Question 9.3: Load-Line Analysis of a Zener-Diode Voltage Regulator The vo...
Load-Line Analysis of a Zener-Diode Voltage Regulator
The voltage-regulator circuit of Figure 9.9 has R = 1 kΩ and uses a Zener diode having the characteristic shown in Figure 9.10. Find the output voltage for V_{SS} = 15 \text{ V}.
Repeat for V_{SS} = 20 \text{ V}.
The load lines for both values of V_{SS} are shown in Figure 9.10. The output voltages are determined from the points where the load lines intersect the diode characteristic. The output voltages are found to be v_o = 10.0 \text{ V for }V_{SS} = 15 \text{ V and }v_o = 10.5 \text{ V for }V_{SS} = 20 \text{ V}. Thus, a 5-V change in the supply voltage results in only a 0.5-V change in the regulated output voltage.
Actual Zener diodes are capable of much better performance than this. The slope of the characteristic has been accentuated in Figure 9.10 for clarity–actual Zener diodes have a more nearly vertical slope in breakdown.