BJT Common-Emitter Amplifier 🎯 Midband Gain, Low-Frequency & High-Frequency Cutoff 👉 FULL DETAILS💡

In this video, we take a detailed look at the frequency response analysis of a BJT Common-Emitter Amplifier using an NPN transistor. The circuit includes four capacitors:

🔹Input coupling capacitor (C1)
🔹Output coupling capacitor (C2)
🔹Emitter bypass capacitor (CE)
🔹Load capacitor (CL)

💡 To structure the discussion clearly, the content is divided into four main parts:

▶️ PART 1 – DC Analysis:
We calculate all required DC operating points (bias voltages and currents), which are essential for building the small-signal model in the next step.

▶️ PART 2 – AC Analysis & Midband Voltage Gain:
We develop the small-signal model and calculate the midband voltage gain of the amplifier using standard AC analysis techniques.

▶️ PART 3 – Low-Frequency Cutoff (SCTC Method):
Using the Short-Circuit Time Constant (SCTC) method, we evaluate the lower cutoff frequency by analyzing the time constants associated with C1, C2, and CE.

▶️ PART 4 – High-Frequency Cutoff (OCTC Method):
We apply the Open-Circuit Time Constant (OCTC) method to determine the upper cutoff frequency, considering the parasitic capacitances of the BJT (Cπ and Cu) and the load capacitor CL.

👉 What You'll Learn:
✅ How to determine the DC values and how they affect the AC response
✅ How to model the amplifier using the small-signal equivalent circuit
✅ How to calculate the midband voltage gain of the amplifier
✅ How to use the Short-Circuit Time Constant (SCTC) method
✅ How to use the Open-Circuit Time Constant (OCTC) method
✅ How the output coupling capacitor introduces a highpass filter behavior
✅ How to determine the cutoff (corner) frequencies (lower and upper cutoff)

🎯 Step-by-Step Analysis:
🔹 DC Analysis
🔹 AC Small-Signal Model – Replace the BJT with its equivalent circuit
🔹 Frequency Response – Effect of the capacitors on voltage gain and cutoff frequency
🔹 Voltage Gain – Calculate using small-signal parameters
🔹 Lower Cutoff Frequency Calculation – Based on Short-Circuit Time Constant (SCTC) Method
🔹 Upper Cutoff Frequency Calculation – Based on Open-Circuit Time Constant (OCTC) Method

🧪 Verification:
All calculations are verified using TINA-TI SPICE simulations for accuracy and practical insights.

💡 Perfect for:
Engineering students, electronics hobbyists, and anyone learning analog circuit design.

🎯 Outline:
⏩ 00:00:00 Introduction
⏩ 00:00:27 Outline Discussion
⏩ 00:00:51 PART 1: DC Analysis Calculations
⏩ 00:06:05 PART 1: DC Simulation Results TINA-TI SPICE
⏩ 00:07:35 PART 2: Small-Signal Model for Voltage Gain
⏩ 00:12:26 PART 3: AC Analysis for Lower Cutoff
⏩ 00:20:09 PART 4: AC Analysis for Upper Cutoff
⏩ 00:41:50 Bode Plot Simulation Results TINA-TI SPICE

👉 Playlist Transistor Circuits:    • Transistor Circuits  
👉 Playlist Analog Electronics:    • Analog Electronics  

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