Issue link: https://resources.pcb.cadence.com/i/1180526
PSpice User Guide Convergence and "time step too small errors" October 2019 841 Product Version 17.4-2019 © 1999-2019 All Rights Reserved. Bias Point (DC) Convergence The hardest part of the whole process is getting started, that is, finding the bias point. PSpice first tries with the power supplies set to 100%. A solution is not guaranteed, but most of the time the PSpice algorithm finds one. If not, then the power supplies are cut back to almost zero. They are cut to a level small enough that all nonlinearities are turned off. When the circuit is linear a solution can be found (very near zero, of course). Then, PSpice works its way back up to 100% power supplies using a variable step size. Once a bias point is found, the transient analysis can be run. It starts from a known solution (the bias point) and steps forward in time. The step size is variable and is reduced as needed to find further solutions. In case the circuit fails to converge, you should first check the circuit topology and connectivity, followed by modelling of circuit components, and finally check if Pspice options are set properly. Checking circuit topology and connectivity ■ Make sure that all of the circuit connections are valid. Check for incorrect node numbering or dangling nodes. Also, verify component polarity. ■ Check for syntax mistakes. Make sure that you used the correct PSPICE units (i.e. MEG for 1E6, not M, which means mili in simulations). ■ PSpice checks for the following conditions and provides messages if they occur: ❑ "Floating node" or "No DC path to ground" messages: ❍ Make sure that there's a DC path from every node to ground. ❍ Make sure that there are at least two connections at every node. ❍ Make sure that capacitors and/or current sources are not connected in series.