Simple Diode Analysis Problem - Calculating Current/Voltage in a diode:

In summary: Thevenin equivalent voltage source, 5k resistor, diode, and the 10k resistor.In summary, the problem involves finding the total current, current in the diode, and current in the 5kΩ resistor, as well as the voltage across the diode. The ideal diode equation and Ohm's Law are used, along with the iteration method, to solve the problem. The Thevenin equivalent can be used to simplify the circuit.
  • #1
ally34
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Homework Statement



Refer to the figure attached. Let IS = 25 fA and VCC = 10V. What is the total current, the current in the diode, and the current in the 5KΩ resistor? What is VD? Use the iteration technique.


Homework Equations



Ideal Diode Equation: I = Is(e^(Vd/Vt) - 1)
Ohm's Law: V= IR
Thermal Voltage: V = kt/q = 25.9mV



The Attempt at a Solution



Total Current in the circuit = 10 V / 10kΩ = 1mA

We need to find the Vd and Id using the constant voltage model and then use the iteration method using the ideal diode equation to get closer and closer to Vd and Id using iterations.

I am not sure how to analyze the circuit using the constant diode equation. I know how to use the iteration method.

Current through the diode = Current through the 5kΩ resistor.


Please help - Any suggestions will be helpful.

Thank you!
 

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  • #2
ally34 said:

Homework Statement



Refer to the figure attached. Let IS = 25 fA and VCC = 10V. What is the total current, the current in the diode, and the current in the 5KΩ resistor? What is VD? Use the iteration technique.


Homework Equations



Ideal Diode Equation: I = Is(e^(Vd/Vt) - 1)
Ohm's Law: V= IR
Thermal Voltage: V = kt/q = 25.9mV



The Attempt at a Solution



Total Current in the circuit = 10 V / 10kΩ = 1mA <--- Why? The 5k resistor and diode are there, too.

We need to find the Vd and Id using the constant voltage model and then use the iteration method using the ideal diode equation to get closer and closer to Vd and Id using iterations.

I am not sure how to analyze the circuit using the constant diode equation. I know how to use the iteration method.

Current through the diode = Current through the 5kΩ resistor. <-- No, that's not true.


Please help - Any suggestions will be helpful.

Thank you!

Why don't you begin by finding the Thevenin equivalent for the the voltage source Vcc and the resistors? This will leave you with a simple series circuit:

attachment.php?attachmentid=43287&stc=1&d=1327933886.gif
 

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1. How do I calculate the current and voltage in a simple diode?

To calculate the current and voltage in a simple diode, you will need to use Ohm's Law. The current can be calculated by dividing the voltage by the resistance. The voltage can be calculated by multiplying the current by the resistance.

2. What is a diode and how does it work?

A diode is a electronic component that allows current to flow in one direction while blocking it in the opposite direction. It works by having a p-n junction, which is a boundary between two different types of semiconductor materials. When a voltage is applied to the diode, it creates an electric field that allows current to flow in one direction.

3. What is the purpose of using a diode in a circuit?

One of the main purposes of using a diode in a circuit is to protect other components from damage. Diodes can also be used to convert alternating current (AC) to direct current (DC) or to regulate voltage levels.

4. What factors affect the current and voltage in a diode?

The current and voltage in a diode can be affected by several factors such as the type of semiconductor material used, the temperature, and the amount of current flowing through the diode. The type of circuit and the voltage being applied can also impact the current and voltage in a diode.

5. What happens if the voltage applied to a diode exceeds its breakdown voltage?

If the voltage applied to a diode exceeds its breakdown voltage, the diode will break down and allow current to flow in the reverse direction. This can cause damage to the diode or other components in the circuit. It is important to ensure that the voltage applied to a diode does not exceed its breakdown voltage to prevent this from happening.

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