The single stage common emitter amplifier is the most widely used BJT amplifier configuration in analog electronics. The single stage common emitter amplifier provides both voltage and current gain, making it the most preferred choice among all BJT amplifier configurations. Because of its simplicity and performance, the single stage common emitter amplifier acts as the foundation for multistage amplifiers and embedded analog front-end circuits.
The single stage common emitter amplifier is a core topic for VTU examinations, core electronics interviews, and practical hardware design. At IIES, students learn the single stage common emitter amplifier in depth as part of the best embedded course in Bangalore, focusing on both theory and real-time applications..
Single stage common emitter amplifier is a fundamental BJT configuration that provides high voltage gain with phase inversion between input and output. By applying proper DC biasing, small signal analysis, and frequency response considerations, the CE amplifier delivers stable and predictable performance.This configuration remains essential for analog circuit design, signal amplification, and embedded electronics applications.
These CE amplifier characteristics make the single stage common emitter amplifier suitable for audio, sensor, and RF circuits.
The CE amplifier circuit diagram of a single stage common emitter amplifier shows the emitter terminal common to both input and output.
This common emitter amplifier configuration uses a voltage divider bias network, coupling capacitors, and an emitter bypass capacitor to improve gain and stability.
Understanding the CE amplifier circuit diagram is essential to analyze the single stage common emitter amplifier performance.
| Component | Role | Typical Value Range |
|---|---|---|
| R1, R2 | Voltage divider | 10kΩ – 100kΩ |
| Rc | Collector resistor | 1kΩ – 10kΩ |
| Re | Emitter resistor | 100Ω – 1kΩ |
| Cin, Cout | Coupling capacitors | 1µF – 10µF |
| Ce | Emitter bypass capacitor | 10µF – 100µF |
The emitter bypass capacitor directly affects the voltage gain of CE amplifier in a single stage common emitter amplifier.
Vb = Vcc × (R2 / (R1 + R2))
Ve = Vb − Vbe ≈ Vb − 0.7 V
Ie = Ve / Re ≈ Ic
Vce = Vcc − Ic (Rc + Re)
The voltage divider bias CE amplifier method ensures thermal stability and a stable Q-point for the
single stage common emitter amplifier.
Stability Factor (S):
S = (1 + β) / [1 + β (Re / (Re + Rth))]
where,
Rth = R1 || R2
Lower values of S indicate better stability of the single stage common emitter amplifier.
Vcc = 12 V
R1 = 68 kΩ
R2 = 12 kΩ
Re = 1 kΩ
β = 100
Vb = 12 × (12 / (68 + 12)) = 1.8 V
Ve = 1.8 − 0.7 = 1.1 V
Ie = 1.1 / 1kΩ = 1.1 mA ≈ Ic
Vce = 12 − 1.1 mA × (4.7 kΩ + 1 kΩ) = 5.73 V
S ≈ 7.3
| Parameter | Formula | Typical Value |
|---|---|---|
| re | 25 mV / Ie | 5 – 50 Ω |
| gm | Ic / 25 mV | 10 – 100 mS |
| β | ΔIc / ΔIb | 50 – 300 |
| rin | β × re | 500 Ω – 15 kΩ |
Voltage Gain of CE Amplifier
Without Ce:
Av = − Rc / (re + Re)
With Ce:
Av = − Rc / re
Input Impedance of CE Amplifier
Without Ce:
Zin = R1 || R2 || β (re + Re)
With Ce:
Zin = R1 || R2 || β re
Output Impedance of CE Amplifier
Zout ≈ Rc
Low-frequency cutoff (Input):
fL ≈ 1 / [2π Cin (Rs + Zin)]
Low-frequency cutoff (Output):
fL ≈ 1 / [2π Cout (Rc + RL)]
High-frequency cutoff:
fH ≈ 1 / [2π (Rc || RL) Cout]
The Miller effect in CE amplifier limits the high-frequency response of the
single stage common emitter amplifier.
GBW = |Av| × BW
BW = fH − fL
Designing a single stage common emitter amplifier involves selecting Rc, Re, and bias resistors to meet gain, stability, and bandwidth requirements.
This design methodology is emphasized in hands-on labs at IIES, making it ideal for learners pursuing the
best embedded course in Bangalore.
Input: 10 mVpp @ 1 kHz
Output: 1 Vpp inverted sine wave
Midband gain: 40 dB
Low cutoff: ~80 Hz
High cutoff: ~150 kHz
The single stage common emitter amplifier remains the most important BJT amplifier because it offers high voltage gain,
stable biasing, and predictable frequency response.
For VTU students, electronics interviews, and embedded careers, mastering the
single stage common emitter amplifier at IIES provides a strong academic and industry advantage through the
best embedded course in Bangalore.
A single stage common emitter amplifier is a BJT amplifier configuration that provides high voltage gain with phase inversion between input and output.
The common emitter amplifier is widely used because it offers good voltage gain, moderate input and output impedance, and stable performance.
The voltage gain of a CE amplifier is high, typically ranging from 50 to 200, depending on circuit components and biasing.
The emitter bypass capacitor increases AC gain by reducing the effect of emitter resistance for AC signals
CE amplifiers are used in audio amplifiers, sensor interfaces, RF stages, and signal conditioning circuits.