HB Simulation with Modulated Signals

[Zhijian Yu]

Hi,

I have been using Xyce for single-tone load-pull simulations with harmonic balance HB, which works well in my experience.

Recently, I tried to evaluate whether Xyce HB can be used with modulated signals for DPD-related simulations. I observed that the simulation speed decreases very rapidly as the number of time-domain samples increases.

For example:
- In spice4qucs.DPD_modulatedSignal_1us.cir, with 61 time-domain samples, the simulation completes within a few seconds.
- When I increase the signal duration to 10 µs (spice4qucs.DPD_modulatedSignal_10us.cir), resulting in 614 samples, the simulation time increases to approximately 1.5 hours.

The circuit itself is very simple: a sampled current source, a 50-ohm load, and a 50-ohm source.

I would appreciate any insight into whether this behavior is expected for HB simulations with modulated signals, or if there are recommended settings or alternative approaches to improve performance.

ZY