PCB trace delays. 2. PCB routing for RF (radio frequency) and antenna design is essential to optimize the performance of wireless communication. Trace LengthTrace Length §Longer trace length ⇒ loss ↑ ü~0. 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. Skew can lead to timing errors and signal degradation. Here’s how length matching in PCB design works. 3 Length and length matching Trace length greatly affects the loss and jitter budgets of the interconnection. Frequency Keeping high speed signals properly timed and synchronized requires PCB trace length matching vs frequency. The PCB Impedance Calculator in Altium Designer. Impedance represents the total opposition offered by a printed circuit board (PCB) trace to alternating current (AC) signals transmitted along its length. Here’s how length matching in PCB design works. PCB Layout Guidelines 50–60Ω impedance (ZO) is recommended for all traces. Length matching for high speed design . Tip #3: Controlled Impedance Traces. Just like a trace on PCB, vias have their own impedance, which is often described using lumped circuit models, similar to a transmission line. Logged. How to do PCB Trace Length Matching vs. 1 Answer Sorted by: 1 1) It all depends on signal speed. SPI vs. Differential pairs are very simple: they are composed of two traces, routed side-by-side, and that carry equal magnitude and opposite polarity signals on each trace. Read Article UART vs. Everything from 8-bit to 32-bit MCUs will use at least one of these protocols alongside GPIOs for programmability and sending signals to simple peripherals. 1. With this kind of help, you can create a high-speed compliant. In particular, the transit time of signals often needs to be synchronized by matching the copper length of the traces on the PCB. 0). How to do PCB Trace Length Matching vs. Frequency Keeping high speed signals properly timed and synchronized requires PCB trace length matching vs frequency. Frequency Keeping high speed signals properly. 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. More important will be to avoid longer stubs. 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. SPI vs. Frequency Keeping high speed signals properly timed and synchronized requires PCB trace length matching vs frequency. High-speed USB signal pair traces should. For example, if you require a 5mil trace to achieve 50Ω impedance and if you have also routed other signals with 5mils width, it will be impossible for the PCB manufacturer to determine which ones are the controlled impedance traces. Frequency Keeping high speed signals properly timed and synchronized requires PCB trace length matching vs frequency. On a high-speed PCB (> 100MHz) where wavelengths are shorter, any critical net (see figure 4a) is electrically long enough to make it an efficient radiator, especially when left exposed on the top or bottom layer. For a standard thickness board (62 mils), it would be roughly 108 mils. Trace Thickness (T) 2. How to do PCB Trace Length Matching vs. Skip to content. 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. CBTL04083A/B also brings in extra insertion loss to the system. 8 A, making it. About 11% of the signal will survive one round trip, 1. This implies trace length matching for the RGMII connections between PHY and MAC. The propagation delay is the time taken by a signal to propagate over a unit length of the transmission line: Where: V is the signal speed in the transmission line. Differences Between I2C vs. However, I have a bit of a length mismatch between the TX+/TX- and RX+/RX- pairs (about 5mm). Frequency Keeping high speed signals properly timed and synchronized requires PCB trace length matching vs frequency. How Trace Impedance Works. 66 mm between this traces and nearby traces? Which rules are stronger?How to do PCB Trace Length Matching vs. Signal reflections result from impedance mismatches and discontinuities. The extent of this problem will depend on the bus speed, the length of the traces, the trace geometries, the type of fiberglass weave used, and the alignment of the traces to the weave pattern of a PCB. Special care needs to be made to match length in all these lines. It's an advanced topic. 1. = Most PCB vendors will size traces for you You just tell them Z0 L0 is inductance per unit length C0 is capacitance per unit length. Keep the spacing between the pair consistent. If you are a PCB board designer, you do not need to perform this calculation manually, you just need to use the. Therefore, you must adjust the trace length for all parallel interfaces. Common impedance values are between 25 and 120. (TMDS) signal traces Ground plane Power plane Low-frequency, single-ended traces Layer 1: Layer 2: Layer 5: Layer 6: High-speed, differential signal traces Ground Vcc2 Low-frequency, single-ended traces Layer 4: Ground Layer 3: Vcc1 5 - 10 mils 20 - 40 mils 5 - 10 mils Fig. It is not necessary to match the lengths of the TX traces and the RX traces on each individual port. The exact trace length required also depends on. Although signals are band-limited when recovered by a high-speed receiver, your interconnect design should account for the entire signal. At 90 degrees, smooth PCB etching is not guaranteed. The termination requirement depends on the trace length of the clock signal. Follow the 8W spacing for differential clocks (or explore other rules) Even greater spacing is needed for high-speed differential signals. magnetic field tends to be stronger when traces are running along the PCB. C. Characteristic impedance of all signal layers to be 50 Ω ± 10%; Differential impedance of 0. High. $egingroup$ 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. If you use a different PCB laminate. Impedance vs. The IC pin to the trace 2. The difference between a cable and a printed circuit board track is length. They allow the PCB fabricator to tweak the gerbers to match their process and materials. PCB design software, like Altium Designer ®, has high-speed design functionality for routing and trace tuning built into it. I2C Routing Guidelines: How to Layout These Common. Here’s how length matching in PCB design works. •The physical length of each trace between the connector and the receiver inputs should be. If the via length is short, then the tanh function will approximate to 0 and the input impedance will be the differential impedance of section (i + 1). 8 Characteristic Impedance: 50 With my values, with a non-standard thickness board (31 mils thick), I arrived at 55 mils. 1 Answer. traces may be narrower for stripline routing. This will be the case in low speed/low. I2C Routing Guidelines: How to Layout These Common. Read Article UART vs. CBTL04083A/B hasand different length. 1. I have managed to. 4. How to do PCB Trace Length Matching vs. 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. Max trace-length mismatch between high-speed USB signal pairs should be no greater than 150 mils. SPI vs. For RF signals at high-speed, the integrity can take a hit (if not designed correctly) at approximately 50 MHz or. the guard traces could also reduce the return path loop then reducing the unwanted. Impedance control. I2C Routing Guidelines: How to Layout These Common. As rise times increase, the resulting impedance becomes more noticeable. Read Article UART vs. The output current for each channel can be adjusted up to 2. 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. Here’s how length matching in PCB design works. For example, a maximum frequency of 100 MHz corresponds to a risetime of 3. The higher the interface frequency, the higher the requirements of the length matching. 203mm. Matching trace lengths at specific frequencies require. So is the PCB trace impedance an impedance or a resistance? It's both (short story). These specifications can be found in datasheets, and you should set your high speed design constraints to hold these length specifications. For a stripline (inner layer) you divide the speed of light in vacuum by the square root of the relative dielectric constant (e_r). You'll have a drop of about 0. If the length of the interconnection is greater than or equal to λm/12, then the PCB must be designed as a high-speed PCB. g. Cite. Length matching is not the case here but adding some ground traces as guard lines could reduce the probable emission and RF immunity problems. How to do PCB Trace Length Matching vs. 0 and 3. From here, the Constraints Manager will open a window that lists all component pins that are present on the net. For the other points, the reflections are a result of impedance mismatching. Frequency is inversely proportional towavelength. Controlled impedance boards provide repeatable high-frequency performance. During that time both traces drive currents into the same direction. But how often do you see a PCB manufacturer at the table in a design review? And it’s not a one-meeting solution. 34 inches to not be considered high-speed. Here’s how length matching in PCB design works. This will help you to route the high-speed traces on your printed circuit board pcb to the correct lengths without having to guess their actual lengths. This question (paraphrased) goes as follows: Do length-tuning structures create an impedance discontinuity? The answer is an unequivocal “yes”, but it might not. Read Article UART vs. 6 inches must be routed as transmission line. Signal distortion in a PCB is a major signal integrity issue. So choose trace width and prepreg thickness to. Let’s dig into this further and get a sense for why you should not route a trace over a gap in a ground plane. . This variance makes Inside the length tuning section, we have something different. PCB Antenna 3. The data sheet also describes the cables attenuation per unit length as a function of frequency. Frequency Keeping high speed signals properly timed and. Trace lengths should be kept to a minimum. 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. I followed the below procedure to design a 700MHz 1/4 wave monopole PCB antenna. 1. I am a little confused about designing the trace between module and antenna. Rule 3 – Keep traces enough separated. Here’s how length matching in. I2C Routing Guidelines: How to Layout These Common. The loss increases linearly with the length of the PCB trace. The minimal trace sizes as well as spacing are producer and also. Observation: A 3cm microstrip and a 3cm stripline can get a very different propagation delay! Conclusion: If we would route a bundle of traces, eg. How to do PCB Trace Length Matching vs. TMDS signal chamfer length to trace width ratio shall be 3 to 5. More important will be to avoid longer stubs. If you are to use a 1. It would be helpful to know the tolerance in length difference that is allowed while designing this PCB. SPI vs. 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. The third trace has a solid reference plane beneath, and its length is identical to trace 2, 120mm. If you know about dispersion, then you know that you’ll have to do PCB trace length matching vs. Vendor may adjust trace widths, trace. 005 inches wide, but you may have specific high speed nets that need 0. For length-matched parallel buses, you'll usually use a mixture of the two. If the signal speed on different traces is the same, length matching will approximate propagation delay. Tightly Coupled Routing Impedance Control. How tightly should trace lengths be matched for a 1Gbps serial databus? It seems to me that 100ps (15mm) should be more than sufficient. IEEE, 1997. Following the 3W rule can. The Fundamental Frequency and Harmonics in Electronics. significantly reduce low-frequency power supply noise and ripple. SPI vs. Again, the allowed trace length mismatch depends on the rise/fall time of digital signals. I2C Routing Guidelines: How to Layout These Common. When you are distributing power, DC and low frequency, the trace resistance becomes important. Use the smallest routing length possible to minimize insertion loss and crosstalk. 1. 5 High Speed USB Bias Filter AT85C51SND3Bx high-speed USB design requires a 6. 6. 1. Read Article UART vs. Length Matching. 4,618 6 6 gold badges 42 42 silver badges 86 86 bronze badges $endgroup$. A very common, but also effective, rule of thumb is to use a minimum spacing of "2W" (better still, a "3W. Meandering the traces elongates them, so the shorter pair would be meandered to match the length of the longer one. 5 to 17. At an impedance mismatch, a portion of the transmitted signal isHow to do PCB Trace Length Matching vs. That limitation comes from their manufacturing (etching) processes and the target yield. The Altium auto router helps PCB designers with the difficult-to-master process of dense trace routing on a PCB. 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. The signal line is equal in width and the line is equidistant from the line. In this article, we’ll examine a few tips and tricks for high-speed printed circuit board designs. frequency (no components attached). If the traces differ in length, the signal on the shorter trace changes its state earlier than the one on the longer trace. Here’s how length matching in. The roughness courses this loss proportional to frequency. There are guidelines5 that must be followed as the 3D antenna exposed in free space is brought to the PCB plane as a 2D PCB 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 isThe list above is not exhaustive, as trace routing is also a special consideration for communications boards. Note: Loosely coupled traces are easier to route and maintain impedance control but take up more routing area. Loosely vs. In the pair with smaller spacing (5 mil), the small traces in our 21 mil amplitude length tuning section have odd-mode impedance of 58. Many FPGAs do have some feature they call "IO delay calibration" or similar, which allows, within boundaries, to add an adjustable delay to IO lines. This variance makes Double data rate three (DDR3) is a type of dynamic random-access memory (DRAM) that succeeds earlier generations of DDR. SPI vs. 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. If the bends are required, then 135° bends should be implemented instead of 90°as shown in figure (5, Right side). 92445. These traces could be one of the following: Multiple. How to do PCB Trace Length Matching vs. also your traces might be perfectly matched for a narrow frequency band, but not for other frequencies. The PCB trace to the flex cable 4. • Intra-pair trace should be matched to within 5-mils. 2. PCB Design and Layout Guide. Trace Length Matching vs. 5in, ~4cm) for a trace on a PCB with a dielectric constant of 4. Initially the single-ended trace had higher bandwidth, however this could be due to its larger width (8. For PICMG COM Express designs, traces on the bus must have differential impedance of 92 Ohms (COMCDG Rev. In the case of a lossless transmission line (R = G = 0. 3. 2/4 =107mm So, the trace length =107mm. Frequency Keeping high speed signals properly timed and synchronized requires PCB trace length matching vs frequency. and by MAC (for RGMII transmit). So I think both needs to be matched if you want to work at rated high frequency. In contrast, for an internal trace with the same dielectric material we need the trace to be less than 10. Read Article UART 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). Assuming that the thickness of the trace, tSo, strive to keep your traces short and far apart in high-speed design. For PCIe® high-speed signals, design trace impedance so as to minimize the reflections in traces. Note: The current of the signal travels through the. 254mm wide and trace seperation to 0. This extra margin could be used to relax layout requirements on trace length matching and impedance control on cost sensitive PCBs. Control the trace impedance to be as close as possible to the recommended values in Table 2-1 . The limited frequency of interest is usually the Nyquist frequency for the receiver or some limit determined from the rise time. The need for multiple lines between the microcontroller and peripheral makes component mounting more of an issue and they should be placed as close together as possible to minimize trace lengths. For instance the minimum trace width on a design may be 0. What Are Pcb Traces Assembly Yun. Determine best routing placement for maintaining. Here’s how length matching in PCB design works. PCB Recommended Layout Footprint Land Pattern. SPI vs. It may be tempting to follow the 3W rule—traces must be separated by a distance equal to three times the width of a single signal trace. Proper interconnect design must account for the lower noise margins of. 7. For most JTAG, SPI, and I2C communication it is probably unnecessary, as these speeds tend to be fairly slow. Firstly, let’s define what really characterizes a high-speed design. It's important to note that the TIA/EIA-644 does not define. Rx and Tx length matching is not critical as there is wide allowed duration. Designers need to begin treating interconnects as a transmission line when the trace length begins to approach or exceed 1/10 the wavelength of the signal’s highest frequency. Each variance affects the characteristic impedance of an RF circuit. How to do PCB Trace Length Matching vs. I am more interested in the impedance, reactance and resistance of traces in my question for given frequencies in pcbcad softwares for a given layer stackup than the antenna shapes. Design rules that interface with your routing tools also make it extremely. To ensu re a robust interface, the designer must address both components. How to do PCB Trace Length Matching vs. Signal distortions in the form of signal losses are common in long PCB traces. 75 and 2. You can create this advanced board with these high speed routing guidelines for advanced PCBs. They are simply the traces on a PCB and depend on the length and the frequency of the signals passing through them. The HIGH level is brought up to a logic level (5 V, 3. Here’s how length matching in PCB design works. FR-4 is commonly used for the dielectric material. For frequency-modulated analog signals, the characteristic impedance of a transmission line has a constant value throughout the signal’s frequency spectrum as long as the relevant frequency range is high enough. SPI vs. Long distance traces should be routed at an off-angle to the X-Y axis of a PCB layer, in2. Read Article UART vs. CSI signals should be routed as 100Ω. 1How to do PCB Trace Length Matching vs. Here’s how length matching in PCB design works. 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. If the line impedance is closer to the target impedance, then the critical length will be longer. Here’s how length matching in PCB design works. The resistance of these conductive elements is low enough to be negligible in most situations. the series termination resistor is chosen to match the trace characteristics imped-ance. Frequency Keeping high speed signals properly timed and synchronized requires PCB trace length matching vs frequency. Read Article 25MHz is some how high for SPI communication and you could have unwanted radiated emission due to long 17 cm traces. The impedance of a PCB trace at RF frequencies depends on the thickness of the trace, its height above the ground plane, and the dielectric constant and loss tangent of PCB dielectric material. Four Rules of PCB Bus Routing. I use EAGLE for my designs. 127 mm traces with 0. 56ns/m). 8 * W + T)]) ohms. The basic idea of this length matching is that the shorter trace follows a detour or meander in order to lengthen it to match the length of the longer trace. Where lis the length of the wire R0 is resistance per unit length. Problems from fiber weave alignment vary from board to board. 3. 7 and μ R ~ 1 for FR4 material. 2. • Adjustable on-die termination (ODT) with dynamic control that provides ODT sup-port during writes without having to wire the ODT signal. Edges of Trace and Grounds). As modern interface frequencies scale higher, care must be taken in the printed circuit board (PCB) layout phase of a design to ensure a robust solution. This might or might not be an issue, as we will see in a minute, because it all depends on the signal frequency and trace length. Another common beginner PCB design mistake is to use the same trace width for any type of trace. ImpedanceOne of these design aspects is the match between PCB via size and pad size. Other aspects such as stack-up and material selection also play crucial roles. Use shorter trace lengths to reduce signal attenuation and propagation delay. How to do PCB Trace Length Matching vs. 50R is not a bad number to use. Impedance Matching and Large Trace Widths. Design PCB traces with controlled impedance to minimize signal reflections. How Do Circuit Boards Work Custom Materials Inc. By controlling the PCB impedance, unexpected damages or errors can be limited to some extent. Some IPC Class 3 fabrication houses will recommend teardrops, but this brings up the question of signal integrity on high-speed interfaces. rise time (tRise). $egingroup$ This is more like what a conductor looks like at extremely high frequency. Trace Widths. RF layout and routing is an art form that is starting to become more critical for digital designers. A 3cm of trace-length would get 181ps of delay. How to do PCB Trace Length Matching vs. Trace length tolerance matching on your differential pairs and single-ended traces makes your high speed routing more precise. 5/5/8 GT/s so the hardware buffers can re-align the striped data. Relation between critical length and tpd. Select a trace impedance profile over the length of the taper. Frequency Keeping high speed signals properly timed and synchronized requires PCB trace length matching vs frequency. Use shorter trace lengths to reduce signal attenuation and propagation delay. CSI-2 (MIPI serial camera): The CM4 supports two camera ports: CAM0 (2 lanes) and CAM1 (4 lanes). For the stripline I simulated above, this equals an allowable length mismatch of 1. The impedance formula is usually represented by Z = R – j/ωC + jωL, where ω = 2πf. The switchback pattern requires a shorter total length than the serpentine pattern for a given level of skew compensation requirement. 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-. If the line impedance is closer to the target impedance, then the critical length will be longer. The traces are 0. This means we need the trace to be under 17. Critical Signal Trace Length To prevent from signal reflection, signal trace length cannot be longer than the following two critical length limitations: (a) 1/16 wavelength of Signal, λ; the relationship between signal wavelength and signal frequency is defined as where ε R = 4. There a several things to keep in mind: The number of stubs should be kept to a minimum. 2 mm. Based on simulations and. The PCB trace on board 3. In contrast, for an internal trace with the same dielectric material we need the trace to be less than 10. Cadence Orcad Guide OrCAD - PCB Solutions | PCB Design Software EDA Tools and IP for Intelligent System Design |. The extent of this problem will depend on the bus speed, the length of the traces, the trace geometries, the type of fiberglass weave used, and the alignment of the traces to the weave pattern of a PCB. 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.