eldo_user

Examples
Example 2—Transient and AC Analysis of a 4th Order Butterworth Filter
Summary of Eldo commands used in this example:
• .AC—AC analysis.
• .TRAN—Transient analysis.
• .PLOT—Plot simulator results.
Netlist Explanation
The first group of lines define the devices in the circuit to be simulated. Each device
instantiation specifies the component name, the nodes to which the component is connected and
the value of the component.
4th Order Butterworth Filter
c1 4 0 1.5307n
c2 3 0 1.0824n
l1 3 4 1.5772u
l2 2 3 .38268u
r1 1 2 1
This line defines an AC source of 1V and a time dependent Piece Wise Linear function between
the nodes 1 and 0. The pwl parameters describe a signal that stays at 0V until 1μs where it rises
to 1V in 1μs. The signal stays at 1V until 20μs where it drops back to 0V in 0.1μs.
v1 1 0 ac 1 pwl (0 0 1u 0 2u 1 20u 1 20.1u 0)
Tip
Refer to the output results for a pictorial representation of this signal.
The line below specifies that Eldo will perform a transient analysis on the circuit lasting 40μs
with a plotting increment for the line printer of 0.2μs.
.tran 0.2u 40u
The lines below specify that voltage/time plots will be generated on separate graphs of the
voltage at node 4 and the voltage at node 1.
.plot tran v(4)
.plot tran v(1)
The line below indicates that Eldo performs an AC analysis on the circuit within the frequency
range 10000Hz to 100MHz with 20 steps per decade. This AC analysis statement specifies that
an AC analysis is performed in addition to the transient analysis. Eldo first performs the AC
analysis, followed by the transient analysis.
.ac dec 20 10000 100meg
The line below sets the simulator accuracy.
Eldo® User's Manual, 15.3 1275