t. Figure 1 New techniques for pc-board-layer-interconnect design provide predictable path impedance and improved signal integrity. The grounded differential coplanar wave guide is the differential version of the grounded coplanar wave guide and is used in high-speed digital systems that require maximum noise immunity. If your structure has two microstrip feed lines, you can extract even and odd modes by creating weak coupling between main resonator and feed lines. 1,235. ; Z 0 is the characteristic impedance of free space (approximately 377 ohms). Atlas Si for TDR. Differential Impedance is the impedance between two differential pair signal traces. 1 to 2. Differential impedance: This is the impedance of a pair of transmission lines. Phone: +44 (0)1425 489 111 / +49 (0) 8104 628 0. ; H. The closer you place the pairs together, the differential impedance gets smaller because LM and CM get larger. Figure 81 shows the topology. ’. Even mode impedance is defined as impedance of a single transmission line when the two lines in a pair are driven with a common mode signal (the same amplitude and the same polarity). Asymmetric Stripline Impedance Formula. H. The IPC-2141 trace Impedance calculator will help make initial design easier by allowing the user to input basic parameters and get a calculated impedance according to the IPC-2141 standard. The characteristic impedance of a cable and its connec-tors should match the impedance of the transmitter and receiver. 331 1 2 5. Press the Analyze button to calculate the electrical parameters. Series Equivalent Differential Impedance (SEDZ) Model Details The SEDZ format schematic is represented by Figure 55. Here are some tips for measuring differential impedance. Figure 8. Once you know the characteristic impedance, the differential. To improve calculation speeds, impedance profiles are calculated in separate threads (when available). mm mils. Matching the differential trace length and keeping the distances properly, this calculator is used to calculate the characteristic impedance of an edge coupled microstrip. Example (PageIndex{1}): CPW; 3. As seen here:On an impedance controlled layer (for example, with 100 diff), find an unused area and run a differential pair and expose at each end to the surface with test pads. Use an online differential microstrip impedance calculator; Use an online differential stripline impedance calculator; Calculating Differential vs. Such a stripline is constructed with two traces referenced to the same reference planes above and below the traces with a dielectric material between them. Neighboring metallic structures will be considered in the calculation. W is the Width of the stripline. With both wires at the same potential there is no capacitance between them so the reference plane (return path) is less clear. PCB Structures / Discrete Structures / Signal Management. You don’t need to care about the common impedance if there are no common signals on the twisted pair. Atlas Si for VNA – Insertion loss test system – Delta-L 4. Differential pair on a reference plane for differential mode (left picture) and common mode (right picture) line impedance In addition to the four line impedance types the Impedance Calculator is also able to calculate the Coupling Factor between two traces on either the same signal layer (horizontal coupling) or between two traces on different. PCB Impedance-Calculation: Help with the dimensioning of the impedances of your circuit board. Data entry is primarily made in the upper left pane, although the bottom middle pane contains some secondary entry fields. Single and differential coplanar structures; Multiple adjacent dielectric layers, with different dielectric properties. Edge Coupled Microstrip Impedance Calculator. 3mm of the microcontroller), therefore i rounded the width to 0. 4 Comments. It seems I could largely do without any impedance matching considerations, given what the trace lengths are. Surface microstrip lines are formed by etching one surface of a double-sided material. 2) S/T > 5. Also differential pairs. 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. Edge Coupled Stripline Differential Impedance Calculator Broadside Coupled Stripline Impedance Calculator Symmetric Stripline Impedance Calculator Asymmetric Stripline. 2. This tool calculates the matching network necessary to terminate a line of the specified characteristic impedence (Z o) in a specific complex load impedence (R L + jX L) at a specified frequency. This calculator will convert voltage or power gains into decibels. In this worst-vase scenario, the via would. Polar or rectangular grids only allow direct reading of S11. Example. Turning over to the digital logic side of things, our favorite way to spew ones and zeros is to calculate the difference between two matching lines rather than trying to read a single line that is subject to momentary instances of noise as a voltage spikes across the landscape. There are some advantages to using a microstrip transmission line over other alternatives. Eurocircuits’ Impedance calculator uses real values as defined in the supplier’s data sheets. *Strictly, a loss quantity when expressed in dB should be positive. This will be increased if you have plated through vias, so you might want to calculate with a thickness of 2. The trace width is important as it determines the single-ended and differential impedance, capacitance, and inductance. Often when working with wires it is easy to create large return path loops if one is not paying close attention. The Impedance Calculator is a tool which allows a quick pre-layout estimation of several kinds of line impedances between different layers. Instead, field solvers normally focus on impedance and calculating the current distribution around the trace. 9 Ohms). This calculator assumes. Email. ”7. What is a Microstrip Differential Impedance? Microstrip Differential Impedance. For better impedance control, use PCB design software you can trust. If you select non-inverting op-amp, the calculator will show 11. Following equation or formula is used for Differential Microstrip Impedance Calculator. Actually the "odd impedance" is the correct impedance to look at for the USB requirement of 90 Ohms differential impedance. 1. GDCPW is known for its balanced configuration, which helps reduce common-mode noise and interference in high-frequency signal. Re: Calculating Differential Impedance for USB Differential Pair. This RLC impedance calculator will help you to determine the impedance formula for RLC, phase difference, and Q of RLC circuit for a given sinusoidal signal frequency. 35,851. That means each trace would be a 50-ohm trace, if there were no coupling between the traces. f c = 1 / (2π × 3. An example of a wire microstrip might most often be found in prototypes or reworked boards where a wire is used over the top of pcb or copper clad material. A differential cable is usually constructed with a UTP, STP, STQ or twin-axial configuration and achieves 100-Ω differential impedance. loop of the amplifier, which tends to drive the impedance at the output terminals, VO– and VO+, to zero, depending on the loop gain. | Created: November 22, 2021 | Updated: June 25, 2023 Table of Contents Differential Impedance Defined Formulas for Differential Impedance Should You Use Characteristic or Odd-mode Impedance? Calculating. Using the Impedance Calculator one can calculate the eigen modes as characteristic line impedance and the characteristic propagation constant gamma of available signals in a given cable segment. Also does diff. The procedure for calculating the differential impedance of an interconnect with a differential via transition is iterative; you calculate the input impedance from the receiver end and work backwards to the load end. to NF The differential impedance calculator supports an asymmetric stripline structure. H1. Differential impedance changes with coupling, which changes with trace separation. A twisted-pair cable is simply two wires that are twisted together so as to reduce radiated EMI (electromagnetic interference) and mitigate the effects of received EMI. This calculator finds both odd and even transmission line impedance. D = Separation between the differential traces. Just enter the given values for trace thickness, substrate heights, trace width, and substrate dielectric. IMPEDANCE CALCULATIONS • Hyperlynx Linsym- Does whole cross section at once, allows mixed materials. Note: The results are only for approximation and rough estimation, the final values and the. In principle, you can calculate the inductance of a trace with a 3D field solver utility, but this is not the norm in transmission line design. Resonant Frequency Calculator. There is also a dielectric material placed above the conductor. In some cases, we can also use 75-ohm differential. We want to follow the specification, selecting components and routing traces at the correct. Differential Impedance of. INPUT DATA. and thats the first time iam doing ethernet things. 50. where. Agilent's LineCalc tool calculates Z odd = 50. This will leave the rest of the signals which are rather non-critical like I2C, power good signals, etc. 3. Power Divider Calculator. This is the same reason we have to consider spacing between traces in differential pairs: the two conductors interact with each other to determine the odd-mode (and differential) impedance . You only need to know the resistance, the inductance, and the capacitance values connected in series or parallel. Other calculators will use different equations for the same system, depending on the relevant approximations used in the derivation of the formula. Choose the type of op-amp, e. The efficiency of transmission of the embedded microstrip greatly depends on its characteristic impedance. 2. In addition to the first-The following formula is used to calculate the value of resistor R1 & R2 of pi type symmetrical attenuator (shown above) for the desired value of attenuation (dB) and matching impedance/characteristic impedance. W W is the PCB trace width, in thousands of an inch (mil); A. Choose from different surface finishes,. Another example of using large distances to separate out unwanted components might be to calculate the impedance of a. It also explains the factors that affect the impedance, such as trace width, dielectric constant, and frequency. Fig. L is the inductance in henries (H),. Both LM and CM converge to zero as spacing goes to infinity. T Match Impedance Calculator. The only requirement is the required attenuation in decibels (dB) and the impedance in ohms. This calculator is designed to calculate the characteristic impedance of an edge coupled microstrip. Rewrote the PDN Impedance calculator, old formula was too confusing. Z = V I = Z0= 1 vC V 1 vC LV = vC Features of the impedance: looks like a resistor dependant on intrinsic properties only is an intrinsic property independent of length. The differential impedance depends upon the D/H ratio. Voltage Divider Calculator 1 (Fixed) Voltage Divider Calculator 2 (Adjusteable) Capacitors. There may be better trace/space combinations but the impedance is in the right range. [m] width of the trace. USB traces must be 90 Ohms differential. 48 e -0. This calculator finds both odd and even transmission line impedance, including four different types of impedance used in characterizing differential trace impedances, for microwave antennas, couplers and filters applications. At higher frequencies, the output impedance of the output amplifier can change, resulting in a small imbalance. Unfortunately, TxLine doesn't do coplanar waveguide for differential traces. For a printed circuit board (PCB) this is a pair of traces, also known as a differential pair. Open the PCB layout tool (pcbnew) and go to File > Board Setup. I see that Dielectric Constant is 4. Given the defaults (1. 2 of the Microstrip Calculator, h=H1 and b=H2-H1. 25mm trace. 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. Read more about designing to a differential impedance specification; Read more about the six important transmission. Calculates Lo and Co. But it lacks the differential impedance (impedance between these two tracks). Try TNT or TxLine. Table 1. How to Use the Calculator. Their hardware design guideline said the traces between the USB and the termination resistors should have a differential impedance of 90 ohms. While this calculator will provide a baseline, any final design considerations should be made towards loss, dispersion. Bandwidth Calculator & Max PCB Trace Length Calculator ; Calculates the bandwidth of a digital signal and maximum trace length, using the IPC-2251 method or the frequency domain method, for transmission line effects. Then calculate R T for impedance matching and the value of the R2 for differential balance. Differential pair routing is one of many aspects of high-speed design. The Differential microstrip impedance calculator is used to compute the differential (Zd) and single-ended impedance (Zo) of an edge-coupled microstrip line just by entering the width, separation and thickness of the trace along with the dielectric thickness and constant of the coupled line. Sierra Circuits’ Via Impedance Calculator uses the physical dimensions of a via to calculate its capacitance, inductance, and impedance. infinite mutual. Coplanar Waveguide Calculator. Where: Y is the electrical admittance. The idea here is to determine the spacing required for a given width with the goal of hitting a specific differential impedance value. Saturn PCB - Toolkit for Impedance Calculation. 2-side PCB, one side with signals, the other with GND. 3) to calculate trace width and. Power Filtering/Distribution x. Z 0, air is the characteristic impedance of air. Design Parameters. For instance, I want a 100 Ω controlled impedance pair, and have used "differential" before which seemed to work fine. on layer 3 from the top, between power and ground plane. They will give very similar answers. Use several of them and compare. The required inputs are the Dk value for the dielectric constant of the PCB substrate, and the. With our handy calculator, you can choose from 50 Ohm, 75 Ohm, 93 Ohm and 95 Ohm coaxial cables. Using a differential pair to avoid common mode noise is common in audio circuits. Near 50 ohms, many of these approximations are within a few percent accurate. This calculator finds both odd and even transmission line impedance. Parallel Wire Impedance, Inductance, Capacitance and Propagation Delay Calculator Results. 2. ; We can use each of these parameters separately in each equation to find the resonant frequency, the Q-factor, and the damping ratio. Click the button corresponding to the characteristic impedance to calculate its value. Z diff equals Ra||(2Rb) (p model) or 2R 1 (T model). 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 yourThe characteristic impedance Z 0, or the load impedance Z L, can be calculated with the value of ρ. 5 (FR-4) ! even for Conductor/Plane layers. e. 1< W/H < 3. e. 1. The online menus contain a calculator to help you to define the correct track and gap values for your layout, for example for 50Ω characteristic and 90Ω differential impedance using material with a guaranteed. They can give you some stackup options, and they can tell you the trace width you will need to reach 50 Ohms for their stackup. , "Characteristic Impedance of the Shielded-Strip Transmission Line," IRE. STEVE: High speed systems today face many simultaneous impedance requirements that must be achieved in the same stack-up – differential impedances at 100 ohms for ethernet, USB at 90 ohms, PCIe at 85 ohms, and a myriad of single-ended DDR requirements. It consists of a pair of center conductors separated by ground planes on the same substrate. IN, then calculate the termination resistor R. 378t} W = 1. Advertise with us;. Agilent's LineCalc tool calculates Z odd = 50. model impedance by combining Polar's proven boundary element field-solving engine with easy graphing of process windows. 6), the impedance will be approximately 50 Ohms. 4. High-speed designs carry a requirement for controlled impedance, crosstalk control, and the need for interplane capacitance. 100 Ohm diferential impedance microstrip PCB traces geometries in. Before, working with a trace impedance calculator, one should be aware of which equations the calculation uses. Two conductors can create a transmission line. ; G is the conductance component of the admittance. The tool provides two networks that will have the desired impedence at that frequency, but their. The calculator shown below uses Wadell’s equations for differential impedance, which can be found in the seminal textbook Transmission Line Design Handbook. 9 Ω, R₂ = 3,062 Ω, and R₃ = 50. Figure 7. R is the resistance in ohms (Ω), . The designer selects the desired gain and the impedance of the signal source (default value of 50 Ω). 6mm board, 100R microstrip differential impedance, they suggest 4/5 mil trace/space, which is a bit different than 9/4. Single ended impedance is the trace impedance with reference to ground. e. Differential Impedance Differential Impedance: the impedance the difference signal sees ( ) ( ) 2 2( ) Z 0 small I V I V diff Z diff one one = = ≈ − Differential impedance decreases as coupling increases +1v -1v I one x I two How will the capacitance matrix elements be affected by spacing? C 12 C 11 C 22 Eric Bogatin 2000 Slide -18. The allegro calculator gives a value of 56. Doing this results in a gain change. If JLCPCB's 4-layer PCB is. Parallel Wire Impedance (Zo) = Ohms. The default units for all given values, except the subtrate. Most often, the only specified requirement of a differential pair is its differential impedance. Signal 1. Open the PCB layout tool (pcbnew) and go to File > Board Setup. It is important to determine the characteristic impedance of a twisted-pair cable because this impedance should match the impedance. 331 1 2 5. This calculator is designed to calculate the characteristic impedance of a symmetric stripline - a flat conductor between two ground planes whose distance between the conductor and the planes is the same for both reference planes. If it this PCB has many power islands AND there are controlled impedance traces, then it may be a better idea to keep all the controlled impedance traces on Signal 1 and Ground on Layer. A coaxial cable is designed with 50-Ω or 75-Ω characteristic impedance. The characteristic impedance is given by: Eq. November 14, 2022. There are a lot of online trace impedance calculators specifically designed for differential traces. Multiply the result by the square root of the ratio of (1 + (2 * h / w)) to (1 – (2 * h / w)). Impedance captures the real. 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). Click on Setup -> Constraints > Electrical Constraints Set - > Differential Pair Value - > Calculator >. Given a value for impedance, it will (in most cases) calculate. ( 0. RF Transformer Calculator. There are a number of pcb transmission line typologies. But, you usually want some decent coupling between the traces, so a good single-ended impedance target for each trace is between. In order to quantify this impact, we calculate the CMRR using Equation 9. characteristic impedance, signal speed, crosstalk and differential impedance. The drawing below is a 3D electromagnetic model of stripline with perfect electrical conductors encasing all four sides along the z and y axes (created using Ansoft's. 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. Hi, I am working on my board Stack-up to tune Single/Differential impedances of my board in Allegro PCB 16. ZL =. Added option to select between default asymmetrical stripline formula and the IPC and Wadell formulas. Figure 1. Dielectric Thickness: mm. Either the desired impedance at a specific frequency is used to determine the waveguide width, or the width is entered and the impedance is calculated. Twisted pair: qquad footnotesize ext {Impedance} = frac {120 imes ln (2s/d)} {sqrt {varepsilon_r}} Impedance = εr120 × ln(2s/d) As you can see, it is not overly complicated to calculate by hand, but it will definitely take longer than using our calculator. Equation 9 For high gain, the CMRR of the 2-op amp instru mentation amplifier is similar to the CMRR of the differential amplifier. Z diff equals Ra||(2Rb) (p model) or 2R 1 (T model). Locally hatched ground plane to increase differential impedance. 8. 2. 50 - 55 ohms). Z o is the impedance of an individual trace. A variant of coplanar waveguide is formed when a ground plane is provided on the opposite side of the dielectric, which is called finite ground-plane coplanar waveguide (FGCPW), or more simply, grounded coplanar waveguide (GCPW). Coplanar Waveguide With Ground Characteristic Impedance Calculator. εeff is the calculated effective dielectric constant of the microstrip line due to the nonhomogeneous nature of the structure (i. This is to avoid unwanted data signal reflections. 1. USB 2 e. Step 1 Calculate singled ended impedance for each: Use "impedance + trace space" from top drop down box: Set Z=50R, click single ened, gives a result of track. The characteristic impedance of your microstrips is determined by the trace width for a given layer stackup. Figure - Single Ended impedance calculator. How to verify performance. Lo: inductance per unit length. Zo (diff) is calculated to be 244 ohms, so dividing by two yields a value of 122 ohms for the semi-coplanar structure. Note that the y-axis is on a logarithmic scale for clarity. The formula for theoretical differential gain is. ϵ r is the substrate dielectric. The amount of the voltage reflected back is given by the following equation. The greater the mismatch. Finally, all calculators provide theoretical impedance values as they cannot take in to account the variables. Calculates the differential impedance of a microstrip pair. Note that Zdiff (differential impedance) is equal to 2 * Zodd, so a Zodd of 45 Ω gives us a Zdiff of 90 Ω. Mutual inductance and capacitance exist between the two traces in a differential pair. The Differential microstrip impedance calculator is used to compute the differential (Zd) and single-ended impedance (Zo) of an edge-coupled microstrip line just by entering the width, separation and thickness of the. Ask the board manufacturer for the values. The article will not go into the details of these other aspects that indirectly are part of the impedance controlled traces challenge. Excite the other end of the trace with the function generator. These values depend upon the geometry. Trace Width. As also noted in the picture, the subsequent calculations are on the: [2] top-layer single-end impedance; [3] top-layer differential impedance; [4] inner-layer differential impedance. Print - Advertisement - This calculator helps you compute the characteristic impedance of an asymmetric stripline Inputs. 96D/H). The calculator is set up to handle an asymmetric arrangement, where traces are not centrally located in the PCB layer stack. H 1 (Dielectric thickness) : mm mils. In other words, if you are designing to hit a differential impedance target. It supports both balanced and unbalanced lines. 3 V, etc. When i put "Factory" cable dimensions in calculator i don"t come close to 90 ohms. Schelkunoff in 1934, is a very convenient parameter for the prediction and control of EMI coupling through cable shields. Even mode impedance for commonly-driven transmission lines . Radio Frequency Engineering Calculator. It has been correlated many times. For this calculation, the units of d and h can be ignored as long as they have the same unit. Differential impedance is defined as impedance between the two lines when the line pair is driven differentially. The differential impedance. The Smith Chart graphically maps S11=reflection coefficient= (ZL-Z0)/ (ZL+Z0) to Load Impedance (ZL), normalized to Z0 (source impedance = center of chart). In addition, the equivalent circuit parameters have been extracted by using an E4991B Keysight Impedance analyzer. 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. Enter the values of Z0 and Zc into their respective input fields. Dual Stripline. Correct track impedance is the first point usually made in various online sources I've found on the subject, so I tried to get the microstrip impedance calculator to get as close the desired 100 Ohm. Several Web sites such as the examples listed below contain additional reference information. Calculate Coplanar impedance for given PCB parameters. Tech Consultant Zach Peterson is talking Signal Integrity again today with a deep dive into Differential Impedance. $endgroup$ – The Photon. Differential impedance: 90 ohms (tolerance: +/- 15%) On a typical 1. An example of this calculation using the Si8000m Quick Solver is shown below in figure 4. Creating and Configuring an Impedance Profile. The following formula is used to calculate the differential impedance of a microstrip: To calculate the differential impedance of a microstrip, divide the characteristic impedance of the microstrip by 2. Thinking about the problem as the impedance the differential signal sees (the thing we care about) compared to the impedance the common mode signal sees (the part of the signal we typically try to eliminate in a difference amplifier) is probably more appropriate for most practical signals, and gives us a nice simple expression. Altium Designer’s differential line impedance calculator will set up your impedance-controlled differential pair routing widths for you. For R D, the value of 25 Ω is inserted, which is the differential output impedance of a typical NFC IC with respect to the ground signal. 2 Loss of CPW lines; 3. Differential Stripline Impedance Calculator. Differential Impedance Calculator. 29 mm width traces to obtain 100 Ohms ZDiff while using 0. Differential Impedance Calculator - Stripline. Tpd: propagation delay. Since it is always important that the trace impedance remain constant over the entire length, this means that the coupling must remain constant over the entire length. The stripline impedance calculator provided below is useful for gaining an initial estimate of trace impedance for striplines. Coplanar Waveguide Calculator. Multiple Differential Pairs Insert multiple Differential Pair definitions per layer. The differential via design shown in Figure 2 was built. Pasternack PCB Microstrip Calculator is an online calculation tool that lets you compute a microstrip's height/width ratio, impedance and relative dielectric constant for a microstrip transmission line. Modeling approximation can be used to understand the impedance of. Grounded Differential Coplanar Wave Guide. Description. Ohm’s Law provides the framework for solving network analysis problems; when the curtain gets pulled back, Ohm’s Law updates to become the relationship between voltage, current, and impedance, not resistance. Using this calculator, you can find the resonant frequency, which means that you can disregard the reactive impedance (reactance) and only pay attention to the resistive impedance (resistance). 77 mm gave me a differential impedance very close to 90 Ω. Our pi attenuator calculator is designed to aid you in calculating the correct values of the resistors R1 and R2, according to the diagram below. 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. 035mm and Er = 4. The most commonly used twisted pair cable impedance is 100 ohms. So, to calculate the differential impedance of Figure 1, simply calculate the impedance of Figure 3, and double it. An operational amplifier (op-amp) is a voltage amplifier with a differential input and a single. ω = 2πf is the angular frequency in rad/s,. Give this class a name (100 ohms in our case). 17mm FR408 - 17um. Going Forward with a Trace Impedance Calculator. Eurocircuits also calculates the correct Differential Impedance values using the correct formula and not a ‘Rule of Thumb’ method. Such a microstrip is constructed with two traces referenced to the same reference plane with a dielectric material between them. Please provide a rating, it takes seconds and helps us to keep this resource free for all to use. A typical 4 Layer stack up. Embedded Microstrip. This is the same reason we have to consider spacing between traces in differential pairs: the two conductors interact with each other to determine the odd-mode (and differential) impedance . To be honest, I am no idea of the impedance on. The calculator is set up to handle an asymmetric arrangement, where traces are not centrally located in the PCB layer stack. For now let us focus on the single ended impedance. • Polar Instruments Si6000c- Calculates single transmission line at a time. Figure 2. 8 substrates of various thicknesses. 01) and dielectric constant (3. If you put 10 in the Line Width, the calculator calculates the single ended as well as differential impedance. Following is the formula for differential impedance for a Stripline. The JLCPCB results are more reliable than (some of) the simple formula-based approaches. However, the main advantage of the current configuration is that it offers high input impedance. Differential Trace Routing. W. As also noted in the picture, the subsequent calculations are on the: [2] top-layer single-end impedance; [3] top-layer differential impedance; [4] inner-layer. s. 4 Differential Line and Coplanar Strip; 3. ; Both the conductance (G) and susceptance (B) components of admittance are real numbers, and the complex term jB accounts for the phase relationship between them. Differential impedance, Z diff, is the impedance between the two conductors. PCB samples, finding that predicted accuracy varies according to target impedance. Modeling approximation can be used to understand the impedance of the edge couple differential stripline transmission line.