Collector Feedback Bias-Basic Electronics Biasing-Lecture Slides, Slides of Basic Electronics

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Basic Electronic Engineering

Lecture 16

Collector Feedback Bias

• Stability of a bias circuit can be improved

by introducing a feedback path from

collector to base

• The sensitivity to changes in beta and

temperature is less compared to fixed

bias and emitter bias circuits

Collector-Emitter Loop

Approximating

Analysis of Collector Feedback Bias

Circuit

VCC IC RC VCE I RE E

IC I E IC

VCC  I RC C  VCE I RC E

V CE  VCC  IC (^)  RC  RE 

Collector Feedback Bias

• Example

Find ICQ and VCEQ for the following circuit

Common Collector Configuration

Emitter-Base Loop

Applying KVL

VEE  I RB B  VBE  I RE E

I E     1 IB

V EE  I RB B  VBE     1 I RB E

EE BE B B E

V V

I

R  R

Common Collector Configuration

Collector-Emitter Loop

Applying KVL

VEE  VCE  I RE E

VCE  VEE  I RE E

Common Base Configuration

• For common base configuration the input signal is connected

to the emitter and base is at ground potential

• Base is common between the input terminal(emitter) and

output terminal(collector)

Common Base Configuration

Base-Emitter Loop

• Applying KVL in the loop

VEE  I RE E VBE

EE BE E E

V V

I

R

Common Base Configuration

Collector-Base Loop

• Applying KVL in the loop

VCC  VCB  I RC C

VCB  VCC I RC C

Common Base Configuration

Find IE IB VCE and VCB for the following circuit