1. Microelectronics Circuit Analysis and Design
Donald A. Neamen
Chapter 2
Diode Circuits

2. In this chapter, we will:
Determine the operation and characteristics of diode rectifier circuits, which is the first stage of the process of converting an ac signal into a dc signal in the electronic power supply.
Apply the characteristics of the Zener diode to a Zener diode voltage regulator circuit.
Apply the nonlinear characteristics of diodes to create waveshaping circuits known as clippers and clampers.
Examine the techniques used to analyze circuits that contain more than one diode.
Understand the operation and characteristics of specialized photodiode and light-emitting diode circuits.

3. Block Diagram for ac to dc Converter
The diode rectifier, filter, and voltage regulator are diode circuits.

4. Problem-Solving Technique: Diode Circuits
Determine the input voltage condition such that the diode is conducting (on).
Find the output signal for this condition.
Determine the input voltage such that the diode is not conducting (off).

5. Half-Wave Rectifier
Voltage Transfer Characteristics

6. Signals of Half Wave Rectifier
Input voltage
Output voltage
Diode voltage

7. Load Line Analysis
Load line when vS is at its maximum forward voltage.
Load line when vS is at its most negative value.

8. Load Line (con’t)
As vS varies with time, the load line also changes, which changes the Q-point (vD and iD) of the diode.

9. Half-Wave Rectifier as Battery Charger

10. Full-Wave Rectifier Voltage transfer characteristics
Input and output waveforms

11. Full-Wave Bridge Rectifier
When vS is positive, D1 and D2 are turned on (a). When vS is negative, D3 and D4 are turned on (b).
In either case, current flows through R in the same direction, resulting in an output voltage, vO, shown in (c).

12. Full-Wave Bridge Rectifier

13. Output Voltage of Full-Wave Rectifier with RC Filter
The ripple on the ‘dc’ output is

14. Output Voltage of Full-Wave Rectifier with RC Filter
Diode conducts current for only a small portion of the period.

15. Equivalent Circuit During Capacitance Charging Cycle

16. PSpice Schematic of Diode Bridge Circuit
Steady state output voltage for a 60Hz sine wave input with peak value of 13.4V.

17. Demodulation of Amplitude-Modulated Signal
Modulated input signal
Detector circuit
Demodulated output signal

18. Voltage Doubler Circuit

19. Equivalent Circuits for Input Cycles
Negative input cycle Positive input cycle

20. Voltage Regulator
The characteristics of the Zener diode determines VL.

21. Design Example 2.5

22. The reverse bias I-V is important for Zener diodes.
Load Line Analysis
The reverse bias I-V is important for Zener diodes.

23. Voltage Rectifier with nonzero Zener resistance
The Zener diode begins to conduct when VPS = VZ.
When VPS ≥ VZ: VL = VZ
IL = VZ/RL,, but VZ ≠ constant
I1 = (VPS – VZ)/Ri
IZ = I1 - IL

24. Voltage Transfer Characteristics of Limiter Circuit

25. Single Diode Clipper

26. Additional Diode Clipper Circuits

27. Parallel-Based Diode Clipper Circuit

28. Series-Based Diode Clipper Circuits

29. Parallel-Based Clipper Circuit Using Zener Diodes

30. Diode Clamper Circuit

31. Diode Clamper Circuit with Voltage Source

32. Diode and Resistor In Series
Voltage shift between input and output voltages in transfer characteristics is because the diode only conducts when v1 ≥ Vg.

33. Diode with Input Voltage Source
Output voltage is a constant when the diode is not conducting, when v1 ≥ Vs - Vg.

34. 2 Diode Circuit
Voltage transfer characteristics

35. Problem-Solving Technique: Multiple Diode Circuits
Assume the state of the diode.
If assumed on, VD = Vg
If assumed off, ID = 0.
2. Analyze the ‘linear’ circuit with assumed diode states.
3. Evaluate the resulting state of each diode.
4. If any initial assumptions are proven incorrect, make new assumption and return to Step 2.

36. Exercise problem
D1 is not on.
D2 is on.
This pins VO to -0.6V

37. Diode Logic Circuits: 2-Input OR Gate
V1 (V)
V2 (V)
VO (V) 5
4.3
Vg = 0.7V

38. Diode Logic Circuits: 2-Input AND Gate
V1 (V)
V2 (V)
VO (V) 5
4.3
Vg = 0.7V

39. Photodiode Circuit

40. Optoisolator

41. Design DC Power Supply Circuit