Fast transient circuit simulation of electronic circuits including a crystal

摘要

The simulation of the output of a crystal circuit is greatly accelerated to steady state by altering the conventional model of a physical crystal to include a constant current source. The constant current source has an oscillating output which is temporarily inserted into the simulated circuit by driving current for only a certain length of time, e.g., for only once cycle of a frequency chosen to correspond to the resonant frequency of the crystal being modeled. The output current of the current source is thereafter forced to zero to effectively remove it from the simulated circuit. The peak current amplitude of the current source is initially selected based on parameters of the crystal being modeled, and estimated by formula, then empirically adjusted if necessary to obtain fast simulation results of the crystal circuit to a steady state. A look-up table can be implemented in SPICE or any other circuit simulation tool to implement the current source in the crystal model.