What causes sudden jumps (disturbance) in Bode plot ?

Hi. Why is there the sudden jumps in the magnitude and phase of my bode plot around 600 rad/s? How can I avoid them?

 this is the transfer function:

6.4e-38 s^21 + 6.371e-34 s^20 + 1.434e-31 s^19 + 1.381e-27 s^18 + 1.355e-25 s^17 + 1.247e-21 s^16 + 6.953e-20 s^15+ 6.007e-16 s^14 + 2.078e-14 s^13 + 1.628e-10 s^12 + 3.562e-09 s^11 + 2.352e-05 s^10 + 0.0003155 s^9 + 1.416 s^8 + 10.43 s^7 + 18.44 s^6 + 8.286 s^5
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
2.56e-41 s^22 + 1.48e-37 s^21 + 6.572e-35 s^20 + 3.222e-31 s^19 + 7.23e-29 s^18 + 2.927e-25 s^17 + 4.418e-23 s^16+ 1.422e-19 s^15 + 1.62e-17 s^14 + 3.911e-14 s^13 + 3.564e-12 s^12 + 5.816e-09 s^11 + 4.358e-07 s^10 + 0.00038 s^9 + 0.02291 s^8 + 3.074 s^7 + 9.918 s^6 + 8.286 s^5

Answer 1

[Star Strider]

You have a zero very close to the imaginary axis at that frequency:

syms s 
tfn = 6.4e-38 * s^21 + 6.371e-34 * s^20 + 1.434e-31 * s^19 + 1.381e-27 * s^18 + 1.355e-25 * s^17 + 1.247e-21 * s^16 + 6.953e-20 * s^15+ 6.007e-16 * s^14 + 2.078e-14 * s^13 + 1.628e-10 * s^12 + 3.562e-09 * s^11 + 2.352e-05 * s^10 + 0.0003155 * s^9 + 1.416 * s^8 + 10.43 * s^7 + 18.44 * s^6 + 8.286 * s^5;
tfd = 2.56e-41 * s^22 + 1.48e-37 * s^21 + 6.572e-35 * s^20 + 3.222e-31 * s^19 + 7.23e-29 * s^18 + 2.927e-25 * s^17 + 4.418e-23 * s^16+ 1.422e-19 * s^15 + 1.62e-17 * s^14 + 3.911e-14 * s^13 + 3.564e-12 * s^12 + 5.816e-09 * s^11 + 4.358e-07 * s^10 + 0.00038 * s^9 + 0.02291 * s^8 + 3.074 * s^7 + 9.918 * s^6 + 8.286 * s^5;
tfnv = sym2poly(tfn);
tfdv = sym2poly(tfd);

sys1 = tf(tfnv, tfdv);

figure(1)
pzplot(sys1)

figure(2)
bode(sys1)

Using the numbers you supplied, it also seems to have poles close to the imaginary axis but in the right-half plane that could give you stability problems. I’ll let you sort that.