Bode Plot: Example 1
Draw the Bode Diagram for the transfer
Step 1: Rewrite the
transfer function in proper form.
Make both the lowest order term in the numerator and
denominator unity. The numerator is an order 0 polynomial, the
denominator is order 1.
Step 2: Separate the
transfer function into its constituent parts.
The transfer function has 2 components:
- A constant of 3.3
- A pole at s=-30
Step 3: Draw the Bode
diagram for each part.
This is done in the diagram below.
- The constant is the cyan line (A
quantity of 3.3 is equal to 10.4 dB). The phase is constant at 0
- The pole at 30 rad/sec is the blue
line. It is 0 dB up to the break frequency, then drops off with a
slope of -20
dB/dec. The phase is 0 degrees up to 1/10 the break frequency (3 rad/sec)
then drops linearly down to -90 degrees at 10 times the break frequency
Step 4: Draw the overall Bode diagram by
adding up the results from step 3.
The overall asymptotic plot is the
translucent pink line, the exact response is the black line.