1. Lecture 351 Thevenin’s Theorem

2. Lecture 352 Thevenin’s Theorem Any circuit with sources (dependent and/or independent) and resistors can be replaced by an equivalent circuit containing a single source and a single resistor. Thevenin’s theorem implies that we can replace arbitrarily complicated networks with simple networks for purposes of analysis.

3. Lecture 353 Implications We Thevenin’s theorem to justify the concept of input and output resistance for amplifier circuits. We model transducers as equivalent sources and resistances. We model stereo speakers as an equivalent resistance.

4. Lecture 354 TT: Independent Sources Circuit with independent sources R Th V oc + - Thevenin equivalent circuit

5. Lecture 355 TT: No Independent Sources Circuit without independent sources R Th Thevenin equivalent circuit

6. Lecture 356 Finding the Thevenin Equivalent I-V characteristics are straight lines (a consequence of the linearity of resistor models). Circuits with independent sources: –Intercepts are v oc (t) and i sc (t) Circuits w/o independent sources: –Slope is R Th

7. Lecture 357 Independent Sources v(t)v(t) i(t)i(t) v oc (t) i sc (t)

8. Lecture 358 Example: CE Amplifier 1k  V in + - 2k  +10V + - VoVo

9. Lecture 359 Small Signal Equivalent 1k  V in 100I b + - VoVo 50  IbIb 2k  + -

10. Lecture 3510 Thevenin Equivalent @ Output 1k  V in 100I b + - VoVo 50  IbIb 2k  + - R Th V oc + - + - VoVo

11. Lecture 3511 Computing Thevenin Equivalent Find v oc Find i sc Compute R Th

12. Lecture 3512 Find v oc 1k  V in 100I b + - V oc 50  IbIb 2k  + - V1V1

13. Lecture 3513 Nodal Analysis

14. Lecture 3514 Solve for V oc V oc = V in

15. Lecture 3515 Find I sc 1k  V in 100I b 50  IbIb 2k  + - V1V1 I sc

16. Lecture 3516 Computing I sc

17. Lecture 3517 Thevenin Equivalent 10  V in + -