eldo_user

Setting Up An Analysis
Pole Zero Analysis
FNS1 IN OUT
+
+ 498057.650621
+ 0.0271151244556 ! * s^(-1)
+ 4.88425501019e-10 ! * s^(-2)
+ 2.65330374224e-18 ! * s^(-3)
+ -3.22583377778e-27 ! * s^(-4)
+ 8.84119411e-37 ! * s^(-5)
+ ,
+ 1
+ 0.0315272851854 ! * s^(-1)
+ 1.08957721435e-09 ! * s^(-2)
+ 1.85561098689e-17 ! * s^(-3)
+ 2.03791858143e-25 ! * s^(-4)
+ 1.03556420914e-33 ! * s^(-5)
If too many poles and zeros are left after the reduction steps, FNS evaluation could fail due to
too high coefficients (a message is displayed in such a case). However, the efficiency of the
reduction algorithm normally enables a reduction of, at most, 6-7 poles, which can give a very
good approximation of the original circuit.
The PZ program produces a .cpz output file for visualization with EZwave, which
shows the Bode diagrams of gain and phase for the original and the reduced circuit. Also, a file
.mpz is produced, showing a scatter map of the circuit’s roots in the complex plane.
Finally, a subcircuit containing FNS is stored in file .pzck, which can be included by
an upper level netlist.
After all these steps, a prompt asks whether to repeat the analysis, typically to alter some
parameters such as threshold, frequency limit, and so on, thereby modifying the accuracy/
simplicity ratio of the whole analysis.
If no is entered, the program exits, leaving an ASCII output file .pzr containing a trace
of all of the program outputs.
Related Topics
Running Pole-Zero Analysis in Batch Mode
Running Pole-Zero Analysis in Interactive Mode
Pole-Zero Analysis Output
Pole-Zero Numerical Issues
Pole-Zero Numerical Issues
There are possible numerical issues with poles and zeros. This topic explains why 500 variables
is a reasonable maximal system size, and suggests a workaround using a two-step S-parameter
block approach.
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Eldo® User's Manual, 15.3