eldo_user

Speed and Accuracy
IEM Overview
When using IEM, the same accuracy control parameters as those used for the default
Newton method are available. Thus the RELTOL and ABSTOL parameters will
primarily control the accuracy of the resolution.
The IEM method is described in more detail, including its limitations, in the following sections:
• “IEM Overview” on page 1261
• “IEM—Supported Circuit Elements” on page 1262
• “IEM Tolerance Parameters” on page 1263
• “Efficient Usage of IEM” on page 1264
IEM Overview
The Integral Equation Method (IEM) is a simulation algorithm developed for transient analog
circuit simulation. With some circuits, IEM provides better performance than classic algorithms
based on the Newton-Raphson method combined with a multi-step discretization scheme (for
example Backward-Euler, Trapezoidal, Gear, and so on).
In some cases, IEM may perform better than Newton methods in terms of stability and
accuracy, which has a favorable incidence on speed. The improvements appear particularly for
circuits requiring high precision or those which exhibit tight coupling or stability problems.
IEM’s performance enhancement derives from the use of a semi-analytic approach combined
with efficient numerical techniques.
Application Domains
IEM is invoked for TRANSIENT analysis of ANALOG circuits only. DC and AC analyses can
only be performed using Newton-Raphson methods.
In a case where Eldo works together with another simulation kernel—digital or analog—then
IEM is not supported.
Related Topics
Integral Equation Method (IEM) Algorithm
IEM—Supported Circuit Elements
IEM Tolerance Parameters
Efficient Usage of IEM
Eldo® User's Manual, 15.3 1261