Maximizing Simulation Speed in Mixed-Mode Simulations

Simulation with SIMPLIS digital devices is 10 to 20 times faster than with SIMPLIS classic digital devices for circuits which have a large number of digital components. Other benefits of using the SIMPLIS digital devices include the following:

  • Digital clock frequencies can be much higher than the switching frequency of the power supply.
  • SIMPLIS digital devices effectively reduce overall power supply simulation complexity by using high-level macro models, such as counters, adders, multipliers, etc.
  • The simulation speed of digitally controlled power supplies is as fast as those with comparable analog functionality.

Simulation speed increases the more you isolate SIMPLIS digital content from the analog circuit. Some general rules apply:

  • In general, simulations run faster if you use SIMPLIS digital devices as much as possible.
  • As much as possible, minimize  the number of interfaces across the analog-digital component boundary by designing your circuitry to isolate "large Islands" of digital content. A ground-reference pin is not required for SIMPLIS digital components within this digital island if they are not connected to any analog components.
  • Strategically, cross from the analog-to-digital and digital-to-analog domains in as few places as possible. In typical SIMPLIS circuits, the boundary from analog to digital would be crossed at the analog-to-digital converters in the design; and the digital-to-analog boundary would be crossed at the output of the pulse-width modulator (PWM).
  • Finally, use logic gates instead of analog switches to implement digital functionality.