Pole-zero analysis: coupled RL stages

Poles of three coupled RL stages.

Three parallel RL stages coupled by voltage-controlled current sources. pz finds the poles of the transfer function from the input current to the third stage's voltage.

Output

pole(1) = -2.00000e+01,2.000000e+03
pole(2) = -2.00000e+01,-2.00000e+03
pole(3) = -2.00000e+01,0.000000e+00
pole(4) = -1.86305e+01,0.000000e+00
pole(5) = -1.72033e+01,0.000000e+00
pole(6) = 1.000000e+00,1.000000e+02
pole(7) = 1.000000e+00,-1.00000e+02

The circuit: examples/pzt.cir

test pz
iin	1	0	ac
r1	1	0	1Ohms
l1	1	0	0.05H

gm2	2	0	1 0 1
r2	2	0	1Ohms
l2	2	0	0.05H

gm3	3	0	2 0 1
r3	3	0	1Ohms
l3	3	0	0.05H

*gm4	4	0	3 0 1
*r4	4	0	1Ohms
*l4	4	0	0.05H

*gm5	5	0	4 0 1
*r5	5	0	10Ohms
*l5	5	0	0.66mH

.control
pz	1 0	3 0	cur pol
print all
.endc
.end

Run it with spice pzt.cir, or open it with File › Load netlist in the Qt window. The plots and output above were made by util/mkexamples.py, which runs the deck in batch mode. All examples