Nonlinear circuits contain components like transistors and diodes whose outputs do not vary linearly with input. This nonlinearity generates harmonics in addition to the fundamental frequency at the output. It is important to study nonlinear circuit behavior because harmonics produced by nonlinear devices can cause electromagnetic interference issues. While ideal circuit elements like resistors and capacitors demonstrate linear characteristics, practical components become nonlinear at high frequencies, requiring their impedance models to account for frequency-dependent behavior to solve electromagnetic compatibility problems.

1. Nonlinearities in Circuits
Kailash Karki
M.Tech
152040006

2. What is nonlinearity?
• Output does not vary linearly with input.
• Transistor , diode, vacuum tubes are the
examples of non linear components.

3. Linear Vs Nonlinear Characterstic

4. Why we have to study non linear
behaviour of the circuits??

5. Nonlinearity of Square Detector
Input(x) output(y)
Output, y(t) = a x(t)+ b x2(t); a and b are constants
* Output contains fundamental frequency plus
other harmonics .
Nonlinear Device

6. Resistor
Ideal resistor Practical Resistor
Impedance Characteristic
Zr = R
R

7. Frequency Vs Impedance(Resistor)
Ideally Practically
* Resistors are not resistors at high frequency.

8. Capacitor
Ideal Capacitor Practical Capacitor
Zc = 1/(wc)

9. Frequency Vs Impedance(Capacitor)

10. Conclusion
• Harmonics generated by non linear devices
causes Electromagnetic Intereference.
• Low frequency circuit components impedance
models must be extended to higher frequency
range while dealing with EMI/EMC problems.

11. Thank you