Estimate the impedance of a symmetric differential stripline pair using Wadell's equations and a simple calculator. Schelkunoff in 1934, is a very convenient parameter for the prediction and control of EMI coupling through cable shields. ; H. One of the features of this type of microstrip is the coupling between lines. Select the box with the geometry that you would like to calculate. Modeling approximation can be used to understand the impedance of. The designer then has the option of selecting a seed. What is the characteristic impedance of twisted pair cables? 100 ohms. ALTIUM DESIGNER For. R is the resistance in ohms (Ω), . Si TRC – Track Resistance Calculator calculates DC. [2] Calculate the top layer signal end impedance: Two tools are giving Zo=48 and Zo=47. Propagation Delay (T pd) = ps/ cm. Going Forward with a Trace Impedance Calculator. Simons, "Coplanar Waveguide Circuits, Components, and Systems", Wiley. Alternatively, Generate R1 and R2 for a wanted attenuation. This is an iterative process that repeatedly adjusts the via dimensions and runs EM simulations until achieving the desired impedance and bandwidth. Inductance (L) = nH/ cm. 50. Relative Dielectric Constant ( εr ): Track Width: mm. Assuming both are accurate enough. 6. The impedance between one differential trace and the ground. **Note: Like our microstrip line impedance calculator, all of our RF calculators allow SI prefix input. We’ll go over how differential pairs can hel. infinite mutual impedance. Figure 1. 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. High-quality circuit boards as prototype and series at reasonable prices. Figure 4. We get a lot of questions about trace impedance and how to calculate the right trace size to hit a specific impedance in a manufacturable PCB. Example (PageIndex{1}): CPW; 3. The JLCPCB Impedance Calculator computes track width values and recommended stack-ups from user-input values of board layer, thickness, copper weight, target impedance, trace spacing (for edge-coupled pairs), and impedance trace to copper gap (coplanar waveguides). This calculator is designed to calculate the characteristic impedance of a broadside couple stripline (see diagram below). For a printed circuit board (PCB) this is a pair of traces, also known as a differential pair. Reflection Coefficient Calculator. ( 0. The microstrip is a very simple yet useful way to create a transmission line with a PCB. Where Z 0 is the characteristic impedance of the asymmetric stripline in ohms (Ω). It is the ratio of voltage and current amplitudes of a single wave propagating along the line in the absence of reflections from other directions. GEGCalculators. 378t} W = 1. 50 Ohms. B = separation between reference planes. While commonly constructed using printed circuit boards, this structure can also be built using other materials as long as there is a conductor separated from. RF Amplifier PAE Calculator. Z0 = (L/C)^0. 0 and (t/h) less than 0. . This is the impedance between the two signal traces of a pair. In addition, the termination resistor value used should take into account the input impedance of the amplifier circuit. They will give very similar. It uses the lan9512 reference schematic. If you're trying to get your own pcb design project , you should use this tool. Class creation for controlled impedance routing using Altium Designer. Differential impedance values are normally specified for impedance matching of differential pairs, rather than odd mode impedance. (Differential Impedance, Ohms) = Note: 1oz = 1. It consists of a pair of center conductors separated by ground planes on the same substrate. Polar or rectangular grids only allow direct reading of S11. PCB Structures / Discrete Structures / Signal Management. INPUT DATA. Enter the number n n of impedances in parallel as a whole number and press "Enter". JLCPCB Impedance Calculator. We care about maintaining the same differential impedance for the same reason we. Most often, the only specified requirement of a differential pair is its differential impedance. Resonant Frequency Calculator. Simply put, differential impedance is the instantaneous impedance of a pair of transmission lines when two complimentary signals are transmitted with opposite polarity. on layer 3 from the top, between power and ground plane. H is the Height of the stripline. It works in parallel with the standard PCBS layer stackup manager and gets the default setting from it. TS. A Pi Attenuator uses a single series resistor, and two shunts to ground (input and output) to attenuate a signal. 1. SET2SEIL. Differential signalling is a method for electrically transmitting information using two complementary signals. SAVE & ACCEPT. 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. Finally, all calculators provide theoretical impedance values as they cannot take in to account the variables and. Also differential pairs. 5. How to verify performance. This calculator assumes the distance between the two reference planes to be an equal distance. Microstrip Impedance Calculator. The fully differential component calculator has six panes. Just a clean step. 75 inches without impedance control; Keep the differential pair length mismatch within 0. 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. What is a Microstrip Differential Impedance? Microstrip Differential Impedance. s. Quartz Crystal Parameter Calculator. 1. Reaction score. Useful converters and calculators. Let’s Get Digital - Differential Pairs in the Real World. 5oz inner copper, 8 mil trace spacing) and a target differential impedance of 100 ohms, JLC's calculator suggests a trace width of 8. 5. 19mm) traces with 7. Series Equivalent Differential Impedance (SEDZ) Model Details The SEDZ format schematic is represented by Figure 55. This calculator is designed to calculate the characteristic impedance of an edge-coupled microstrip. To see how this works, consider the diagram below. thanks to 6 layers I am now pretty confident that I can place all diff pairs on top and bottom layers, directly above the ground planes. ”7. You can interpret the name 'RLC circuit' to mean. The desired behavior of the differential amplifier is to amplify the differential mode voltage and attenuate the common mode voltage. Asymmetric Stripline Impedance Formula. Based on Zo Equation Per: IPC-D-317A:. εeff is the calculated effective dielectric constant of the microstrip line due to the nonhomogeneous nature of the structure (i. Microstrip is a single trace on the top layer, with no ground close to it on the same layer. Typical values for most common differential signal types are 90 ohms differential, 100 ohms differential or 120 ohms differential. Both gives me only 20 Ohm differential impedance. 331 1 2 5. 75 mA corresponds to a CE range of 1V to 8V. net Forum comes closest to the proper track width. The two most common impedances. Figure 4. High-speed designs carry a requirement for controlled impedance, crosstalk control, and the need for interplane capacitance. 2. Following is the list of useful converters and calculators. Co: capacitance per unit length. The typical common impedance of an unshielded twisted pair will vary from around 100 Ω to 200 Ω. 6mm thick. [2] Calculate the top layer signal end impedance: Two tools are giving Zo=48 and Zo=47. Single and differential coplanar structures; Multiple adjacent dielectric layers, with different dielectric properties. Embedded Microstrip. 0. The trace impedance (single-ended) in an individual trace is normally calculated by ignoring any neighboring traces, so no coupling to other conductors in the design will be. Differential Pair Impedance (Z_diff) = (2 × Z_single) / sqrt(1 + (2d / s)) Where: Differential Pair Impedance (Z_diff) represents the characteristic impedance of the differential pair, typically measured in ohms (Ω). The only requirement is the required attenuation in decibels (dB) and the impedance in ohms. 254mm. If there is an insulator around the wire then this. Common-mode (CM) noise current flows in power lines with same direction CM noise behavior “Voltage driven”, dv/dt, electric field, high impedance DM noise behavior “Current driven”, di/dt, magnetic field, low impedance Buck Boost Vin Cin Cout Lf Q1. Mutual inductance and capacitance exist between the two traces in a differential pair. High speed digital designers should. Supports Anritsu ShockLine™ MS46524B and VectorStar™ MS4647B. 1. Thus, the TDR method is use-ful for measuring Z 0 and changes in Z 0 of a transmission line. Relative Dielectric Constant ( εr ): Track Width. Microstrip allows for thinner flexible. 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. 2 Calculating Impedance The following equations can be used to calculate the differential impedance of the board. I used some online calculator to calculate parameters of trace so it has 50 Ohm impedance. 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. THESE FORMULAS ARE. 25, but gives me nice trace from the module to the stub then to microcontroller. 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. 8. Such a microstrip is constructed with two traces referenced to the same reference plane with a dielectric material between them. When the op-amp working, the voltages at the inverting and non-inverting inputs. calculate the impedance and capacitance of PCB traces. eu. Open the PCB layout tool (pcbnew) and go to File > Board Setup. USB traces must be 90 Ohms differential. Or the odd mode impedance is half of the differential impedance. Differential impedance at low frequency represents the sum of inductance resistances of the filter. The advantage a 2D field solver wields over an approximation is the flexibility to consider almost any arbitrary cross-section geometry. Jul 8, 2014 at 21:15. Click on Setup -> Constraints > Electrical Constraints Set - > Differential Pair Value - > Calculator >. The impedance always represented by Z. To obtain a particular value of differential impedance, the two signal tracks are usually assumed to have the same cross-section — the balanced track case, used in most impedance calculation software. then the differential impedance will be less sensitive to over-etching or under-etching during pcb fabrication. The calculator shown below uses Wadell’s equations for differential impedance, which can be found in the seminal textbook Transmission Line Design Handbook. Loss is calculated as a combination of dielectric loss and conductor loss at the analyzed/synthesized length. Finally, calculate and adjust the feedback resistor for the correct gain. The following formulas are used for the calculation: where . e. For these reasons, it is difficult to calculate optimum component values for a fully differential amplifier design whose input is single ended and terminated . Note that the y-axis is on a logarithmic scale for clarity. Impedance. 10. Z diff = 2 * Z o ( 1 – 0. Usually Microstrip separated from the ground by using dielectric substrate. 5 Ohms higher than the formula method. 75 mm track on a 0. L is the inductance in henries (H),. And this leads to our third rule: The separation between the two traces (of the differential. 5 (FR-4) ! even for Conductor/Plane layers. Z 0 = ( Z 0o * Z 0e )^0. Figure 3 shows the respective p and T models used to calculate the differential impedance (Z diff). s + JX s (1) The “+“ implies “in series”. This calculator lets the user enter in the desired attenuation (in dB) and the system impedance (Zo in Ω’s) and it will calculate the needed shunt resistors (R1) and series resistor (R2). Differential impedance, Z diff, is the impedance between the two conductors. How to verify performance. Speedstack Si – Insertion loss & impedance PCB stackup design including Si9000e. This calculator will convert voltage or power gains into decibels. ; 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. Also, be aware, 90 ohms is the differential impedance, the characteristic or single ended impedance will be more than half (ie. Twisted Pair Impedance (Transmission Line) Calculator. It seems I could largely do without any impedance matching considerations, given what the trace lengths are. The PCB Impedance Calculator in Altium Designer. If the impedance of the TDR unit is known via proper calibration, then the Z 0 of the transmission line attached to the TDR unit may be determined. Moreover, this tool can also compute the signal propagation delay in inches per nanosecond (ns/in), the inductance per unit length in nano-Henrys per inch (nH/in), and. 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. The top surface and the sides of the traces are exposed to air and are referenced to a power or ground plane. While commonly constructed using printed circuit boards, this structure can also be built using other materials as long as there is a conductor separated from. Type: Options are microstrip (single-ended), coplanar (single-ended), edge-coupled (differential), and dual coplanar (differential). You can use a trace impedance calculator for stripline and just make the H (height above the ground plane) very large. An FDA with equal-value resistors in each output to provide differential output termination is shown in Figure 1. For instance, I want a 100 Ω controlled impedance pair, and have used "differential" before which seemed to work fine. To make an effect transmission line with two wires it is best to create a twisted pair. This makes the problem of determining impedance much more complex, and building an initial lossless model requires a larger set of formulas. I used the KiCAD PCB calculator, asked the PCB manufacturer about the tangent loss (0. Altium Designer’s differential line impedance calculator will set up your impedance-controlled differential pair routing widths for you. This is 1. Grounded Differential Coplanar Wave Guide. 1. The impedance of a differential via pair cannot be treated with a single via impedance calculator unless the vias are spaced far apart. Quarter Wave Transformer Impedance Calculator. , "Characteristic Impedance of the Shielded-Strip Transmission Line," IRE. Impedance and PCB Stacking The trace impedance is affected by many factors such as the width of the trace, th e thickness of the copper, the PCB material, the PCB stacking specification, and the spacing between the differential pairs. These values result in the following complex filter impedance:PI Attenuator Calculator. In some cases, we can also use 75-ohm differential. Sierra Circuits’ Via Impedance Calculator uses the physical dimensions of a via to calculate its capacitance, inductance, and impedance. Trace Width. Input impedance matching with fully differential amplifiers Introduction Impedance matching is widely used in the transmission of signals in many end applica-tions across the industrial, communications, video, medi-cal, test, measurement, and military markets. ; Er is the relative permittivity (dielectric constant) of the substrate material. But for extreme geometries and for many differential pair structures, these approximations can. Z o is the impedance of an individual trace. Pi Attenuator Calculator. 5. The JLCPCB results are more reliable than (some of) the simple formula-based approaches. Hello Community, iam currently designing a board that contains an 100MBit Ethernet connection. Just as important. Differential Impedance Calculator - Microstrip The differential impedance between the positive and negative trace of the transmission line is slightly less than twice the impedance of the single ended impedance. You only need to know the resistance, the inductance, and the capacitance values connected in series or parallel. For example, if you wish to input. 8. T. The bottom line is, study carefully, and take PCB trace impedance equations with a proper dose of. This sets the single-ended impedance AND differential impedance to the target value, even if there is no. This calculator is designed to calculate the characteristic impedance of an edge coupled microstrip. The Twisted Pair Impedance Calculator is able to compute the characteristic impedance Z 0(twisted pair) based on the dimensions of the twisted-pair cable. Give this class a name (100 ohms in our case). With both wires at the same potential there is no capacitance between them so the reference plane (return path) is less clear. This 26 mil clearance between copper pour and the 13 mil trace is sufficient to ensure 50 Ohm impedance. Z0 = (60 / √εr) * ln ( (8h) / (w + s)) Where εr is the dielectric constant of the substrate material, h is the substrate height, w is the trace width, and s is the spacing between traces. If you don't have access to a differential impedance calculator, or you don't know how to calculate it, then just keep trace lengths less than 0. this type of termination. Reference: R. The range of accepted values is 20 to 90 Ω for single-ended and 50 to 150 Ω for differential signals. Z diff equals Ra||(2Rb) (p model) or 2R 1 (T model). Capacitance (C) = pF/ cm. Asymmetric Stripline Impedance Calculator. The required values are trace thickness, substrate heights, trace width, and subtrate dielectric in the calculator above and press the "calculate" button. Not all calculators will explicitly state. 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). For this calculation, the units of d and h can be ignored as long as they have the same unit. Differential signaling in flex circuits follows the design method of surface microstrip transmission lines. 5. Differential impedance is the ratio of voltage to current on a pair of transmission lines when driven in the differential. The differential impedance of MIPI tracks should be 100 Ohms, not 90 (USB requires 90). In the next page we will see what factor effect the differential impedance and how to calculate it. The formula used in this calculator is an approximation for the characteristic impedance of a coplanar waveguide: scssCopy code. Keep the spacing between the pair consistent. I found that a W of 0. Some of them include Microstrip, Stripline and Coplanar Waveguide. 5. I am routing differential pairs in Altium 20 and using controlled impedance profiles. Hi, I am working on my board Stack-up to tune Single/Differential impedances of my board in Allegro PCB 16. 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. They will give very similar answers. We get a lot of questions about trace impedance and how to calculate the right trace size to hit a specific impedance in a manufacturable PCB. I believe the 100-ohm differential equates to 50-ohm single ended because you can think of the two 100-ohm impedances as being in parallel resulting in an effective 50-ohm single-ended equivalence. A coaxial cable is designed with 50-Ω or 75-Ω characteristic impedance. Ask the board manufacturer for the values. 4 Differential Line and Coplanar Strip; 3. Stripline. This calculator helps calculate the values of the output voltage and the inverting and non-inverting gains of an operational amplifier. This calculator is designed to calculate the characteristic impedance of a microstrip - a flat conductor suspended over a ground plane with a dielectric between them (see diagram below). You will need to know the thickness of the dielectric you will be using as well as the relative permittivity (dielectric constant). 03) it gives me almost 160 Ohm - and even if use 53mil conductor height or. 6mm FR4 PCB with 7628 type stackup (4 layers), the above specifications usually result in 4. The impedance is based on the cross-sectional geometry of the trace. There are four types of impedance used in. 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. There is also a dielectric material placed above the conductor. 3 CPW Structures; 3. For example, the equation for the trace impedance in a differential pair of asymmetric striplines includes an approximation on the dielectric constant and geometry. Microstrip is the conducting medium used to transmit the electric signals at microwave frequency and fabricated using PCB - printed circuit board. ; G is the conductance component of the admittance. Enter values for R1 and R2 to calculate attenuator loss and impedance. We will call the high speed traces the Transmission Line. For budgetting reasons I'm tied to a stock pooling layer stackup, so I went for OSHpark's 4-layer stackup (35um copper - 0. Calculating the Differential impedance is a two-step process, first Calculate the single ended impedance Zo and then use this value to calculate the differential impedance. The vias for these high-speed traces will be backdrilled to be a total length of 23 mil, keeping the via stubs no longer than roughly 1/20th of a wavelength. $egingroup$ So basically your answer shows that the JLCPCB impedance calculator results are generally in the same ballpark as the proven field simulators. has two length-matched 45 Ohm lines. Choose a calculator to tune your PCB design. e. The characteristic impedance is given by: Eq. Because the traces are together on the same layer (plane) I'm not sure how "coplanar". The cloder the two traces, the smaller is 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). This tool is valuable for engineers, hobbyists, and anyone working with microstrip. 1. 1,235. when two coupled tracks are used to give a differential impedance. Take note that this assumes that the distance between the conductor and the. t. Differential Impedance is the impedance between two differential pair signal traces. Enter one of the three values and the calculator will output the other two. Zdiff. Depending on the configuration of the components you can construct a low pass or high pass filter. 25mm between the differential pair with a width of 0. Zo (diff) is calculated to be 244 ohms, so dividing by two yields a value of 122 ohms for the semi-coplanar structure. Also, intuitively, from an examination of the field pattern, the even mode impedance Z 0e is likely to be high because the. Differential Trace Routing. g. The equipment can be an impedance meter such as the E4991A from Agilent technology, working up to 3 GHz. Press the Analyze button to calculate the electrical parameters. If a. *The structure may propagate in 3 modes: coplanar waveguide, coupled slot lines and microstrip. It is important todetermine the characteristic impedance of a twisted-pair cable because this impedance should match the impedance. It is important to determine the characteristic impedance of a twisted-pair cable because this impedance should match the impedance. Figure - Single Ended impedance calculator. Though this is an "imaginary" or "virtual" ground its influence is the same as a real copper wall. • Keep single-ended signals away from differential traces – distances should be at least at least 2x the trace width. ZL =. Or we can input them within the RLC circuit calculator all at once and quickly get what we need without relying. The values L 0 and C 0 must be substituted into equation (11) to calculate the complex filter impedance. IPC 2141 Trace Impedance Calculator. Voltage Divider Calculator 1 (Fixed) Voltage Divider Calculator 2 (Adjusteable) Capacitors. Figure 5. 9 Ω, R₂ = 3,062 Ω, and R₃ = 50. There are four different types of impedance used in characterizing differential trace impedances. . Print - Advertisement - This calculator helps you compute the characteristic impedance of an asymmetric stripline Inputs. Signal 1. Example. A 3-D EM simulator is used to design a differential via with the desired impedance and bandwidth. So move to your left, use Omni's Cable impedance calculator and enjoy. Just enter the given values for trace thickness, substrate heights, trace width, and substrate dielectric. dBm to Watt converter Stripline Impedance calculator Microstrip line impedance Antenna G/T Noise temp. Whatever the geometry, the following holds true. Conceptual overview of LISN-based measurement of differential-mode and common-mode conducted EMI of a switch-mode supply. 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. Go to ‘ Design’ >> ‘Classes’ >> ‘Net classes. (1+ρ) (1-ρ) With most of today's TDR-capable instruments, such as the Tektronix sampling oscilloscope, TDR measurements can be displayed with units of volts, ohms, or ρ (rho) on the vertical magnitude scale. 08mm - this is the border of manufacturability, I don't think it is practical to go there but for the calculation it is just fun - and I get some 31Ohms. Overview. 25mm trace. IMPEDANCE CALCULATIONS • Hyperlynx Linsym- Does whole cross section at once, allows mixed materials. Another example of using large distances to separate out unwanted components might be to calculate the impedance of a. Single Ended Impedance Ω. Differential pair into PCB calculator. so i have had a look at a App-Note of the PHY chip: it. The desired behavior of the differential amplifier is to amplify the differential mode voltage and attenuate the common mode voltage. In the ZS box, type a value of 75 Ω. | 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. L is the inductance in henries (H), and . Differential and common mode impedance measurement Figure 8 shows the variation of impedance versus frequency. Modeling approximation can be used to design the microstrip trace. , equal in magnitude but opposite in polarity). Impedance captures the real. e. Trace Thickness. Doing this results in a gain change. Let’s start new project together!. The surface finish is neglected. Distance units: Substrate Height, H Trace Width, W Thickness, TChapter 3: Capacitors, Inductors, and Complex Impedance - 21 - To study a constant supply voltage on an RC circuit, we set the left side of equation 3. I am trying to design a USB circuit, where the signaling is over a differential pair D+ and D- and these two lines are required by the spec to have 90 ohms of differential impedance. The designer selects the desired gain and the impedance of the signal source (default value of 50 Ω). 2. model impedance by combining Polar's proven boundary element field-solving engine with easy graphing of process windows. C is. Calculate the differential microstrip impedance and characteristic impedance of a differential microstrip line using dielectric constant, trace width, separation, thickness,. φ is the phase difference between the total voltage V T and the total current I T in degrees (°). We recommend the software from Polar Instruments if you want to get exact impedance calculation. This calculator finds both odd and even transmission line impedance. This tool will help you create a matching circuit so that optimal power transfer occurs between unmatched loads. 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. The amount of the voltage reflected back is given by the following equation. Matching the differential trace length and keeping the distances properly, this calculator is used to calculate the characteristic impedance of an edge coupled microstrip. Differential impedance changes with coupling, which changes with trace separation. Such a circuit will deliver an exact cutoff frequency of. 7, if that is what you were doing. Neighboring metallic structures will be considered in the calculation. 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. It consists of a pair of center conductors separated by ground planes on the same substrate. *Strictly, a loss quantity when expressed in dB should be positive. Make sure the correct Layer is selected before changing this option. Z 0 Differential impedance (Ω): Calculate. when i use Saturn PCB design to match the differential impedance to 100ohms i get 0. In case I reduce the width and the distance of tracks to 0. For example, if you wish to input "25000000", just type "25M" instead. 1 of the Microstrip Calculator using H2 in place of h, εr,eff can be computed as specified in Eq. Figure 3 shows the respective p and T models used to calculate the differential impedance (Z diff). Calculate Coplanar impedance for given PCB parameters. 6. The differential impedance will be a bit less than 2x the single-ended impedance. 4. What this means to you is that at the resonant frequency, depending on whether the circuit is in parallel or series, the impedance is the highest or.