1. Diode Circuit Analysis Techniques Section 4.3

2. In this Lecture, we will:  Examine dc analysis techniques for diode circuits using various models to describe the nonlinear diode characteristics  Determine the operation and characteristics of a half-wave diode rectifier circuits.

3. Example Simple diode circuit where I D and V D are not known.

4. Example Problem

9. Another Approach: Graphical Analysis Technique Simple diode circuit where I D and V D are not known.

10. Trial and Error Solution of Prior Example Simple diode circuit where I D and V D are not known.

11. Load Line Analysis of Prior Example The x intercept of the load line is the open circuit voltage and the y intercept is the short circuit current. The quiescent point or Q- point is the intersection of diode I-V characteristic with the load line. I-V characteristics of diode must be known.

12. Piecewise Linear Model Two linear approximations are used to form piecewise linear model of diode.

13. Diode Piecewise Equivalent Circuit The diode is replaced by a battery with voltage, V , with a a resistor, r f, in series when in the ‘on’ condition (a) and is replaced by an open when in the ‘off’ condition, V D < V  (b). If r f = 0, V D = V  when the diode is conducting (c).

14. The x intercept of the load line is the open circuit voltage and the y intercept is the short circuit current. The Q-point is dependent on the power supply voltage and the resistance of the rest of the circuit as well as on the diode I-V characteristics. Q-point

15. Example Problem

18. Trial and Error Solution

19. Load Line Solution

20. Circuit Simulation Example Circuit schematic Diode voltageDiode current