eldo_user

Speed and Accuracy
Efficient Usage of IEM
(because all blocks contain unsupported objects or the circuit is loosely coupled and can be
simulated with OSR) then the IEM option is removed, and a warning message is issued.
RELTOL and VNTOL parameters can be used in the same way as for SPICE-like simulators.
These control both convergence of iteration loops and step size.
Note
For Newton-Raphson, RELTOL does not control the step size.
If RELTOL or VNTOL are not explicitly specified in the netlist, then EPS can be used to
control their values, as follows:
• RELTOL = (1.0×10 −9 × EPS) 1/4
RELTOL is then limited in the range 1.0×10 −2 to 1.0×10 −5
• VNTOL = (1.0×10 −7 × EPS) 1/2
VNTOL is then limited in the range 1.0×10 −3 to 1.0×10 −9
For IEM, the option LVLTIM is set to 2 by default, in other words, truncation error is used to
control the time step. It is possible to set LVLTIM=3 in the netlist, which will also enable the
truncation error to control the time step. Additionally, it will impose calculated points at
TPRINT values in the .TRAN command. Other settings of LVLTIM are not allowed since they
produce less accurate results that would be meaningless with IEM.
All other SPICE-compatible options (for example ABSTOL, ITOL, and so on) behave in the
same way as for Newton-Raphson. This of course does not include integration scheme options
(BE, TRAP, GEAR, ...) which do not apply to IEM.
To maintain compatibility with previous Eldo versions and Newton usage, EPS may still be
used in the Eldo sense—that is, as a means to control all precision parameters.
Related Topics
Integral Equation Method (IEM) Algorithm
One Step Relaxation (OSR) Algorithm
Efficient Usage of IEM
Efficient Usage of IEM
This section describes approaches to achieve the best accuracy and performance results with
IEM, used alone or in combination with OSR.
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Eldo® User's Manual, 15.3