Bode plots & margins worksheet with answers

Free printable Bode plots & margins worksheet: 6 problems from easy to exam level, with an answer key. Print it or save it as a PDF.

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1.Easy
|H| (dB)0.111010010000204060ω (rad/s)

Find the low-frequency (DC) gain of G(s) = 3100(s + 15)/((s + 1)(s + 80)) in decibels, |G(0)| in dB.

G(s) = 3100(s + 15)/((s + 1)(s + 80))
|G(0)| = dB
2.Easy
vin​R = 4.7 kΩC = 47 nFvout​

Find the corner (−3 dB) frequency ωc of the RC low-pass filter shown, with R = 4.7 kΩ, C = 47 nF. Give it in rad/s.

R = 4.7 kΩC = 47 nF
ωc = rad/s
3.Medium
vin​C = 22 nFR = 10 kΩvout​

The RC high-pass filter shown has R = 10 kΩ, C = 22 nF. A sinusoidal input of 2.9 kHz is applied. Find the phase shift φ of vout relative to vin, in degrees.

R = 10 kΩC = 22 nFf = 2.9 kHz
φ = °
4.Medium
vin​R = 10 kΩC = 100 nFvout​

The RC low-pass filter shown has R = 10 kΩ, C = 100 nF. A sinusoidal input of 80 Hz is applied. Find the phase shift φ of vout relative to vin, in degrees.

R = 10 kΩC = 100 nFf = 80 Hz
φ = °
5.Hard
|H| (dB)0.10.1111010100100−60−40−200204060ω (rad/s)φ (°)ω (rad/s)−180−135−90−450ωc​ = ?

A unity-feedback loop has the open-loop transfer function L(s) = 35/(s(s + 2)). Find the gain crossover frequency ωc, where |L(jω)| = 1.

L(s) = 35/(s(s + 2))
ωc = rad/s
6.Hard
|H| (dB)0.10.1111010100100−80−60−40−2002040ω (rad/s)φ (°)ω (rad/s)−270−180−900ω180​ = ?

A unity-feedback loop has the open-loop transfer function L(s) = 10/(s(s + 1)(s + 3)). Find the phase crossover frequency ω180, where ∠L(jω) = −180°.

L(s) = 10/(s(s + 1)(s + 3))
ω180 = rad/s

Answer key

  1. 1. |G(0)| = 55.29 dB
  2. 2. ωc = 4527 rad/s
  3. 3. φ = 14.01 °
  4. 4. φ = −26.69 °
  5. 5. ωc = 5.75 rad/s
  6. 6. ω180 = 1.732 rad/s

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