1. Analysis of Diode Circuits
A simple diode circuit
solution: graphical or iterative

2. Graphical analysis
for simple diode circuit

3. Iterative analysis
while convergence is relatively fast, it can still be too slow for a pencil-paper design of a complex circuit :
i.e., need rapid analysis, with less precision

4. Simplified Diode Models
straight lines
A and B

5. piecewise-linear model (cont.)
equivalent circuit

6. Constant-Voltage Drop Model
Approximate steep rise by the vertical straight line B

7. constant voltage drop model (cont.)
equivalent circuit

8. Small-Signal Diode (n=2)

9. Small-Signal Model Small-signal approximation Diode conductance
Diode resistance (incremental resistance)
Quiescent point Q

10. equivalent circuit model

11. analysis of circuit
circuit in (a) contains both dc and signal. Replacing diode, obtain (b).
This allows separating the dc analysis [the circuit in (c)]
from the signal analysis [the circuit in (d)].

12. small-signal model (cont.)
use of diode forward drop in voltage regulation
diode high-frequency model