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Lossless Calculations

Lossless calculations are typically performed first when designing high-speed and high-frequency printed circuit boards.

Lossless calculations allow you to perform the following tasks:

  • Calculate the characteristic impedance of a transmission line based on known geometric and electrophysical parameters.
  • Determine the geometric parameters of a transmission line for a target characteristic impedance and PCB stackup parameters.

  • Calculate secondary transmission line parameters:

    • Propagation delay
    • Capacitance per unit length
    • Inductance per unit length
    • Signal propagation velocity
    • Effective dielectric constant
    • Transmission line geometric parameters
    • PCB stackup parameters

Lossless calculation

The following calculation types are available in Lossless mode:

  • Single calculation – Calculates an impedance value and secondary parameters of a transmission line.
  • Reverse calculation – Calculates transmission line parameters for a target impedance.
  • Parametric sweep – Calculates impedance values (along with secondary parameters) at varying values of a selected sweep parameter. The sweep parameter is defined by a range of values and a step.
  • Reverse parametric sweep – Calculates transmission line parameters for a target impedance at varying values of a selected sweep parameter. The sweep parameter is defined by a range of values and a step.

Calculation Names

Calculations are identified by names in the Projects panel. The names are generated according to the following templates:

  • Single calculation – The name includes the calculated characteristic impedance (Zo) or differential characteristic impedance (Zdiff). Example: Zo=51.344 Ohm.
  • Reverse calculation – The name includes the calculated value of the target parameter and the target impedance value. Example: H1=0.0956 mm, Zo=50 Ohm.
  • Parametric sweep – The name specifies the range of calculated impedance values, the range of values for the sweep parameter, and the sweep step. Example: Zo=64.7438...45.6891 Ohm, W1=0.1;0.2;0.01 mm.
  • Reverse parametric sweep – The name specifies the range of calculated values for the target parameter, the target impedance value, the range of values for the sweep parameter, and the sweep step. Example: H1=0.0588...0.1112 mm, Zo=50 Ohm, W1=0.1;0.2;0.01 mm.