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
vin​C = 47 nFR = 3.3 kΩvout​

Find the corner (−3 dB) frequency ωc of the RC high-pass filter shown, with R = 3.3 kΩ, C = 47 nF. Give it in rad/s.

R = 3.3 kΩC = 47 nF
ωc = rad/s
2.Easy
|H| (dB)0.11101001000−60−40−20020ω (rad/s)

Find the low-frequency (DC) gain of G(s) = 2300/((s + 40)(s + 7)) in decibels, |G(0)| in dB.

G(s) = 2300/((s + 40)(s + 7))
|G(0)| = dB
3.Medium
vin​R = 22 kΩC = 100 nFvout​

The RC low-pass filter shown has R = 22 kΩ, C = 100 nF. A sinusoidal input of 140 Hz is applied. Find the gain |H| = |vout/vin| in dB.

R = 22 kΩC = 100 nFf = 140 Hz
|H| = dB
4.Medium
vin​R = 4.7 kΩC = 4.7 nFvout​

The RC low-pass filter shown has R = 4.7 kΩ, C = 4.7 nF. A sinusoidal input of 1.8 kHz is applied. Find the phase shift φ of vout relative to vin, in degrees.

R = 4.7 kΩC = 4.7 nFf = 1.8 kHz
φ = °
5.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) = 304/(s(s + 6)(s + 10)). Find the phase crossover frequency ω180, where ∠L(jω) = −180°.

L(s) = 304/(s(s + 6)(s + 10))
ω180 = 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) = 68/(s(s + 2)(s + 6)). Find the phase crossover frequency ω180, where ∠L(jω) = −180°.

L(s) = 68/(s(s + 2)(s + 6))
ω180 = rad/s

Answer key

  1. 1. ωc = 6447 rad/s
  2. 2. |G(0)| = 18.29 dB
  3. 3. |H| = −6.762 dB
  4. 4. φ = −14.03 °
  5. 5. ω180 = 7.746 rad/s
  6. 6. ω180 = 3.464 rad/s

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