Full Wave Subcircuits

Four formats are available for a full wave subcircuit: Maxwell SPICE, HSPICE, Spectre, and Nexxim.

• Maxwell SPICE

  Full-wave SPICE models use a proprietary convolution-based technique to simulate high-speed structures. S-parameter matrices are computed at an evenly spaced set of frequency points (specified by Num Points and Max Frequency). This data is then written out in a form suitable for simulation in SPICE. The resulting model represents full-wave effects accurately. An added advantage is that it captures the frequency-dependence of the metal and dielectric losses.

• HSPICE and Spectre

  HSPICE models in SIwave employ a least squares fitting procedure to closely approximate the full-wave S-parameters with an HSPICE pole-zero model:

  

  Reduce the appropriate Fitting Error to obtain a closer approximation to the full-wave S-parameters.

  The minimum and maximum order parameters control the search for the number of poles N, when state-space fitting is by iterative rational function. The software attempts to find an approximation by first trying the minimum order and then checking the fitting errors. If it is too high, it raises the number of poles and tries again. The number of poles per matrix entry is never higher than the maximum order.

• Nexxim

  Nexxim also employs the least squares fitting procedure to closely approximate the full-wave S-parameters with an HSPICE pole-zero model. Nexxim provides time domain and frequency domain simulations from the same HSPICE compatible netlist or from the command line. SIwave allows a full wave parasitic extraction, and Nexxim allows the detailed verification.