PRESENTATION TOPIC

IDEAL DIODE

SYED HASHIR AHMEDROLL# 130

Objectives Understand the characteristics of an ideal diode.

Analyze simple circuits involving ideal diodes.

Current-Voltage CharacteristicForward/Reverse Bias

Computing iD and vD

What is the current through the diode (iD) and the voltage across the diode (vD) for the following two circuits?

Rectifier Circuit

What voltage waveform would we observe across the output of this circuit?

Rectifier Circuit Operation

Rectifier Circuit Operation (Cont’d)What voltage waveform would we observe across the diode vD?

Voltage Transfer Characteristic of the Rectifier Circuit

The Interesting Phenomenon of Charging a Battery

The source vS is a sinusoid with a 24 Vpeak amplitude. The diode is used to charge a 12 V battery and the 100 W resistor limits the current.

We want to determine the fraction of each cycle during which the diode conducts. We also wish to find the peak-value of the diode current and the maximum reverse-bias voltage that appears across the diode.

Solution

We reason that the diode will not begin to conduct until vS exceeds 12 V. Likewise, the diode will stop conducting once vS again reaches 12 V.

This defines the conduction angle, 2 (i.e., the fraction of the sinusoidal cycle over which the diode conducts). Hence, we reason that the diode will conduct provided that 24V sin 12 V. Or 30o ≤ ≤ 150o (or 1/3 of a cycle).

The peak value of the diode current is 12.0

100

1224

VV

ID Amps

Solution (Cont’d)

The maximum reverse-bias voltage that appears across the diode is simply:

24 V + 12 V = 36 V

DETERMINE I AND V FOR THE FOLLOWING CIRCUITS:

For this second circuit the same assumption gives nonsensical results (verify this)

We assume that D1 is OFF and D2 is ON. Consequently, VB = 3.3 V (verify).

Let’s begin by assuming that diodes D1 and D2 are conducting:

mAk

ID 110

0102

mAIk

mAI 15

)10(01

KCL (node B):

FEEDBACKsyedhashir@ymail.com

Contect:03133116593