Diode Circuit Analysis Problems And Solutions Pdf May 2026

Circuit: Diode forward biased at I = 1 mA.

Question: Estimate change in forward voltage with temperature (approximate slope).

Solution:

Two identical 0.7V diodes in parallel, a 1kΩ resistor, and a 5V source. diode circuit analysis problems and solutions pdf

Assumption: Both conduct, but current divides. However, if perfectly matched, current splits equally. Often only one conducts if small differences exist.

KVL: 5 – I*1k – 0.7 = 0 → I = 4.3mA total. If two diodes share equally, each gets 2.15mA.

Let's apply the Constant Voltage Drop Model to a standard problem. Circuit: Diode forward biased at I = 1 mA

Problem: Calculate the current ($I$) flowing through the circuit and the output voltage ($V_out$) across the resistor.

Solution Step 1: Assume the Diode State Since the source voltage is positive and higher than the knee voltage, we assume the diode is Forward Biased.

Solution Step 2: Replace Diode with Model Using the CVD model, replace the diode symbol with a battery of $0.7V$. Let's apply the Constant Voltage Drop Model to

Solution Step 3: Apply Kirchhoff’s Voltage Law (KVL) The KVL equation for the loop becomes: $$V_source - V_D - I \cdot R = 0$$

Solution Step 4: Solve for Current ($I$) Rearrange the equation: $$I = \fracV_source - V_DR$$

Substitute the values: $$I = \frac10V - 0.7V1000\Omega$$ $$I = \frac9.3V1000\Omega$$ $$I = 9.3 mA$$

Solution Step 5: Calculate Output Voltage ($V_out$) The output voltage is the voltage across the resistor. $$V_out = I \cdot R$$ $$V_out = 9.3mA \cdot 1k\Omega = 9.3V$$ (Alternatively, $V_out = V_source - V_D$)