I can't do the case of a "bare trace".
2) S/T.0, enter dimensions: Trace width (W) mils, trace thickness (T) mils, trace spacing (S) mils, distance between planes (B) mils, relative Dielectric constant (Er differential Trace Impedance ohms.
Approximations for the impedance, delay, inductance, and capacitance of microstrips and striplines, as a function of trace geometry, are reproduced in my book, High-Speed Digital Design, iSBN.
Cohn, Seymour., "Shielded Coupled-Strip Transmission Line IRE Transactions on Microwave Theory and Techniques, Vol MTT-3,.Home, notes: 1) Calculation assumes traces are centered vertically.For a stripline trace embedded in a dielectric material, the delay equals 85*sqrt(Er) ps/inch, where Er is the relative permittivity of the dielectric (about.3 for FR-4 material).Wadell, Brian., Transmission Line Design Handbook, Artech House, Norwood, MA, winzip courier 4.0 registration code 1991,.Differential Impedance Definitions, differential Impedance, the impedance measured between the two lines when they are driven with opposite polarity signals.References, cohn, Seymour., "Characteristic Impedance of the Shielded-Strip Transmission Line IRE Transactions on Microwave Theory and Techniques, Vol MTT-2,.A 70-ohm trace, with a delay of 140 ps/inch, yields about 10,000 pH/inch (10 nH/inch).Microstrip Transmission Line Models, models have been created to approximate the characteristics of the microstrip transmission line.Zcommon is half the value of Zeven.Zdiff is equal to twice the value of Zodd.There is a dielectric material between them.
Typical plating of top surface copper is 40um thick.
PCB Differential Microstrip Impedance Calculator, introduction, the edge couple differential microstrip transmission line is a common technique for routing differential traces.
This coupling is one of the features of differential traces.Zeven is twice the value of Zcommon.There is also some coupling between the lines.Johnson replies: Thanks for your interest in high-speed digital design.Also avoid placing vias and other structures between these traces.Comparisons show minimal differences to ADS linecalc and Polar Instruments Quicksolver industry standard tools.